Sample records for radar antenna comparison

  1. Comparison of the impedance cardiogram with continuous wave radar using body-contact antennas.

    PubMed

    Buxi, Dilpreet; Dugar, Rahul; Redoute, Jean-Michel; Yuce, Mehmet Rasit

    2017-07-01

    This paper describes a continuous wave (CW) radar system with body-contact antennas and basic signal processing. The goal is to assess the signals' reproducibility across different subjects as well as a respiration cycle. Radar signals using body-contact antennas with a carrier frequency of 868 MHz are used to acquire the cardiac activity at the sternum. The radar I and Q channel signals are combined to form their magnitude. Signals are collected from six healthy males during paced breathing conditions. The electrocardiogram (ECG) and impedance cardiogram (ICG) signals are acquired simultaneously as reference. The chosen feature in the radar signal is the maximum of its second derivative, which is closest to the ICG B-point. The median and mean absolute errors in pre-ejection period (PEP) in milliseconds between the ICG's B-point and chosen feature in the radar signal range from -6-119.7 ms and 7.8-62.3 ms for all subjects. The results indicate that a reproducible radar signal is obtained from all six subjects. More work is needed on understanding the origin of the radar signals using ultrasound as a comparison.

  2. Initial results from SKiYMET meteor radar at Thumba (8.5°N, 77°E): 1. Comparison of wind measurements with MF spaced antenna radar system

    NASA Astrophysics Data System (ADS)

    Kumar, Karanam Kishore; Ramkumar, Geetha; Shelbi, S. T.

    2007-12-01

    In the present communication, initial results from the allSKy interferometric METeor (SKiYMET) radar installed at Thumba (8.5°N, 77°E) are presented. The meteor radar system provides hourly zonal and meridional winds in the mesosphere lower thermosphere (MLT) region. The meteor radar measured zonal and meridional winds are compared with nearby MF radar at Tirunalveli (8.7°N, 77.8°E). The present study provided an opportunity to compare the winds measured by the two different techniques, namely, interferometry and spaced antenna drift methods. Simultaneous wind measurements for a total number of 273 days during September 2004 to May 2005 are compared. The comparison showed a very good agreement between these two techniques in the height region 82-90 km and poor agreement above this height region. In general, the zonal winds compare very well as compared to the meridional winds. The observed discrepancies in the wind comparison above 90 km are discussed in the light of existing limitations of both the radars. The detailed analysis revealed the consistency of the measured winds by both the techniques. However, the discrepancies are observed at higher altitudes and are attributed to the contamination of MF radar neutral wind measurements with Equatorial Electro Jet (EEJ) induced inospheric drifts rather than the limitations of the spaced antenna technique. The comparison of diurnal variation of zonal winds above 90 km measured by both the radars is in reasonably good agreement in the absence of EEJ (during local nighttime). It is also been noted that the difference in the zonal wind measurements by both the radars is directly related to the strength of EEJ, which is a noteworthy result from the present study.

  3. Foliage Penetration Radar: History and Developed Technology

    DTIC Science & Technology

    1974-05-01

    26 M-FOPEN Antenna Mast with Delta- Loop Antennas 44 27 AB-577/GRC Antenna Mast Used to Extend the Range of the Man-Portable Radar 45 28 Base Station...Ground Control Unit 47 29 Base Station Tov.er with Delta- Loop Antennas 48 30 Test Configuration for the AN/fPS-5 Comparison Test and Tactical Exercise...00 UNDERGROW 1H TRANSMTTTING ANTENN . HEIG IT: 2 m 5(6- 13 m ) \\\\7 \\ Seo \\................ $A1 U, -< o\\ 31 I~ ~ A ,M\\;’ I10 31 ’•...GJ, FIGURE 3

  4. Comparison of sigma(o) obtained from the conventional definition with sigma(o) appearing in the radar equation for randomly rough surfaces

    NASA Technical Reports Server (NTRS)

    Levine, D. M.

    1981-01-01

    A comparison is made of the radar cross section of rough surface calculated in one case from the conventional definition and obtained in the second case directly from the radar equation. The validity of the conventional definition representing the cross section appearing in the radar equation is determined. The analysis is executed in the special case of perfectly conducting, randomly corrugated surfaces in the physical optics limit. The radar equation is obtained by solving for the radiation scattered from an arbitrary source back to a colocated antenna. The signal out of the receiving antenna is computed from this solution and the result put into a form recognizeable as the radar equation. The conventional definition is obtained by solving a similar problem but for backscatter from an incident planewave. It is shown that these tow forms for sigma are the same if the observer is far enough from the surface.

  5. A convenient technique for polarimetric calibration of single-antenna radar systems

    NASA Technical Reports Server (NTRS)

    Sarabandi, Kamal; Ulaby, Fawwaz T.

    1990-01-01

    A practical technique for calibrating single-antenna polarimetric radar systems is introduced. This technique requires only a single calibration target such as a conducting sphere or a trihedral corner reflector to calibrate the radar system, both in amplitude and phase, for all linear polarization configurations. By using a metal sphere, which is orientation independent, error in calibration measurement is minimized while simultaneously calibrating the crosspolarization channels. The antenna system and two orthogonal channels (in free space) are modeled as a four-port passive network. Upon using the reciprocity relations for the passive network and assuming the crosscoupling terms of the antenna to be equal, the crosstalk factors of the antenna system and the transmit and receive channel imbalances can be obtained from measurement of the backscatter from a metal sphere. For an X-band radar system with crosspolarization isolation of 25 dB, comparison of values measured for a sphere and a cylinder with theoretical values shows agreement within 0.4 dB in magnitude and 5 deg in phase. An effective polarization isolation of 50 dB is achieved using this calibration technique.

  6. Calibration of polarimetric radar systems with good polarization isolation

    NASA Technical Reports Server (NTRS)

    Sarabandi, Kamal; Ulaby, Fawwaz T.; Tassoudji, M. Ali

    1990-01-01

    A practical technique is proposed for calibrating single-antenna polarimetric radar systems using a metal sphere plus any second target with a strong cross-polarized radar cross section. This technique assumes perfect isolation between antenna ports. It is shown that all magnitudes and phases (relative to one of the like-polarized linear polarization configurations) of the radar transfer function can be calibrated without knowledge of the scattering matrix of the second target. Comparison of the values measured (using this calibration technique) for a tilted cylinder at X-band with theoretical values shows agreement within + or - 0.3 dB in magnitude and + or - 5 degrees in phase. The radar overall cross-polarization isolation was 25 dB. The technique is particularly useful for calibrating a radar under field conditions, because it does not require the careful alignment of calibration targets.

  7. Attitude errors arising from antenna/satellite altitude errors - Recognition and reduction

    NASA Technical Reports Server (NTRS)

    Godbey, T. W.; Lambert, R.; Milano, G.

    1972-01-01

    A review is presented of the three basic types of pulsed radar altimeter designs, as well as the source and form of altitude bias errors arising from antenna/satellite attitude errors in each design type. A quantitative comparison of the three systems was also made.

  8. Multifrequency synthetic aperture radar antenna comparison study. [for remote sensing

    NASA Technical Reports Server (NTRS)

    Blevins, B. A.

    1983-01-01

    Three multifrequency, dual polarization SAR antenna designs are reviewed. The SAR antenna design specifications were for a "straw man' SAR which would approximate the requirements for projected shuttle-based SAR's. Therefore, the physical dimensions were constrained to be compatible with the space shuttle. The electrical specifications were similar to those of SIR-A and SIR-B with the addition of dual polarization and the addition of C and X band operation. Early in the antenna design considerations, three candidate technologies emerged as having promise. They were: (1) microstrip patch planar array antennas, (2) slotted waveguide planar array antennas, and (3) open-ended waveguide planar array antennas.

  9. Design of Vivaldi Microstrip Antenna for Ultra-Wideband Radar Applications

    NASA Astrophysics Data System (ADS)

    Perdana, M. Y.; Hariyadi, T.; Wahyu, Y.

    2017-03-01

    The development of radar technology has an important role in several fields such as aviation, civil engineering, geology, and medicine. One of the essential components of the radar system is the antenna. The bandwidth can specify the resolution of the radar. The wider the bandwidth, the higher the resolution of radar. For Ground penetrating radar (GPR) or medical applications need with a high-resolution radar so it needs an antenna with a wide bandwidth. In addition, for the radar application is required antenna with directional radiation pattern. So, we need an antenna with wide bandwidth and directional radiation pattern. One of antenna that has meet with these characteristics is vivaldi antenna. In previous research, has designed several vivaldi microstrip antenna for ultra-wideband radar applications which has a working frequency of 3.1 to 10.7 GHz. However, these studies there is still a shortage of one of them is the radiation pattern from lowest to highest frequency radiation pattern is not uniform in the sense that not all directional. Besides the antenna material used is also not easily available and the price is not cheap. This paper will discuss the design of a vivaldi microstrip antenna which has a wide bandwidth with directional radiation pattern works on 3.1 to 10.7 GHz and using cheaper substrate. Substrates used for vivaldi microstrip antenna vivaldi is FR4 with a dielectric constant of 4.3 and a thickness of 1.6 mm. Based on the simulation results we obtained that the antenna design has frequency range 3.1-10.7 GHz for return loss less than -10 dB with a directional radiation pattern. This antenna gain is 4.8 to 8 dBi with the largest dimension is 50 mm x 40 mm.

  10. Detail of antenna array, looking northnorthwest OvertheHorizon Backscatter Radar ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Detail of antenna array, looking north-northwest - Over-the-Horizon Backscatter Radar Network, Tulelake Radar Site Receive Sector Five Antenna Array, Unnamed Road West of Double Head Road, Tulelake, Siskiyou County, CA

  11. Study to investigate and evaluate means of optimizing the radar function for the space shuttle. [(pulse radar)

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Results are discussed of a study to define a radar and antenna system which best suits the space shuttle rendezvous requirements. Topics considered include antenna characteristics and antenna size tradeoffs, fundamental sources of measurement errors inherent in the target itself, backscattering crosssection models of the target and three basic candidate radar types. Antennas up to 1.5 meters in diameter are within specified installation constraints, however, a 1 meter diameter paraboloid and a folding, four slot backfeed on a two gimbal mount implemented for a spiral acquisition scan is recommended. The candidate radar types discussed are: (1) noncoherent pulse radar (2) coherent pulse radar and (3) pulse Doppler radar with linear FM ranging. The radar type recommended is a pulse Doppler with linear FM ranging. Block diagrams of each radar system are shown.

  12. An estimation of the electrical characteristics of planetary shallow subsurfaces with TAPIR antennas

    NASA Astrophysics Data System (ADS)

    Le Gall, A.; Reineix, A.; Ciarletti, V.; Berthelier, J. J.; Ney, R.; Dolon, F.; Corbel, C.

    2006-06-01

    In the frame of the NETLANDER program, we have developed the Terrestrial And Planetary Investigation by Radar (TAPIR) imaging ground-penetrating radar to explore the Martian subsurface at kilometric depths and search for potential water reservoirs. This instrument which is to operate from a fixed lander is based on a new concept which allows one to image the various underground reflectors by determining the direction of propagation of the reflected waves. The electrical parameters of the shallow subsurface (permittivity and conductivity) need to be known to correctly determine the propagation vector. In addition, these electrical parameters can bring valuable information on the nature of the materials close to the surface. The electric antennas of the radar are 35 m long resistively loaded monopoles that are laid on the ground. Their impedance, measured during a dedicated mode of operation of the radar, depends on the electrical parameters of soil and is used to infer the permittivity and conductivity of the upper layer of the subsurface. This paper presents an experimental and theoretical study of the antenna impedance and shows that the frequency profile of the antenna complex impedance can be used to retrieve the geoelectrical characteristics of the soil. Comparisons between a numerical modeling and in situ measurements have been successfully carried over various soils, showing a very good agreement.

  13. Portable receiver for radar detection

    DOEpatents

    Lopes, Christopher D.; Kotter, Dale K.

    2008-10-14

    Various embodiments are described relating to a portable antenna-equipped device for multi-band radar detection. The detection device includes a plurality of antennas on a flexible substrate, a detection-and-control circuit, an indicator and a power source. The antenna may include one or more planar lithographic antennas that may be fabricated on a thin-film substrate. Each antenna may be tuned to a different selection frequency or band. The antennas may include a bolometer for radar detection. Each antenna may include a frequency selective surface for tuning to the selection frequency.

  14. Measurement and calibration of differential Mueller matrix of distributed targets

    NASA Technical Reports Server (NTRS)

    Sarabandi, Kamal; Oh, Yisok; Ulaby, Fawwaz T.

    1992-01-01

    A rigorous method for calibrating polarimetric backscatter measurements of distributed targets is presented. By characterizing the radar distortions over the entire mainlobe of the antenna, the differential Mueller matrix is derived from the measured scattering matrices with a high degree of accuracy. It is shown that the radar distortions can be determined by measuring the polarimetric response of a metallic sphere over the main lobe of the antenna. Comparison of results obtained with the new algorithm with the results derived from the old calibration method show that the discrepancy between the two methods is less than 1 dB for the backscattering coefficients. The discrepancy is more drastic for the phase-difference statistics, indicating that removal of the radar distortions from the cross products of the scattering matrix elements cannot be accomplished with the traditional calibration methods.

  15. View north of the antenna array, note the communications antenna ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View north of the antenna array, note the communications antenna in the middleground - Over-the-Horizon Backscatter Radar Network, Christmas Valley Radar Site Transmit Sector Four Antenna Array, On unnamed road west of Lost Forest Road, Christmas Valley, Lake County, OR

  16. A Dual Polarization, Active, Microstrip Antenna for an Orbital Imaging Radar System Operating at L-Band

    NASA Technical Reports Server (NTRS)

    Kelly, Kenneth C.; Huang, John

    1999-01-01

    A highly successful Earth orbiting synthetic antenna aperture radar (SAR) system, known as the SIR-C mission, was carried into orbit in 1994 on a U.S. Shuttle (Space Transportation System) mission. The radar system was mounted in the cargo bay with no need to fold, or in any other way reduce the size of the antennas for launch. Weight and size were not limited for the L-Band, C-Band, and X-Band radar systems of the SIR-C radar imaging mission; the set of antennas weighed 10,500 kg, the L-Band antenna having the major share of the weight. This paper treats designing an L-Band antenna functionally similar to that used for SIR-C, but at a fraction of the cost and at a weight in the order of 250 kg. Further, the antenna must be folded to fit into the small payload shroud of low cost booster rocket systems. Over 31 square meters of antenna area is required. This low weight, foldable, electronic scanning antenna is for the proposed LightSAR radar system which is to be placed in Earth orbit on a small, dedicated space craft at the lowest possible cost for an efficient L-Band radar imaging system. This LightSAR spacecraft radar is to be continuously available for at least five operational years, and have the ability to map or repeat-map any area on earth within a few days of any request. A microstrip patch array, with microstrip transmission lines heavily employed in the aperture and in the corporate feed network, was chosen as the low cost approach for this active dual-polarization, 80 MHz (6.4%) bandwidth antenna design.

  17. A Dual Polarization, Active, Microstrip Antenna for an Orbital Imaging Radar System Operating at L-Band

    NASA Technical Reports Server (NTRS)

    Kelly, Kenneth C.; Huang, John

    2000-01-01

    A highly successful Earth orbiting synthetic antenna aperture radar (SAR) system, known as the SIR-C mission, was carried into orbit in 1994 on a U.S. Shuttle (Space Transportation System) mission. The radar system was mounted in the cargo bay with no need to fold, or in any other way reduce the size of the antennas for launch. Weight and size were not limited for the L-Band, C-Band, and X-Band radar systems of the SIR-C radar imaging mission; the set of antennas weighed 10,500 kg, the L-Band antenna having the major share of the weight. This paper treats designing an L-Band antenna functionally similar to that used for SIR-C, but at a fraction of the cost and at a weight in the order of 250 kg. Further, the antenna must be folded to fit into the small payload shroud of low cost booster rocket systems. Over 31 square meters of antenna area is required. This low weight, foldable, electronic scanning antenna is for the proposed LightSAR radar system which is to be placed in Earth orbit on a small, dedicated space craft at the lowest possible cost for an efficient L- Band radar imaging system. This LightSAR spacecraft radar is to be continuously available for at least five operational years, and have the ability to map or repeat-map any area on earth within a few days of any request. A microstrip patch array, with microstrip transmission lines heavily employed in the aperture and in the corporate feed network, was chosen as the low cost approach for this active dual-polarization, 80 MHz (6.4%) bandwidth antenna design.

  18. From Vision to Reality: 50 Years of Phased Array Development

    DTIC Science & Technology

    2016-09-30

    This paper cites the most prominent U.S.-deployed phased array radars as viewed by one phased-array radar advocate. Key words: radar, antenna array...phased array, phased array radar, radar antennas , array I. INTRODUCTION I welcome the opportunity to talk with today’s phased array engineers and...their test site in Fullerton, CA in the mid-1960s and was impressed by the size of the antennas . Eight apertures were deployed on each ship to

  19. Monitoring of the MU radar antenna pattern by Satellite Ohzora (EXOS-C)

    NASA Technical Reports Server (NTRS)

    Sato, T.; Inooka, Y.; Fukao, S.; Kato, S.

    1986-01-01

    As the first attempt among MST (mesosphere stratosphere troposphere) type radars, the MU (middle and upper atmosphere) radar features an active phased array system. Unlike the conventional large VHF radars, in which output power of a large vacuum tube is distributed to individual antenna elements, each of 475 solid state power amplifier feeds each antenna element. This system configuration enables very fast beam steering as well as various flexible operations by dividing the antenna into independent subarrays, because phase shift and signal division/combination are performed at a low signal level using electronic devices under control of a computer network. The antenna beam can be switched within 10 microsec to any direction within the zenith angle of 30 deg. Since a precise phase alignment of each element is crucial to realize the excellent performance of this system, careful calibration of the output phase of each power amplifier and antenna element was carried out. Among various aircraft which may be used for this purpose artificial satellites have an advantage of being able to make a long term monitoring with the same system. An antenna pattern monitoring system for the MU radar was developed using the scientific satellite OHZORA (EXOS-C). A receiver named MUM (MU radar antenna Monitor) on board the satellite measures a CW signal of 100 to 400 watts transmitted from the MU radar. The principle of the measurement and results are discussed.

  20. Automated target recognition using passive radar and coordinated flight models

    NASA Astrophysics Data System (ADS)

    Ehrman, Lisa M.; Lanterman, Aaron D.

    2003-09-01

    Rather than emitting pulses, passive radar systems rely on illuminators of opportunity, such as TV and FM radio, to illuminate potential targets. These systems are particularly attractive since they allow receivers to operate without emitting energy, rendering them covert. Many existing passive radar systems estimate the locations and velocities of targets. This paper focuses on adding an automatic target recognition (ATR) component to such systems. Our approach to ATR compares the Radar Cross Section (RCS) of targets detected by a passive radar system to the simulated RCS of known targets. To make the comparison as accurate as possible, the received signal model accounts for aircraft position and orientation, propagation losses, and antenna gain patterns. The estimated positions become inputs for an algorithm that uses a coordinated flight model to compute probable aircraft orientation angles. The Fast Illinois Solver Code (FISC) simulates the RCS of several potential target classes as they execute the estimated maneuvers. The RCS is then scaled by the Advanced Refractive Effects Prediction System (AREPS) code to account for propagation losses that occur as functions of altitude and range. The Numerical Electromagnetic Code (NEC2) computes the antenna gain pattern, so that the RCS can be further scaled. The Rician model compares the RCS of the illuminated aircraft with those of the potential targets. This comparison results in target identification.

  1. ATCRBS Antenna Modification Kit

    DOT National Transportation Integrated Search

    1976-06-01

    The report describes the design, fabrication and test results of an improved ATCRBS (Air Traffic Control Radar Beacon System) array antenna for mounting on the reflector of an ASR radar antenna. The antenna consists of a 4-foot high by 26-foot wide a...

  2. General view looking northnorthwest at antenna array. Troposhperic scatter communications ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    General view looking north-northwest at antenna array. Troposhperic scatter communications antennas are seen at far left, transmitter building is in center, antenna array at right - Over-the-Horizon Backscatter Radar Network, Moscow Radar Site Transmit Sector One Antenna Array, At the end of Steam Road, Moscow, Somerset County, ME

  3. ATCRBS Antenna Modification Kit - Phase I

    DOT National Transportation Integrated Search

    1973-06-01

    The report describes the design, fabrication and test results of an improved ATCRBS (Air Traffic Control Radar Beacon System) array antenna for mounting on the reflector of an ASR radar antenna. The antenna consists of a 4-foot high by 26-foot wide a...

  4. A new technique to characterize foliage attenuation using passive radar in the L-band

    NASA Astrophysics Data System (ADS)

    Lesturgie, Marc; Thirion-Lefèvre, Laetitia; Saillant, Stéphane; Dorey, Philippe

    2016-11-01

    The goal of the experiment proposed in this paper is to give rapidly and with a limited equipment the attenuation level in the L-band for various elevation angles, between 20 and 70 degrees. The original principle is to use the L-band signal transmitted from an airport radar. The signal backscattered by a plane flying over the forest next to the airport is received on many antennas: some are over the canopy; others are on the ground under the foliage. The direct path signal transmitted by the airport radar is received by the antennas located above the forest. This signal is used to synchronize the temporal signals by detecting the waveform of the transmitting pulses. The signal backscattered by the plane is received by two H and V polar antennas located over the forest and by two other antennas placed under the foliage. The signals received by these antennas are digitized and processed to extract the plots of the opportunistic targets that approach the airport. The magnitudes of each plane echo are measured on each channel, and a comparison of the level of signal is made between the antenna above and under the forest. The ratio of magnitude between the two measurements on each polarization component gives the absorption factor of the foliage at the place of experiment. The position of the plane is given by an ADS-B receiver. For each elevation position of the antennas, the pattern of the chosen target will describe all the angles of arrival. This experiment has been deployed on two forested sites near an airport in South-East Asia. xml:lang="fr"

  5. Design and fabrication of a microstrip patch antenna with a low radar cross section in the X-band

    NASA Astrophysics Data System (ADS)

    Jang, Hong-Kyu; Lee, Won-Jun; Kim, Chun-Gon

    2011-01-01

    In this study, the authors developed a radar absorbing method to reduce the antenna radar cross section (RCS) without any loss of antenna performance. The new method was based upon an electromagnetic bandgap (EBG) absorber using conducting polymer (CP). First, a microstrip patch antenna was made by using a copper film and glass/epoxy composite materials, which are typically used for load-bearing structures, such as aircraft and other vehicles. Then, CP EBG patterns were also designed that had a 90% electromagnetic (EM) wave absorbing performance within the X-band (8.2-12.4 GHz). Finally, the CP EBG patterns were printed on the top surface of the microstrip patch antenna. The measured radar absorbing performance of the fabricated patch antenna showed that the frontal RCS of the antenna declined by nearly 95% at 10 GHz frequency while the CP EBG patterns had almost no effect on the antenna's performance.

  6. Microwave emissions from police radar.

    PubMed

    Fink, J M; Wagner, J P; Congleton, J J; Rock, J C

    1999-01-01

    This study evaluated police officers' exposures to microwaves emitted by traffic radar units. Exposure measurements were taken at approximated ocular and testicular levels of officers seated in patrol vehicles. Comparisons were made of the radar manufacturers' published maximum power density specifications and actual measured power densities taken at the antenna faces of those units. Four speed-enforcement agencies and one transportation research institute provided 54 radar units for evaluation; 17 different models, encompassing 4 frequency bands and 3 antenna configurations, were included. Four of the 986 measurements taken exceeded the 5 mW/cm2 limit accepted by the International Radiation Protection Association and the National Council on Radiation Protection and Measurement, though none exceeded the American Conference of Governmental Industrial Hygienists, American National Standards Institute, Institute of Electrical and Electronic Engineers, or Occupational Safety and Health Administration standard of 10 mW/cm2. The four high measurements were maximum power density readings taken directly in front of the radar. Of the 812 measurements taken at the officers' seated ocular and testicular positions, none exceeded 0.04 mW/cm2; the highest of these (0.034 mW/cm2) was less than 1% of the most conservative current safety standards. High exposures in the limited region directly in front of the radar aperture are easily avoided with proper training. Results of this study indicate that police officer exposure to microwave radiation is apparently minimal. However, because of uncertainty in the medical and scientific communities concerning nonionizing radiation, it is recommended that law enforcement agencies implement a policy of prudent avoidance, including purchasing units with the lowest published maximum power densities, purchasing dash/rear deck-mounted units with antennae mounted outside the patrol vehicle, and training police officers to use the "stand-by" mode when not actually using radar.

  7. Detail view looking eastnortheast at elements of antenna array ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Detail view looking east-northeast at elements of antenna array - Over-the-Horizon Backscatter Radar Network, Moscow Radar Site Transmit Sector One Antenna Array, At the end of Steam Road, Moscow, Somerset County, ME

  8. General view looking northnortheast at antenna array OvertheHorizon Backscatter ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    General view looking north-northeast at antenna array - Over-the-Horizon Backscatter Radar Network, Moscow Radar Site Transmit Sector Two Antenna Array, At the end of Steam Road, Moscow, Somerset County, ME

  9. General view looking northnortheast at antenna array OvertheHorizon Backscatter ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    General view looking north-northeast at antenna array - Over-the-Horizon Backscatter Radar Network, Moscow Radar Site Transmit Sector One Antenna Array, At the end of Steam Road, Moscow, Somerset County, ME

  10. General view of Antenna Array, looking west OvertheHorizon Backscatter ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    General view of Antenna Array, looking west - Over-the-Horizon Backscatter Radar Network, Tulelake Radar Site Receive Sector Six Antenna Array, Unnamed Road West of Double Head Road, Tulelake, Siskiyou County, CA

  11. Detail of antenna tower structure, looking northnorthwest OvertheHorizon Backscatter ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Detail of antenna tower structure, looking north-northwest - Over-the-Horizon Backscatter Radar Network, Tulelake Radar Site Receive Sector Five Antenna Array, Unnamed Road West of Double Head Road, Tulelake, Siskiyou County, CA

  12. General view of Sector Four Compound, looking north. Antenna Array ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    General view of Sector Four Compound, looking north. Antenna Array is in background, behind Communications Antennas, Receiver Building, and Water Storage Tank - Over-the-Horizon Backscatter Radar Network, Tulelake Radar Site Receive Sector Four Antenna Array, Unnamed Road West of Double Head Road, Tulelake, Siskiyou County, CA

  13. Radiation pattern of a borehole radar antenna

    USGS Publications Warehouse

    Ellefsen, K.J.; Wright, D.L.

    2002-01-01

    To understand better how a borehole antenna radiates radar waves into a formation, this phenomenon is simulated numerically using the finite-difference, time-domain method. The simulations are of two different antenna models that include features like a driving point fed by a coaxial cable, resistive loading of the antenna, and a water-filled borehole. For each model, traces are calculated in the far-field region, and then, from these traces, radiation patterns are calculated. The radiation patterns show that the amplitude of the radar wave is strongly affected by its frequency, its propagation direction, and the resistive loading of the antenna.

  14. General view of Antenna Array and building complex, looking northeast ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    General view of Antenna Array and building complex, looking northeast - Over-the-Horizon Backscatter Radar Network, Tulelake Radar Site Receive Sector Six Antenna Array, Unnamed Road West of Double Head Road, Tulelake, Siskiyou County, CA

  15. General view of Antenna Array and building complex, looking southwest ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    General view of Antenna Array and building complex, looking southwest - Over-the-Horizon Backscatter Radar Network, Tulelake Radar Site Receive Sector Six Antenna Array, Unnamed Road West of Double Head Road, Tulelake, Siskiyou County, CA

  16. General view to northnortheast, troposhperic scatter communications antennas to left, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    General view to north-northeast, troposhperic scatter communications antennas to left, receiver building and garage in center, antenna array to right, helipad in foreground. - Over-the-Horizon Backscatter Radar Network, Columbia Falls Radar Site Receive Sector One Communications Antennas, At the end of Shadagee Ridge Road, Columbia Falls, Washington County, ME

  17. Antenna induced range smearing in MST radars

    NASA Technical Reports Server (NTRS)

    Watkins, B. J.; Johnston, P. E.

    1984-01-01

    There is considerable interest in developing stratosphere troposphere (ST) and mesosphere stratosphere troposphere (MST) radars for higher resolution to study small-scale turbulent structures and waves. At present most ST and MST radars have resolutions of 150 meters or larger, and are not able to distinguish the thin (40 - 100 m) turbulent layers that are known to occur in the troposphere and stratosphere, and possibly in the mesosphere. However the antenna beam width and sidelobe level become important considerations for radars with superior height resolution. The objective of this paper is to point out that for radars with range resolutions of about 150 meters or less, there may be significant range smearing of the signals from mesospheric altitudes due to the finite beam width of the radar antenna. At both stratospheric and mesospheric heights the antenna sidelobe level for lear equally spaced phased arrays may also produce range aliased signals. To illustrate this effect the range smearing functions for two vertically directed antennas have been calculated, (1) an array of 32 coaxial-collinear strings each with 48 elements that simulates the vertical beam of the Poker Flat, Glaska, MST radar; and (2) a similar, but smaller, array of 16 coaxial-collinear strings each with 24 elements.

  18. View to the eastnortheast of the Sounder Antenna OvertheHorizon ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View to the east-northeast of the Sounder Antenna - Over-the-Horizon Backscatter Radar Network, Christmas Valley Radar Site Transmit Sector Five Sounder Antennas, On unnamed road west of Lost Forest Road, Christmas Valley, Lake County, OR

  19. View to the northeast of the antenna array OvertheHorizon ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View to the northeast of the antenna array - Over-the-Horizon Backscatter Radar Network, Christmas Valley Radar Site Transmit Sector Four Antenna Array, On unnamed road west of Lost Forest Road, Christmas Valley, Lake County, OR

  20. View to the eastnortheast of the Antenna Array OvertheHorizon ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View to the east-northeast of the Antenna Array - Over-the-Horizon Backscatter Radar Network, Christmas Valley Radar Site Transmit Sector Six Antenna Array, On unnamed road west of Lost Forest Road, Christmas Valley, Lake County, OR

  1. General view to the south of the antenna array ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    General view to the south of the antenna array - Over-the-Horizon Backscatter Radar Network, Christmas Valley Radar Site Transmit Sector Five Antenna Array, On unnamed road west of Lost Forest Road, Christmas Valley, Lake County, OR

  2. Detail view to the east of the Antenna Array ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Detail view to the east of the Antenna Array - Over-the-Horizon Backscatter Radar Network, Christmas Valley Radar Site Transmit Sector Six Antenna Array, On unnamed road west of Lost Forest Road, Christmas Valley, Lake County, OR

  3. View to the east of the Antenna Array OvertheHorizon ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View to the east of the Antenna Array - Over-the-Horizon Backscatter Radar Network, Christmas Valley Radar Site Transmit Sector Six Antenna Array, On unnamed road west of Lost Forest Road, Christmas Valley, Lake County, OR

  4. Oblique view to the northwest of the Antenna Array ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Oblique view to the northwest of the Antenna Array - Over-the-Horizon Backscatter Radar Network, Christmas Valley Radar Site Transmit Sector Six Antenna Array, On unnamed road west of Lost Forest Road, Christmas Valley, Lake County, OR

  5. View to the north of the Two Communications Antenna ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View to the north of the Two Communications Antenna - Over-the-Horizon Backscatter Radar Network, Christmas Valley Radar Site Transmit Sector Four Communications Antennas, On unnamed road west of Lost Forest Road, Christmas Valley, Lake County, OR

  6. General view to the northwest of the antenna array ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    General view to the northwest of the antenna array - Over-the-Horizon Backscatter Radar Network, Christmas Valley Radar Site Transmit Sector Five Antenna Array, On unnamed road west of Lost Forest Road, Christmas Valley, Lake County, OR

  7. View to the northeast of the Sounder Antenna OvertheHorizon ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View to the northeast of the Sounder Antenna - Over-the-Horizon Backscatter Radar Network, Christmas Valley Radar Site Transmit Sector Five Sounder Antennas, On unnamed road west of Lost Forest Road, Christmas Valley, Lake County, OR

  8. Radar antenna pointing for optimized signal to noise ratio.

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Doerry, Armin Walter; Marquette, Brandeis

    2013-01-01

    The Signal-to-Noise Ratio (SNR) of a radar echo signal will vary across a range swath, due to spherical wavefront spreading, atmospheric attenuation, and antenna beam illumination. The antenna beam illumination will depend on antenna pointing. Calculations of geometry are complicated by the curved earth, and atmospheric refraction. This report investigates optimizing antenna pointing to maximize the minimum SNR across the range swath.

  9. All-digital radar architecture

    NASA Astrophysics Data System (ADS)

    Molchanov, Pavlo A.

    2014-10-01

    All digital radar architecture requires exclude mechanical scan system. The phase antenna array is necessarily large because the array elements must be co-located with very precise dimensions and will need high accuracy phase processing system for aggregate and distribute T/R modules data to/from antenna elements. Even phase array cannot provide wide field of view. New nature inspired all digital radar architecture proposed. The fly's eye consists of multiple angularly spaced sensors giving the fly simultaneously thee wide-area visual coverage it needs to detect and avoid the threats around him. Fly eye radar antenna array consist multiple directional antennas loose distributed along perimeter of ground vehicle or aircraft and coupled with receiving/transmitting front end modules connected by digital interface to central processor. Non-steering antenna array allows creating all-digital radar with extreme flexible architecture. Fly eye radar architecture provides wide possibility of digital modulation and different waveform generation. Simultaneous correlation and integration of thousands signals per second from each point of surveillance area allows not only detecting of low level signals ((low profile targets), but help to recognize and classify signals (targets) by using diversity signals, polarization modulation and intelligent processing. Proposed all digital radar architecture with distributed directional antenna array can provide a 3D space vector to the jammer by verification direction of arrival for signals sources and as result jam/spoof protection not only for radar systems, but for communication systems and any navigation constellation system, for both encrypted or unencrypted signals, for not limited number or close positioned jammers.

  10. Antenna array geometry optimization for a passive coherent localisation system

    NASA Astrophysics Data System (ADS)

    Knott, Peter; Kuschel, Heiner; O'Hagan, Daniel

    2012-11-01

    Passive Coherent Localisation (PCL), also known as Passive Radar, making use of RF sources of opportunity such as Radio or TV Broadcasting Stations, Cellular Phone Network Base Stations, etc. is an advancing technology for covert operation because no active radar transmitter is required. It is also an attractive addition to existing active radar stations because it has the potential to discover low-flying and low-observable targets. The CORA (Covert Radar) experimental passive radar system currently developed at Fraunhofer-FHR features a multi-channel digital radar receiver and a circular antenna array with separate elements for the VHF- and the UHF-range and is used to exploit alternatively Digital Audio (DAB) or Video Broadcasting (DVB-T) signals. For an extension of the system, a wideband antenna array is being designed for which a new discone antenna element has been developed covering the full DVB-T frequency range. The present paper describes the outline of the system and the numerical modelling and optimisation methods applied to solve the complex task of antenna array design: Electromagnetic full wave analysis is required for the parametric design of the antenna elements while combinatorial optimization methods are applied to find the best array positions and excitation coefficients for a regular omni-directional antenna performance. The different steps are combined in an iterative loop until the optimum array layout is found. Simulation and experimental results for the current system will be shown.

  11. Two-Way Pattern Design for Distributed Subarray Antennas

    DTIC Science & Technology

    2012-09-01

    GUI Graphical User Interface HPBW Half-power Beamwidth MFR Multifunction Radar RCS Radar Cross Section RRE Radar Range Equation...The Aegis ships in the US Navy use phased arrays for the AN/SPY-1 multifunction radar ( MFR ) [2]. The phased array for the AN/SPY-1 radar is shown in...arrays. This is a challenge for design of antenna apertures for shipboard radar systems. One design approach is to use multi-function subarray

  12. Electromagnetic Modeling, Optimization and Uncertainty Quantification for Antenna and Radar Systems Surfaces Scattering and Energy Absorption

    DTIC Science & Technology

    2017-03-06

    design of antenna and radar systems, energy absorption and scattering by rough-surfaces. This work has lead to significant new methodologies , including...problems in the field of electromagnetic propagation and scattering, with applicability to design of antenna and radar systems, energy absorption...and scattering by rough-surfaces. This work has lead to significant new methodologies , including introduction of a certain Windowed Green Function

  13. View to the southwest of the Two Communications Antenna and ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View to the southwest of the Two Communications Antenna and their associated structures - Over-the-Horizon Backscatter Radar Network, Christmas Valley Radar Site Transmit Sector Four Communications Antennas, On unnamed road west of Lost Forest Road, Christmas Valley, Lake County, OR

  14. View to the south with the Two Sounder Antennas on ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View to the south with the Two Sounder Antennas on the left - Over-the-Horizon Backscatter Radar Network, Christmas Valley Radar Site Transmit Sector Four Sounder Antennas, On unnamed road west of Lost Forest Road, Christmas Valley, Lake County, OR

  15. Linear Frequency Modulated Signals VS Orthogonal Frequency Division Multiplexing Signals for Synthetic Aperture Radar Systems

    DTIC Science & Technology

    2014-06-01

    antenna beamwidth and R is the range distance. Antenna beam width  is proportional to the real aperture size and is given as antennaL ...18) where  is the wavelength and antennaL is the physical length of the radar antenna; therefore, cross-range resolution for a real aperture... antennaL R  (20) A value of 50 meters for cross-range resolution is rather high and signifies poor resolution. Under these conditions, obtaining

  16. View to the southwest of the antenna array, note the ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View to the southwest of the antenna array, note the site fence in the foreground - Over-the-Horizon Backscatter Radar Network, Christmas Valley Radar Site Transmit Sector Four Antenna Array, On unnamed road west of Lost Forest Road, Christmas Valley, Lake County, OR

  17. Model 0102 Flat Plate Antenna for Use in Automobile Radar Anticipatory Crash Sensors

    DOT National Transportation Integrated Search

    1973-09-01

    The report analyzed alternative methods of construction and production costs for a flat plate antenna based on the use of etched circuit techniques. The antenna is proposed for use in certain new automotive radar anticipatory crash sensor systems now...

  18. Tropical Rainfall Measuring Mission (TRMM) project. VI - Spacecraft, scientific instruments, and launching rocket. Part 4 - TRMM rain radar

    NASA Technical Reports Server (NTRS)

    Meneghini, Robert; Atlas, David; Awaka, Jun; Okamoto, Ken'ichi; Ihara, Toshio; Nakamura, Kenji; Kozu, Toshiaki; Manabe, Takeshi

    1990-01-01

    The basic system parameters for the Tropical Rainfall Measuring Mission (TRMM) radar system are frequency, beamwidth, scan angle, resolution, number of independent samples, pulse repetition frequency, data rate, and so on. These parameters were chosen to satisfy NASA's mission requirements. Six candidates for the TRMM rain radar were studied. The study considered three major competitive items: (1) a pulse-compression radar vs. a conventional radar; (2) an active-array radar with a solid state power amplifier vs. a passive-array radar with a traveling-wave-tube amplifier; and (3) antenna types (planar-array antenna vs. cylindrical parabolic antenna). Basic system parameters such as radar sensitivities, power consumption, weight, and size of these six types are described. Trade-off studies of these cases show that the non-pulse-compression active-array radar with a planar array is considered to be the most suitable candidate for the TRMM rain radar at 13.8 GHz.

  19. Multi-Antenna Radar Systems for Doppler Rain Measurements

    NASA Technical Reports Server (NTRS)

    Durden, Stephen; Tanelli, Simone; Siqueira, Paul

    2007-01-01

    Use of multiple-antenna radar systems aboard moving high-altitude platforms has been proposed for measuring rainfall. The basic principle of the proposed systems is a variant of that of along-track interferometric synthetic-aperture radar systems used previously to measure ocean waves and currents.

  20. State-of-the-art and trends of Ground-Penetrating Radar antenna arrays

    NASA Astrophysics Data System (ADS)

    Vescovo, Roberto; Pajewski, Lara; Tosti, Fabio

    2016-04-01

    The aim of this contribution is to offer an overview on the antenna arrays for GPR systems, current trends and open issues. Antennas are a critical hardware component of a radar system, dictating its performance in terms of capability to detect targets. Nevertheless, most of the research efforts in the Ground-Penetrating Radar (GPR) area focus on the use of this imaging technique in a plethora of different applications and on the improvement of modelling/inversion/processing techniques, whereas a limited number of studies deal with technological issues related to the design of novel systems, including the synthesis, optimisation and characterisation of advanced antennas. Even fewer are the research activities carried out to develop innovative antenna arrays. GPR antennas operate in a strongly demanding environment and should satisfy a number of requirements, somehow unique and very different than those of conventional radar antennas. The same applies to GPR antenna arrays. The first requirement is an ultra-wide frequency band: the radar has to transmit and receive short-duration time-domain waveforms, in the order of a few nanoseconds, the time-duration of the emitted pulses being a trade-off between the desired radar resolution and penetration depth. Furthermore, GPR antennas should have a linear phase characteristic over the whole operational frequency range, predictable polarisation and gain. Due to the fact that a subsurface imaging system is essentially a short-range radar, the coupling between transmitting and receiving antennas has to be low and short in time. GPR antennas should have quick ring-down characteristics, in order to prevent masking of targets and guarantee a good resolution. The radiation patterns should ensure minimal interference with unwanted objects, usually present in the complex operational environment; to this aim, antennas should provide high directivity and concentrate the electromagnetic energy into a narrow solid angle. As GPR antennas work very close to the matter or even in contact with it, changes in electrical properties of the matter should not affect strongly the antenna performance, so that a wide applicability of the radar system can be achieved. Moreover, antennas should provide stable performance at different elevation levels. For an efficient coupling of electromagnetic waves into the ground/investigated structure, good impedance matching is necessary at the antenna/matter interface. Another important requirement concerns the weight and size of the antennas: for ease of utilisation and to allow a wide applicability, the antennas shall be light and compact. Array of antennas can be used in GPR systems to enable a faster data collection by increasing the extension of investigated area per time unit. This can be a significant advantage in archaeological prospection, road and bridge inspection, mine detection, as well as in several other civil-engineering and geoscience applications where the collection of data requires the execution of a large number of profiles. Moreover, antenna arrays allow collecting multi-offset measurements simultaneously, thereby providing additional information for a more effective imaging and characterisation of the natural or manmade scenario under test. Two approaches are possible to GPR array design. The simplest and most common is to conceive the array as a multi-channel radar system composed of single-channel radars. Much more can be achieved, if array-design techniques are employed to synthesise the whole system. This second approach is just beginning in the GPR field and is definitely promising, as it gives the possibility to fully exploit the potentiality of arrays. Another important issue, when using GPR systems on irregular surfaces, is that the position of array elements has to be recorded during the surveys, by using suitable high-precision positioning systems. Current research activities on the design of GPR arrays are progressing in various directions, including the synthesis of arrays with a high directivity achieved by using simple elements, arrays with the capability of a steerable beam as in smart antennas, arrays composed of adaptive antennas with electronic control of characteristics to adapt to different soils and materials, and application-specific arrays. Acknowledgement This abstract is a contribution to COST (European COoperation in Science and Technology) Action TU1208 "Civil engineering applications of Ground Penetrating Radar" (www.GPRadar.eu). The Authors thank COST for funding the Action TU1208.

  1. The contribution of the Georges Heights Experimental Radar Antenna to Australian radio astronomy

    NASA Astrophysics Data System (ADS)

    Orchiston, Wayne; Wendt, Harry

    2017-12-01

    During the late 1940s and throughout the1950s Australia was one of the world’s foremost astronomical nations owing primarily to the dynamic Radio Astronomy Group within the Commonwealth Scientific and Industrial Organisation’s Division of Radiophysics based in Sydney. The earliest celestial observations were made with former WWII radar antennas and simple Yagi aerials attached to recycled radar receivers, before more sophisticated purpose-built radio telescopes of various types were designed and developed. One of the recycled WWII antennas that was used extensively for pioneering radio astronomical research was an experimental radar antenna that initially was located at the Division’s short-lived Georges Heights Field Station but in 1948 was relocated to the new Potts Hill Field Station in suburban Sydney. In this paper we describe this unique antenna, and discuss the wide-ranging solar, galactic and extragalactic research programs that it was used for.

  2. KSC-04PD-1605

    NASA Technical Reports Server (NTRS)

    2004-01-01

    KENNEDY SPACE CENTER, FLA. A C-band radar antenna stands ready to observe the MESSENGER (Mercury Surface, Space Environment, Geochemistry and Ranging) launch. This antenna and an X-band radar antenna are on loan to KSC from the USNS Pathfinder, a U.S. Navy instrumentation ship. They have been installed at site north of Haulover Canal where the National Center for Atmospheric Research previously had a radar for thunderstorm research. NASA is evaluating the pair of radars for their ability to observe possible debris coming from the Space Shuttle during launch, part of NASAs initiative to return the Space Shuttle to flight.

  3. KSC-04PD-1606

    NASA Technical Reports Server (NTRS)

    2004-01-01

    KENNEDY SPACE CENTER, FLA. An X-band radar antenna is in place to observe the MESSENGER (Mercury Surface, Space Environment, Geochemistry and Ranging) launch. This antenna and a C-band radar antenna are on loan to KSC from the USNS Pathfinder, a U.S. Navy instrumentation ship. They have been installed at site north of Haulover Canal where the National Center for Atmospheric Research previously had a radar for thunderstorm research. NASA is evaluating the pair of radars for their ability to observe possible debris coming from the Space Shuttle during launch, part of NASAs initiative to return the Space Shuttle to flight.

  4. KSC-04pd1609

    NASA Image and Video Library

    2004-07-31

    KENNEDY SPACE CENTER, FLA. - A C-band radar antenna is prepared to observe the MESSENGER (Mercury Surface, Space Environment, Geochemistry and Ranging) launch. This antenna and an X-band radar antenna are on loan to KSC from the USNS Pathfinder, a U.S. Navy instrumentation ship. They have been installed at site north of Haulover Canal where the National Center for Atmospheric Research previously had a radar for thunderstorm research. NASA is evaluating the pair of radars for their ability to observe possible debris coming from the Space Shuttle during launch, part of NASA’s initiative to return the Space Shuttle to flight.

  5. KSC-04pd1605

    NASA Image and Video Library

    2004-07-31

    KENNEDY SPACE CENTER, FLA. - A C-band radar antenna stands ready to observe the MESSENGER (Mercury Surface, Space Environment, Geochemistry and Ranging) launch. This antenna and an X-band radar antenna are on loan to KSC from the USNS Pathfinder, a U.S. Navy instrumentation ship. They have been installed at site north of Haulover Canal where the National Center for Atmospheric Research previously had a radar for thunderstorm research. NASA is evaluating the pair of radars for their ability to observe possible debris coming from the Space Shuttle during launch, part of NASA’s initiative to return the Space Shuttle to flight.

  6. KSC-04pd1606

    NASA Image and Video Library

    2004-07-31

    KENNEDY SPACE CENTER, FLA. - An X-band radar antenna is in place to observe the MESSENGER (Mercury Surface, Space Environment, Geochemistry and Ranging) launch. This antenna and a C-band radar antenna are on loan to KSC from the USNS Pathfinder, a U.S. Navy instrumentation ship. They have been installed at site north of Haulover Canal where the National Center for Atmospheric Research previously had a radar for thunderstorm research. NASA is evaluating the pair of radars for their ability to observe possible debris coming from the Space Shuttle during launch, part of NASA’s initiative to return the Space Shuttle to flight.

  7. KSC-04pd1608

    NASA Image and Video Library

    2004-07-31

    KENNEDY SPACE CENTER, FLA. - An X-band radar antenna is prepared to observe the MESSENGER (Mercury Surface, Space Environment, Geochemistry and Ranging) launch. This antenna and a C-band radar antenna are on loan to KSC from the USNS Pathfinder, a U.S. Navy instrumentation ship. They have been installed at site north of Haulover Canal where the National Center for Atmospheric Research previously had a radar for thunderstorm research. NASA is evaluating the pair of radars for their ability to observe possible debris coming from the Space Shuttle during launch, part of NASA’s initiative to return the Space Shuttle to flight.

  8. KSC-04PD-1609

    NASA Technical Reports Server (NTRS)

    2004-01-01

    KENNEDY SPACE CENTER, FLA. A C-band radar antenna is prepared to observe the MESSENGER (Mercury Surface, Space Environment, Geochemistry and Ranging) launch. This antenna and an X-band radar antenna are on loan to KSC from the USNS Pathfinder, a U.S. Navy instrumentation ship. They have been installed at site north of Haulover Canal where the National Center for Atmospheric Research previously had a radar for thunderstorm research. NASA is evaluating the pair of radars for their ability to observe possible debris coming from the Space Shuttle during launch, part of NASAs initiative to return the Space Shuttle to flight.

  9. KSC-04PD-1608

    NASA Technical Reports Server (NTRS)

    2004-01-01

    KENNEDY SPACE CENTER, FLA. An X-band radar antenna is prepared to observe the MESSENGER (Mercury Surface, Space Environment, Geochemistry and Ranging) launch. This antenna and a C-band radar antenna are on loan to KSC from the USNS Pathfinder, a U.S. Navy instrumentation ship. They have been installed at site north of Haulover Canal where the National Center for Atmospheric Research previously had a radar for thunderstorm research. NASA is evaluating the pair of radars for their ability to observe possible debris coming from the Space Shuttle during launch, part of NASAs initiative to return the Space Shuttle to flight.

  10. 'Invisible' antenna takes up less space

    NASA Astrophysics Data System (ADS)

    Shelley, M.; Bond, K.

    1986-06-01

    A compensated microstrip patch design is described that also uses grounded coplanar waveguide to permit a second, independent antenna to be mounted on any type of existing primary radar antenna aboard an aircraft without affecting its radiation. Successful integration of the IFF (identification friend or foe) antenna, which works at D-band, and the primary radar antenna is possible because of the diversity in frequency between the two antennas. Construction of a microstrip radiating element, electromagnetically invisible to the primary antenna, requires orthogonal grating elements and use of the primary antenna as the ground plane. Coplanar mounting of a stripline array with the primary antenna reduces the manufacturing costs and increases the functional performance of the IFF antenna.

  11. Space Radar Laboratory photos taken at Kennedy Space Center

    NASA Image and Video Library

    1994-03-18

    S94-30393 (23 Nov 1993) --- In the south level IV stand of the Operations and Checkout Building low bay, the Space Radar Laboratory -1 (SRL-1) antenna is being placed atop a pallet which holds the antenna electronics. SRL-1 is scheduled to fly on Space Shuttle mission STS-59 next year. It is comprised of two different imaging radars, the Spaceborne Imaging Radar-C (SIR-C) and the X-band Synthetic Aperture Radar (X-SAR). These radars are the most advanced of their kind to fly in space to date, and will allow scientists to make highly detailed studies of the Earth's surface on a global scale. An Interface Verification Test of the antenna and a Mission Sequence Test will be performed on the fully assembled SRL-1 later this month.

  12. Antenna dimensions of synthetic aperture radar systems on satellites

    NASA Technical Reports Server (NTRS)

    Richter, K. R.

    1973-01-01

    Design of a synthetic aperture radar (SAR) for a satellite must take into account the limitation in weight and dimensions of the antenna. The lower limits of the antenna area are derived from the conditions of unambiguity of the SAR system. This result is applied to estimate the antenna requirements for SARs on satellites in circular orbits of various altitudes around Earth and Venus.

  13. Mathematical modeling and simulation of the space shuttle imaging radar antennas

    NASA Technical Reports Server (NTRS)

    Campbell, R. W.; Melick, K. E.; Coffey, E. L., III

    1978-01-01

    Simulations of space shuttle synthetic aperture radar antennas under the influence of space environmental conditions were carried out at L, C, and X-band. Mathematical difficulties in modeling large, non-planar array antennas are discussed, and an approximate modeling technique is presented. Results for several antenna error conditions are illustrated in far-field profile patterns, earth surface footprint contours, and summary graphs.

  14. HELIRADAR technology for helicopter all-weather operations

    NASA Astrophysics Data System (ADS)

    Kreitmair-Steck, Wolfgang; Braun, Guenter

    1997-06-01

    Currently available radar instruments are not capable of guiding a helicopter pilot safely during approach and landing under poor visibility conditions. This is due to lack of resolution and lack of elevation information. The RADAR technology that promises to improve this situation is called ROSAR, which stands for Synthetic Aperture Radar based on ROtating Antennas. In 1992 Eurocopter and Daimler- Benz Aerospace investigated the feasibility of an imaging radar based on ROSAR technology. The objective was to provide a video-like image with a resolution good enough to safely guide a helicopter pilot under poor visibility conditions. ROSAR proved to be especially well suited for this type of application since it allows for a stationary carrier platform: Rotating arms with antennas integrated into their tips can be mounted on top of the rotor head. In this way the scanning region of the antennas can cover 360 degree(s). While rotating, the antenna scans the environment from various visual angles without assuming a movement of the carrier platform itself. The signal is then processed as a function of the rotation angle of the antenna movement along a circular path. A radar system of this type is now under development at Eurocopter and Daimler-Benz Aerospace: HeliRadar. HeliRadar is designed as a frequency modulated continuous wave radar working in a frequency band around 35 GHz. The complete transmitter/receiver system is fixed mounted on top of the rotating axis of the helicopter. The received signals are transferred through the center of the rotor axis down into the cabin of the helicopter, where they are processed in a high performance digital signal processor (processing power: 10 GFLOPS). First encouraging results have been obtained from an experiment with `slow motion' movement of the antenna arm.

  15. Research in Antenna Technology, Radar Technology and Electromagnetic Scattering Phenomena

    DTIC Science & Technology

    2015-03-01

    efforts of a group of six researchers in the fields of electromagnetics , radar and antenna technology. Research was conducted during this reporting...Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std. Z39.18 Research in Antenna technology, Radar Technology and Electromagnetic Scattering...Scattering-Matrix Theory Based on Gaussian Beams………...65 4.5.3 Array realization of complex-source beam……………………………85 4.5.4 Electromagnetic Scattering

  16. Research in Antenna Technology, Radar Technology and Electromagnetic Scattering Phenomena

    DTIC Science & Technology

    2015-04-06

    a group of six researchers in the fields of electromagnetics , radar and antenna technology. Research was conducted during this reporting period in...Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std. Z39.18 Research in Antenna technology, Radar Technology and Electromagnetic Scattering Phenomena...Matrix Theory Based on Gaussian Beams………...65 4.5.3 Array realization of complex-source beam……………………………85 4.5.4 Electromagnetic Scattering-Matrix

  17. A Huygens Surface Approach to Antenna Implementation in Near-Field Radar Imaging System Simulations

    DTIC Science & Technology

    2015-08-01

    environment. The model consists of an ultra - wideband , forward-looking radar imaging system, equipped with a multi-static antenna array and mounted on a...of the receiving antenna. 2.2 Huygens Surface Implementation Details The NAFDTD code implements the excitation waveform as a short, ultra - wideband ...

  18. Shielded loaded bowtie antenna incorporating the presence of paving structure for improved GPR pipe detection

    NASA Astrophysics Data System (ADS)

    Seyfried, Daniel; Jansen, Ronald; Schoebel, Joerg

    2014-12-01

    In civil engineering Ground Penetrating Radar becomes more and more a considerable tool for nondestructive testing and exploration of the underground. For example, the detection of existence of utilization pipe networks prior to construction works or detection of damaged spot beneath a paved street is a highly advantageous application. However, different surface conditions as well as ground bounce reflection and antenna cross-talk may seriously affect the detection capability of the entire radar system. Therefore, proper antenna design is an essential part in order to obtain radar data of high quality. In this paper we redesign a given loaded bowtie antenna in order to reduce strong and unwanted signal contributions such as ground bounce reflection and antenna cross-talk. During the optimization process we also review all parameters of our existing antenna in order to maximize energy transfer into ground. The entire process incorporating appropriate simulations along with running measurements on our GPR test site where we buried different types of pipes and cables for testing and developing radar hardware and software algorithms under quasi-real conditions is described in this paper.

  19. The Effect of Sea Surface Slicks on the Doppler Spectrum Width of a Backscattered Microwave Signal.

    PubMed

    Karaev, Vladimir; Kanevsky, Mikhail; Meshkov, Eugeny

    2008-06-06

    The influence of a surface-active substance (SAS) film on the Doppler spectrum width at small incidence angles is theoretically investigated for the first time for microwave radars with narrow-beam and knife-beam antenna patterns. It is shown that the requirements specified for the antenna system depend on the radar motion velocity. A narrow-beam antenna pattern should be used to detect slicks by an immobile radar, whereas radar with a knife-beam antenna pattern is needed for diagnostics from a moving platform. The study has revealed that the slick contrast in the Doppler spectrum width increases as the radar wavelength diminishes, thus it is preferable to utilize wavelengths not larger than 2 cm for solving diagnostic problems. The contrast in the Doppler spectrum width is generally weaker than that in the radar backscattering cross section; however, spatial and temporal fluctuations of the Doppler spectrum width are much weaker than those of the reflected signal power. This enables one to consider the Doppler spectrum as a promising indicator of slicks on water surface.

  20. Antenna Allocation in MIMO Radar with Widely Separated Antennas for Multi-Target Detection

    PubMed Central

    Gao, Hao; Wang, Jian; Jiang, Chunxiao; Zhang, Xudong

    2014-01-01

    In this paper, we explore a new resource called multi-target diversity to optimize the performance of multiple input multiple output (MIMO) radar with widely separated antennas for detecting multiple targets. In particular, we allocate antennas of the MIMO radar to probe different targets simultaneously in a flexible manner based on the performance metric of relative entropy. Two antenna allocation schemes are proposed. In the first scheme, each antenna is allocated to illuminate a proper target over the entire illumination time, so that the detection performance of each target is guaranteed. The problem is formulated as a minimum makespan scheduling problem in the combinatorial optimization framework. Antenna allocation is implemented through a branch-and-bound algorithm and an enhanced factor 2 algorithm. In the second scheme, called antenna-time allocation, each antenna is allocated to illuminate different targets with different illumination time. Both antenna allocation and time allocation are optimized based on illumination probabilities. Over a large range of transmitted power, target fluctuations and target numbers, both of the proposed antenna allocation schemes outperform the scheme without antenna allocation. Moreover, the antenna-time allocation scheme achieves a more robust detection performance than branch-and-bound algorithm and the enhanced factor 2 algorithm when the target number changes. PMID:25350505

  1. Antenna allocation in MIMO radar with widely separated antennas for multi-target detection.

    PubMed

    Gao, Hao; Wang, Jian; Jiang, Chunxiao; Zhang, Xudong

    2014-10-27

    In this paper, we explore a new resource called multi-target diversity to optimize the performance of multiple input multiple output (MIMO) radar with widely separated antennas for detecting multiple targets. In particular, we allocate antennas of the MIMO radar to probe different targets simultaneously in a flexible manner based on the performance metric of relative entropy. Two antenna allocation schemes are proposed. In the first scheme, each antenna is allocated to illuminate a proper target over the entire illumination time, so that the detection performance of each target is guaranteed. The problem is formulated as a minimum makespan scheduling problem in the combinatorial optimization framework. Antenna allocation is implemented through a branch-and-bound algorithm and an enhanced factor 2 algorithm. In the second scheme, called antenna-time allocation, each antenna is allocated to illuminate different targets with different illumination time. Both antenna allocation and time allocation are optimized based on illumination probabilities. Over a large range of transmitted power, target fluctuations and target numbers, both of the proposed antenna allocation schemes outperform the scheme without antenna allocation. Moreover, the antenna-time allocation scheme achieves a more robust detection performance than branch-and-bound algorithm and the enhanced factor 2 algorithm when the target number changes.

  2. Multibeam monopulse radar for airborne sense and avoid system

    NASA Astrophysics Data System (ADS)

    Gorwara, Ashok; Molchanov, Pavlo

    2016-10-01

    The multibeam monopulse radar for Airborne Based Sense and Avoid (ABSAA) system concept is the next step in the development of passive monopulse direction finder proposed by Stephen E. Lipsky in the 80s. In the proposed system the multibeam monopulse radar with an array of directional antennas is positioned on a small aircaraft or Unmanned Aircraft System (UAS). Radar signals are simultaneously transmitted and received by multiple angle shifted directional antennas with overlapping antenna patterns and the entire sky, 360° for both horizontal and vertical coverage. Digitizing of amplitude and phase of signals in separate directional antennas relative to reference signals provides high-accuracy high-resolution range and azimuth measurement and allows to record real time amplitude and phase of reflected from non-cooperative aircraft signals. High resolution range and azimuth measurement provides minimal tracking errors in both position and velocity of non-cooperative aircraft and determined by sampling frequency of the digitizer. High speed sampling with high-accuracy processor clock provides high resolution phase/time domain measurement even for directional antennas with wide Field of View (FOV). Fourier transform (frequency domain processing) of received radar signals provides signatures and dramatically increases probability of detection for non-cooperative aircraft. Steering of transmitting power and integration, correlation period of received reflected signals for separate antennas (directions) allows dramatically decreased ground clutter for low altitude flights. An open architecture, modular construction allows the combination of a radar sensor with Automatic Dependent Surveillance - Broadcast (ADS-B), electro-optic, acoustic sensors.

  3. Two antenna, two pass interferometric synthetic aperture radar

    DOEpatents

    Martinez, Ana; Doerry, Armin W.; Bickel, Douglas L.

    2005-06-28

    A multi-antenna, multi-pass IFSAR mode utilizing data driven alignment of multiple independent passes can combine the scaling accuracy of a two-antenna, one-pass IFSAR mode with the height-noise performance of a one-antenna, two-pass IFSAR mode. A two-antenna, two-pass IFSAR mode can accurately estimate the larger antenna baseline from the data itself and reduce height-noise, allowing for more accurate information about target ground position locations and heights. The two-antenna, two-pass IFSAR mode can use coarser IFSAR data to estimate the larger antenna baseline. Multi-pass IFSAR can be extended to more than two (2) passes, thereby allowing true three-dimensional radar imaging from stand-off aircraft and satellite platforms.

  4. Radar cross calibration investigation TAMU radar polarimeter calibration measurements

    NASA Technical Reports Server (NTRS)

    Blanchard, A. J.; Newton, R. W.; Bong, S.; Kronke, C.; Warren, G. L.; Carey, D.

    1982-01-01

    A short pulse, 20 MHz bandwidth, three frequency radar polarimeter system (RPS) operates at center frequencies of 10.003 GHz, 4.75 GHz, and 1.6 GHz and utilizes dual polarized transmit and receive antennas for each frequency. The basic lay-out of the RPS is different from other truck mounted systems in that it uses a pulse compression IF section common to all three RF heads. Separate transmit and receive antennas are used to improve the cross-polarization isolation at each particular frequency. The receive is a digitally controlled gain modulated subsystem and is interfaced directly with a microprocesser computer for control and data manipulation. Antenna focusing distance, focusing each antenna pair, rf head stability, and polarization characteristics of RPS antennas are discussed. Platform and data acquisition procedures are described.

  5. A Dielectric-Filled Waveguide Antenna Element for 3D Imaging Radar in High Temperature and Excessive Dust Conditions.

    PubMed

    Xu, Ding; Li, Zhiping; Chen, Xianzhong; Wang, Zhengpeng; Wu, Jianhua

    2016-08-22

    Three-dimensional information of the burden surface in high temperature and excessive dust industrial conditions has been previously hard to obtain. This paper presents a novel microstrip-fed dielectric-filled waveguide antenna element which is resistant to dust and high temperatures. A novel microstrip-to-dielectric-loaded waveguide transition was developed. A cylinder and cuboid composite structure was employed at the terminal of the antenna element, which improved the return loss performance and reduced the size. The proposed antenna element was easily integrated into a T-shape multiple-input multiple-output (MIMO) imaging radar system and tested in both the laboratory environment and real blast furnace environment. The measurement results show that the proposed antenna element works very well in industrial 3D imaging radar.

  6. Inter-comparison of SMAP, Aquarius and SMOS L-band brightness temperature observations

    USDA-ARS?s Scientific Manuscript database

    Soil Moisture Active Passive (SMAP) mission is scheduled for launch on January 29, 2015. SMAP will make observations with an L-band radar and radiometer using a shared 6 m rotating reflector antenna. SMAP is a fully polarimetric radiometer with the center frequency of 1.41 GHz. The target accuracy o...

  7. Safety assessment of ultra-wideband antennas for microwave breast imaging.

    PubMed

    De Santis, Valerio; Sill, Jeff M; Bourqui, Jeremie; Fear, Elise C

    2012-04-01

    This article deals with the safety assessment of several ultra-wideband (UWB) antenna designs for use in prototype microwave breast imaging systems. First, the performances of the antennas are validated by comparison of measured and simulated data collected for a simple test case. An efficient approach to estimating the specific energy absorption (SA) is introduced and validated. Next, SA produced by the UWB antennas inside more realistic breast models is computed. In particular, the power levels and pulse repetition periods adopted for the SA evaluation follow the measurement protocol employed by a tissue sensing adaptive radar (TSAR) prototype system. Results indicate that the SA for the antennas examined is below limits prescribed in standards for exposure of the general population; however, the difficulties inherent in applying such standards to UWB exposures are discussed. The results also suggest that effective tools for the rapid evaluation of new sensors have been developed. © 2011 Wiley Periodicals, Inc.

  8. Radiation pattern of a borehole radar antenna

    USGS Publications Warehouse

    Ellefsen, K.J.; Wright, D.L.

    2005-01-01

    The finite-difference time-domain method was used to simulate radar waves that were generated by a transmitting antenna inside a borehole. The simulations were of four different models that included features such as a water-filled borehole and an antenna with resistive loading. For each model, radiation patterns for the far-field region were calculated. The radiation patterns show that the amplitude of the radar wave was strongly affected by its frequency, the water-filled borehole, the resistive loading of the antenna, and the external metal parts of the antenna (e.g., the cable head and the battery pack). For the models with a water-filled borehole, their normalized radiation patterns were practically identical to the normalized radiation pattern of a finite-length electric dipole when the wavelength in the formation was significantly greater than the total length of the radiating elements of the model antenna. The minimum wavelength at which this criterion was satisfied depended upon the features of the antenna, especially its external metal parts. ?? 2005 Society of Exploration Geophysicists. All rights reserved.

  9. Ultra-Wide Patch Antenna Array Design at 60 GHz Band for Remote Vital Sign Monitoring with Doppler Radar Principle

    NASA Astrophysics Data System (ADS)

    Rabbani, Muhammad Saqib; Ghafouri-Shiraz, Hooshang

    2017-05-01

    In this paper, ultra-wide patch antenna arrays have been presented at 60 GHz band (57.24-65.88 GHz) with improved gain and beam-width capabilities for remote detection of respiration and heart beat rate of a person with Doppler radar principle. The antennas measured and simulation results showed close agreement. The breathing rate (BR) and heart rate (HR) of a 31-year-old man have been accurately detected from various distances ranging from 5 to 200 cm with both single-antenna and dual-antenna operations. In the case of single-antenna operation, the signal is transmitted and received with the same antenna, whereas in dual-antenna operation, two identical antennas are employed, one for signal transmission and the other for reception. It has been found that in case of the single-antenna operation, the accuracy of the remote vital sign monitoring (RVSM) is good for short distance; however, in the case of the dual-antenna operations, the RVSM can be accurately carried out at relatively much longer distance. On the other hand, it has also been seen that the visual results are more obvious with higher gain antennas when the radar beam is confined just on the subject's body area.

  10. A new polarimetric active radar calibrator and calibration technique

    NASA Astrophysics Data System (ADS)

    Tang, Jianguo; Xu, Xiaojian

    2015-10-01

    Polarimetric active radar calibrator (PARC) is one of the most important calibrators with high radar cross section (RCS) for polarimetry measurement. In this paper, a new double-antenna polarimetric active radar calibrator (DPARC) is proposed, which consists of two rotatable antennas with wideband electromagnetic polarization filters (EMPF) to achieve lower cross-polarization for transmission and reception. With two antennas which are rotatable around the radar line of sight (LOS), the DPARC provides a variety of standard polarimetric scattering matrices (PSM) through the rotation combination of receiving and transmitting polarization, which are useful for polarimatric calibration in different applications. In addition, a technique based on Fourier analysis is proposed for calibration processing. Numerical simulation results are presented to demonstrate the superior performance of the proposed DPARC and processing technique.

  11. Wrist Pulse Rate Monitor Using Self-Injection-Locked Radar Technology

    PubMed Central

    Wang, Fu-Kang; Tang, Mu-Cyun; Su, Sheng-Chao; Horng, Tzyy-Sheng

    2016-01-01

    To achieve sensitivity, comfort, and durability in vital sign monitoring, this study explores the use of radar technologies in wearable devices. The study first detected the respiratory rates and heart rates of a subject at a one-meter distance using a self-injection-locked (SIL) radar and a conventional continuous-wave (CW) radar to compare the sensitivity versus power consumption between the two radars. Then, a pulse rate monitor was constructed based on a bistatic SIL radar architecture. This monitor uses an active antenna that is composed of a SIL oscillator (SILO) and a patch antenna. When attached to a band worn on the subject’s wrist, the active antenna can monitor the pulse on the subject’s wrist by modulating the SILO with the associated Doppler signal. Subsequently, the SILO’s output signal is received and demodulated by a remote frequency discriminator to obtain the pulse rate information. PMID:27792176

  12. Optimal frequency range for medical radar measurements of human heartbeats using body-contact radar.

    PubMed

    Brovoll, Sverre; Aardal, Øyvind; Paichard, Yoann; Berger, Tor; Lande, Tor Sverre; Hamran, Svein-Erik

    2013-01-01

    In this paper the optimal frequency range for heartbeat measurements using body-contact radar is experimentally evaluated. A Body-contact radar senses electromagnetic waves that have penetrated the human body, but the range of frequencies that can be used are limited by the electric properties of the human tissue. The optimal frequency range is an important property needed for the design of body-contact radar systems for heartbeat measurements. In this study heartbeats are measured using three different antennas at discrete frequencies from 0.1 - 10 GHz, and the strength of the received heartbeat signal is calculated. To characterize the antennas, when in contact with the body, two port S-parameters(†) are measured for the antennas using a pork rib as a phantom for the human body. The results shows that frequencies up to 2.5 GHz can be used for heartbeat measurements with body-contact radar.

  13. Wrist Pulse Rate Monitor Using Self-Injection-Locked Radar Technology.

    PubMed

    Wang, Fu-Kang; Tang, Mu-Cyun; Su, Sheng-Chao; Horng, Tzyy-Sheng

    2016-10-26

    To achieve sensitivity, comfort, and durability in vital sign monitoring, this study explores the use of radar technologies in wearable devices. The study first detected the respiratory rates and heart rates of a subject at a one-meter distance using a self-injection-locked (SIL) radar and a conventional continuous-wave (CW) radar to compare the sensitivity versus power consumption between the two radars. Then, a pulse rate monitor was constructed based on a bistatic SIL radar architecture. This monitor uses an active antenna that is composed of a SIL oscillator (SILO) and a patch antenna. When attached to a band worn on the subject's wrist, the active antenna can monitor the pulse on the subject's wrist by modulating the SILO with the associated Doppler signal. Subsequently, the SILO's output signal is received and demodulated by a remote frequency discriminator to obtain the pulse rate information.

  14. 1. View of three detection radar (DR) antennas. DR 1 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. View of three detection radar (DR) antennas. DR 1 (structure no. 735) on left, DR 2 (structure no. 736) in center, and DR 3 (structure no. 737) looking north 30 degrees west, with tracking radar (large radome) and satcom (satellite communication) system in small radome in view between DR 2 and DR 3 antennae. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  15. Radar for tracer particles

    NASA Astrophysics Data System (ADS)

    Ott, Felix; Herminghaus, Stephan; Huang, Kai

    2017-05-01

    We introduce a radar system capable of tracking a 5 mm spherical target continuously in three dimensions. The 10 GHz (X-band) radar system has a transmission power of 1 W and operates in the near field of the horn antennae. By comparing the phase shift of the electromagnetic wave traveling through the free space with an IQ-mixer, we obtain the relative movement of the target with respect to the antennae. From the azimuth and inclination angles of the receiving antennae obtained in the calibration, we reconstruct the target trajectory in a three-dimensional Cartesian system. Finally, we test the tracking algorithm with target moving in circular as well as in pendulum motions and discuss the capability of the radar system.

  16. Synchronized Radar-Target Simulator

    NASA Technical Reports Server (NTRS)

    Chin, B. C.

    1985-01-01

    Apparatus for testing radar system generates signals that simulate amplitude and phase characteristics of target returns and their variation with antenna-pointing direction. Antenna movement causes equipment to alter test signal in imitation of behavior of real signal received during tracking.

  17. An Algorithm Based Wavelet Entropy for Shadowing Effect of Human Detection Using Ultra-Wideband Bio-Radar

    PubMed Central

    Liu, Miao; Zhang, Yang; Liang, Fulai; Qi, Fugui; Lv, Hao; Wang, Jianqi; Zhang, Yang

    2017-01-01

    Ultra-wide band (UWB) radar for short-range human target detection is widely used to find and locate survivors in some rescue missions after a disaster. The results of the application of bistatic UWB radar for detecting multi-stationary human targets have shown that human targets close to the radar antennas are very often visible, while those farther from radar antennas are detected with less reliability. In this paper, on account of the significant difference of frequency content between the echo signal of the human target and that of noise in the shadowing region, an algorithm based on wavelet entropy is proposed to detect multiple targets. Our findings indicate that the entropy value of human targets was much lower than that of noise. Compared with the method of adaptive filtering and the energy spectrum, wavelet entropy can accurately detect the person farther from the radar antennas, and it can be employed as a useful tool in detecting multiple targets by bistatic UWB radar. PMID:28973988

  18. An Algorithm Based Wavelet Entropy for Shadowing Effect of Human Detection Using Ultra-Wideband Bio-Radar.

    PubMed

    Xue, Huijun; Liu, Miao; Zhang, Yang; Liang, Fulai; Qi, Fugui; Chen, Fuming; Lv, Hao; Wang, Jianqi; Zhang, Yang

    2017-09-30

    Ultra-wide band (UWB) radar for short-range human target detection is widely used to find and locate survivors in some rescue missions after a disaster. The results of the application of bistatic UWB radar for detecting multi-stationary human targets have shown that human targets close to the radar antennas are very often visible, while those farther from radar antennas are detected with less reliability. In this paper, on account of the significant difference of frequency content between the echo signal of the human target and that of noise in the shadowing region, an algorithm based on wavelet entropy is proposed to detect multiple targets. Our findings indicate that the entropy value of human targets was much lower than that of noise. Compared with the method of adaptive filtering and the energy spectrum, wavelet entropy can accurately detect the person farther from the radar antennas, and it can be employed as a useful tool in detecting multiple targets by bistatic UWB radar.

  19. KSC-99pp1010

    NASA Image and Video Library

    1999-08-05

    KENNEDY SPACE CENTER, FLA. -- In the Orbiter Processing Facility, a radar antenna, part of the Shuttle Radar Topography Mission (SRTM), is stored in the payload bay of the orbiter Endeavour before door closure. SRTM is the primary payload on mission STS-99, scheduled to launch Sept. 16 at 8:47 a.m. EDT from Launch Pad 39A. A specially modified radar system, the SRTM will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. The SRTM hardware consists of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle. SRTM is an international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR

  20. KSC-99pp1009

    NASA Image and Video Library

    1999-08-05

    KENNEDY SPACE CENTER, FLA. -- In the Orbiter Processing Facility, a radar antenna, part of the Shuttle Radar Topography Mission (SRTM), is ready to be stored in the payload bay of the orbiter Endeavour before door closure. SRTM is the primary payload on mission STS-99, scheduled to launch Sept. 16 at 8:47 a.m. EDT from Launch Pad 39A. A specially modified radar system, the SRTM will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. The SRTM hardware consists of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle. SRTM is an international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR

  1. KSC-99pp1008

    NASA Image and Video Library

    1999-08-05

    KENNEDY SPACE CENTER, FLA. -- In the Orbiter Processing Facility, a radar antenna, part of the Shuttle Radar Topography Mission (SRTM), is nestled in the cargo bay of the orbiter Endeavour just before door closure. SRTM is the primary payload on mission STS-99, scheduled to launch Sept. 16 at 8:47 a.m. EDT from Launch Pad 39A. A specially modified radar system, the SRTM will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. The SRTM hardware consists of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle. SRTM is an international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR

  2. A Dielectric-Filled Waveguide Antenna Element for 3D Imaging Radar in High Temperature and Excessive Dust Conditions

    PubMed Central

    Xu, Ding; Li, Zhiping; Chen, Xianzhong; Wang, Zhengpeng; Wu, Jianhua

    2016-01-01

    Three-dimensional information of the burden surface in high temperature and excessive dust industrial conditions has been previously hard to obtain. This paper presents a novel microstrip-fed dielectric-filled waveguide antenna element which is resistant to dust and high temperatures. A novel microstrip-to-dielectric-loaded waveguide transition was developed. A cylinder and cuboid composite structure was employed at the terminal of the antenna element, which improved the return loss performance and reduced the size. The proposed antenna element was easily integrated into a T-shape multiple-input multiple-output (MIMO) imaging radar system and tested in both the laboratory environment and real blast furnace environment. The measurement results show that the proposed antenna element works very well in industrial 3D imaging radar. PMID:27556469

  3. See-through Detection and 3D Reconstruction Using Terahertz Leaky-Wave Radar Based on Sparse Signal Processing

    NASA Astrophysics Data System (ADS)

    Murata, Koji; Murano, Kosuke; Watanabe, Issei; Kasamatsu, Akifumi; Tanaka, Toshiyuki; Monnai, Yasuaki

    2018-02-01

    We experimentally demonstrate see-through detection and 3D reconstruction using terahertz leaky-wave radar based on sparse signal processing. The application of terahertz waves to radar has received increasing attention in recent years for its potential to high-resolution and see-through detection. Among others, the implementation using a leaky-wave antenna is promising for compact system integration with beam steering capability based on frequency sweep. However, the use of a leaky-wave antenna poses a challenge on signal processing. Since a leaky-wave antenna combines the entire signal captured by each part of the aperture into a single output, the conventional array signal processing assuming access to a respective antenna element is not applicable. In this paper, we apply an iterative recovery algorithm "CoSaMP" to signals acquired with terahertz leaky-wave radar for clutter mitigation and aperture synthesis. We firstly demonstrate see-through detection of target location even when the radar is covered with an opaque screen, and therefore, the radar signal is disturbed by clutter. Furthermore, leveraging the robustness of the algorithm against noise, we also demonstrate 3D reconstruction of distributed targets by synthesizing signals collected from different orientations. The proposed approach will contribute to the smart implementation of terahertz leaky-wave radar.

  4. Downhole pulse radar

    DOEpatents

    Chang, Hsi-Tien

    1989-01-01

    A borehole logging tool generates a fast rise-time, short duration, high peak-power radar pulse having broad energy distribution between 30 MHz and 300 MHz through a directional transmitting and receiving antennas having barium titanate in the electromagnetically active region to reduce the wavelength to within an order of magnitude of the diameter of the antenna. Radar returns from geological discontinuities are sampled for transmission uphole.

  5. Electronically steerable millimeter wave antenna techniques for space shuttle applications

    NASA Technical Reports Server (NTRS)

    Kummer, W. H.

    1975-01-01

    A large multi-function antenna aperture and related components are described which will perform electronic steering of one or more beams for two of the three applications envisioned: (1) communications, (2) radar, and (3) radiometry. The array consists of a 6-meter folded antenna that fits into two pallets. The communications frequencies are 20 and 30 GHz, while the radar is to operate at 13.9 GHz. Weight, prime power, and volumes are given parametrically; antenna designs, electronics configurations, and mechanical design were studied.

  6. IoSiS: a radar system for imaging of satellites in space

    NASA Astrophysics Data System (ADS)

    Jirousek, M.; Anger, S.; Dill, S.; Schreiber, E.; Peichl, M.

    2017-05-01

    Space debris nowadays is one of the main threats for satellite systems especially in low earth orbit (LEO). More than 700,000 debris objects with potential to destroy or damage a satellite are estimated. The effects of an impact often are not identifiable directly from ground. High-resolution radar images are helpful in analyzing a possible damage. Therefor DLR is currently developing a radar system called IoSiS (Imaging of Satellites in Space), being based on an existing steering antenna structure and our multi-purpose high-performance radar system GigaRad for experimental investigations. GigaRad is a multi-channel system operating at X band and using a bandwidth of up to 4.4 GHz in the IoSiS configuration, providing fully separated transmit (TX) and receive (RX) channels, and separated antennas. For the observation of small satellites or space debris a highpower traveling-wave-tube amplifier (TWTA) is mounted close to the TX antenna feed. For the experimental phase IoSiS uses a 9 m TX and a 1 m RX antenna mounted on a common steerable positioner. High-resolution radar images are obtained by using Inverse Synthetic Aperture Radar (ISAR) techniques. The guided tracking of known objects during overpass allows here wide azimuth observation angles. Thus high azimuth resolution comparable to the range resolution can be achieved. This paper outlines technical main characteristics of the IoSiS radar system including the basic setup of the antenna, the radar instrument with the RF error correction, and the measurement strategy. Also a short description about a simulation tool for the whole instrument and expected images is shown.

  7. Range and azimuth resolution enhancement for 94 GHz real-beam radar

    NASA Astrophysics Data System (ADS)

    Liu, Guoqing; Yang, Ken; Sykora, Brian; Salha, Imad

    2008-04-01

    In this paper, two-dimensional (2D) (range and azimuth) resolution enhancement is investigated for millimeter wave (mmW) real-beam radar (RBR) with linear or non-linear antenna scan in the azimuth dimension. We design a new architecture of super resolution processing, in which a dual-mode approach is used for defining region of interest for 2D resolution enhancement and a combined approach is deployed for obtaining accurate location and amplitude estimations of targets within the region of interest. To achieve 2D resolution enhancement, we first adopt the Capon Beamformer (CB) approach (also known as the minimum variance method (MVM)) to enhance range resolution. A generalized CB (GCB) approach is then applied to azimuth dimension for azimuth resolution enhancement. The GCB approach does not rely on whether the azimuth sampling is even or not and thus can be used in both linear and non-linear antenna scanning modes. The effectiveness of the resolution enhancement is demonstrated by using both simulation and test data. The results of using a 94 GHz real-beam frequency modulation continuous wave (FMCW) radar data show that the overall image quality is significantly improved per visual evaluation and comparison with respect to the original real-beam radar image.

  8. Middle Atmosphere Program. Handbook for MAP, volume 9

    NASA Technical Reports Server (NTRS)

    Bowhill, S. A. (Editor); Edwards, B. (Editor)

    1983-01-01

    The term Mesosphere-Stratosphere-Troposphere radar (MST) was invented to describe the use of a high power radar transmitter together with a large vertically, or near vertically, pointing antenna to study the dynamics and structure of the atmosphere from about 10 to 100 km, using the very weak coherently scattered radiation returned from small scale irregularities in refractive index. Nine topics were addressed including: meteorological and dynamic requirements for MST radar networks; interpretation of radar returns for clear air; techniques for the measurement of horizontal and vertical velocities; techniques for studying gravity waves and turbulence; capabilities and limitations of existing MST radar; design considerations for high power VHF radar transceivers; optimum radar antenna configurations; and data analysis techniques.

  9. Distributed micro-radar system for detection and tracking of low-profile, low-altitude targets

    NASA Astrophysics Data System (ADS)

    Gorwara, Ashok; Molchanov, Pavlo

    2016-05-01

    Proposed airborne surveillance radar system can detect, locate, track, and classify low-profile, low-altitude targets: from traditional fixed and rotary wing aircraft to non-traditional targets like unmanned aircraft systems (drones) and even small projectiles. Distributed micro-radar system is the next step in the development of passive monopulse direction finder proposed by Stephen E. Lipsky in the 80s. To extend high frequency limit and provide high sensitivity over the broadband of frequencies, multiple angularly spaced directional antennas are coupled with front end circuits and separately connected to a direction finder processor by a digital interface. Integration of antennas with front end circuits allows to exclude waveguide lines which limits system bandwidth and creates frequency dependent phase errors. Digitizing of received signals proximate to antennas allows loose distribution of antennas and dramatically decrease phase errors connected with waveguides. Accuracy of direction finding in proposed micro-radar in this case will be determined by time accuracy of digital processor and sampling frequency. Multi-band, multi-functional antennas can be distributed around the perimeter of a Unmanned Aircraft System (UAS) and connected to the processor by digital interface or can be distributed between swarm/formation of mini/micro UAS and connected wirelessly. Expendable micro-radars can be distributed by perimeter of defense object and create multi-static radar network. Low-profile, lowaltitude, high speed targets, like small projectiles, create a Doppler shift in a narrow frequency band. This signal can be effectively filtrated and detected with high probability. Proposed micro-radar can work in passive, monostatic or bistatic regime.

  10. Advanced Borehole Radar for Hydrogeology

    NASA Astrophysics Data System (ADS)

    Sato, M.

    2014-12-01

    Ground Penetrating Radar is a useful tool for monitoring the hydrogeological environment. We have developed GPR systems which can be applied to these purposes, and we will demonstrate examples borehole radar measurements. In order to have longer radar detection range, frequency lower than100MHz has been normally adopted in borehole radar. Typical subsurface fractures of our interests have a few mm aperture and radar resolution is much poorer than a few cm in this frequency range. We are proposing and demonstrating to use radar polarimetry to solve this problem. We have demonstrated that a full-polarimetry borehole radar can be used for characterization of subsurface fractures. Together with signal processing for antenna characteristic compensation to equalize the signal by a dipole antenna and slot antennas, we could demonstrate that polarimetric borehole radar can estimate the surface roughness of subsurface fractures, We believe the surface roughness is closely related to water permeability through the fractures. We then developed a directional borehole radar, which uses optical field sensor. A dipole antenna in a borehole has omni-directional radiation pattern, and we cannot get azimuthal information about the scatterers. We use multiple dipole antennas set around the borehole axis, and from the phase differences, we can estimate the 3-diemnational orientation of subsurface structures. We are using optical electric field sensor for receiver of borehole radar. This is a passive sensor and connected only with optical fibers and does not require any electric power supply to operate the receiver. It has two major advantages; the first one is that the receiver can be electrically isolated from other parts, and wave coupling to a logging cable is avoided. Then, secondary, it can operate for a long time, because it does not require battery installed inside the system. It makes it possible to set sensors in fixed positions to monitor the change of environmental conditions for a long period. We demonstrated this idea using cross- hole borehole radar measurement. We think this method is useful for detecting any changes in hydrogeological situations, which will be useful for subsurface storage such as LNG and nuclear waste.

  11. Microstrip reflectarray antenna for the SCANSCAT radar application

    NASA Technical Reports Server (NTRS)

    Huang, John

    1990-01-01

    This publication presents an antenna system that has been proposed as one of the candidates for the SCANSCAT (Scanned Scatterometer) radar application. It is the mechanically steered planar microstrip reflectarray. Due to its thin, lightweight structure, the antenna's mechanical rotation will impose minimum angular momentum for the spacecraft. Since no power-dividing circuitry is needed for its many radiating microstrip patches, this electrically large array antenna demonstrates excellent power efficiency. In addition, this fairly new antenna concept can provide many significant advantages over a conventional parabolic reflector. The basic formulation for the radiation fields of the microstrip reflectarray is presented. This formulation is based on the array theory augmented by the Uniform Geometrical Theory of Diffraction (UTD). A computer code for analyzing the microstrip reflectarray's performances, such as far-field patterns, efficiency, etc., is also listed in this report. It is proposed here that a breadboard unit of this microstrip reflectarray should be constructed and tested in the future to validate the calculated performance. The antenna concept presented here can also be applied in many other types of radars where a large array antenna is needed.

  12. Downhole pulse radar

    DOEpatents

    Chang, Hsi-Tien

    1987-09-28

    A borehole logging tool generates a fast rise-time, short duration, high peak-power radar pulse having broad energy distribution between 30 MHz and 300 MHz through a directional transmitting and receiving antennas having barium titanate in the electromagnetically active region to reduce the wavelength to within an order of magnitude of the diameter of the antenna. Radar returns from geological discontinuities are sampled for transmission uphole. 7 figs.

  13. Active and passive microwave measurements in Hurricane Allen

    NASA Technical Reports Server (NTRS)

    Delnore, V. E.; Bahn, G. S.; Grantham, W. L.; Harrington, R. F.; Jones, W. L.

    1985-01-01

    The NASA Langley Research Center analysis of the airborne microwave remote sensing measurements of Hurricane Allen obtained on August 5 and 8, 1980 is summarized. The instruments were the C-band stepped frequency microwave radiometer and the Ku-band airborne microwave scatterometer. They were carried aboard a NOAA aircraft making storm penetrations at an altitude of 3000 m and are sensitive to rain rate, surface wind speed, and surface wind vector. The wind speed is calculated from the increase in antenna brightness temperature above the estimated calm sea value. The rain rate is obtained from the difference between antenna temperature increases measured at two frequencies, and wind vector is determined from the sea surface normalized radar cross section measured at several azimuths. Comparison wind data were provided from the inertial navigation systems aboard both the C-130 aircraft at 3000 m and a second NOAA aircraft (a P-3) operating between 500 and 1500 m. Comparison rain rate data were obtained with a rain radar aboard the P-3. Evaluation of the surface winds obtained with the two microwave instruments was limited to comparisons with each other and with the flight level winds. Two important conclusions are drawn from these comparisons: (1) the radiometer is accurate when predicting flight level wind speeds and rain; and (2) the scatterometer produces well behaved and consistent wind vectors for the rain free periods.

  14. Smart skin spiral antenna with chiral absorber

    NASA Astrophysics Data System (ADS)

    Varadan, Vijay K.; Varadan, Vasundara V.

    1995-05-01

    Recently there has been considerable interest toward designing 'smart skins' for aircraft. The smart skin is a composite layer which may contain conformal radars, conformal microstrip antennas or spiral antennas for electromagnetic applications. These embedded antennas will give rise to very low radar cross section (RCS) or can be completely 'hidden' to tracking radar. In addition, they can be used to detect, monitor or even jam other unwanted electromagnetic field signatures. This paper is designed to address some technical advances made to reduce the size of spiral antennas using tunable dielectric materials and chiral absorbers. The purpose is to design, develop and fabricate a thin, wideband, conformal spiral antenna architecture that is structurally integrable and which uses advanced Penn State dielectric and absorber materials to achieve wideband ground planes, and together with low RCS. Traditional practice has been to design radome and antenna as separate entities and then resolve any interface problems during an integration phase. A structurally integrable conformal antenna, however, demands that the functional components be highly integrated both conceptually and in practice. Our concept is to use the lower skin of the radome as a substrate on which the radiator can be made using standard photolithography, thick film or LTCC techniques.

  15. Characterisation and optimisation of Ground Penetrating Radar antennas

    NASA Astrophysics Data System (ADS)

    Warren, Craig; Giannopoulos, Antonios

    2014-05-01

    Research on the characterisation and optimisation of Ground Penetrating Radar (GPR) antennas will be presented as part of COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar". This work falls within the remit of Working Group 1 - "Novel GPR instrumentation" which focuses on the design of innovative GPR equipment for Civil Engineering (CE) applications, on the building of prototypes and on the testing and optimisation of new systems. The diversity of applications of GPR has meant there are a number of different GPR antenna designs available to the end-user as well as those being used in the research community. The type and size of a GPR antenna is usually dependent on the application, e.g. low frequency antennas, which are physically larger, are used where significant depth of penetration is important, whereas high frequency antennas, which are physically smaller, are used where less penetration and better resolution are required. Understanding how energy is transmitted and received by a particular GPR antenna has many benefits: it could lead to more informed usage of the antenna in GPR surveys; improvements in antenna design; and better interpretation of GPR signal returns from the ground/structure. The radiation characteristics of a particular antenna are usually investigated by studying the radiation patterns and directivity. For GPR antennas it is also important to study these characteristics when the antenna is in different environments that would typically be encountered in GPR surveys. In this work Finite-Difference Time-Domain (FDTD) numerical models of GPR antennas have been developed. These antenna models replicate all the detailed geometry and main components of the real antennas. The models are representative of typical high-frequency, high-resolution GPR antennas primarily used in CE for the evaluation of structural features in concrete: the location of rebar, conduits, and post-tensioned cables, as well as the estimation of material thickness on bridge decks and pavements. Radiation patterns obtained using the antenna models as well as physical measurements have been used to investigate the radiation characteristics of high-frequency GPR antennas. Studies were conducted with homogeneous materials of different dielectric constants (Er=3, 10, 30, & 72) and at a range of observation distances. The first objective was to compare, using the FDTD antenna model, 'traditional' transmitted field patterns with field patterns obtained using responses from a target spaced at regular intervals around the circumference of a circle, i.e. received energy. Our initial results show, for the same dielectric and observation distance, E- and H-field patterns obtained using the received energy approach have a significantly narrower main lobe than the traditional transmitted patterns. This raises the question of which approach is more beneficial for the characterisation of GPR antennas, and hence better interpretation of GPR responses. The second objective was to compare modelled field patterns with measured patterns obtained from a commercial high-frequency GPR antenna using the received energy approach. The measurements were made in different oil-in-water emulsions which were used to simulate materials with different permittivities and conductivities. Initial comparisons of the measured and modelled data show a very good correlation, which validates use of the antenna model for further studies.

  16. Space shuttle Ku-band integrated rendezvous radar/communications system study

    NASA Technical Reports Server (NTRS)

    1976-01-01

    The results are presented of work performed on the Space Shuttle Ku-Band Integrated Rendezvous Radar/Communications System Study. The recommendations and conclusions are included as well as the details explaining the results. The requirements upon which the study was based are presented along with the predicted performance of the recommended system configuration. In addition, shuttle orbiter vehicle constraints (e.g., size, weight, power, stowage space) are discussed. The tradeoffs considered and the operation of the recommended configuration are described for an optimized, integrated Ku-band radar/communications system. Basic system tradeoffs, communication design, radar design, antenna tradeoffs, antenna gimbal and drive design, antenna servo design, and deployed assembly packaging design are discussed. The communications and radar performance analyses necessary to support the system design effort are presented. Detailed derivations of the communications thermal noise error, the radar range, range rate, and angle tracking errors, and the communications transmitter distortion parameter effect on crosstalk between the unbalanced quadriphase signals are included.

  17. Advanced Antenna Design for NASA's EcoSAR Instrument

    NASA Technical Reports Server (NTRS)

    Du Toit, Cornelis F.; Deshpande, Manohar; Rincon, Rafael F.

    2016-01-01

    Advanced antenna arrays were designed for NASA's EcoSAR airborne radar instrument. EcoSAR is a beamforming synthetic aperture radar instrument designed to make polarimetric and "single pass" interferometric measurements of Earth surface parameters. EcoSAR's operational requirements of a 435MHz center frequency with up to 200MHz bandwidth, dual polarization, high cross-polarization isolation (> 30 dB), +/- 45deg beam scan range and antenna form-factor constraints imposed stringent requirements on the antenna design. The EcoSAR project successfully developed, characterized, and tested two array antennas in an anechoic chamber. EcoSAR's first airborne campaign conducted in the spring of 2014 generated rich data sets of scientific and engineering value, demonstrating the successful operation of the antennas.

  18. Moving receive beam method and apparatus for synthetic aperture radar

    DOEpatents

    Kare, Jordin T.

    2001-01-01

    A method and apparatus for improving the performance of Synthetic Aperture Radar (SAR) systems by reducing the effect of "edge losses" associated with nonuniform receiver antenna gain. By moving the receiver antenna pattern in synchrony with the apparent motion of the transmitted pulse along the ground, the maximum available receiver antenna gain can be used at all times. Also, the receiver antenna gain for range-ambiguous return signals may be reduced, in some cases, by a large factor. The beam motion can be implemented by real-time adjustment of phase shifters in an electronically-steered phased-array antenna or by electronic switching of feed horns in a reflector antenna system.

  19. Time-lapse imaging of human heart motion with switched array UWB radar.

    PubMed

    Brovoll, Sverre; Berger, Tor; Paichard, Yoann; Aardal, Øyvind; Lande, Tor Sverre; Hamran, Svein-Erik

    2014-10-01

    Radar systems for detection of human heartbeats have mostly been single-channel systems with limited spatial resolution. In this paper, a radar system for ultra-wideband (UWB) imaging of the human heart is presented. To make the radar waves penetrate the human tissue the antenna is placed very close to the body. The antenna is an array with eight elements, and an antenna switch system connects the radar to the individual elements in sequence to form an image. Successive images are used to build up time-lapse movies of the beating heart. Measurements on a human test subject are presented and the heart motion is estimated at different locations inside the body. The movies show rhythmic motion consistent with the beating heart, and the location and shape of the reflections correspond well with the expected response form the heart wall. The spatial dependent heart motion is compared to ECG recordings, and it is confirmed that heartbeat modulations are seen in the radar data. This work shows that radar imaging of the human heart may provide valuable information on the mechanical movement of the heart.

  20. A Digital Bistatic Radar Instrument for High-Latitude Ionospheric E-region Research

    NASA Astrophysics Data System (ADS)

    Huyghebaert, D. R.; Hussey, G. C.; McWilliams, K. A.; St-Maurice, J. P.

    2015-12-01

    A new 50 MHz ionospheric E-region radar is currently being developed and will be operational for the summer of 2016. The radar group in the Institute of Space and Atmospheric Studies (ISAS) at the University of Saskatchewan is designing and building the radar which will be located near the university in Saskatoon, SK, Canada and will have a field of view over Wollaston Lake in northern Saskatchewan. This novel radar will simultaneously obtain high spatial and temporal resolution through the use of a bistatic setup and pulse modulation techniques. The bistatic setup allows the radar to transmit and receive continuously, while pulse modulation techniques allow for enhanced spatial resolution, only constrained by the radio bandwidth licensing available. A ten antenna array will be used on both the transmitter and receiver sides, with each antenna having an independent radio path. This enables complete digital control of the transmitted 1 kW signal at each antenna, allowing for digital beam steering and multimode broadcasting. On the receiver side the raw digitized signal will be recorded from each antenna, allowing for complete digital post-processing to be performed on the data. From the measurements provided using these modern digital radar capabilities, further insights into the physics of E-region phenomena, such as Alfvén waves propagating from the magnetosphere above and ionospheric irregularities, may be investigated.

  1. Planar near-field scanning for compact range bistatic radar cross-section measurement. Thesis Final Report

    NASA Technical Reports Server (NTRS)

    Tuhela-Reuning, S. R.; Walton, E. K.

    1991-01-01

    The design, construction, and testing of a low cost, planar scanning system to be used in a compact range environment for bistatic radar cross-section (bistatic RCS) measurement data are discussed. This scanning system is similar to structures used for measuring near-field antenna patterns. A synthetic aperture technique is used for plane wave reception. System testing entailed comparison of measured and theoretical bistatic RCS of a sphere and a right circular cylinder. Bistatic scattering analysis of the ogival target support, target and pedestal interactions, and compact range room was necessary to determine measurement validity.

  2. Breast surface estimation for radar-based breast imaging systems.

    PubMed

    Williams, Trevor C; Sill, Jeff M; Fear, Elise C

    2008-06-01

    Radar-based microwave breast-imaging techniques typically require the antennas to be placed at a certain distance from or on the breast surface. This requires prior knowledge of the breast location, shape, and size. The method proposed in this paper for obtaining this information is based on a modified tissue sensing adaptive radar algorithm. First, a breast surface detection scan is performed. Data from this scan are used to localize the breast by creating an estimate of the breast surface. If required, the antennas may then be placed at specified distances from the breast surface for a second tumor-sensing scan. This paper introduces the breast surface estimation and antenna placement algorithms. Surface estimation and antenna placement results are demonstrated on three-dimensional breast models derived from magnetic resonance images.

  3. Development and Evaluation of a Multistatic Ultrawideband Random Noise Radar

    DTIC Science & Technology

    2010-03-01

    noncoherent MIMO investigates 13 a statistical diversity gain available to systems with widely separated antennas per- forming a distributed detection...design. When widely distributed antenna are operating as a MIMO radar system, research shows a noncoherent signal gain is realized, if there exists

  4. Two microstrip arrays for interferometric SAR applications

    NASA Technical Reports Server (NTRS)

    Huang, J.

    1993-01-01

    Two types of C-band aircraft interferometric Synthetic Aperture Radar (SAR) are being developed at JPL to measure the ocean wave characteristics. Each type requires two identical antennas with each having a long rectangular aperture to radiate fan-shaped beam(s). One type of these radars requires each of its antennas to radiate a broadside beam that will measure the target's cross-track velocity. The other type, having each of its antennas to radiate two off-broadside pointed beams, will allow the measurement of both the cross-track and the along-track velocities of the target. Because flush mounting of the antenna on the aircraft fuselage is desirable, microstrip patch array is selected for these interferometric SAR antennas. To meet the radar system requirement, each array needs a total of 76 microstrip patches which are arranged in a 38 x 2 rectangular aperture with a physical size of 1.6m x 16.5cm. To minimize the insertion loss and physical real estate of this relatively long array, a combined series/parallel feed technique is used. Techniques to suppress cross-pol radiation and to effectively utilize the RF power are also implemented. Cross-pol level of lower than -30 dB from the co-pol peak and low insertion loss of 0.36 dB have been achieved for both types of arrays. For the type of radar that requires two off-braodside pointed beams, a simple phasing technique is used to achieve this dual-beam capability with adequate antenna gain (20 dBi) and sidelobe level (-14 dB). Both radar arrays have been flight tested on aircraft with excellent antenna performance demonstrated.

  5. The Spaceborne Imaging Radar program: SIR-C - The next step toward EOS

    NASA Technical Reports Server (NTRS)

    Evans, Diane; Elachi, Charles; Cimino, Jobea

    1987-01-01

    The NASA Shuttle Imaging Radar SIR-C experiments will investigate earth surface and environment phenomena to deepen understanding of terra firma, biosphere, hydrosphere, cryosphere, and atmosphere components of the earth system, capitalizing on the observational capabilities of orbiting multiparameter radar sensors alone or in combination with other sensors. The SIR-C sensor encompasses an antenna array, an exciter, receivers, a data-handling network, and the ground SAR processor. It will be possible to steer the antenna beam electronically, so that the radar look angle can be varied.

  6. 4. View of northerly DR 3 antenna looking north 35 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. View of northerly DR 3 antenna looking north 35 degrees west and showing radar scanner building no. 106 east face through antenna and partial view of satcom communication dome (attached to radar transmitter building 102) in left side of photograph. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  7. Design considerations for MST radar antennas

    NASA Technical Reports Server (NTRS)

    Bowhill, S. A.

    1983-01-01

    The design of antenna systems for radar capable of probing the mesosphere are discussed. The spatial wavelength dependency of turbulent advected ionization are cut off rapidly below wavelengths of about 3 m, imply frequencies of 100 MHz and below. The frequency and aperture requirements point to an array antenna of some kind as the most economical solution. Such an array could consist of dipoles or more directive elements; these elements can be either active or passive.

  8. Performance Analysis for Joint Target Parameter Estimation in UMTS-Based Passive Multistatic Radar with Antenna Arrays Using Modified Cramér-Rao Lower Bounds.

    PubMed

    Shi, Chenguang; Wang, Fei; Salous, Sana; Zhou, Jianjiang

    2017-10-18

    In this study, the modified Cramér-Rao lower bounds (MCRLBs) on the joint estimation of target position and velocity is investigated for a universal mobile telecommunication system (UMTS)-based passive multistatic radar system with antenna arrays. First, we analyze the log-likelihood redfunction of the received signal for a complex Gaussian extended target. Then, due to the non-deterministic transmitted data symbols, the analytically closed-form expressions of the MCRLBs on the Cartesian coordinates of target position and velocity are derived for a multistatic radar system with N t UMTS-based transmit station of L t antenna elements and N r receive stations of L r antenna elements. With the aid of numerical simulations, it is shown that increasing the number of receiving elements in each receive station can reduce the estimation errors. In addition, it is demonstrated that the MCRLB is not only a function of signal-to-noise ratio (SNR), the number of receiving antenna elements and the properties of the transmitted UMTS signals, but also a function of the relative geometric configuration between the target and the multistatic radar system.The analytical expressions for MCRLB will open up a new dimension for passive multistatic radar system by aiding the optimal placement of receive stations to improve the target parameter estimation performance.

  9. Performance Analysis for Joint Target Parameter Estimation in UMTS-Based Passive Multistatic Radar with Antenna Arrays Using Modified Cramér-Rao Lower Bounds

    PubMed Central

    Wang, Fei; Salous, Sana; Zhou, Jianjiang

    2017-01-01

    In this study, the modified Cramér-Rao lower bounds (MCRLBs) on the joint estimation of target position and velocity is investigated for a universal mobile telecommunication system (UMTS)-based passive multistatic radar system with antenna arrays. First, we analyze the log-likelihood redfunction of the received signal for a complex Gaussian extended target. Then, due to the non-deterministic transmitted data symbols, the analytically closed-form expressions of the MCRLBs on the Cartesian coordinates of target position and velocity are derived for a multistatic radar system with Nt UMTS-based transmit station of Lt antenna elements and Nr receive stations of Lr antenna elements. With the aid of numerical simulations, it is shown that increasing the number of receiving elements in each receive station can reduce the estimation errors. In addition, it is demonstrated that the MCRLB is not only a function of signal-to-noise ratio (SNR), the number of receiving antenna elements and the properties of the transmitted UMTS signals, but also a function of the relative geometric configuration between the target and the multistatic radar system.The analytical expressions for MCRLB will open up a new dimension for passive multistatic radar system by aiding the optimal placement of receive stations to improve the target parameter estimation performance. PMID:29057805

  10. Ground penetrating radar antenna system analysis for prediction of earth material properties

    USGS Publications Warehouse

    Oden, C.P.; Wright, D.L.; Powers, M.H.; Olhoeft, G.

    2005-01-01

    The electrical properties of the ground directly beneath a ground penetrating radar (GPR) antenna very close to the earth's surface (ground-coupled) must be known in order to predict the antenna response. In order to investigate changing antenna response with varying ground properties, a series of finite difference time domain (FDTD) simulations were made for a bi-static (fixed horizontal offset between transmitting and receiving antennas) antenna array over a homogeneous ground. We examine the viability of using an inversion algorithm based on the simulated received waveforms to estimate the material properties of the earth near the antennas. Our analysis shows that, for a constant antenna height above the earth, the amplitude of certain frequencies in the received signal can be used to invert for the permittivity and conductivity of the ground. Once the antenna response is known, then the wave field near the antenna can be determined and sharper images of the subsurface near the antenna can be made. ?? 2005 IEEE.

  11. Specification for a standard radar sea clutter model

    NASA Astrophysics Data System (ADS)

    Paulus, Richard A.

    1990-09-01

    A model for the average sea clutter radar cross section is proposed for the Oceanographic and Atmospheric Master Library. This model is a function of wind speed (or sea state), wind direction relative to the antenna, refractive conditions, radar antenna height, frequency, polarization, horizontal beamwidth, and compressed pulse length. The model is fully described, a FORTRAN 77 computer listing is provided, and test cases are given to demonstrate the proper operation of the program.

  12. Assessment of Gravity Wave Momentum Flux Measurement Capabilities by Meteor Radars Having Different Transmitter Power and Antenna Configurations

    NASA Technical Reports Server (NTRS)

    Fritts, D. C.; Janches, D.; Hocking, W. K.; Mitchell, N. J.; Taylor, M. J.

    2011-01-01

    Measurement capabilities of five meteor radars are assessed and compared to determine how well radars having different transmitted power and antenna configurations perform in defining mean winds, tidal amplitudes, and gravity wave (GW) momentum fluxes. The five radars include two new-generation meteor radars on Tierra del Fuego, Argentina (53.8 deg S) and on King George Island in the Antarctic (62.1 deg S) and conventional meteor radars at Socorro, New Mexico (34.1 deg N, 106.9 deg W), Bear Lake Observatory, Utah (approx 41.9 deg N, 111.4 deg W), and Yellowknife, Canada (62.5 deg N, 114.3 deg W). Our assessment employs observed meteor distributions for June of 2009, 2010, or 2011 for each radar and a set of seven test motion fields including various superpositions of mean winds, constant diurnal tides, constant and variable semidiurnal tides, and superposed GWs having various amplitudes, scales, periods, directions of propagation, momentum fluxes, and intermittencies. Radars having higher power and/or antenna patterns yielding higher meteor counts at small zenith angles perform well in defining monthly and daily mean winds, tidal amplitudes, and GW momentum fluxes, though with expected larger uncertainties in the daily estimates. Conventional radars having lower power and a single transmitting antenna are able to describe monthly mean winds and tidal amplitudes reasonably well, especially at altitudes having the highest meteor counts. They also provide qualitative estimates of GW momentum fluxes at the altitudes having the highest meteor counts; however, these estimates are subject to uncertainties of approx 20 to 50% and uncertainties rapidly become excessive at higher and lower altitudes. Estimates of all quantities degrade somewhat for more complex motion fields.

  13. Improvement of antenna decoupling in radar systems

    NASA Astrophysics Data System (ADS)

    Anchidin, Liliana; Topor, Raluca; Tamas, Razvan D.; Dumitrascu, Ana; Danisor, Alin; Berescu, Serban

    2015-02-01

    In this paper we present a type of antipodal Vivaldi antenna design, which can be used for pulse radiation in UWB communication. The Vivaldi antenna is a special tapered slot antenna with planar structure which is easily to be integrated with transmitting elements and receiving elements to form a compact structure. When the permittivity is very large, the wavelength of slot mode is so short that the electromagnetic fields concentrate in the slot to form an effective and balanced transmission line. Due to its simple structure and small size the Vivaldi antennas are one of the most popular designs used in UWB applications. However, for a two-antenna radar system, there is a high mutual coupling between two such antennas due to open configuration. In this paper, we propose a new method for reducing this effect. The method was validated by simulating a system of two Vivaldi antennas in front of a standard target.

  14. STS-59 payload SIR-C/X-SAR antenna view

    NASA Image and Video Library

    1993-10-30

    S93-48551 (October 1993) --- The Spaceborne Imaging Radar-C and X-Band Synthetic Aperture Radar (SIR-C/X-SAR) antenna, developed by the Jet Propulsion Laboratory (JPL) as part of NASA's Mission to Planet Earth (MTPE), will fly aboard the Space Shuttle Endeavour. The radar antenna uses microwave energy which gives it the ability to collect data over virtually any region at any time, regardless of weather or sunlight conditions. The radar waves can penetrate clouds, and under certain conditions the radar can also see through vegetation, ice and dry sand. In many cases, spaceborne radar is the only way scientists can explore large-scale and inaccessible regions of the Earth's surface. SIR-C/X-SAR uses three microwave wavelengths: L-Band (24 cm), C-Band (6 cm) and X-Ban (3 cm). The multi-frequency data will be used by the international scientific community to monitor global environmental processes with a focus on climate change. The MTPE spaceborne data, complemented by aircraft and ground studies, will give scientists clearer insights into those environmental changes which are caused by nature and those changes which are induced by human activity.

  15. An Airborne Radar Model For Non-Uniformly Spaced Antenna Arrays

    DTIC Science & Technology

    2006-03-01

    Department of Defense, or the United States Government . AFIT-GE-ENG-06-58 An Airborne Radar Model For Non-Uniformly Spaced Antenna Arrays THESIS Presented...different circular arrays, one containing 24 elements and one containing 15 elements. The circular array per- formance is compared to that of a 6 × 6...model and compared to the radar model of [5, 6, 13]. The two models are mathematically equivalent when the uniformly spaced array is linear. The two

  16. The UAH/NSSTC Advanced Radar for Meteorological and Operational Research (ARMOR)

    NASA Technical Reports Server (NTRS)

    Petersen, Walter A.; Knupp, Kevin; Carey, Lawrence D.; Phillips, Dustin; Deierling, Wiebke; Gatlin, Patrick

    2009-01-01

    The past four years have seen a marked enhancement in meteorological-radar infrastructure and radar-research capability at the University of Alabama-Huntsville (UAH) and National Space Science and Technology Center (NSSTC; a collaborative center supported by UAH, NASA-MSFC and USRA). This enhancement is due in part to the development of the ARMOR C-band dual-polarimetric radar facility (amongst other mobile radar facilities also discussed in this conference). The ARMOR radar, located at Huntsville International Airport, originated as a unique collaboration between university, government and broadcast meteorologists (the very first of its kind relative to concurrent operational, research and broadcast applications of dual-polarimetry). Contributions from each of these entities resulted in the upgrade of a surplus National Weather Service WSR-74C radar to a research-grade C-band polarimetric radar. The initial upgrade of the radar took place in late 2004 with WHNT-TV purchase and installation of a SIGMET (now Vaisala) Antenna Mounted Receiver (AMR), RVP8/RCP8 radar processor/antenna controller, new radome, and a new dual-polarimetric antenna feed. The AMR enabled simultaneous transmit and receive (STSR) capability and hence collection of dual-polarimetric moments. During the initial part of the AMR upgrade the original WSR74C antenna reflector and 250 kW magnetron-transmitter were used. In early 2005, a new 350 kW magnetron transmitter was purchased from Baron Services and installed. In October of 2006 a new high performance parabolic antenna and dual-pol feed (Seavey) were installed together with a new Orbit pedestal. ARMOR Radar control and data delivery are facilitated through the use of T-1 lines that run from the airport to both NSSTC and WHNT-TV in Huntsville. Under current operating protocols radar scanning and product development are completed at NSSTC, though meteorologists at WHNT-TV can also control the radar if desired. In its default scanning configuration the radar is operated 24/7 in an STSR polarimetric rain scan mode alternating with a surveillance scan on a 5-minute cycle; scans separated by 2.5 minutes. Every 2.5 minutes the raw data arrive at NSSTC where they are corrected in real time for attenuation and differential attenuation (using a constrained ZDR/Z-PHI approach) and new products are generated (e.g., rain maps, hydrometeor identification etc.). The raw and derived products are archived at NSSTC and also redistributed locally in real time over the network within NSSTC to the National Weather Service Forecast Office in Huntsville (collocated with NSSTC) for operational use. During periods of interesting weather the radar is often operated in full, sector, or RHI volume modes from NSSTC and coincident with UAH mobile radar or NWS NEXRAD radar platforms as needed.

  17. Radar Imaging with a Network of Digital Noise Radar Systems

    DTIC Science & Technology

    2009-03-01

    This chapter develops the theoretical foundations of noise radar technology. Comprehensive theoretical models are developed for UWB noise radar, digital...Power to the Antenna +23 dBm Polarization HH Antenna Gain 6 dB ADC 8 Bits Sampling Rate 1.5 GHz/per channel Dynamic Range (0.8 Pd, 0.2 Pf ) 20 dB Range...from Eq. 3.25, can be found by solving Eq. 3.23 for E[XY ]. µrXY = E[XY ] = 〈xy〉 = ρσ2 (3.26) σrXY , from Eq. 3.25 can be derived through the

  18. Time-Varying Vocal Folds Vibration Detection Using a 24 GHz Portable Auditory Radar

    PubMed Central

    Hong, Hong; Zhao, Heng; Peng, Zhengyu; Li, Hui; Gu, Chen; Li, Changzhi; Zhu, Xiaohua

    2016-01-01

    Time-varying vocal folds vibration information is of crucial importance in speech processing, and the traditional devices to acquire speech signals are easily smeared by the high background noise and voice interference. In this paper, we present a non-acoustic way to capture the human vocal folds vibration using a 24-GHz portable auditory radar. Since the vocal folds vibration only reaches several millimeters, the high operating frequency and the 4 × 4 array antennas are applied to achieve the high sensitivity. The Variational Mode Decomposition (VMD) based algorithm is proposed to decompose the radar-detected auditory signal into a sequence of intrinsic modes firstly, and then, extract the time-varying vocal folds vibration frequency from the corresponding mode. Feasibility demonstration, evaluation, and comparison are conducted with tonal and non-tonal languages, and the low relative errors show a high consistency between the radar-detected auditory time-varying vocal folds vibration and acoustic fundamental frequency, except that the auditory radar significantly improves the frequency-resolving power. PMID:27483261

  19. Time-Varying Vocal Folds Vibration Detection Using a 24 GHz Portable Auditory Radar.

    PubMed

    Hong, Hong; Zhao, Heng; Peng, Zhengyu; Li, Hui; Gu, Chen; Li, Changzhi; Zhu, Xiaohua

    2016-07-28

    Time-varying vocal folds vibration information is of crucial importance in speech processing, and the traditional devices to acquire speech signals are easily smeared by the high background noise and voice interference. In this paper, we present a non-acoustic way to capture the human vocal folds vibration using a 24-GHz portable auditory radar. Since the vocal folds vibration only reaches several millimeters, the high operating frequency and the 4 × 4 array antennas are applied to achieve the high sensitivity. The Variational Mode Decomposition (VMD) based algorithm is proposed to decompose the radar-detected auditory signal into a sequence of intrinsic modes firstly, and then, extract the time-varying vocal folds vibration frequency from the corresponding mode. Feasibility demonstration, evaluation, and comparison are conducted with tonal and non-tonal languages, and the low relative errors show a high consistency between the radar-detected auditory time-varying vocal folds vibration and acoustic fundamental frequency, except that the auditory radar significantly improves the frequency-resolving power.

  20. Ground-based measurements of inflight antenna patterns for imaging radar systems

    NASA Astrophysics Data System (ADS)

    Seifert, Pedro; Lentz, Harald; Zink, Manfred; Heel, Franz

    1992-11-01

    An approach is presented on how to determine the inflight antenna pattern in the cross-track direction for air- and spaceborne synthetic aperture radar (SAR) systems. In the 1991 Oberpfaffenhofen DC-8/E-SAR calibration campaign there was a good opportunity to test ground-based measurement equipment comprising 18 precision calibration receivers and nine polarimetric active radar calibrators (PARC's), all operating in C-band. These devices were designed and manufactured by the Institute of Navigation at the University of Stuttgart (INS). These instruments are capable of handling various pulse lengths, PRF's, and have a very high dynamic range. Together with precise internal clocks, these instruments are suitable for recording the actual radar transmit pulse shape for the later evaluation of the desired inflight antenna pattern. Lining up these devices in the cross-track direction, each receiver yields an azimuth cut of the three-dimensional antenna pattern. The elevation pattern was then obtained by time correlation of these azimuth cuts. Further results concerning pulse shapes, squint angles, and H-V pattern misalignment are presented.

  1. Planetary Radar Imaging with the Deep-Space Network's 34 Meter Uplink Array

    NASA Technical Reports Server (NTRS)

    Vilnrotter, V.; Tsao, P.; Lee, D.; Cornish, T.; Jao, J.; Slade, M.

    2011-01-01

    A coherent uplink array consisting of up to three 34-meter antennas of NASA's Deep Space Network has been developed for the primary purpose of increasing EIRP at the spacecraft. Greater EIRP ensures greater reach, higher uplink data rates for command and configuration control, as well as improved search and recovery capabilities during spacecraft emergencies. It has been conjectured that Doppler-delay radar imaging of lunar targets can be extended to planetary imaging, where the long baseline of the uplink array can provide greater resolution than a single antenna, as well as potentially higher EIRP. However, due to the well known R-4 loss in radar links, imaging of distant planets is a very challenging endeavor, requiring accurate phasing of the Uplink Array antennas, cryogenically cooled low-noise receiver amplifiers, and sophisticated processing of the received data to extract the weak echoes characteristic of planetary radar. This article describes experiments currently under way to image the planets Mercury and Venus, highlights improvements in equipment and techniques, and presents planetary images obtained to date with two 34 meter antennas configured as a coherently phased Uplink Array.

  2. Planetary Radar Imaging with the Deep-Space Network's 34 Meter Uplink Array

    NASA Technical Reports Server (NTRS)

    Vilnrotter, Victor; Tsao, P.; Lee, D.; Cornish, T.; Jao, J.; Slade, M.

    2011-01-01

    A coherent Uplink Array consisting of two or three 34-meter antennas of NASA's Deep Space Network has been developed for the primary purpose of increasing EIRP at the spacecraft. Greater EIRP ensures greater reach, higher uplink data rates for command and configuration control, as well as improved search and recovery capabilities during spacecraft emergencies. It has been conjectured that Doppler-delay radar imaging of lunar targets can be extended to planetary imaging, where the long baseline of the uplink array can provide greater resolution than a single antenna, as well as potentially higher EIRP. However, due to the well known R4 loss in radar links, imaging of distant planets is a very challenging endeavor, requiring accurate phasing of the Uplink Array antennas, cryogenically cooled low-noise receiver amplifiers, and sophisticated processing of the received data to extract the weak echoes characteristic of planetary radar. This article describes experiments currently under way to image the planets Mercury and Venus, highlights improvements in equipment and techniques, and presents planetary images obtained to date with two 34 meter antennas configured as a coherently phased Uplink Array.

  3. Large Phased Array Radar Using Networked Small Parabolic Reflectors

    NASA Technical Reports Server (NTRS)

    Amoozegar, Farid

    2006-01-01

    Multifunction phased array systems with radar, telecom, and imaging applications have already been established for flat plate phased arrays of dipoles, or waveguides. In this paper the design trades and candidate options for combining the radar and telecom functions of the Deep Space Network (DSN) into a single large transmit array of small parabolic reflectors will be discussed. In particular the effect of combing the radar and telecom functions on the sizes of individual antenna apertures and the corresponding spacing between the antenna elements of the array will be analyzed. A heterogeneous architecture for the DSN large transmit array is proposed to meet the radar and telecom requirements while considering the budget, scheduling, and strategic planning constrains.

  4. Study to investigate and evaluate means of optimizing the radar function for the space shuttle

    NASA Technical Reports Server (NTRS)

    1976-01-01

    A detailed analysis of the spiral scan was performed for antenna sizes ranging from 20 inches to 36 inches in diameter and for search angles characteristic of both the radar and the communication acquisition modes. The power budgets for passive target radar detection were calculated for antenna diameters ranging from 20 to 36 inches. Dwell times commensurate with spiral scan were used for these budget calculations. The signal design for the candidate pulse Doppler system is summarized. Ground return analysis carried out for the passive target radar mode is examined, and the details are presented. A concluding description of the proposed candidate radar/communication system configuration is given.

  5. A validation study of the simulation software gprMax by varying antenna stand-off height

    NASA Astrophysics Data System (ADS)

    Wilkinson, Josh; Davidson, Nigel

    2018-04-01

    The design and subsequent testing of suitable antennas and of complete ground-penetrating radar (GPR) systems can be both time consuming and expensive, with the need to understand the performance of a system in realistic environments of great importance to the end user. Through the use of suitably validated simulations, these costs could be significantly reduced, allowing an economical capability to be built which can accurately predict the performance of novel GPR antennas and existing commercial-off-the-shelf (COTS) systems in a user defined environment. This paper focuses on a preliminary validation of the open source software gprMax1 which features the ability to custom define antennas, targets, clutter objects and realistic heterogeneous soils. As an initial step in the assessment of the software, a comparison of the modelled response of targets buried in sand to experimental data has been undertaken, with the variation in response with antenna stand-off height investigated. This was conducted for both a simple bespoke bow-tie antenna design as well as for a Geophysical Survey Systems, Inc. (GSSI) commercial system,2 building upon previous work3 which explored the fidelity of gprMax in reproducing the S11 of simple antenna designs.

  6. UHF Antenna Design for AFIT Random Noise Radar

    DTIC Science & Technology

    2012-03-01

    relatives of monopole , dipole, and slot antennas. One particularly interesting style amongst these is the Vivaldi antenna. There are two primary... monopole versions using Earth’s surface as a ground plane [26]. Antenna design and construction caught up with these early innovations over the next...Frequency independent antennas  Electric antennas (e.g. dipoles and monopoles )  Magnetic antennas (e.g. loops)  Electrically small antennas

  7. Determination of antennae patterns and radar reflection characteristics of aircraft

    NASA Astrophysics Data System (ADS)

    Bothe, H.; MacDonald, D.; Pool, A.

    1986-05-01

    The different types of aircraft antennas, their radiation characteristics and their preferred siting on the airframe are described. Emphasis is placed on the various methods for determining aircraft antenna radiation patterns (ARP) and advantages, disadvantages and limitations of each method are indicated. Mathematical modelling, model measurements and in-flight measurements in conjunction with the applied flight test techniques are included. Examples of practical results are given. Methods of determining aircraft radar characteristics are also described, indicating advantages, disadvantages and limitations of each method. Relevant fundamentals of radar theory are included only as necessary to appreciation of the real meaning of radar cross section (RCS) and angular glint. The measuring methods included are dynamic full-scale, static full-scale, sub-scale optical, ultrasonic and radio modelling. References are made to RCS measuring facilities in the USA and Europe and the UK Radio Modelling Facility is used extensively to exemplify the sub scale technique.

  8. The 8-18 GHz radar spectrometer

    NASA Technical Reports Server (NTRS)

    Bush, T. F.; Ulaby, F. T.

    1973-01-01

    The design, construction, testing, and accuracy of an 8-18 GHz radar spectrometer, an FM-CW system which employs a dual antenna system, is described. The antennas, transmitter, and a portion of the receiver are mounted at the top of a 26 meter hydraulic boom which is in turn mounted on a truck for system mobility. HH and VV polarized measurements are possible at incidence angles ranging from 0 deg. to 80 deg. Calibration is accomplished by referencing the measurements against a Luneberg lens of known radar cross section.

  9. System and method for measuring ocean surface currents at locations remote from land masses using synthetic aperture radar

    NASA Technical Reports Server (NTRS)

    Young, Lawrence E. (Inventor)

    1991-01-01

    A system for measuring ocean surface currents from an airborne platform is disclosed. A radar system having two spaced antennas wherein one antenna is driven and return signals from the ocean surface are detected by both antennas is employed to get raw ocean current data which are saved for later processing. There are a pair of global positioning system (GPS) systems including a first antenna carried by the platform at a first location and a second antenna carried by the platform at a second location displaced from the first antenna for determining the position of the antennas from signals from orbiting GPS navigational satellites. Data are also saved for later processing. The saved data are subsequently processed by a ground-based computer system to determine the position, orientation, and velocity of the platform as well as to derive measurements of currents on the ocean surface.

  10. Development and Observation of the Phase Array Radar at X band

    NASA Astrophysics Data System (ADS)

    Ushio, T.; Shimamura, S.; Wu, T.; Kikuchi, H.; Yoshida, S.; Kawasaki, Z.; Mizutani, F.; Wada, M.; Satoh, S.; Iguchi, T.

    2013-12-01

    A new Phased Array Radar (PAR) system for thunderstorm observation has been developed by Toshiba Corporation and Osaka University under a grant of NICT, and installed in Osaka University, Japan last year. It is now well known that rapidly evolving severe weather phenomena (e.g., microbursts, severe thunderstorms, tornadoes) are a threat to our lives particularly in a densely populated area and is closely related to the production of lightning discharges. Over the past decade, mechanically rotating radar systems at the C-band or S-band have been proved to be effective for weather surveillance especially in a wide area more than 100 km in range. However, severe thunderstorm sometimes develops rapidly on the temporal and spatial scales comparable to the resolution limit (-10 min. and -500m) of typical S-band or C-band radar systems, and cannot be fully resolved with these radar systems. In order to understand the fundamental process and dynamics of such fast changing weather phenomena like lightning and tornado producing thunderstorm, volumetric observations with both high temporal and spatial resolution are required. The phased array radar system developed has the unique capability of scanning the whole sky with 100m and 10 to 30 second resolution up to 60 km. The system adopts the digital beam forming technique for elevation scanning and mechanically rotates the array antenna in azimuth direction within 10 to 30 seconds. The radar transmits a broad beam of several degrees with 24 antenna elements and receives the back scattered signal with 128 elements digitizing at each elements. Then by digitally forming the beam in the signal processor, the fast scanning is realized. After the installation of the PAR system in Osaka University, the initial observation campaign was conducted in Osaka urban area with Ku-band Broad Band Radar (BBR) network, C-band weather radar, and lightning location system. The initial comparison with C band radar system shows that the developed PAR system can observe the behavior of the thunderstorm structure in much more detail than any other radar system. The observed high temporal resolution images of the severe thunderstorm and lightning are introduced, showing the potential capabilities of the PAR and lightning location system.

  11. Joint stars phased array radar antenna

    NASA Astrophysics Data System (ADS)

    Shnitkin, Harold

    1994-10-01

    The Joint STARS phased array radar system is capable of performing long range airborne surveillance and was used during the Persian Gulf war on two E8-A aircraft to fly many around-the-clock missions to monitor the Kuwait and Iraq battlefield from a safe distance behind the front lines. This paper is a follow-on to previous publications on the subject of the Joint STARS antenna and deals mainly with mission performance and technical aspects not previously covered. Radar data of troop movements and armament installations will be presented, a brief review of the antenna design is given, followed by technical discussions concerning the three-port interferometry, gain and sidelobe design approach, cost control, range test implementation and future improvements.

  12. Design of a Forward Looking Synthetic Aperture Radar for an Autonomous Cryobot for Subsurface Exploration of Europa and Enceladus

    NASA Astrophysics Data System (ADS)

    Pradhan, O.; Gasiewski, A. J.; Stone, W.

    2017-12-01

    We present the design, analyses and field testing of a forward-looking endfire synthetic aperture radar (SAR) for the `Very deep Autonomous Laser-powered Kilowatt-class Yo-yoing Robotic Ice explorer' (VALKYRIE) ice-penetrating cryobot. This design demonstrates critical technologies that will support an eventual landing and ice penetrating mission to Jupiter's icy moon, Europa. The project consists of (1) design of an array of four conformal cavity-backed log-periodic folded slot dipole array (LPFSA) antennas that form the radiating elements, (2) design of a radar system that includes RF signal generation, 4x4 transmit-receive antenna switching and isolation and digital SAR data processing and (3) field testing of the SAR system. The antennas were designed, fabricated, and lab tested at the Center for Environmental Technology (CET) at CU-Boulder. The radar analog and digital system were also designed and integrated at CET utilizing rugged RF components and FPGA based digital waveform generation. Field testing was performed in conjunction with VALKYRIE tests by Stone Aerospace in June, 2015 on Matanuska Glacier, Alaska. In this presentation we will describe in detail the following aspects pertaining to the design, analysis and testing of the endfire SAR system; (1) Waveform generation capability of the radar as well as transmit and receive channel calibration (2) Theoretical analysis of the radial resolution improvement made possible by using the radar in an endfire SAR mode along with the free space radar tests performed to validate the proposed endfire SAR system (3) A method for azimuth ambiguity resolution by operating the endfire SAR in a bistatic mode (4) Modal analysis of the layered cylindrical LPFSA antenna structure and a forward model of the wave propagation path through planar layered ice medium and (5) Analysis and interpretation of the in-situ measurements of the antennas and endfire SAR operation on the Matanuska glacier.

  13. Shuttle orbiter Ku-band radar/communications system design evaluation: High gain antenna/widebeam horn

    NASA Technical Reports Server (NTRS)

    Iwasaki, R.; Dodds, J. G.; Broad, P.

    1979-01-01

    The physical characteristics of the high gain antenna reflector and feed elements are described. Deficiencies in the sum feed are discussed, and lack of atmospheric venting is posed as a potential problem area. The measured RF performance of the high gain antenna is examined and the high sidelobe levels measured are related to the physical characteristics of the antenna. An examination of the attributes of the feed which might be influenced by temperature extremes shows that the antenna should be insensitive to temperature variations. Because the feed support bipod structure is considered a significant contributor to the high sidelobe levels measured in the azimuth plane, pod relocation, material changes, and shaping are suggested as improvements. Alternate feed designs are presented to further improve system performance. The widebeam horn and potential temperature effects due to the polarizer are discussed as well as in the effects of linear polarization on TDRS acquisition, and the effects of circular polarization on radar sidelobe avoidance. The radar detection probability is analyzed as a function of scan overlap and target range.

  14. Electromagnetic Performances Analysis of an Ultra-wideband and Flexible Material Antenna in Microwave Breast Imaging: To Implement A Wearable Medical Bra.

    PubMed

    Rahman, Ashiqur; Islam, Mohammad Tariqul; Singh, Mandeep Jit; Kibria, Salehin; Akhtaruzzaman, Md

    2016-12-23

    In this paper, we report a compact and ultra-wide band antenna on a flexible substrate using the 5-(4-(perfluorohexyl)phenyl)thiophene-2-carbaldehyde compound for microwave imaging. In contrast to other microwave based imaging systems, such as an array of 16 antennas, we proposed a bi-static radar based imaging system consisting of two omnidirectional antennas, which reduces complexity and the overall dimension. The proposed compact antennas are 20 × 14 mm 2 and designed for operating at frequencies from 4 to 6 GHz. To allow for implantation into a bra, the electromagnetic performances of the antennas must be considered in bending conditions. In comparison with the recently reported flexible antennas, we demonstrated both electromagnetic performance and imaging reconstruction for bending conditions. For the proof of concept, the electromagnetic performances both at flat and bending conditions have been verified using a homogeneous multilayer model of the human breast phantom. Our results demonstrate that the antenna, even at bending conditions, exhibits an excellent omni-directional radiation pattern with an average efficiency above 70% and average gain above 1 dBi, within the operational frequency band. The comprehensive aim of the realized antenna is to design a biodegradable and wearable antenna-based bra for early breast cancer detection in the future.

  15. Electromagnetic Performances Analysis of an Ultra-wideband and Flexible Material Antenna in Microwave Breast Imaging: To Implement A Wearable Medical Bra

    NASA Astrophysics Data System (ADS)

    Rahman, Ashiqur; Islam, Mohammad Tariqul; Singh, Mandeep Jit; Kibria, Salehin; Akhtaruzzaman, Md.

    2016-12-01

    In this paper, we report a compact and ultra-wide band antenna on a flexible substrate using the 5-(4-(perfluorohexyl)phenyl)thiophene-2-carbaldehyde compound for microwave imaging. In contrast to other microwave based imaging systems, such as an array of 16 antennas, we proposed a bi-static radar based imaging system consisting of two omnidirectional antennas, which reduces complexity and the overall dimension. The proposed compact antennas are 20 × 14 mm2 and designed for operating at frequencies from 4 to 6 GHz. To allow for implantation into a bra, the electromagnetic performances of the antennas must be considered in bending conditions. In comparison with the recently reported flexible antennas, we demonstrated both electromagnetic performance and imaging reconstruction for bending conditions. For the proof of concept, the electromagnetic performances both at flat and bending conditions have been verified using a homogeneous multilayer model of the human breast phantom. Our results demonstrate that the antenna, even at bending conditions, exhibits an excellent omni-directional radiation pattern with an average efficiency above 70% and average gain above 1 dBi, within the operational frequency band. The comprehensive aim of the realized antenna is to design a biodegradable and wearable antenna-based bra for early breast cancer detection in the future.

  16. An Accurate Method for Measuring Airplane-Borne Conformal Antenna's Radar Cross Section

    NASA Astrophysics Data System (ADS)

    Guo, Shuxia; Zhang, Lei; Wang, Yafeng; Hu, Chufeng

    2016-09-01

    The airplane-borne conformal antenna attaches itself tightly with the airplane skin, so the conventional measurement method cannot determine the contribution of the airplane-borne conformal antenna to its radar cross section (RCS). This paper uses the 2D microwave imaging to isolate and extract the distribution of the reflectivity of the airplane-borne conformal antenna. It obtains the 2D spatial spectra of the conformal antenna through the wave spectral transform between the 2D spatial image and the 2D spatial spectrum. After the interpolation from the rectangular coordinate domain to the polar coordinate domain, the spectral domain data for the variation of the scatter of the conformal antenna with frequency and angle is obtained. The experimental results show that the measurement method proposed in this paper greatly enhances the airplane-borne conformal antenna's RCS measurement accuracy, essentially eliminates the influences caused by the airplane skin and more accurately reveals the airplane-borne conformal antenna's RCS scatter properties.

  17. KSC-99pp1367

    NASA Image and Video Library

    1999-11-29

    KENNEDY SPACE CENTER, FLA. -- Orbiter Endeavour waits in the Orbiter Processing Facility bay 2 for the closing of its payload bay doors. The Ku-band antenna (upper right) is still in the open position, outside the payload bay. Endeavour is expected to roll over to the Vehicle Assembly Building in three days for mating to the external tank and solid rocket boosters in high bay 1. Space Shuttle Endeavour is targeted for launch on mission STS-99 Jan. 13, 2000 at 1:11 p.m. EST. STS-99 is the Shuttle Radar Topography Mission, an international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR. The SRTM consists of a specially modified radar system that will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. The SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle

  18. KSC-99pp1368

    NASA Image and Video Library

    1999-11-01

    KENNEDY SPACE CENTER, FLA. -- Orbiter Endeavour waits in the Orbiter Processing Facility bay 2 for the closing of its payload bay doors. The Ku-band antenna (upper right) is now in its closed position inside the payload bay. Endeavour is expected to roll over to the Vehicle Assembly Building in three days for mating to the external tank and solid rocket boosters in high bay 1. Space Shuttle Endeavour is targeted for launch on mission STS-99 Jan. 13, 2000 at 1:11 p.m. EST. STS-99 is the Shuttle Radar Topography Mission, an international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR. The SRTM consists of a specially modified radar system that will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. The SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle

  19. Military microwaves '84; Proceedings of the Conference, London, England, October 24-26, 1984

    NASA Astrophysics Data System (ADS)

    The present conference on microwave frequency electronic warfare and military sensor equipment developments consider radar warning receivers, optical frequency spread spectrum systems, mobile digital communications troposcatter effects, wideband bulk encryption, long range air defense radars (such as the AR320, W-2000 and Martello), multistatic radars, and multimode airborne and interceptor radars. IR system and subsystem component topics encompass thermal imaging and active IR countermeasures, class 1 modules, and diamond coatings, while additional radar-related topics include radar clutter in airborne maritime reconnaissance systems, microstrip antennas with dual polarization capability, the synthesis of shaped beam antenna patterns, planar phased arrays, radar signal processing, radar cross section measurement techniques, and radar imaging and pattern analysis. Attention is also given to optical control and signal processing, mm-wave control technology and EW systems, W-band operations, planar mm-wave arrays, mm-wave monolithic solid state components, mm-wave sensor technology, GaAs monolithic ICs, and dielectric resonator and wideband tunable oscillators.

  20. A Doppler centroid estimation algorithm for SAR systems optimized for the quasi-homogeneous source

    NASA Technical Reports Server (NTRS)

    Jin, Michael Y.

    1989-01-01

    Radar signal processing applications frequently require an estimate of the Doppler centroid of a received signal. The Doppler centroid estimate is required for synthetic aperture radar (SAR) processing. It is also required for some applications involving target motion estimation and antenna pointing direction estimation. In some cases, the Doppler centroid can be accurately estimated based on available information regarding the terrain topography, the relative motion between the sensor and the terrain, and the antenna pointing direction. Often, the accuracy of the Doppler centroid estimate can be improved by analyzing the characteristics of the received SAR signal. This kind of signal processing is also referred to as clutterlock processing. A Doppler centroid estimation (DCE) algorithm is described which contains a linear estimator optimized for the type of terrain surface that can be modeled by a quasi-homogeneous source (QHS). Information on the following topics is presented: (1) an introduction to the theory of Doppler centroid estimation; (2) analysis of the performance characteristics of previously reported DCE algorithms; (3) comparison of these analysis results with experimental results; (4) a description and performance analysis of a Doppler centroid estimator which is optimized for a QHS; and (5) comparison of the performance of the optimal QHS Doppler centroid estimator with that of previously reported methods.

  1. Fly eye radar or micro-radar sensor technology

    NASA Astrophysics Data System (ADS)

    Molchanov, Pavlo; Asmolova, Olga

    2014-05-01

    To compensate for its eye's inability to point its eye at a target, the fly's eye consists of multiple angularly spaced sensors giving the fly the wide-area visual coverage it needs to detect and avoid the threats around him. Based on a similar concept a revolutionary new micro-radar sensor technology is proposed for detecting and tracking ground and/or airborne low profile low altitude targets in harsh urban environments. Distributed along a border or around a protected object (military facility and buildings, camp, stadium) small size, low power unattended radar sensors can be used for target detection and tracking, threat warning, pre-shot sniper protection and provides effective support for homeland security. In addition it can provide 3D recognition and targets classification due to its use of five orders more pulses than any scanning radar to each space point, by using few points of view, diversity signals and intelligent processing. The application of an array of directional antennas eliminates the need for a mechanical scanning antenna or phase processor. It radically decreases radar size and increases bearing accuracy several folds. The proposed micro-radar sensors can be easy connected to one or several operators by point-to-point invisible protected communication. The directional antennas have higher gain, can be multi-frequency and connected to a multi-functional network. Fly eye micro-radars are inexpensive, can be expendable and will reduce cost of defense.

  2. Spaced antenna drift

    NASA Technical Reports Server (NTRS)

    Royrvik, O.

    1983-01-01

    It has been suggested that the spaced antenna drift (SAD) technique could be successfully used by VHF radars and that it would be superior to a Doppler-beam-swinging (DBS) technique because it would take advantage of the aspect sensitivity of the scattered signal, and might also benefit from returns from single meteors. It appears, however, that the technique suffers from several limitations. On the basis of one SAD experiment performed at the very large Jicamarca radar, it is concluded that the SAD technique can be compared in accuracy to the DBS technique only if small antenna dimensions are used.

  3. KSC-99pp0974

    NASA Image and Video Library

    1999-07-21

    KENNEDY SPACE CENTER, FLA. -- A crane lowers the Shuttle Radar Topography Mission (SRTM), the primary payload on STS-99, into the payload bay of the orbiter Endeavour in Orbiter Processing Facility bay 2. The SRTM consists of a specially modified radar system that will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation. The SRTM hardware includes one radar antenna in the Shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) from the shuttle. STS-99 is scheduled to launch Sept. 16 at 8:47 a.m. from Launch Pad 39A

  4. KSC-99pp0973

    NASA Image and Video Library

    1999-07-21

    KENNEDY SPACE CENTER, FLA. -- A crane lowers the Shuttle Radar Topography Mission (SRTM), the primary payload on STS-99, into the payload bay of the orbiter Endeavour in Orbiter Processing Facility (OPF) bay 2. The SRTM consists of a specially modified radar system that will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation. The SRTM hardware includes one radar antenna in the Shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) from the shuttle. STS-99 is scheduled to launch Sept. 16 at 8:47 a.m. from Launch Pad 39A

  5. Use of borehole radar tomography to monitor steam injection in fractured limestone

    USGS Publications Warehouse

    Gregoire, C.; Joesten, P.K.

    2006-01-01

    Borehole radar tomography was used as part of a pilot study to monitor steam-enhanced remediation of a fractured limestone contaminated with volatile organic compounds at the former Loring Air Force Base, Maine, USA. Radar tomography data were collected using 100-MHz electric-dipole antennae before and during steam injection to evaluate whether cross-hole radar methods could detect changes in medium properties resulting from the steam injection. Cross-hole levelrun profiles, in which transmitting and receiving antennae are positioned at a common depth, were made before and after the collection of each full tomography data set to check the stability of the radar instruments. Before tomographic inversion, the levelrun profiles were used to calibrate the radar tomography data to compensate for changes in traveltime and antenna power caused by instrument drift. Observed changes in cross-hole radar traveltime and attenuation before and during steam injection were small. Slowness- and attenuation-difference tomograms indicate small increases in radar slowness and attenuation at depths greater than about 22 m below the surface, consistent with increases in water temperature observed in the boreholes used for the tomography. Based on theoretical modelling results, increases in slowness and attenuation are interpreted as delineating zones where steam injection heating increased the electrical conductivity of the limestone matrix and fluid. The results of this study show the potential of cross-hole radar tomography methods to monitor the effects of steam-induced heating in fractured rock environments. ?? 2006 European Association of Geoscientists & Engineers.

  6. Radar cross-section measurements and simulation of a tethered satellite. The small expendable deployer system end-mass payload

    NASA Technical Reports Server (NTRS)

    Cravey, Robin L.; Fralick, Dion T.; Vedeler, Erik

    1995-01-01

    The first Small Expendable Deployer System (SEDS-1), a tethered satellite system, was developed by NASA and launched March 29, 1993 as a secondary payload on a United State Air Force (USAF) Delta-2 launch vehicle. The SEDS-1 successfully deployed an instrumented end-mass payload (EMP) on a 20-km nonconducting tether from the second stage of the Delta 2. This paper describes the effort of NASA Langley Research Center's Antenna and Microwave Research Branch to provide assistance to the SEDS Investigators Working Group (IWG) in determining EMP dynamics by analyzing the mission radar skin track data. The radar cross section measurements taken and simulations done for this study are described and comparisons of the measured data with the simulated data for the EMP at 6 GHz are presented.

  7. Separation of Doppler radar-based respiratory signatures.

    PubMed

    Lee, Yee Siong; Pathirana, Pubudu N; Evans, Robin J; Steinfort, Christopher L

    2016-08-01

    Respiration detection using microwave Doppler radar has attracted significant interest primarily due to its unobtrusive form of measurement. With less preparation in comparison with attaching physical sensors on the body or wearing special clothing, Doppler radar for respiration detection and monitoring is particularly useful for long-term monitoring applications such as sleep studies (i.e. sleep apnoea, SIDS). However, motion artefacts and interference from multiple sources limit the widespread use and the scope of potential applications of this technique. Utilising the recent advances in independent component analysis (ICA) and multiple antenna configuration schemes, this work investigates the feasibility of decomposing respiratory signatures into each subject from the Doppler-based measurements. Experimental results demonstrated that FastICA is capable of separating two distinct respiratory signatures from two subjects adjacent to each other even in the presence of apnoea. In each test scenario, the separated respiratory patterns correlate closely to the reference respiration strap readings. The effectiveness of FastICA in dealing with the mixed Doppler radar respiration signals confirms its applicability in healthcare applications, especially in long-term home-based monitoring as it usually involves at least two people in the same environment (i.e. two people sleeping next to each other). Further, the use of FastICA to separate involuntary movements such as the arm swing from the respiratory signatures of a single subject was explored in a multiple antenna environment. The separated respiratory signal indeed demonstrated a high correlation with the measurements made by a respiratory strap used currently in clinical settings.

  8. The new method to send energy

    NASA Astrophysics Data System (ADS)

    Shin, Philip

    2012-03-01

    I feel the electricity as radar. We can send the energy from antenna to another antenna, and it is moving easy and better than an electrical wire and safe. As a result, the transistor radio is more accurate and move stronger than the digital radio by the fact that electricity flows as a substance. To explain how the energy flows, the trees do not move by itself to hurt man(it is to be.). So the energy flow from antenna to another antenna safely and possibly without hurt as a sword. I understand that energy, the electricity is existing as radar and it proves the fact that how it flows from one place to another.

  9. Application of MIMO Techniques in sky-surface wave hybrid networking sea-state radar system

    NASA Astrophysics Data System (ADS)

    Zhang, L.; Wu, X.; Yue, X.; Liu, J.; Li, C.

    2016-12-01

    The sky-surface wave hybrid networking sea-state radar system contains of the sky wave transmission stations at different sites and several surface wave radar stations. The subject comes from the national 863 High-tech Project of China. The hybrid sky-surface wave system and the HF surface wave system work simultaneously and the HF surface wave radar (HFSWR) can work in multi-static and surface-wave networking mode. Compared with the single mode radar system, this system has advantages of better detection performance at the far ranges in ocean dynamics parameters inversion. We have applied multiple-input multiple-output(MIMO) techniques in this sea-state radar system. Based on the multiple channel and non-causal transmit beam-forming techniques, the MIMO radar architecture can reduce the size of the receiving antennas and simplify antenna installation. Besides, by efficiently utilizing the system's available degrees of freedom, it can provide a feasible approach for mitigating multipath effect and Doppler-spread clutter in Over-the-horizon Radar. In this radar, slow-time phase-coded MIMO method is used. The transmitting waveforms are phase-coded in slow-time so as to be orthogonal after Doppler processing at the receiver. So the MIMO method can be easily implemented without the need to modify the receiver hardware. After the radar system design, the MIMO experiments of this system have been completed by Wuhan University during 2015 and 2016. The experiment used Wuhan multi-channel ionospheric sounding system(WMISS) as sky-wave transmitting source and three dual-frequency HFSWR developed by the Oceanography Laboratory of Wuhan University. The transmitter system located at Chongyang with five element linear equi-spaced antenna array and Wuhan with one log-periodic antenna. The RF signals are generated by synchronized, but independent digital waveform generators - providing complete flexibility in element phase and amplitude control, and waveform type and parameters. The field experimental results show the presented method is effective. The echoes are obvious and distinguishable both in co-located MIMO mode and widely distributed MIMO mode. Key words: sky-surface wave hybrid networking; sea-state radar; MIMO; phase-coded

  10. 3D Target Localization of Modified 3D MUSIC for a Triple-Channel K-Band Radar.

    PubMed

    Li, Ying-Chun; Choi, Byunggil; Chong, Jong-Wha; Oh, Daegun

    2018-05-20

    In this paper, a modified 3D multiple signal classification (MUSIC) algorithm is proposed for joint estimation of range, azimuth, and elevation angles of K-band radar with a small 2 × 2 horn antenna array. Three channels of the 2 × 2 horn antenna array are utilized as receiving channels, and the other one is a transmitting antenna. The proposed modified 3D MUSIC is designed to make use of a stacked autocorrelation matrix, whose element matrices are related to each other in the spatial domain. An augmented 2D steering vector based on the stacked autocorrelation matrix is proposed for the modified 3D MUSIC, instead of the conventional 3D steering vector. The effectiveness of the proposed modified 3D MUSIC is verified through implementation with a K-band frequency-modulated continuous-wave (FMCW) radar with the 2 × 2 horn antenna array through a variety of experiments in a chamber.

  11. A Cloud and Precipitation Radar System Concept for the ACE Mission

    NASA Technical Reports Server (NTRS)

    Durden, S. L.; Tanelli, S.; Epp, L.; Jamnejad, V.; Perez, R.; Prata, A.; Samoska, L.; Long, E; Fang, H.; Esteban-Fernandez, D.; hide

    2011-01-01

    One of the instruments recommended for deployment on the Aerosol/Cloud/Ecosystems (ACE) mission is a new advanced cloud profiling radar. In this paper, we describe such a radar design, called ACERAD, which has 35- and 94-GHz channels, each having Doppler and dual-polarization capabilities. ACERAD will scan at Ka-band and will be nadir-looking at W-band. To get a swath of 25-30 km, considered the minimum useful for Ka-band, ACERAD needs to scan at least 2 degrees off nadir; this is at least 20 beamwidths, which is quite large for a typical parabolic reflector. This problem is being solved with a Dragonian design; a scaled prototype of the antenna is being fabricated and will be tested on an antenna range. ACERAD also uses a quasi-optical transmission line at W-band to connect the transmitter to the antenna and antenna to the receiver. A design for this has been completed and is being laboratory tested. This paper describes the current ACERAD design and status.

  12. Near- and Far-Field Characterization of Planar mm-Wave Antenna Arrays with Waveguide-to-Microstrip Transition

    NASA Astrophysics Data System (ADS)

    Salhi, Mohammed Adnan; Kazemipour, Alireza; Gentille, Gennaro; Spirito, Marco; Kleine-Ostmann, Thomas; Schrader, Thorsten

    2016-09-01

    We present the design and characterization of planar mm-wave patch antenna arrays with waveguide-to-microstrip transition using both near- and far-field methods. The arrays were designed for metrological assessment of error sources in antenna measurement. One antenna was designed for the automotive radar frequency range at 77 GHz, while another was designed for the frequency of 94 GHz, which is used, e.g., for imaging radar applications. In addition to the antennas, a simple transition from rectangular waveguide WR-10 to planar microstrip line on Rogers 3003™ substrate has been designed based on probe coupling. For determination of the far-field radiation pattern of the antennas, we compare results from two different measurement methods to simulations. Both a far-field antenna measurement system and a planar near-field scanner with near-to-far-field transformation were used to determine the antenna diagrams. The fabricated antennas achieve a good matching and a good agreement between measured and simulated antenna diagrams. The results also show that the far-field scanner achieves more accurate measurement results with regard to simulations than the near-field scanner. The far-field antenna scanning system is built for metrological assessment and antenna calibration. The antennas are the first which were designed to be tested with the measurement system.

  13. Study and verification of multibeam ability for a new VHF-radar in northern Norway

    NASA Astrophysics Data System (ADS)

    Renkwitz, Toralf; Singer, Werner; Latteck, Ralph

    2010-05-01

    The Leibniz-Institute of Atmospheric Physics in Kühlungsborn (IAP) has been operating the ALWIN MST radar system at 53.5 MHz on the North-Norwegian island Andoya for more than 10 years. The antenna array of 144 Yagi antennas has been used to form a 6 degree wide beam on transmission and reception. With this radar, the characteristics of Polar Mesospheric Summer Echoes (PMSE) have been investigated with high time resolution. For future studies of horizontal structures of winds, waves, turbulence and PMSE, the IAP is currently building a new advanced VHF-Radar to replace ALWIN. For this purpose an additional module (Butler matrix) for the receiver of this VHF-Radar has been built which allows the generation of multiple beams in azimuth and zenith angles for simultaneous observations. In 2009 IAP started to build the successor system of the ALWIN radar, called MAARSY (Middle Atmosphere Alomar Radar SYstem). In the first step this new system will consist of a phased array of 217 individual 3-element Yagi antennas arranged in an equilateral grid structure and the same amount of transceiver modules. Furthermore 64 Yagi antennas of the former ALWIN antenna array are still available for reception (ALWIN64). On reception the Butler matrix will be used to form simultaneously 16 beams in hardware with the ALWIN64 array, while for transmission an equal illumination with the MAARSY array will be generated. A Butler matrix is a reciprocal structure composed of half-power 90° hybrid couplers and phase shifters, first described by Butler [1961]. In this structure the total number of available beams is determined by the amount of independent receivers and antenna feeds. A 4-Port Butler matrix simultaneously generates 4 individual in- and outputs. For the current 16 channel radar receiver a 16-Port Butler matrix was built by the concatenation of 8x 4-Port Butler matrices. Using this 16-Port Butler matrix with the ALWIN64 array 16 individual beams with a beam width of approximately 9° are generated. For the height of PMSE-layers the beam width results in a target area of roughly 14km diameter for each single beam. Since the installation of the 16-Port Butler matrix in November 2009 the ALWIN64 antenna array has been used to sample galactic noise. To verify the functionality of the Butler matrix 6 out of 16 beams have been selected to e.g. monitor the supernova remnant Cassiopeia A. It is furthermore planned to verify the Butler matrix measurements by comparing the data with the AIRIS Riometer which is also located on the Island Andoya.

  14. Relationship of strength of turbulence to received power

    NASA Technical Reports Server (NTRS)

    Rottger, J.

    1983-01-01

    Because of contributions due to reflection, the determination of the turbulence refractive index structure constant may be affected. For pure scattering from turbulence in the inertial subrange, the radar echo power can be used to calculate the refractive index structure constant. The radar power is determined by a convolution integral. If the antenna beam is swung to sufficiently large off-zenith angles ( 12.5 deg) so that a quasi-isotropic response from the tail ends of the Gaussian angular distribution can be anticipated, the evaluation of the convolution integral depends only on the known antenna pattern of the radar. This procedure, swinging the radar beam to attenuate the reflected component, may be called angular or direction filtering. The tilted antenna also may be pick up reflected components from near the zenith through the sidelobes. This can be tested by the evaluation of the correlation function. This method applies a time domain filtering of the intensity time series but needs a very careful selection of the high pass filters.

  15. A doubly curved reflector X-band antenna with integrated IFF array

    NASA Astrophysics Data System (ADS)

    Alia, F.; Barbati, S.

    Primary radar antennas and Identification Friend or Foe (IFF) antennas must rotate with the same speed and synchronism, so that the target echo and IFF transponder mark will appear to the operator at the same time and at the same angular direction. A doubly-curved reflector antenna with a six-element microstrip array integrated in the reflector surface is presented to meet this requirement. The main antenna operates at X-band for low angle search radar, while the secondary antenna operates at L-band for IFF functions. The new configuration minimizes masking of the X-band radiated energy as a result of the IFF L-band elements. In fact, the only effect of the microstrip array on the X-band radiation pattern is the presence of several sidelobes in the + or - 90 deg angular region. The proposed new solution is compared to three other L-band/X-band integrated antenna configurations, and is found to be more advantageous with respect to masking, mechanical aspects, and production costs.

  16. Radar based Ground Level Reconstruction Utilizing a Hypocycloid Antenna Positioning System

    NASA Astrophysics Data System (ADS)

    Baer, Christoph; Musch, Thomas

    2015-01-01

    In this contribution we introduce a novel radar positioning system. It makes use of a mathematical curve, called hypocycloid, for a slanting movement of the radar antenna. By means of a planetary gear, a ball, and a universal joint as well as a stepping motor, a two dimensional positioning is provided by a uniaxial drive shaft exclusively. The fundamental position calculation and different signal processing algorithms are presented. By means of an 80 GHz FMCW radar system we performed several measurements on objects with discrete heights as well as on objects with continuous surfaces. The results of these investigations are essential part of this contribution and are discussed in detail.

  17. DBSAR's First Multimode Flight Campaign

    NASA Technical Reports Server (NTRS)

    Rincon, Rafael F.; Vega, Manuel; Buenfil, Manuel; Geist, Alessandro; Hilliard, Lawrence; Racette, Paul

    2010-01-01

    The Digital Beamforming SAR (DBSAR) is an airborne imaging radar system that combines phased array technology, reconfigurable on-board processing and waveform generation, and advances in signal processing to enable techniques not possible with conventional SARs. The system exploits the versatility inherently in phased-array technology with a state-of-the-art data acquisition and real-time processor in order to implement multi-mode measurement techniques in a single radar system. Operational modes include scatterometry over multiple antenna beams, Synthetic Aperture Radar (SAR) over several antenna beams, or Altimetry. The radar was flight tested in October 2008 on board of the NASA P3 aircraft over the Delmarva Peninsula, MD. The results from the DBSAR system performance is presented.

  18. Test Plan for SSR Antenna Rotation Rate Stabilization

    DOT National Transportation Integrated Search

    1981-10-01

    A comprehensive test plan is presented to evaluate the impact of wind and ice loading on the rotation rate stability of a Secondary Surveillance Radar (SSR) antenna used for air traffic control surveillance. Antenna rotation rate variations may intro...

  19. Comparison of Rising Resonator Relative Permittivity Measurements to Ground Penetrating Radar Data

    DTIC Science & Technology

    2014-04-01

    permittivity of the soil and the target is critical in determining the strength of the reflection from the target. In this paper, a microstrip ring resonator...is used to measure the relative permittivity of the soil and various target fill materials. For this measurement technique, a microstrip ring... antennas of varying frequencies to take measurements of the two port transmission coefficient. This coefficient is measured from the input feedline to

  20. Comparison of Ring Resonator Relative Permittivity Measurements to Ground Penetrating Radar Data

    DTIC Science & Technology

    2014-04-01

    permittivity of the soil and the target is critical in determining the strength of the reflection from the target. In this paper, a microstrip ring resonator...is used to measure the relative permittivity of the soil and various target fill materials. For this measurement technique, a microstrip ring... antennas of varying frequencies to take measurements of the two port transmission coefficient. This coefficient is measured from the input feedline to

  1. KSC-99pp0925

    NASA Image and Video Library

    1999-07-21

    KENNEDY SPACE CENTER, FLA. -- In the Space Station Processing Facility, a crane lowers the Shuttle Radar Topography Mission (SRTM) toward the opening of the payload bay canister below. The canister will then be moved to the Orbiter Processing Facility and placed in the bay of the orbiter Endeavour. The SRTM consists of a specially modified radar system that will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. The SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle. STS-99 is scheduled to launch Sept. 16 at 8:47 a.m. from Launch Pad 39A

  2. KSC-99pp0972

    NASA Image and Video Library

    1999-07-21

    KENNEDY SPACE CENTER, FLA. -- A crane lifts the Shuttle Radar Topography Mission (SRTM), the primary payload on STS-99, from a payload canister used to transport it to Orbiter Processing Facility (OPF) bay 2 to the payload bay of the orbiter Endeavour. The SRTM consists of a specially modified radar system that will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation. The SRTM hardware includes one radar antenna in the Shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) from the shuttle. STS-99 is scheduled to launch Sept. 16 at 8:47 a.m. from Launch Pad 39A

  3. KSC-99pp0923

    NASA Image and Video Library

    1999-07-21

    KENNEDY SPACE CENTER, FLA. -- In the Space Station Processing Facility, the Shuttle Radar Topography Mission (SRTM) is lifted for its move to a payload bay canister on the floor. The canister will then be moved to the Orbiter Processing Facility and placed in the bay of the orbiter Endeavour. The SRTM consists of a specially modified radar system that will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. The SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle. STS-99 is scheduled to launch Sept. 16 at 8:47 a.m. from Launch Pad 39A

  4. KSC-99pp0969

    NASA Image and Video Library

    1999-07-21

    KENNEDY SPACE CENTER, FLA. -- A payload transporter, carrying a payload canister with the Shuttle Radar Topography Mission (SRTM) inside, pulls into Orbiter Processing Facility (OPF) bay 2. The SRTM, the primary payload on STS-99, will soon be installed into the payload bay of the orbiter Endeavour already undergoing processing in bay 2. The SRTM consists of a specially modified radar system that will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation. The SRTM hardware includes one radar antenna in the Shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) from the shuttle. STS-99 is scheduled to launch Sept. 16 at 8:47 a.m. from Launch Pad 39A

  5. KSC-99pp0968

    NASA Image and Video Library

    1999-07-21

    KENNEDY SPACE CENTER, FLA. -- A payload canister containing the Shuttle Radar Topography Mission (SRTM), riding atop a payload transporter, is moved from the Space Station Processing Facility to Orbiter Processing Facility (OPF) bay 2. Once there, the SRTM, the primary payload on STS-99, will be installed into the payload bay of the orbiter Endeavour. The SRTM consists of a specially modified radar system that will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation. The SRTM hardware includes one radar antenna in the Shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) from the shuttle. STS-99 is scheduled to launch Sept. 16 at 8:47 a.m. from Launch Pad 39A

  6. KSC-99pp0970

    NASA Image and Video Library

    1999-07-21

    KENNEDY SPACE CENTER, FLA. -- A crane is lowered over the payload canister with the Shuttle Radar Topography Mission (SRTM) inside in Orbiter Processing Facility (OPF) bay 2. The primary payload on STS-99, the SRTM will soon be lifted out of the canister and installed into the payload bay of the orbiter Endeavour. The SRTM consists of a specially modified radar system that will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation. The SRTM hardware includes one radar antenna in the Shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) from the shuttle. STS-99 is scheduled to launch Sept. 16 at 8:47 a.m. from Launch Pad 39A

  7. KSC-99pp0971

    NASA Image and Video Library

    1999-07-21

    KENNEDY SPACE CENTER, FLA. -- A crane lifts the Shuttle Radar Topography Mission (SRTM), the primary payload on STS-99, from a payload canister used to transport it to Orbiter Processing Facility (OPF) bay 2. The SRTM will soon be installed into the payload bay of the orbiter Endeavour. The SRTM consists of a specially modified radar system that will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation. The SRTM hardware includes one radar antenna in the Shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) from the shuttle. STS-99 is scheduled to launch Sept. 16 at 8:47 a.m. from Launch Pad 39A

  8. FEED FORWARD EQUATIONS.

    DTIC Science & Technology

    and feed forward stabilization) have been implemented. An on-mount gyro system consists of gyroscopes mounted on the radar antenna which sense...antenna motion and send compensating signals back to the antenna servo mechanism. Feed forward stabilization consists of determining antenna angular rates...caused by ships attitude changes, as measured by a stable platform (such as SINS), and feeding compensating signals back to the antenna servo

  9. Improved spatial and temporal characteristics of ionospheric irregularities and polar mesospheric summer echoes using coherent MIMO and aperture synthesis radar imaging

    NASA Astrophysics Data System (ADS)

    Chau, J. L.; Urco, J. M.; Milla, M. A.; Vierinen, J.

    2017-12-01

    We have recently implemented Multiple-input multiple-output (MIMO) radar techniques to resolve temporal and spatial ambiguities of ionospheric and atmospheric irregularities, with improve capabilities than previously experiments using single-input multi-output (SIMO) techniques. SIMO techniques in the atmospheric and ionospheric coherent scatter radar field are usually called aperture synthesis radar imaging. Our implementations have done at the Jicamarca Radio Observatory (JRO) in Lima, Peru, and at the Middle Atmosphere Alomar Radar System (MAARSY) in Andenes, Norway, to study equatorial electrojet (EEJ) field-aligned irregularities and polar mesospheric summer echoes (PMSE), respectively. Figure 1 shows an example of a configuration used at MAARSY and the comparison between the SIMO and MIMO resulting antenna point spread functions, respectively. Although in this work we present the details of the implementations at each facility, we will focus on the observed peculiarities of each phenomenon, making emphasis in the underlying physical mechanisms that govern their existence and their spatial and temporal modulation. For example, what are the typical horizontal scales of PMSE variability in both intensity and wind field?

  10. A 24-GHz portable FMCW radar with continuous beam steering phased array (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Peng, Zhengyu; Li, Changzhi

    2017-05-01

    A portable 24-GHz frequency-modulated continuous-wave (FMCW) radar with continuous beam steering phased array is presented. This board-level integrated radar system consists of a phased array antenna, a radar transceiver and a baseband. The phased array used by the receiver is a 4-element linear array. The beam of the phased array can be continuously steered with a range of ±30° on the H-plane through an array of vector controllers. The vector controller is based on the concept of vector sum with binary-phase-shift attenuators. Each vector controller is capable of independently controlling the phase and the amplitude of each element of the linear array. The radar transceiver is based on the six-port technique. A free-running voltage controlled oscillator (VCO) is controlled by an analog "sawtooth" voltage generator to produce frequency-modulated chirp signal. This chirp signal is used as the transmitter signal, as well as the local oscillator (LO) signal to drive the six-port circuit. The transmitter antenna is a single patch antenna. In the baseband, the beat signal of the FMCW radar is detected by the six-port circuit and then processed by a laptop in real time. Experiments have been performed to reveal the capabilities of the proposed radar system for applications including indoor inverse synthetic aperture radar (ISAR) imaging, vital sign detection, and short-range navigation, etc. (This abstract is for the profiles session.)

  11. Ultra-wideband horn antenna with abrupt radiator

    DOEpatents

    McEwan, Thomas E.

    1998-01-01

    An ultra-wideband horn antenna transmits and receives impulse waveforms for short-range radars and impulse time-of flight systems. The antenna reduces or eliminates various sources of close-in radar clutter, including pulse dispersion and ringing, sidelobe clutter, and feedline coupling into the antenna. Dispersion is minimized with an abrupt launch point radiator element; sidelobe and feedline coupling are minimized by recessing the radiator into a metallic horn. Low frequency cut-off associated with a horn is extended by configuring the radiator drive impedance to approach a short circuit at low frequencies. A tapered feed plate connects at one end to a feedline, and at the other end to a launcher plate which is mounted to an inside wall of the horn. The launcher plate and feed plate join at an abrupt edge which forms the single launch point of the antenna.

  12. KSC-99pp1369

    NASA Image and Video Library

    1999-11-29

    KENNEDY SPACE CENTER, FLA. -- Viewed end to end, the interior of orbiter Endeavour's payload bay can be seen with its cargo (center and right) in place, before the close of its payload bay doors. The Ku-band antenna (lower right) is now in its closed position inside the payload bay. Endeavour is expected to roll over to the Vehicle Assembly Building in three days for mating to the external tank and solid rocket boosters in high bay 1. Space Shuttle Endeavour is targeted for launch on mission STS-99 Jan. 13, 2000 at 1:11 p.m. EST. STS-99 is the Shuttle Radar Topography Mission, an international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR. The SRTM consists of a specially modified radar system that will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. The SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle

  13. MAARSY: The new MST radar on Andøya—System description and first results

    NASA Astrophysics Data System (ADS)

    Latteck, R.; Singer, W.; Rapp, M.; Vandepeer, B.; Renkwitz, T.; Zecha, M.; Stober, G.

    2012-02-01

    The Middle Atmosphere Alomar Radar System (MAARSY) on the North-Norwegian island Andøya is a 53.5 MHz monostatic radar with an active phased array antenna consisting of 433 Yagi antennas. The 3-element Yagi antennas are arranged in an equilateral triangle grid forming a circular aperture of approximately 6300 m2. Each individual antenna is connected to its own transceiver with independent phase control and a scalable power output up to 2 kW. This arrangement provides a very high flexibility of beam forming and beam steering with a symmetric radar beam of a minimum beam width of 3.6° allowing classical beam swinging operation as well as experiments with simultaneous multiple beams and the use of interferometric applications for improved studies of the Arctic atmosphere from the troposphere up to the lower thermosphere with high spatio-temporal resolution. The installation of the antenna array was completed in August 2009. The radar control and data acquisition hardware as well as an initial expansion stage of 196 transceiver modules was installed in spring 2010 and upgraded to 343 transceiver modules in November 2010. The final extension to 433 transceiver modules has recently been completed in May 2011. Beside standard observations of tropospheric winds and Polar Mesosphere Summer Echoes, the first multi-beam experiments using up to 97 quasi-simultaneous beams in the mesosphere have been carried out in 2010 and 2011. These results provide a first insight into the horizontal variability of polar mesosphere summer and winter echoes with time resolutions between 3 and 9 minutes. In addition, first meteor head echo observations were conducted during the Geminid meteor shower in December 2010.

  14. ASDE-3 Antenna Development and Test

    DOT National Transportation Integrated Search

    1981-01-01

    The ASDE-3 radar antenna was developed so that closely spaced targets on an airport surface could be resolved. The requirement of accurately detecting targets as close as 500 feet from the antenna necessitated some type of near field focussing. A var...

  15. Delivering both sum and difference beam distributions to a planar monopulse antenna array

    DOEpatents

    Strassner, II, Bernd H.

    2015-12-22

    A planar monopulse radar apparatus includes a planar distribution matrix coupled to a planar antenna array having a linear configuration of antenna elements. The planar distribution matrix is responsive to first and second pluralities of weights applied thereto for providing both sum and difference beam distributions across the antenna array.

  16. Using dynamic interferometric synthetic aperature radar (InSAR) to image fast-moving surface waves

    DOEpatents

    Vincent, Paul

    2005-06-28

    A new differential technique and system for imaging dynamic (fast moving) surface waves using Dynamic Interferometric Synthetic Aperture Radar (InSAR) is introduced. This differential technique and system can sample the fast-moving surface displacement waves from a plurality of moving platform positions in either a repeat-pass single-antenna or a single-pass mode having a single-antenna dual-phase receiver or having dual physically separate antennas, and reconstruct a plurality of phase differentials from a plurality of platform positions to produce a series of desired interferometric images of the fast moving waves.

  17. Applications of FM-CW laser radar to antenna contour mapping

    NASA Technical Reports Server (NTRS)

    Slotwinski, A. R.

    1989-01-01

    The FM-CW coherent laser radar concept, based on the FM radar principle which makes use of the coherence and lunability of injection laser diodes, is discussed. Laser radar precision/time tradeoffs, block diagrams, system performance, fiber optic system implantation, and receiver improvements are briefly described.

  18. A Novel Reflector/Reflectarray Antenna: An Enabling Technology for NASA's Dual-Frequency ACE Radar

    NASA Technical Reports Server (NTRS)

    Racette, Paul E.; Heymsfield, Gerald; Li, Lihua; Cooley, Michael E.; Park, Richard; Stenger, Peter

    2011-01-01

    This paper describes a novel dual-frequency shared aperture Ka/W-band antenna design that enables wide-swath Imaging via electronic scanning at Ka-band and Is specifically applicable to NASA's Aerosol, Cloud and Ecosystems (ACE) mission. The innovative antenna design minimizes size and weight via use of a shared aperture and builds upon NASA's investments in large-aperture reflectors and high technology-readiness-level (TRL) W-band radar architectures. The antenna is comprised of a primary cylindrical reflector/reflectarray surface illuminated by a fixed W-band feed and a Ka-band Active Electronically Scanned Array (AESA) line feed. The reflectarray surface provides beam focusing at W-band, but is transparent at Ka-band.

  19. KSC-99pp0658

    NASA Image and Video Library

    1999-05-25

    STS-99 Mission Specialist Janice Voss conducts a system verification test on the Shuttle Radar Topography Mission in the Space Station Processing Facility. The primary payload on mission STS-99, the SRTM consists of a specially modified radar system that will fly onboard the Space Shuttle during the 11-day mission targeted for launch Sept. 16, 1999. This radar system will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM is an international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. The SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle

  20. 1. Northeast face of missile site control building, commonly known ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. Northeast face of missile site control building, commonly known as the missile site radar building, showing open blast door #BD2. This emergency escape, at stair no. 12, is NEMP/RFI-shielded and 16" thick. The large circle in the center is the radar face, also known as the antennae array aperture. The small circle to the right of the radar face is the "Q" channel. The antennae atop the turret provided lightning protection for the building - Stanley R. Mickelsen Safeguard Complex, Missile Site Control Building, Northeast of Tactical Road; southeast of Tactical Road South, Nekoma, Cavalier County, ND

  1. KSC-04pd1607

    NASA Image and Video Library

    2004-07-31

    KENNEDY SPACE CENTER, FLA. - A C-band (left) and an X-band radar antenna are positioned to observe the MESSENGER (Mercury Surface, Space Environment, Geochemistry and Ranging) launch. The antennas are on loan to KSC from the USNS Pathfinder, a U.S. Navy instrumentation ship. They have been installed at site north of Haulover Canal where the National Center for Atmospheric Research previously had a radar for thunderstorm research. NASA is evaluating the pair of radars for their ability to observe possible debris coming from the Space Shuttle during launch, part of NASA’s initiative to return the Space Shuttle to flight.

  2. KSC-04pd1610

    NASA Image and Video Library

    2004-07-31

    KENNEDY SPACE CENTER, FLA. - An X-band (left) and a C-band radar antenna are prepared to observe the MESSENGER (Mercury Surface, Space Environment, Geochemistry and Ranging) launch. The antennas are on loan to KSC from the USNS Pathfinder, a U.S. Navy instrumentation ship. They have been installed at site north of Haulover Canal where the National Center for Atmospheric Research previously had a radar for thunderstorm research. NASA is evaluating the pair of radars for their ability to observe possible debris coming from the Space Shuttle during launch, part of NASA’s initiative to return the Space Shuttle to flight.

  3. KSC-04PD-1607

    NASA Technical Reports Server (NTRS)

    2004-01-01

    KENNEDY SPACE CENTER, FLA. A C-band (left) and an X-band radar antenna are positioned to observe the MESSENGER (Mercury Surface, Space Environment, Geochemistry and Ranging) launch. The antennas are on loan to KSC from the USNS Pathfinder, a U.S. Navy instrumentation ship. They have been installed at site north of Haulover Canal where the National Center for Atmospheric Research previously had a radar for thunderstorm research. NASA is evaluating the pair of radars for their ability to observe possible debris coming from the Space Shuttle during launch, part of NASAs initiative to return the Space Shuttle to flight.

  4. KSC-04PD-1610

    NASA Technical Reports Server (NTRS)

    2004-01-01

    KENNEDY SPACE CENTER, FLA. An X-band (left) and a C-band radar antenna are prepared to observe the MESSENGER (Mercury Surface, Space Environment, Geochemistry and Ranging) launch. The antennas are on loan to KSC from the USNS Pathfinder, a U.S. Navy instrumentation ship. They have been installed at site north of Haulover Canal where the National Center for Atmospheric Research previously had a radar for thunderstorm research. NASA is evaluating the pair of radars for their ability to observe possible debris coming from the Space Shuttle during launch, part of NASAs initiative to return the Space Shuttle to flight.

  5. Weather radar performance monitoring using a metallic-grid ground-scatterer

    NASA Astrophysics Data System (ADS)

    Falconi, Marta Tecla; Montopoli, Mario; Marzano, Frank Silvio; Baldini, Luca

    2017-10-01

    The use of ground return signals is investigated for checks on the calibration of power measurements of a polarimetric C-band radar. To this aim, a peculiar permanent single scatterer (PSS) consisting of a big metallic roof with a periodic mesh grid structure and having a hemisphere-like shape is considered. The latter is positioned in the near-field region of the weather radar and its use, as a reference calibrator, shows fairly good results in terms of reflectivity and differential reflectivity monitoring. In addition, the use of PSS indirectly allows to check for the radar antenna de-pointing which is another issue usually underestimated when dealing with weather radars. Because of the periodic structure of the considered PSS, simulations of its electromagnetic behavior were relatively easy to perform. To this goal, we used an electromagnetic Computer-Aided-Design (CAD) with an ad-hoc numerical implementation of a full-wave solution to model our PSS in terms of reflectivity and differential reflectivity factor. Comparison of model results and experimental measurements are then shown in this work. Our preliminary investigation can pave the way for future studies aiming at characterizing ground-clutter returns in a more accurate way for radar calibration purposes.

  6. Information for space radar designers: Required dynamic range vs resolution and antenna calibration using the Amazon rain forest

    NASA Technical Reports Server (NTRS)

    Moore, R. K.; Frost, V. S.

    1985-01-01

    Calibration of the vertical pattern of the antennas for the SEASAT scatterometer was accomplished using the nearly-uniform radar return from the Amazon rain forest. A similar calibration will be attempted for the SIR-B antenna. Thick calibration is important to establish the radiometric calibration across the swath of the SIR-B, and the developed methodology will provide an important tool in the evaluation of future spaceborne imaging radars. This calibration was made by the very-wide-beam SEASAT scatterometer antennas because at 14.65 GHz the scattering coefficient of the rain forest is almost independent of angle of incidence. It is expected that the variation in scattering coefficient for the rain forest across the relatively narrow vertical beam of the SIR-B will be very small; even at L band the forest should be essentially impenetrable for radar signals, the volume scatter from the treetops will predominate as at higher frequencies. The basic research elements include: (1) examination of SIR-B images over the rain forest to establish the variability of the scattering coefficient at finer resolutions than that of the SEASAT scatterometer; (2) analysis of the variability of SIR-B data detected prior to processing for either azimuth compression or; possibly, range compression so that averages over relatively large footprints can be used; (3) processing of data of the form of (2) using algorithms that can recover the vertical pattern of the antenna.

  7. 11. View of south side of radar scanner building no. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. View of south side of radar scanner building no. 104 showing personnel exit door at side building, showing DR 1 antenna from oblique angle on foundation berm with DR 2 and DR 3 antennae in background. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  8. Range Sidelobe Suppression Using Complementary Sets in Distributed Multistatic Radar Networks

    PubMed Central

    Wang, Xuezhi; Song, Yongping; Huang, Xiaotao; Moran, Bill

    2017-01-01

    We propose an alternative waveform scheme built on mutually-orthogonal complementary sets for a distributed multistatic radar. Our analysis and simulation show a reduced frequency band requirement for signal separation between antennas with centralized signal processing using the same carrier frequency. While the scheme can tolerate fluctuations of carrier frequencies and phases, range sidelobes arise when carrier frequencies between antennas are significantly different. PMID:29295566

  9. Two-dimensional acousto-optic processor using circular antenna array with a Butler matrix

    NASA Astrophysics Data System (ADS)

    Lee, Jim P.

    1992-09-01

    A two-dimensional acousto-optic signal processor is shown to be useful for providing simultaneous spectrum analysis and direction finding of radar signals over an instantaneous field of view of 360 deg. A system analysis with emphasis on the direction-finding aspect of this new architecture is presented. The peak location of the optical pattern provides a direct measure of bearing, independent of signal frequency. In addition, the sidelobe levels of the pattern can be effectively reduced using amplitude weighting. Performance parameters, such as mainlobe beamwidth, peak-sidelobe level, and pointing error, are analyzed as a function of the Gaussian laser illumination profile and the number of channels. Finally, a comparison with a linear antenna array architecture is also discussed.

  10. Transmitter and receiver antenna gain analysis for laser radar and communication systems

    NASA Technical Reports Server (NTRS)

    Klein, B. J.; Degnan, J. J.

    1973-01-01

    A comprehensive and fairly self-contained study of centrally obscured optical transmitting and receiving antennas is presented and is intended for use by the laser radar and communication systems designer. The material is presented in a format which allows the rapid and accurate evaluation of antenna gain. The Fresnel approximation to scalar wave theory is reviewed and the antenna analysis proceeds in terms of the power gain. Conventional range equations may then be used to calculate the power budget. The transmitter calculations, resulting in near and far field antenna gain patterns, assumes the antenna is illuminated by a laser operating in the fundamental cavity mode. A simple equation is derived for matching the incident source distribution to a general antenna configuration for maximum on-axis gain. An interpretation of the resultant gain curves allows a number of auxiliary design curves to be drawn which display the losses in antenna gain due to pointing errors and the cone angle of the outgoing beam as a function of antenna size and central obscuration. The use of telescope defocusing as an approach to spreading the beam for target acquisition is compared to some alternate methods.

  11. UAVSAR Phased Array Aperture

    NASA Technical Reports Server (NTRS)

    Chamberlain, Neil; Zawadzki, Mark; Sadowy, Greg; Oakes, Eric; Brown, Kyle; Hodges, Richard

    2009-01-01

    This paper describes the development of a patch antenna array for an L-band repeat-pass interferometric synthetic aperture radar (InSAR) instrument that is to be flown on an unmanned aerial vehicle (UAV). The antenna operates at a center frequency of 1.2575 GHz and with a bandwidth of 80 MHz, consistent with a number of radar instruments that JPL has previously flown. The antenna is designed to radiate orthogonal linear polarizations in order to facilitate fully-polarimetric measurements. Beam-pointing requirements for repeat-pass SAR interferometry necessitate electronic scanning in azimuth over a range of -20degrees in order to compensate for aircraft yaw. Beam-steering is accomplished by transmit/receive (T/R) modules and a beamforming network implemented in a stripline circuit board. This paper, while providing an overview of phased array architecture, focuses on the electromagnetic design of the antenna tiles and associated interconnects. An important aspect of the design of this antenna is that it has an amplitude taper of 10dB in the elevation direction. This is to reduce multipath reflections from the wing that would otherwise be detrimental to interferometric radar measurements. This taper is provided by coupling networks in the interconnect circuits as opposed to attenuating the output of the T/R modules. Details are given of material choices and fabrication techniques that meet the demanding environmental conditions that the antenna must operate in. Predicted array performance is reported in terms of co-polarized and crosspolarized far-field antenna patterns, and also in terms of active reflection coefficient.

  12. Monitoring cardiac motion in CT using a continuous wave radar embedded in the patient table.

    PubMed

    Pfanner, Florian; Allmendinger, Thomas; Bohn, Birgit; Flohr, Thomas; Kachelrieß, Marc

    2014-08-01

    To avoid motion artifacts, medical imaging devices are often synchronized with the patient's cardiac motion. Today, the ECG is used to determine the heartbeat and therewith trigger the imaging device. However, the ECG requires additional effort to prepare the patient, e.g., mount and wire electrodes and it is not able to determine the motion of the heart. An interesting alternative to assess the cardiac motion is continuous wave radar. The aim of this work is to evaluate such a radar system focusing on measuring the cardiac motion. A radar system operating in the 860 MHz band is used. In the intended application of the radar system, the antennas are located close to the patient's body, for example, inside the table of a CT system. The radar waves propagate into the patient's body and are reflected at tissue boundaries, for example, at the borderline between muscle and adipose tissue, or at the boundaries of organs. Here, the authors focus on the detection of cardiac motion. The radar system consists of hardware as well as of dedicated signal processing software to extract the desired information from the radar signals. The radar system hardware and the signal processing algorithms were tested with data from ten volunteers. As a reference, the ECG was recorded simultaneously with the radar measurements. Additionally, ultrasound measurements are performed and compared with the motion information from the radar data. According to the authors' measurements on volunteers (test persons), the heartbeat and heart rate can be detected well using the proposed radar system. The authors were further able to extract the amplitude and phase of the heart motion itself from the radar data. This was confirmed by the ultrasound measurements. However, this motion assessment is dependent on the antenna position and it remains unclear which antenna sees the motion that is the most relevant to CT imaging. A continuous wave radar operating in the near field of the antennas can be used to determine the heartbeat and the cardiac motion of humans without special patient preparation. The authors' radar system is very close to the patient because it is embedded in the patient table, but it has no direct contact to the patient or to the patient skin (as it would be necessary to acquire the ECG of the patient). Therefore, radar motion monitoring does not require special patient preparation. In contrast to other methods used today, this is a significant improvement. The authors' radar system may allow to trigger a CT scan in dependency of the cardiac phase, without requiring an ECG, and it allows to determine quiet, and thus favorable, heart phases prior to the scan start.

  13. Ultra-wideband horn antenna with abrupt radiator

    DOEpatents

    McEwan, T.E.

    1998-05-19

    An ultra-wideband horn antenna transmits and receives impulse waveforms for short-range radars and impulse time-of flight systems. The antenna reduces or eliminates various sources of close-in radar clutter, including pulse dispersion and ringing, sidelobe clutter, and feedline coupling into the antenna. Dispersion is minimized with an abrupt launch point radiator element; sidelobe and feedline coupling are minimized by recessing the radiator into a metallic horn. Low frequency cut-off associated with a horn is extended by configuring the radiator drive impedance to approach a short circuit at low frequencies. A tapered feed plate connects at one end to a feedline, and at the other end to a launcher plate which is mounted to an inside wall of the horn. The launcher plate and feed plate join at an abrupt edge which forms the single launch point of the antenna. 8 figs.

  14. UHF Microstrip Antenna Array for Synthetic- Aperture Radar

    NASA Technical Reports Server (NTRS)

    Thomas, Robert F.; Huang, John

    2003-01-01

    An ultra-high-frequency microstrippatch antenna has been built for use in airborne synthetic-aperture radar (SAR). The antenna design satisfies requirements specific to the GeoSAR program, which is dedicated to the development of a terrain-mapping SAR system that can provide information on geology, seismicity, vegetation, and other terrain-related topics. One of the requirements is for ultra-wide-band performance: the antenna must be capable of operating with dual linear polarization in the frequency range of 350 plus or minus 80 MHz, with a peak gain of 10 dB at the middle frequency of 350 MHz and a gain of at least 8 dB at the upper and lower ends (270 and 430 MHz) of the band. Another requirement is compactness: the antenna must fit in the wingtip pod of a Gulfstream II airplane. The antenna includes a linear array of microstrip-patch radiating elements supported over square cavities. Each patch is square (except for small corner cuts) and has a small square hole at its center.

  15. A new design of an S/X dual band circular slot antenna for radar applications.

    PubMed

    Ghnimi, Said; Wali, Rawia; Gharsallh, Ali; Razban, Tchanguiz

    2013-01-01

    A novel design of dual-band slot antenna with a circular patch for radar applications is presented and studied. It is fed by a micro-strip line and built on a FR-4 substrate with a whole size of 18 x 30 mm2. A dual band printed antenna is created by introducing slots on the radiating element. By this, two bandwidth, covering C and X band, are achieved. In order to obtain a good fundamental antenna design, the initial studies were carried out theoretically, using CST Microwave Studio simulation software. In this case, the frequency range at return loss < 10 dB is 5.24 - 6.16 GHz for low frequency and is 7.9 -11.7 GHz for high frequency. In addition, the proposed antenna has good radiation characteristics and stable gains over the whole operating bands. A prototype of antenna is fabricated and tested. Experimental data show good agreement between simulated and measured results.

  16. NASA Tech Briefs, June 2010

    NASA Technical Reports Server (NTRS)

    2010-01-01

    Topics covered include: Situational Awareness from a Low-Cost Camera System; Data Acquisition System for Multi-Frequency Radar Flight Operations Preparation; Mercury Toolset for Spatiotemporal Metadata; Social Tagging of Mission Data; Integrating Radar Image Data with Google Maps; Demonstration of a Submillimeter-Wave HEMT Oscillator Module at 330 GHz; Flexible Peripheral Component Interconnect Input/Output Card; Interface Supports Lightweight Subsystem Routing for Flight Applications; MMIC Amplifiers and Wafer Probes for 350 to 500 GHz; Public Risk Assessment Program; Particle Swarm Optimization Toolbox; Telescience Support Center Data System Software; Update on PISCES; Ground and Space Radar Volume Matching and Comparison Software; Web-Based Interface for Command and Control of Network Sensors; Orbit Determination Toolbox; Distributed Observer Network; Computer-Automated Evolution of Spacecraft X-Band Antennas; Practical Loop-Shaping Design of Feedback Control Systems; Fully Printed High-Frequency Phased-Array Antenna on Flexible Substrate; Formula for the Removal and Remediation of Polychlorinated Biphenyls in Painted Structures; Integrated Solar Concentrator and Shielded Radiator; Water Membrane Evaporator; Modeling of Failure for Analysis of Triaxial Braided Carbon Fiber Composites; Catalyst for Carbon Monoxide Oxidation; Titanium Hydroxide - a Volatile Species at High Temperature; Selective Functionalization of Carbon Nanotubes: Part II; Steerable Hopping Six-Legged Robot; Launchable and Retrievable Tetherobot; Hybrid Heat Exchangers; Orbital Winch for High-Strength, Space-Survivable Tethers; Parameterized Linear Longitudinal Airship Model; and Physics of Life: A Model for Non-Newtonian Properties of Living Systems.

  17. RCS tests utilize ground-plane effects

    NASA Astrophysics Data System (ADS)

    Knott, E. F.

    1984-03-01

    It is noted that the ground effects must be thoroughly understood to attain the proper radar cross section (RCS) configurations for a specific test. If the ground is sufficiently smooth, it acts as a mirror. Ground reflections then serve to enhance the incident field strength. If an asphalt or concrete ground plane has not been constructed, the soil must be kept free of vegetation and must be graded and leveled to exploit the effect. To elucidate the role of the ground plane, the various ways that energy propagates to the target and back are considered. In implementing a ground-plane RCS measurement program, it is important that the target height, antenna height, target range, and radar wavelength be chosen so as to place the target at a peak in the interference pattern. It is pointed out that in order to maximize the received signal, the antenna should be depressed below the bisector of the angle between the direct and indirect paths subtended at the radar receiving antenna. The precise amount of depression depends on the antenna radiation pattern.

  18. Information content in frequency-dependent, multi-offset GPR data for layered media reconstruction using full-wave inversion

    NASA Astrophysics Data System (ADS)

    De Coster, Albéric; Phuong Tran, Anh; Lambot, Sébastien

    2014-05-01

    Water lost through leaks can represent high percentages of the total production in water supply systems and constitutes an important issue. Leak detection can be tackled with various techniques such as the ground-penetrating radar (GPR). Based on this technology, various procedures have been elaborated to characterize a leak and its evolution. In this study, we focus on a new full-wave radar modelling approach for near-field conditions, which takes into account the antenna effects as well as the interactions between the antenna(s) and the medium through frequency-dependent global transmission and reflection coefficients. This approach is applied to layered media for which 3-D Green's functions can be calculated. The model allows for a quantitative estimation of the properties of multilayered media by using full-wave inversion. This method, however, proves to be limited to provide users with an on-demand assessment as it is generally computationally demanding and time consuming, depending on the medium configuration as well as the number of unknown parameters to retrieve. In that respect, we propose two leads in order to enhance the parameter retrieval step. The first one consists in analyzing the impact of the reduction of the number of frequencies on the information content. For both numerical and laboratory experiments, this operation has been achieved by investigating the response surface topography of objective functions arising from the comparison between measured and modelled data. The second one involves the numerical implementation of multistatic antenna configurations with constant and variable offsets in the model. These two kinds of analyses are then combined in numerical experiments to observe the conjugated effect of the number of frequencies and the offset configuration. To perform the numerical analyses, synthetic Green's functions were simulated for different multilayered medium configurations. The results show that an antenna offset increase leads to an improvement in the response surface topography, which is more or less marked according to the initial information content. It also highlights the theoretical possibility of significantly reducing the number of frequencies without degrading the information content. This last statement is confirmed with the laboratory experiment which incorporates measurements done with a Vivaldi antenna above a medium composed of one or more sand layers characterized by different water contents. As a conclusion, the offset and frequency analyses highlight the great potential of the model for improving the soil parameter retrieval while reducing the computation time for a given antenna(s) - medium configuration. Acknowledgments: This work benefited from networking activities carried out within the EU funded COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar" and was supported by the Walloon Region through the "SENSPORT" project (Convention n°1217720) undertook in the framework of the WBGreen research program.

  19. Imaging and modeling new VETEM data

    USGS Publications Warehouse

    Wright, David L.; Smith, David V.; Abraham, Jared D.; Hutton, Raymond S.; Bond, E. Kent; Cui, Tie Jun; Aydiner, Alaeddin A.; Chew, Weng Cho

    2000-01-01

    In previously reported work (Wright and others, 2000) we found that the very early time electromagnetic (VETEM) prototype system produced data from which high resolution images of a buried former foundry site at the Denver Federal Center were made. The soil covering the site is about 30 mS/m conductivity, and is thus relatively unfavorable for ground penetrating radar (GPR) imaging. We have surveyed portions of this site again with new electric field dipole antennas and a new receiver designed for these antennas. Comparisons of the images produced using the loop antennas to those produced using the electric field dipole antennas illustrate that for this application the loop antennas produced more useful images. The larger man-made structures can be seen more clearly because they are not masked by dispersion and/or smaller scale variations as with the electric field dipole antennas. The VETEM system now contains an array of antennas with appropriate transmitters and receivers and can be operated as a low frequency time domain GPR or as a high frequency time domain electromagnetic (EM) system with several possible antenna spacings and polarizations. We plan to examine additional configurations. Numerical modeling of the perpendicular loop antenna configuration has been done and depth estimates produced. We conclude that, as with other GPR and time domain EM systems, the best choice of operating parameters depends on the application and the environment, but the inherent flexibility of the VETEM system allows a wide range of options.

  20. Phased-array radar for airborne systems

    NASA Astrophysics Data System (ADS)

    Tahim, Raghbir S.; Foshee, James J.; Chang, Kai

    2003-09-01

    Phased array antenna systems, which support high pulse rates and high transmit power, are well suited for radar and large-scale surveillance. Sensors and communication systems can function as the eyes and ears for ballistic missile defense applications, providing early warning of attack, target detection and identification, target tracking, and countermeasure decision. In such applications, active array radar systems that contain solid-state transmitter sources and low-noise preamplifiers for transmission and reception are preferred over the conventional radar antennas, because the phased array radar offers the advantages of power management and efficiency, reliability, signal reception, beam steering target detection. The current phased array radar designs are very large, complex and expensive and less efficient because of high RF losses in the phase control circuits used for beam scan. Several thousands of phase shifters and drivers may be required for a single system thus making the system very complex and expensive. This paper describes the phased array radar system based on high power T/R modules, wide-band radiating planar antenna elements and very low loss wide-band phase control circuits (requiring reduced power levels) for beam scan. The phase shifter design is based on micro-strip feed lines perturbed by the proximity of voltage controlled piezoelectric transducer (PET). Measured results have shown an added insertion loss of less than 1 dB for a phase shift of 450 degrees from 2 to 20 GHz. The new wideband phased array radar design provides significant reduction in size cost and weight. Compared to the conventional phased array systems, the cost saving is more than 15 to 1.

  1. Report 11HL: Technologies for Trusted Maritime Situational Awareness

    DTIC Science & Technology

    2011-10-01

    Olympics. The AIS antenna can be seen on the wooden pole to the right. The ASIA camera is contained within the Pelco enclosure (i.e., white case) on...tracks based on GPS and radar. The physical deployment of ASIA, radar and the acoustic array are also shown...the 2010 Vancouver Olympics. The AIS antenna can be seen on the wooden pole to the right. The ASIA camera is contained within the Pelco enclosure

  2. MW 08-multi-beam air and surface surveillance radar

    NASA Astrophysics Data System (ADS)

    1989-09-01

    Signal of the Netherlands has developed and is marketing the MW 08, a 3-D radar to be used for short to medium range surveillance, target acquisition, and tracking. MW 08 is a fully automated detecting and tracking radar. It is designed to counter threats from aircraft and low flying antiship missiles. It can also deal with the high level missile threat. MW 08 operates in the 5 cm band using one antenna for both transmitting and receiving. The antenna is an array, consisting of 8 stripline antennas. The received radar energy is processed by 8 receiver channels. These channels come together in the beam forming network, in which 8 virtual beams are formed. From this beam pattern, 6 beams are used for the elevation coverage of 0-70 degrees. MW 08's output signals of the beam former are further handled by FFT and plot processors for target speed information, clutter rejection, and jamming suppression. A general purpose computer handles target track initiation, and tracking. Tracking data are transferred to the command and control systems with 3-D target information for fastest possible lockon.

  3. 41. Perimeter acquisition radar building radar element and coaxial display, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    41. Perimeter acquisition radar building radar element and coaxial display, with drawing of typical antenna section. Drawing, from left to right, shows element, aluminum ground plane, cable connectors and hardware, cable, and back-up ring. Grey area is the concrete wall - Stanley R. Mickelsen Safeguard Complex, Perimeter Acquisition Radar Building, Limited Access Area, between Limited Access Patrol Road & Service Road A, Nekoma, Cavalier County, ND

  4. Shuttle communication and tracking systems signal design and interface compatibility analysis

    NASA Technical Reports Server (NTRS)

    1986-01-01

    Various options for the Dedicated Payload Communication Link (DPCL) were evaluated. Specific subjects addressed include: payload to DPCL power transfer in the proximity of the payload, DPCL antenna pointing considerations, and DPCL transceiver implementations which can be mounted on the deployed antenna boom. Additional analysis of the Space Telescope performance was conducted. The feasibility of using the Global Positioning System (GPS) for attitude determination and control for large spacecraft was examined. The objective of the Shuttle Orbiter Radar Test and Evaluation (SORTE) program was to quantify the Ku-band radar tracking accuracy using White Sands Missile Range (WSMR) radar and optical tracking equipment, with helicopter and balloon targets.

  5. A crane is lowered over the payload canister with the SRTM inside

    NASA Technical Reports Server (NTRS)

    1999-01-01

    A crane is lowered over the payload canister with the Shuttle Radar Topography Mission (SRTM) inside in Orbiter Processing Facility (OPF) bay 2. The primary payload on STS-99, the SRTM will soon be lifted out of the canister and installed into the payload bay of the orbiter Endeavour. The SRTM consists of a specially modified radar system that will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation. The SRTM hardware includes one radar antenna in the Shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) from the shuttle. STS-99 is scheduled to launch Sept. 16 at 8:47 a.m. from Launch Pad 39A.

  6. Producing Science-Ready Radar Datasets for the Retrieval of Forest Structure Parameters from Backscatter: Correcting for Terrain Topography and Changes in Vegetation Reflectivity

    NASA Technical Reports Server (NTRS)

    Simard, M.; Riel, Bryan; Hensley, S.; Lavalle, Marco

    2011-01-01

    Radar backscatter data contain both geometric and radiometric distortions due to underlying topography and the radar viewing geometry. Our objective is to develop a radiometric correction algorithm specific to the UAVSAR system configuration that would improve retrieval of forest structure parameters. UAVSAR is an airborne Lband radar capable of repeat?pass interferometry producing images with a spatial resolution of 5m. It is characterized by an electronically steerable antenna to compensate for aircraft attitude. Thus, the computation of viewing angles (i.e. look, incidence and projection) must include aircraft attitude angles (i.e. yaw, pitch and roll) in addition to the antenna steering angle. In this presentation, we address two components of radiometric correction: area projection and vegetation reflectivity. The first correction is applied by normalization of the radar backscatter by the local ground area illuminated by the radar beam. The second is a correction due to changes in vegetation reflectivity with viewing geometry.

  7. KSC-99pp1385

    NASA Image and Video Library

    1999-12-03

    KENNEDY SPACE CENTER, FLA. -- Lights frame the orbiter Endeavour as it is lowered onto the platform for mating with the external tank and solid rocket boosters. Space Shuttle Endeavour is targeted for launch on mission STS-99 Jan. 13, 2000, at 1:11 p.m. EST. STS-99 is the Shuttle Radar Topography Mission, an international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR. The SRTM consists of a specially modified radar system that will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. The SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle

  8. KSC-99pp1383

    NASA Image and Video Library

    1999-12-03

    KENNEDY SPACE CENTER, FLA. -- In high bay 1 of the VAB, the orbiter Endeavour is lowered for mating with the external tank below (on right), and the solid rocket boosters. Space Shuttle Endeavour is targeted for launch on mission STS-99 Jan. 13, 2000, at 1:11 p.m. EST. STS-99 is the Shuttle Radar Topography Mission, an international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR. The SRTM consists of a specially modified radar system that will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. The SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle

  9. KSC-99pp1373

    NASA Image and Video Library

    1999-12-02

    KENNEDY SPACE CENTER, FLA. -- Orbiter Endeavour rolls inside the Vehicle Assembly Building where it will be lifted to vertical and mated to the external tank and solid rocket boosters in high bay 1. Space Shuttle Endeavour is targeted for launch on mission STS-99 Jan. 13, 2000 at 1:11 p.m. EST. STS-99 is the Shuttle Radar Topography Mission, an international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR. The SRTM consists of a specially modified radar system that will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. The SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle

  10. KSC-99pp0924

    NASA Image and Video Library

    1999-07-21

    KENNEDY SPACE CENTER, FLA. -- In the Space Station Processing Facility, the Shuttle Radar Topography Mission (SRTM) clears the railing on the right as a crane moves it toward the open payload bay canister in the background (left). The canister will then be moved to the Orbiter Processing Facility and placed in the bay of the orbiter Endeavour. The SRTM consists of a specially modified radar system that will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. The SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle. STS-99 is scheduled to launch Sept. 16 at 8:47 a.m. from Launch Pad 39A

  11. KSC-99pp1381

    NASA Image and Video Library

    1999-12-03

    KENNEDY SPACE CENTER, FLA. -- Inside the VAB, orbiter Endeavour is lifted to a vertical position before being mated to the external tank (bottom of photo) and solid rocket boosters in high bay 1. Space Shuttle Endeavour is targeted for launch on mission STS-99 Jan. 13, 2000, at 1:11 p.m. EST. STS-99 is the Shuttle Radar Topography Mission, an international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR. The SRTM consists of a specially modified radar system that will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. The SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle

  12. KSC-99pp1372

    NASA Image and Video Library

    1999-12-02

    KENNEDY SPACE CENTER, FLA. -- Orbiter Endeavour rolls into the Vehicle Assembly Building on its orbiter transfer vehicle. In high bay 1 it will be mated to the external tank and solid rocket boosters. Space Shuttle Endeavour is targeted for launch on mission STS-99 Jan. 13, 2000 at 1:11 p.m. EST. STS-99 is the Shuttle Radar Topography Mission, an international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR. The SRTM consists of a specially modified radar system that will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. The SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle

  13. Millimeter wave radar system on a rotating platform for combined search and track functionality with SAR imaging

    NASA Astrophysics Data System (ADS)

    Aulenbacher, Uwe; Rech, Klaus; Sedlmeier, Johannes; Pratisto, Hans; Wellig, Peter

    2014-10-01

    Ground based millimeter wave radar sensors offer the potential for a weather-independent automatic ground surveillance at day and night, e.g. for camp protection applications. The basic principle and the experimental verification of a radar system concept is described, which by means of an extreme off-axis positioning of the antenna(s) combines azimuthal mechanical beam steering with the formation of a circular-arc shaped synthetic aperture (SA). In automatic ground surveillance the function of search and detection of moving ground targets is performed by means of the conventional mechanical scan mode. The rotated antenna structure designed as a small array with two or more RX antenna elements with simultaneous receiver chains allows to instantaneous track multiple moving targets (monopulse principle). The simultaneously operated SAR mode yields areal images of the distribution of stationary scatterers. For ground surveillance application this SAR mode is best suited for identifying possible threats by means of change detection. The feasibility of this concept was tested by means of an experimental radar system comprising of a 94 GHz (W band) FM-CW module with 1 GHz bandwidth and two RX antennas with parallel receiver channels, placed off-axis at a rotating platform. SAR mode and search/track mode were tested during an outdoor measurement campaign. The scenery of two persons walking along a road and partially through forest served as test for the capability to track multiple moving targets. For SAR mode verification an image of the area composed of roads, grassland, woodland and several man-made objects was reconstructed from the measured data.

  14. Mercury radar imaging: evidence for polar ice.

    PubMed

    Slade, M A; Butler, B J; Muhleman, D O

    1992-10-23

    The first unambiguous full-disk radar mapping of Mercury at 3.5-centimeter wavelength, with the Goldstone 70-meter antenna transmitting and 26 antennas of the Very Large Array receiving, has provided evidence for the presence of polar ice. The radar experiments, conducted on 8 and 23 August 1991, were designed to image the half of Mercury not photographed by Mariner 10. The orbital geometry allowed viewing beyond the north pole of Mercury; a highly reflective region was clearly visible on the north pole during both experiments. This polar region has areas in which the circular polarization ratio (pt) was 1.0 to 1.4; values < approximately 0.1 are typical for terrestrial planets. Such high values of have hitherto been observed in radar observations only from icy regions of Mars and icy outer planet satellites.

  15. Antenna Pattern Measurements for Oceanographic Radars Using Small Aerial Drones

    NASA Astrophysics Data System (ADS)

    Washburn, L.; Romero, E.; Johnson, C.; Emery, B.; Gotschalk, C.

    2016-12-01

    We describe a method employing small, quadrotor drone aircraft for antenna pattern measurements (APMs) of high-frequency (HF) oceanographic radars used for observing ocean surface currents. During APMs, the drones carry small radio signal sources in circular arcs centered on receive antenna arrays at HF radar sites, similarly to conventional boat-based APMs. Previous studies have shown that accurate surface current measurements using HF radar require APMs. In the absence of APMs so-called "ideal" antenna patterns are assumed and these can differ substantially from measured patterns. Typically APMs are obtained using small research vessels, an expensive procedure requiring sea-going technicians, a vessel, and other equipment necessary to support small boat operations. Adverse sea conditions and obstacles in the water can limit the ability of small vessels to conduct APMs. In contrast, drones can successfully conduct APMs at much lower cost and in a broader range of sea states with comparable accuracy. Drone-based patterns can extend farther shoreward since they are not affected by the surf zone and thereby expand the range of bearings over which APMs are conducted. We describe recent progress in the use of drones for APMs including: (1) evaluation of the accuracy APM flight trajectories; (2) estimates of radial velocity components due to deviation of flight paths from circular arcs; and (3) the effects of altitude with respect to ground wave versus direct signal propagation. Use of drones simplifies APMs and it is hoped that this will lead to more frequent APMs and improved surface current measurements from HF radar networks.

  16. A combined radar-radiometer with variable polarization

    NASA Technical Reports Server (NTRS)

    Martin, D. P.

    1972-01-01

    An instrument is described that provides both radar and radiometer data at the same time. The antenna and receiver are time shared for the two sensor functions. The antenna polarization can be electronically scanned at rates up to 5000 changes for both the transmit and receive signal paths. This equipment is to investigate target signatures for remote sensing applications. The function of the equipment is described and the results for observations of asphalt, grass, and gravel surfaces are presented.

  17. Spaced-antenna wind estimation using an X-band active phased-array weather radar

    NASA Astrophysics Data System (ADS)

    Venkatesh, Vijay

    Over the past few decades, several single radar methods have been developed to probe the kinematic structure of storms. All these methods trade angular-resolution to retrieve the wind-field. To date, the spaced-antenna method has been employed for profiling the ionosphere and the precipitation free lower atmosphere. This work focuses on applying the spaced-antenna method on an X-band active phased-array radar for high resolution horizontal wind-field retrieval from precipitation echoes. The ability to segment the array face into multiple displaced apertures allows for flexible spaced-antenna implementations. The methodology employed herein comprises of Monte-Carlo simulations to optimize the spaced-antenna system design and analysis of real data collected with the designed phased-array system. The contribution that underpins this dissertation is the demonstration of qualitative agreement between spaced-antenna and Doppler beam swinging retrievals based on real data. First, simulations of backscattered electric fields at the antenna array elements are validated using theoretical expressions. Based on the simulations, the degrees of freedom in the spaced-antenna system design are optimized for retrieval of mean baseline wind. We show that the designed X-band spaced-antenna system has lower retrieval uncertainty than the existing S-band spaced-antenna implementation on the NWRT. This is because of the flexibility to synthesize small overlapping apertures and the ability to obtain statistically independent samples at a faster rate at X-band. We then demonstrate a technique to make relative phase-center displacement measurements based on simulations and real data from the phased-array spaced-antenna system. This simple method uses statistics of precipitation echoes and apriori beamwidth measurements to make field repeatable phase-center displacement measurements. Finally, we test the hypothesis that wind-field curvature effects are common to both the spaced-antenna and Doppler beam swinging methods. Based on a close-range winter storm data set, we find that the spaced-antenna and fine-resolution Doppler beam swinging retrievals are in qualitative agreement. The correlation between the spaced-antenna and fine-resolution Doppler beam swinging retrievals was 0.57. The lowered correlation coefficient was, in part, due to the high standard deviation of the DBS retrievals. At high wind-speeds, the spaced-antenna retrievals significantly departed from variational retrievals of mean baseline wind.

  18. Radar attenuation tomography using the centroid frequency downshift method

    USGS Publications Warehouse

    Liu, L.; Lane, J.W.; Quan, Y.

    1998-01-01

    A method for tomographically estimating electromagnetic (EM) wave attenuation based on analysis of centroid frequency downshift (CFDS) of impulse radar signals is described and applied to cross-hole radar data. The method is based on a constant-Q model, which assumes a linear frequency dependence of attenuation for EM wave propagation above the transition frequency. The method uses the CFDS to construct the projection function. In comparison with other methods for estimating attenuation, the CFDS method is relatively insensitive to the effects of geometric spreading, instrument response, and antenna coupling and radiation pattern, but requires the data to be broadband so that the frequency shift and variance can be easily measured. The method is well-suited for difference tomography experiments using electrically conductive tracers. The CFDS method was tested using cross-hole radar data collected at the U.S. Geological Survey Fractured Rock Research Site at Mirror Lake, New Hampshire (NH) during a saline-tracer injection experiment. The attenuation-difference tomogram created with the CFDS method outlines the spatial distribution of saline tracer within the tomography plane. ?? 1998 Elsevier Science B.V. All rights reserved.

  19. KSC-99pp0522

    NASA Image and Video Library

    1999-05-13

    Inside the Space Station Processing Facility, the Shuttle Radar Topography Mission (SRTM) is maneuvered by an overhead crane toward a workstand below. The SRTM, which is the primary payload on mission STS-99, consists of a specially modified radar system that will fly onboard the Space Shuttle during the 11-day mission scheduled for launch in September 1999. The objective of this radar system is to obtain the most complete high-resolution digital topographic database of the Earth. It will gather data that will result in the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM is an international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR. SRTM will be making use of a technique called radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. To get two radar images taken from different locations, the SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle

  20. KSC-99pp0524

    NASA Image and Video Library

    1999-05-13

    The move of the Shuttle Radar Topography Mission (SRTM) is nearly complete as it is lowered onto the workstand in the Space Station Processing Facility. The SRTM, which is the primary payload on mission STS-99, consists of a specially modified radar system that will fly onboard the Space Shuttle during the 11-day mission scheduled for launch in September 1999. The objective of this radar system is to obtain the most complete high-resolution digital topographic database of the Earth. It will gather data that will result in the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM is an international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR. SRTM will be making use of a technique called radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. To get two radar images taken from different locations, the SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle

  1. KSC-99pp0521

    NASA Image and Video Library

    1999-05-13

    After being lifted off the transporter (lower right) in the Space Station Processing Facility, the Shuttle Radar Topography Mission (SRTM) moves across the floor toward a workstand. The SRTM, which is the primary payload on mission STS-99, consists of a specially modified radar system that will fly onboard the Space Shuttle during the 11-day mission scheduled for launch in September 1999. The objective of this radar system is to obtain the most complete high-resolution digital topographic database of the Earth. It will gather data that will result in the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM is an international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR. SRTM will be making use of a technique called radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. To get two radar images taken from different locations, the SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle

  2. KSC-99pp0523

    NASA Image and Video Library

    1999-05-13

    Inside the Space Station Processing Facility, workers at each end of a workstand watch as the Shuttle Radar Topography Mission (SRTM) begins its descent onto it. The SRTM, which is the primary payload on mission STS-99, consists of a specially modified radar system that will fly onboard the Space Shuttle during the 11-day mission scheduled for launch in September 1999. The objective of this radar system is to obtain the most complete high-resolution digital topographic database of the Earth. It will gather data that will result in the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM is an international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR. SRTM will be making use of a technique called radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. To get two radar images taken from different locations, the SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle

  3. Three dimensional scattering center imaging techniques

    NASA Technical Reports Server (NTRS)

    Younger, P. R.; Burnside, W. D.

    1991-01-01

    Two methods to image scattering centers in 3-D are presented. The first method uses 2-D images generated from Inverse Synthetic Aperture Radar (ISAR) measurements taken by two vertically offset antennas. This technique is shown to provide accurate 3-D imaging capability which can be added to an existing ISAR measurement system, requiring only the addition of a second antenna. The second technique uses target impulse responses generated from wideband radar measurements from three slightly different offset antennas. This technique is shown to identify the dominant scattering centers on a target in nearly real time. The number of measurements required to image a target using this technique is very small relative to traditional imaging techniques.

  4. Synthetic aperture radar range - Azimuth ambiguity design and constraints

    NASA Technical Reports Server (NTRS)

    Mehlis, J. G.

    1980-01-01

    Problems concerning the design of a system for mapping a planetary surface with a synthetic aperture radar (SAR) are considered. Given an ambiguity level, resolution, and swath width, the problems are related to the determination of optimum antenna apertures and the most suitable pulse repetition frequency (PRF). From the set of normalized azimuth ambiguity ratio curves, the designer can arrive at the azimuth antenna length, and from the sets of normalized range ambiguity ratio curves, he can arrive at the range aperture length or pulse repetition frequency. A procedure based on this design method is shown in an example. The normalized curves provide results for a SAR using a uniformly or cosine weighted rectangular antenna aperture.

  5. 47 CFR 80.213 - Modulation requirements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... transmission period. (g) Radar stations operating in the bands above 2.4 GHz may use any type of modulation consistent with the bandwidth requirements in § 80.209(b). (h) Radar transponder coast stations using the... designed to reduce interference caused by triggering from radar antenna sidelobes. (i) Variable frequency...

  6. The PROUST radar

    NASA Technical Reports Server (NTRS)

    Bertin, F.; Glass, M.; Ney, R.; Petitdidier, M.

    1986-01-01

    The Stratosphere-Troposphere (ST) radar called PROUST works at 935 MHz using the same klystron and antenna as the coherent-scatter radar. The use of this equipment for ST work has required some important modifications of the transmitting system and the development of receiving, data processing and acquisition (1984,1985) equipment. The modifications are discussed.

  7. Simulations of Aperture Synthesis Imaging Radar for the EISCAT_3D Project

    NASA Astrophysics Data System (ADS)

    La Hoz, C.; Belyey, V.

    2012-12-01

    EISCAT_3D is a project to build the next generation of incoherent scatter radars endowed with multiple 3-dimensional capabilities that will replace the current EISCAT radars in Northern Scandinavia. Aperture Synthesis Imaging Radar (ASIR) is one of the technologies adopted by the EISCAT_3D project to endow it with imaging capabilities in 3-dimensions that includes sub-beam resolution. Complemented by pulse compression, it will provide 3-dimensional images of certain types of incoherent scatter radar targets resolved to about 100 metres at 100 km range, depending on the signal-to-noise ratio. This ability will open new research opportunities to map small structures associated with non-homogeneous, unstable processes such as aurora, summer and winter polar radar echoes (PMSE and PMWE), Natural Enhanced Ion Acoustic Lines (NEIALs), structures excited by HF ionospheric heating, meteors, space debris, and others. To demonstrate the feasibility of the antenna configurations and the imaging inversion algorithms a simulation of synthetic incoherent scattering data has been performed. The simulation algorithm incorporates the ability to control the background plasma parameters with non-homogeneous, non-stationary components over an extended 3-dimensional space. Control over the positions of a number of separated receiving antennas, their signal-to-noise-ratios and arriving phases allows realistic simulation of a multi-baseline interferometric imaging radar system. The resulting simulated data is fed into various inversion algorithms. This simulation package is a powerful tool to evaluate various antenna configurations and inversion algorithms. Results applied to realistic design alternatives of EISCAT_3D will be described.

  8. Design and verification of mechanisms for a large foldable antenna

    NASA Technical Reports Server (NTRS)

    Luhmann, Hans Jurgen; Etzler, Carl Christian; Wagner, Rudolf

    1989-01-01

    The characteristics of the Synthetic Aperture Radar (SAR) antenna aboard the ESA Remote Sensing Satellite (ERS-1) are presented. The antenna is folded into a dense package for launch and is deployed in orbit. The design requirements and constraints, their impact on the design, and the resulting features of the mechanisms are discussed.

  9. Relationship of spaced antenna and Doppler techniques for velocity measurements (keynote paper), part 3

    NASA Technical Reports Server (NTRS)

    Vincent, R. A.

    1984-01-01

    The Doppler, spaced-antenna and interferometric methods of measuring wind velocities all use the same basic information, the Doppler shifts imposed on backscattered radio waves, but they process it in different ways. The Doppler technique is most commonly used at VHF since the narrow radar beams are readily available. However, the spaced antenna (SA) method has been successfully used with the SOUSY and Adelaide radars. At MF/HF the spaced antenna method is widely used since the large antenna arrays (diameter 1 km) required to generate narrow beams are expensive to construct. Where such arrays of this size are available then the Doppler method has been successfully used (e.g., Adelaide and Brisbane). In principle, the factors which influence the choice of beam pointing angle, the optimum antenna spacing will be the same whether operation is at MF or VHF. Many of the parameters which govern the efficient use of wind measuring systems have been discussed at previous MST workshops. Some of the points raised by these workshops are summarized.

  10. 1. View toward south, facade (north side or "A" wall) ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. View toward south, facade (north side or "A" wall) of perimeter acquisition radar building. The globe on the upper left is a shelter housing the Hercules tracker antenna. To the right is the utility tunnel leading to the par power plant. The antennae for the par are contained in the large lighter-toned shape covering most of the wall - Stanley R. Mickelsen Safeguard Complex, Perimeter Acquisition Radar Building, Limited Access Area, between Limited Access Patrol Road & Service Road A, Nekoma, Cavalier County, ND

  11. Integrated, Dual Orthogonal Antennas for Polarimetric Ground Penetrating Radar

    NASA Astrophysics Data System (ADS)

    Pauli, Mario; Wiesbeck, Werner

    2015-04-01

    Ground penetrating radar systems are mostly equipped with single polarized antennas, for example with single linear polarization or with circular polarization. The radiated waves are partly reflected at the ground surface and very often the penetrating waves are distorted in their polarization. The distortion depends on the ground homogeneity and the orientation of the antennas relative to the ground structure. The received signals from the reflecting objects may most times only be classified according to their coverage and intensity. This makes the recognition of the objects difficult or impossible. In airborne and spaceborne Remote Sensing the systems are meanwhile mostly equipped with front ends with dual orthogonal polarized antennas for a full polarimetric operation. The received signals, registered in 2x2 scattering matrices according to co- and cross polarization, are processed for the evaluation of all features of the targets. Ground penetrating radars could also profit from the scientific results of Remote Sensing. The classification of detected objects for their structure and orientation requires more information in the reflected signal than can be measured with a single polarization [1, 2]. In this paper dual linear, orthogonal polarized antennas with a common single, frequency independent phase center, are presented [3]. The relative bandwidth of these antennas can be 1:3, up to 1:4. The antenna is designed to work in the frequency range between 3 GHz and 11 GHz, but can be easily adapted to the GPR frequency range by scaling. The size of the antenna scaled for operation in typical GPR frequencies would approximately be 20 by 20 cm2. By the implementation in a dielectric carrier it could be reduced in size if required. The major problem for ultra wide band, dual polarized antennas is the frequency independent feed network, realizing the required phase shifts. For these antennas a network, which is frequency independent over a wide range, has been developed [4]. If OFDM signals are used for the radiation, the carriers can be split in even and odd carriers and fed to the two orthogonally polarized transmit antennas. By using OFDM, the de-correlation of the two subcarrier groups becomes inherently high. Due to the orthogonality of OFDM subcarriers the de-correlation only depends on the quality of the hardware and the signal processing. They can be simultaneously radiated and received by the two antennas. This could result in a significant improvement of the GPR sensor system. The antenna has been realized and first measurements have been conducted. During the forthcoming EGU 2015 General Assembly the detailed electromagnetic background and the function of the dual linear, orthogonal polarized antenna will be presented as well as results in GPR relevant frequencies. Also, an approach of a planar feeding network will be presented. This abstract is a contribution to Session GI3.1 "Civil Engineering Applications of Ground Penetrating Radar," organized by the COST Action TU1208. References [1] Carin, L.; Kapoor, R.; Baum, C.E., "Polarimetric SAR imaging of buried landmines," IEEE Transactions on Geoscience and Remote Sensing, vol. 36 iss. 6, pp.1985-1988, 1998. [2] T. Schultze, M. Porebska, W. Wiesbeck, and I. Willms, "Onsets for the recognition of objects and image refinement using UWB Radar," in Proceedings of the German Microwave Conference GeMiC 2008, CD-ROM, Hamburg-Harburg, Germany, Mar. 2008. [3] G. Adamiuk, S. Beer, W. Wiesbeck, and T. Zwick, "Dual-Orthogonal Polarized Antenna for UWB-IR Technology," IEEE Antennas and Wireless Propagation Letters, vol. 8, pp. 981-984, Jul. 2009. [4] Adamiuk, W. Wiesbeck, and T. Zwick, "Differential Feeding as a Concept for the Realization of Broadband Dual-Polarized Antennas with Very High Polarization Purity," in 2009 IEEE International Symposium on Antennas & Propagation, Charleston, South Carolina, USA, Jun. 2009.

  12. Spectral line and continuum studies using Haystack antenna

    NASA Technical Reports Server (NTRS)

    1973-01-01

    During the last half of 1972, the Haystack antenna was utilized 88% of the time. Of this useful time, 81% was devoted to radio astronomy investigations, 8% was spent on radar-related research and 11% was scheduled for maintenance and system improvements. Thirteen programs were completed of which 10 were spectral-line studies involving primarily recombination lines and H2O vapor investigations. The others involved 2 cm and 1.3 cm continuum observations. Fifteen new programs were accepted and the currently active radio observing programs totalled 24 as of 31 December 1973. The last radar measurements in the lunar topography program have now been completed. Radar activity, including measurements on Mercury, Venus and synchronous satellites has continued.

  13. Flight test of a synthetic aperture radar antenna using STEP

    NASA Technical Reports Server (NTRS)

    Zimcik, D. G.; Vigeron, F. R.; Ahmed, S.

    1984-01-01

    To establish confidence in its overall performance, credible information on the synthetic aperture radar antenna's mechanical properties in orbit must be obtained. However, the antenna's size, design, and operating environment make it difficult to simulate operating conditions under 1-g Earth conditions. The Space Technology Experiments Platform (STEP) offers a timely opportunity to mechanically qualify and characterize the antenna design in a representative environment. The proposed experimental configuration would employ a half-system of the full-scale RADARSAT antenna which would be mounted on the STEP platform in the orbiter cargo bay such that it could be deployed and retracted in orbit (as shown in this figure). The antenna would be subjected to typical environmental exposures while an array of targets and sensors on the antenna support structure and reflecting surface are observed and monitored. In particular, the typical environments would include deployment and retraction, dynamic response to vehicle thruster or base exciter inputs, and thermal soak and transient effects upon entering or exiting Earth eclipse. The proposed experiment would also provide generic information on the properties of large space structures in space and on techniques to obtain the desired information.

  14. Three-Dimensional ISAR Imaging Method for High-Speed Targets in Short-Range Using Impulse Radar Based on SIMO Array.

    PubMed

    Zhou, Xinpeng; Wei, Guohua; Wu, Siliang; Wang, Dawei

    2016-03-11

    This paper proposes a three-dimensional inverse synthetic aperture radar (ISAR) imaging method for high-speed targets in short-range using an impulse radar. According to the requirements for high-speed target measurement in short-range, this paper establishes the single-input multiple-output (SIMO) antenna array, and further proposes a missile motion parameter estimation method based on impulse radar. By analyzing the motion geometry relationship of the warhead scattering center after translational compensation, this paper derives the receiving antenna position and the time delay after translational compensation, and thus overcomes the shortcomings of conventional translational compensation methods. By analyzing the motion characteristics of the missile, this paper estimates the missile's rotation angle and the rotation matrix by establishing a new coordinate system. Simulation results validate the performance of the proposed algorithm.

  15. Improving angular resolution with Scan-MUSIC algorithm for real complex targets using 35-GHz millimeter-wave radar

    NASA Astrophysics Data System (ADS)

    Ly, Canh

    2004-08-01

    Scan-MUSIC algorithm, developed by the U.S. Army Research Laboratory (ARL), improves angular resolution for target detection with the use of a single rotatable radar scanning the angular region of interest. This algorithm has been adapted and extended from the MUSIC algorithm that has been used for a linear sensor array. Previously, it was shown that the SMUSIC algorithm and a Millimeter Wave radar can be used to resolve two closely spaced point targets that exhibited constructive interference, but not for the targets that exhibited destructive interference. Therefore, there were some limitations of the algorithm for the point targets. In this paper, the SMUSIC algorithm is applied to a problem of resolving real complex scatterer-type targets, which is more useful and of greater practical interest, particular for the future Army radar system. The paper presents results of the angular resolution of the targets, an M60 tank and an M113 Armored Personnel Carrier (APC), that are within the mainlobe of a Κα-band radar antenna. In particular, we applied the algorithm to resolve centroids of the targets that were placed within the beamwidth of the antenna. The collected coherent data using the stepped-frequency radar were compute magnitudely for the SMUSIC calculation. Even though there were significantly different signal returns for different orientations and offsets of the two targets, we resolved those two target centroids when they were as close as about 1/3 of the antenna beamwidth.

  16. ATCRBS Improvement Program Reflector Antenna Development

    DOT National Transportation Integrated Search

    1976-06-01

    This report describes the results of a program undertaken by Texas Instruments Incorporated, under contract to the Transportation Systems Center (TSC), to investigate improved antennas for the Air Traffic Control Radar Beacon System (ATCRBS). Under t...

  17. Design of a dual linear polarization antenna using split ring resonators at X-band

    NASA Astrophysics Data System (ADS)

    Ahmed, Sadiq; Chandra, Madhukar

    2017-11-01

    Dual linear polarization microstrip antenna configurations are very suitable for high-performance satellites, wireless communication and radar applications. This paper presents a new method to improve the co-cross polarization discrimination (XPD) for dual linear polarized microstrip antennas at 10 GHz. For this, three various configurations of a dual linear polarization antenna utilizing metamaterial unit cells are shown. In the first layout, the microstrip patch antenna is loaded with two pairs of spiral ring resonators, in the second model, a split ring resonator is placed between two microstrip feed lines, and in the third design, a complementary split ring resonators are etched in the ground plane. This work has two primary goals: the first is related to the addition of metamaterial unit cells to the antenna structure which permits compensation for an asymmetric current distribution flow on the microstrip antenna and thus yields a symmetrical current distribution on it. This compensation leads to an important enhancement in the XPD in comparison to a conventional dual linear polarized microstrip patch antenna. The simulation reveals an improvement of 7.9, 8.8, and 4 dB in the E and H planes for the three designs, respectively, in the XPD as compared to the conventional dual linear polarized patch antenna. The second objective of this paper is to present the characteristics and performances of the designs of the spiral ring resonator (S-RR), split ring resonator (SRR), and complementary split ring resonator (CSRR) metamaterial unit cells. The simulations are evaluated using the commercial full-wave simulator, Ansoft High-Frequency Structure Simulator (HFSS).

  18. SAR Ambiguity Study for the Cassini Radar

    NASA Technical Reports Server (NTRS)

    Hensley, Scott; Im, Eastwood; Johnson, William T. K.

    1993-01-01

    The Cassini Radar's synthetic aperture radar (SAR) ambiguity analysis is unique with respect to other spaceborne SAR ambiguity analyses owing to the non-orbiting spacecraft trajectory, asymmetric antenna pattern, and burst mode of data collection. By properly varying the pointing, burst mode timing, and radar parameters along the trajectory this study shows that the signal-to-ambiguity ratio of better than 15 dB can be achieved for all images obtained by the Cassini Radar.

  19. Using doppler radar images to estimate aircraft navigational heading error

    DOEpatents

    Doerry, Armin W [Albuquerque, NM; Jordan, Jay D [Albuquerque, NM; Kim, Theodore J [Albuquerque, NM

    2012-07-03

    A yaw angle error of a motion measurement system carried on an aircraft for navigation is estimated from Doppler radar images captured using the aircraft. At least two radar pulses aimed at respectively different physical locations in a targeted area are transmitted from a radar antenna carried on the aircraft. At least two Doppler radar images that respectively correspond to the at least two transmitted radar pulses are produced. These images are used to produce an estimate of the yaw angle error.

  20. Measurement of electromagnetic fields generated by air traffic control radar systems with spectrum analysers.

    PubMed

    Barellini, A; Bogi, L; Licitra, G; Silvi, A M; Zari, A

    2009-12-01

    Air traffic control (ATC) primary radars are 'classical' radars that use echoes of radiofrequency (RF) pulses from aircraft to determine their position. High-power RF pulses radiated from radar antennas may produce high electromagnetic field levels in the surrounding area. Measurement of electromagnetic fields produced by RF-pulsed radar by means of a swept-tuned spectrum analyser are investigated here. Measurements have been carried out both in the laboratory and in situ on signals generated by an ATC primary radar.

  1. The Shuttle Radar Topography Mission is moved to a workstand

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Workers inside the Space Station Processing Facility keep watch as an overhead crane begins lifting the Shuttle Radar Topography Mission (SRTM) from the transporter below. The SRTM is being moved to a workstand. The primary payload on mission STS-99, the SRTM consists of a specially modified radar system that will fly onboard the Space Shuttle during the 11-day mission scheduled for launch in September 1999. The objective of this radar system is to obtain the most complete high-resolution digital topographic database of the Earth. It will gather data that will result in the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM is an international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR. SRTM will be making use of a technique called radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. To get two radar images taken from different locations, the SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle.

  2. The Shuttle Radar Topography Mission is moved to a workstand

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Inside the Space Station Processing Facility, workers watch as an overhead crane is lowered for lifting the Shuttle Radar Topography Mission (SRTM) from the transporter it is resting on. The SRTM is being moved to a workstand. The primary payload on mission STS-99, the SRTM consists of a specially modified radar system that will fly onboard the Space Shuttle during the 11-day mission scheduled for launch in September 1999. The objective of this radar system is to obtain the most complete high-resolution digital topographic database of the Earth. It will gather data that will result in the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM is an international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR. SRTM will be making use of a technique called radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. To get two radar images taken from different locations, the SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle.

  3. Spaceborne Microwave Instrument for High Resolution Remote Sensing of the Earth's Surface Using a Large-Aperture Mesh Antenna

    NASA Technical Reports Server (NTRS)

    Njoku, E.; Wilson, W.; Yueh, S.; Freeland, R.; Helms, R.; Edelstein, W.; Sadowy, G.; Farra, D.; West, R.; Oxnevad, K.

    2001-01-01

    This report describes a two-year study of a large-aperture, lightweight, deployable mesh antenna system for radiometer and radar remote sensing of the Earth from space. The study focused specifically on an instrument to measure ocean salinity and Soil moisture. Measurements of ocean salinity and soil moisture are of critical . importance in improving knowledge and prediction of key ocean and land surface processes, but are not currently obtainable from space. A mission using this instrument would be the first demonstration of deployable mesh antenna technology for remote sensing and could lead to potential applications in other remote sensing disciplines that require high spatial resolution measurements. The study concept features a rotating 6-m-diameter deployable mesh antenna, with radiometer and radar sensors, to measure microwave emission and backscatter from the Earth's surface. The sensors operate at L and S bands, with multiple polarizations and a constant look angle, scanning across a wide swath. The study included detailed analyses of science requirements, reflector and feedhorn design and performance, microwave emissivity measurements of mesh samples, design and test of lightweight radar electronic., launch vehicle accommodations, rotational dynamics simulations, and an analysis of attitude control issues associated with the antenna and spacecraft, The goal of the study was to advance the technology readiness of the overall concept to a level appropriate for an Earth science emission.

  4. School of Electrical Engineering.

    NASA Technical Reports Server (NTRS)

    Farley, D. T.

    1983-01-01

    The possibility of making the antenna of an MST radar too large is pointed out. It is not that the signal ceases to become stronger beyond some critical antenna size; the received scattered signal actually becomes weaker as the antenna size is increased whenever the target is in the near field, Fresnel region of the antenna. The Arecibo antenna is a case in point. It is supposed that MST work would benefit to use a feed which illuminated only a portion of the dish.

  5. The instrumental principles of MST radars and incoherent scatter radars and the configuration of radar system hardware

    NASA Technical Reports Server (NTRS)

    Roettger, Juergen

    1989-01-01

    The principle of pulse modulation used in the case of coherent scatter radars (MST radars) is discussed. Coherent detection and the corresponding system configuration is delineated. Antenna requirements and design are outlined and the phase-coherent transmitter/receiver system is described. Transmit/receive duplexers, transmitters, receivers, and quadrature detectors are explained. The radar controller, integrator, decoder and correlator design as well as the data transfer and the control and monitoring by the host computer are delineated. Typical operation parameters of some well-known radars are summarized.

  6. Inspection of a large concrete block containing embedded defects using ground penetrating radar

    NASA Astrophysics Data System (ADS)

    Eisenmann, David; Margetan, Frank J.; Koester, Lucas; Clayton, Dwight

    2016-02-01

    Ground penetrating radar (GPR), also known as impulse response radar, was used to examine a thick concrete block containing reinforcing steel bars (rebar) and embedded defects. The block was located at the University of Minnesota, measured approximately 7 feet tall by 7 feet wide by 40 inches deep, and was intended to simulate certain aspects of a concrete containment wall at a nuclear power plant. This paper describes the measurements that were made and various analyses of the data. We begin with a description of the block itself and the GPR equipment and methods used in our inspections. The methods include the application of synthetic aperture focusing techniques (SAFT). We then present and discuss GPR images of the block's interior made using 1600-MHz, 900-MHz, and 400-MHz antennas operating in pulse/echo mode. A number of the embedded defects can be seen, and we discuss how their relative detectability can be quantified by comparison to the response from nearby rebar. We next discuss through-transmission measurements made using pairs of 1600-MHz and 900-MHz antennas, and the analysis of that data to deduce the average electromagnetic (EM) wave speed and attenuation of the concrete. Through the 40-inch thickness, attenuation rises approximately linearly with frequency at a rate near 0.7 dB/inch/GHz. However, there is evidence that EM properties vary with depth in the block. We conclude with a brief summary and a discussion of possible future work.

  7. Dual Channel S-Band Frequency Modulated Continuous Wave Through-Wall Radar Imaging

    PubMed Central

    Oh, Daegun; Kim, Sunwoo; Chong, Jong-Wha

    2018-01-01

    This article deals with the development of a dual channel S-Band frequency-modulated continuous wave (FMCW) system for a through-the-wall imaging (TWRI) system. Most existing TWRI systems using FMCW were developed for synthetic aperture radar (SAR) which has many drawbacks such as the need for several antenna elements and movement of the system. Our implemented TWRI system comprises a transmitting antenna and two receiving antennas, resulting in a significant reduction of the number of antenna elements. Moreover, a proposed algorithm for range-angle-Doppler 3D estimation based on a 3D shift invariant structure is utilized in our implemented dual channel S-band FMCW TWRI system. Indoor and outdoor experiments were conducted to image the scene beyond a wall for water targets and person targets, respectively. The experimental results demonstrate that high-quality imaging can be achieved under both experimental scenarios. PMID:29361777

  8. A Novel Compact Wideband TSA Array for Near-Surface Ice Sheet Penetrating Radar Applications

    NASA Astrophysics Data System (ADS)

    Zhang, Feng; Liu, Xiaojun; Fang, Guangyou

    2014-03-01

    A novel compact tapered slot antenna (TSA) array for near-surface ice sheet penetrating radar applications is presented. This TSA array is composed of eight compact antenna elements which are etched on two 480mm × 283mm FR4 substrates. Each antenna element is fed by a wideband coplanar waveguide (CPW) to coupled strip-line (CPS) balun. The two antenna substrates are connected together with a metallic baffle. To obtain wideband properties, another two metallic baffles are used along broadsides of the array. This array is fed by a 1 × 8 wideband power divider. The measured S11 of the array is less than -10dB in the band of 500MHz-2GHz, and the measured gain is more than 6dBi in the whole band which agrees well with the simulated results.

  9. Radar, target and ranging

    NASA Astrophysics Data System (ADS)

    1984-09-01

    This Test Operations Procedure (TOP) provides conventional test methods employing conventional test instrumentation for testing conventional radars. Single tests and subtests designed to test radar components, transmitters, receivers, antennas, etc., and system performance are conducted with single item instruments such as meters, generators, attenuators, counters, oscillators, plotters, etc., and with adequate land areas for conducting field tests.

  10. Ground-penetrating radar research in Belgium: from developments to applications

    NASA Astrophysics Data System (ADS)

    Lambot, Sébastien; Van Meirvenne, Marc; Craeye, Christophe

    2014-05-01

    Ground-penetrating radar research in Belgium spans a series of developments and applications, including mainly ultra wideband radar antenna design and optimization, non-destructive testing for the characterization of the electrical properties of soils and materials, and high-resolution subsurface imaging in agricultural engineering, archeology and transport infrastructures (e.g., road inspection and pipe detection). Security applications have also been the topic of active research for several years (i.e., landmine detection) and developments in forestry have recently been initiated (i.e., for root zone and tree trunk imaging and characterization). In particular, longstanding research has been devoted to the intrinsic modeling of antenna-medium systems for full-wave inversion, thereby providing an effective way for retrieving the electrical properties of soils and materials. Full-wave modeling is a prerequisite for benefiting from the full information contained in the radar data and is necessary to provide robust and accurate estimates of the properties of interest. Nevertheless, this has remained a major challenge in geophysics and electromagnetics for many years, mainly due to the complex interactions between the antennas and the media as well as to the significant computing resources that are usually required. Efforts have also been dedicated to the development of specific inversion strategies to cope with the complexity of the inverse problems usually dealt with as well as ill-posedness issues that arise from a lack of information in the radar data. To circumvent this last limitation, antenna arrays have been developed and modeled in order to provide additional information. Moreover, data fusion ways have been investigated, by mainly combining GPR data with electromagnetic induction complementary information in joint interpretation analyses and inversion procedures. Finally, inversions have been regularized by combining electromagnetics models together with soil hydrodynamic models in mechanistic data assimilation frameworks, assuming process knowledge as information as well. Acknowledgement: GPR research in Belgium benefits from networking activities carried out within the EU funded COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar".

  11. Nile Delta Fisheries, Egypt

    NASA Image and Video Library

    2015-12-09

    On the left is a radar image of asteroid 1998 WT24 taken in December 2001 by scientists using NASA's the 230-foot (70-meter) DSS-14 antenna at Goldstone, California. On the right is a radar image of the same asteroid acquired on Dec. 11, 2015, during the asteroid's most recent Earth flyby. The radar images from 2001 (on the left), have a resolution of about 60 feet (19 meters) per pixel. The radar image from 2015 (on the right) achieved a spatial resolution as fine as 25 feet (7.5 meters) per pixel. The 2015 radar image was obtained using the same DSS-14 antenna at Goldstone to transmit high-power microwaves toward the asteroid. However, this time, the radar echoes bounced off the asteroid were received by the National Radio Astronomy Observatory's 100-meter (330-foot) Green Bank Telescope in West Virginia. The next visit of asteroid 1998 WT24 to Earth's neighborhood will be on Nov. 11, 2018, when it will make a distant pass at about 12.5-million miles (52 lunar distances). http://photojournal.jpl.nasa.gov/catalog/PIA20216

  12. KSC-99pp1374

    NASA Image and Video Library

    1999-12-02

    KENNEDY SPACE CENTER, FLA. -- Orbiter Endeavour aims its nose toward the Vehicle Assembly Building (left) where it will be lifted to vertical and mated to the external tank and solid rocket boosters in high bay 1. Space Shuttle Endeavour is targeted for launch on mission STS-99 Jan. 13, 2000 at 1:11 p.m. EST. STS-99 is the Shuttle Radar Topography Mission, an international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR. The SRTM consists of a specially modified radar system that will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. The SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle

  13. KSC-99pp1382

    NASA Image and Video Library

    1999-12-03

    KENNEDY SPACE CENTER, FLA. -- In this dizzying view from overhead in high bay 1 of the VAB, the orbiter Endeavour is lowered for mating with the external tank below (on left), and the solid rocket boosters. Space Shuttle Endeavour is targeted for launch on mission STS-99 Jan. 13, 2000, at 1:11 p.m. EST. STS-99 is the Shuttle Radar Topography Mission, an international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR. The SRTM consists of a specially modified radar system that will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. The SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle

  14. KSC-99pp1371

    NASA Image and Video Library

    1999-12-02

    KENNEDY SPACE CENTER, FLA. -- Workers at KSC lead the way as Orbiter Endeavour, on an orbiter transfer vehicle, rolls from the Orbiter Processing Facility to the Vehicle Assembly Building, where it will be mated to the external tank and solid rocket boosters in high bay 1. Space Shuttle Endeavour is targeted for launch on mission STS-99 Jan. 13, 2000 at 1:11 p.m. EST. STS-99 is the Shuttle Radar Topography Mission, an international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR. The SRTM consists of a specially modified radar system that will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. The SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle

  15. KSC-99pp1370

    NASA Image and Video Library

    1999-12-02

    KENNEDY SPACE CENTER, FLA. -- Orbiter Endeavour rolls out of the Orbiter Processing Facility bay 2 for transfer to the Vehicle Assembly Building. There it will be mated to the external tank and solid rocket boosters in high bay 1. Space Shuttle Endeavour is targeted for launch on mission STS-99 Jan. 13, 2000 at 1:11 p.m. EST. STS-99 is the Shuttle Radar Topography Mission, an international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR. The SRTM consists of a specially modified radar system that will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. The SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle

  16. KSC-99pp1384

    NASA Image and Video Library

    1999-12-03

    KENNEDY SPACE CENTER, FLA. -- Viewed from the ground level in high bay 1 of the VAB, the orbiter Endeavour seems to float in mid-air as it is lowered for mating with the external tank and solid rocket boosters behind and below it. Space Shuttle Endeavour is targeted for launch on mission STS-99 Jan. 13, 2000, at 1:11 p.m. EST. STS-99 is the Shuttle Radar Topography Mission, an international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR. The SRTM consists of a specially modified radar system that will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. The SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle

  17. UAVSAR Active Electronically-Scanned Array

    NASA Technical Reports Server (NTRS)

    Sadowy, Gregory; Brown, Kyle; Chamberlain, Neil; Figueroa, Harry; Fisher, Charlie; Grando, Maurio; Hamilton, Gary; Vorperian, Vatche; Zawadzki, Mark

    2010-01-01

    The Uninhabited Airborne Vehicle Synthetic Aperture Radar (UAVSAR) L-band (1.2-1.3 GHz) repeat pass, interferometric synthetic aperture radar (InSAR) used for Earth science applications. Using complex radar images collected during separate passes on time scales of hours to years, changes in surface topography can be measured. The repeat-pass InSAR technique requires that the radar look angle be approximately the same on successive passes. Due to variations in aircraft attitude between passes, antenna beam steering is required to replicate the radar look angle. This paper describes an active, electronically steered array (AESA) that provides beam steering capability in the antenna azimuth plane. The array contains 24 transmit/receive modules generating 2800 W of radiated power and is capable of pulse-to-pulse beam steering and polarization agility. Designed for high reliability as well as serviceability, all array electronics are contained in single 178cm x 62cm x 12 cm air-cooled panel suitable for operation up 60,000 ft altitude.

  18. Monitoring internal organ motion with continuous wave radar in CT.

    PubMed

    Pfanner, Florian; Maier, Joscha; Allmendinger, Thomas; Flohr, Thomas; Kachelrieß, Marc

    2013-09-01

    To avoid motion artifacts in medical imaging or to minimize the exposure of healthy tissues in radiation therapy, medical devices are often synchronized with the patient's respiratory motion. Today's respiratory motion monitors require additional effort to prepare the patients, e.g., mounting a motion belt or placing an optical reflector on the patient's breast. Furthermore, they are not able to measure internal organ motion without implanting markers. An interesting alternative to assess the patient's organ motion is continuous wave radar. The aim of this work is to design, implement, and evaluate such a radar system focusing on application in CT. The authors designed a radar system operating in the 860 MHz band to monitor the patient motion. In the intended application of the radar system, the antennas are located close to the patient's body inside the table of a CT system. One receive and four transmitting antennas are used to avoid the requirement of exact patient positioning. The radar waves propagate into the patient's body and are reflected at tissue boundaries, for example at the borderline between muscle and adipose tissue, or at the boundaries of organs. At present, the authors focus on the detection of respiratory motion. The radar system consists of the hardware mentioned above as well as of dedicated signal processing software to extract the desired information from the radar signal. The system was evaluated using simulations and measurements. To simulate the radar system, a simulation model based on radar and wave field equations was designed and 4D respiratory-gated CT data sets were used as input. The simulated radar signals and the measured data were processed in the same way. The radar system hardware and the signal processing algorithms were tested with data from ten volunteers. As a reference, the respiratory motion signal was recorded using a breast belt simultaneously with the radar measurements. Concerning the measurements of the test persons, there is a very good correlation (ρ = 0.917) between the respiratory motion phases received by the radar system and the external motion monitor. Our concept of using an array of transmitting antennas turned out to be widely insensitive to the positioning of the test persons. A time shift between the respiratory motion curves recorded with the radar system and the motion curves from the external respiratory monitor was observed which indicates a slight difference between internal organ motion and motion detected by the external respiratory monitor. The simulations were in good accordance with the measurements. A continuous wave radar operating in the near field of the antennas can be used to determine the respiratory motion of humans accurately. In contrast to trigger systems used today, the radar system is able to measure motion inside the body. If such a monitor was routinely available in clinical CT, it would be possible optimizing the scan start with respect to the respiratory state of the patient. Breathing commands would potentially widely be avoided, and as far as uncooperative patients or children are concerned, less sedation might be necessary. Further applications of the radar system could be in radiation therapy or interventional imaging for instance.

  19. Distortion effects in a switch array UWB radar for time-lapse imaging of human heartbeats

    NASA Astrophysics Data System (ADS)

    Brovoll, Sverre; Berger, Tor; Aardal, Åyvind; Lande, Tor S.; Hamran, Svein-Erik

    2014-05-01

    Cardiovascular diseases (CVD) are a major cause of deaths all over the world. Microwave radar can be an alternative sensor for heart diagnostics and monitoring in modern healthcare that aids early detection of CVD symptoms. In this paper measurements from a switch array radar system are presented. This UWB system operates below 3 GHz and does time-lapse imaging of the beating heart inside the human body. The array consists of eight fat dipole elements. With a switch system, every possible sequence of transmit/receive element pairs can be selected to build a radar image from the recordings. To make the radar waves penetrate the human tissue, the antenna array is placed in contact with the body. Removal of the direct signal leakage through the antennas and body surface are done by high-pass (HP) filtering of the data prior to image processing. To analyze the results, measurements of moving spheres in air and simulations are carried out. We see that removal of the direct signal introduces amplitude distortion in the images. In addition, the effect of small target motion between the collection times of data from the individual elements is analyzed. With low pulse repetition frequency (PRF) this motion will distort the image. By using data from real measurements of heart motion in simulations, we analyze how the PRF and the antenna geometry influence this distortions.

  20. 2. View of southerly DR 1 antenna looking north 25 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. View of southerly DR 1 antenna looking north 25 degrees west and and showing radar scanner building no. 105 east face through antenna. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  1. 78 FR 14649 - Amendment of Class B Airspace Description; Tampa, FL

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-07

    ... surveillance radar (ASR) antenna'' to ``Point of Origin.'' In addition, the description is edited throughout to... the airspace, the area was designed using the latitude/longitude position of the ASR antenna as the centerpoint. In 2012, the ASR antenna was moved to another location on the airport. So that there will be no...

  2. 3. View of middle DR 2 antenna looking north 30 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. View of middle DR 2 antenna looking north 30 degrees west and showing radar scanner building no. 105 east face through antenna. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  3. A transceiver module of the Mu radar

    NASA Technical Reports Server (NTRS)

    Kato, S.; Ogawa, T.; Tsuda, T.; Sato, T.; Kimura, I.; Fukao, S.

    1983-01-01

    The transceiver (TR) module of a middle and upper atmospheric radar is described. The TR module used in the radar is mainly composed of two units: a mixer (MIX unit) and a power amplifier (PA unit). The former generates the RF wave for transmission and converts the received echo to the IF signal. A 41.5-MHz local signal fed to mixers passes through a digitally controlled 8-bit phase shifter which can change its value up to 1,000 times in a second, so that the MU radar has the ability to steer its antenna direction quickly and flexibly. The MIX unit also contains a buffer amplifier and a gate for the transmitting signal and preamplifier for the received one whose noise figure is less than 5 dB. The PA unit amplifies the RF signal supplied from the MIX unit up to 63.7 dBm (2350 W), and feeds it to the crossed Yagi antenna.

  4. Passive coherent location direct signal suppression using hardware mixing techniques

    NASA Astrophysics Data System (ADS)

    Kaiser, Sean A.; Christianson, Andrew J.; Narayanan, Ram M.

    2017-05-01

    Passive coherent location (PCL) is a radar technique, in which the system uses reflections from opportunistic illumination sources in the environment for detection and tracking. Typically, PCL uses civilian communication transmitters not ideally suited for radar. The physical geometry of PCL is developed on the basis of bistatic radar without control of the transmitter antenna or waveform design. This poses the problem that often the receiver is designed with two antennas and channels, one for reference and one for surveillance. The surveillance channel is also contaminated with the direct signal and thus direct signal suppression (DSS) techniques must be used. This paper proposes an analytical solution based around hardware for DSS which is compared to other methods available in the literature. The methods are tested in varying bistatic geometries and with varying target radar cross section (RCS) and signal-to-noise ratio (SNR).

  5. Three-Dimensional ISAR Imaging Method for High-Speed Targets in Short-Range Using Impulse Radar Based on SIMO Array

    PubMed Central

    Zhou, Xinpeng; Wei, Guohua; Wu, Siliang; Wang, Dawei

    2016-01-01

    This paper proposes a three-dimensional inverse synthetic aperture radar (ISAR) imaging method for high-speed targets in short-range using an impulse radar. According to the requirements for high-speed target measurement in short-range, this paper establishes the single-input multiple-output (SIMO) antenna array, and further proposes a missile motion parameter estimation method based on impulse radar. By analyzing the motion geometry relationship of the warhead scattering center after translational compensation, this paper derives the receiving antenna position and the time delay after translational compensation, and thus overcomes the shortcomings of conventional translational compensation methods. By analyzing the motion characteristics of the missile, this paper estimates the missile’s rotation angle and the rotation matrix by establishing a new coordinate system. Simulation results validate the performance of the proposed algorithm. PMID:26978372

  6. Oblique view to the west of two communications antennas ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Oblique view to the west of two communications antennas - Over-the-Horizon Backscatter Radar Network, Mountain Home Air Force Operations Building, On Desert Street at 9th Avenue Mountain Home Air Force Base, Mountain Home, Elmore County, ID

  7. KSC-99pp0519

    NASA Image and Video Library

    1999-05-13

    Inside the Space Station Processing Facility, workers watch as an overhead crane is lowered for lifting the Shuttle Radar Topography Mission (SRTM) from the transporter it is resting on. The SRTM is being moved to a workstand. The primary payload on mission STS-99, the SRTM consists of a specially modified radar system that will fly onboard the Space Shuttle during the 11-day mission scheduled for launch in September 1999. The objective of this radar system is to obtain the most complete high-resolution digital topographic database of the Earth. It will gather data that will result in the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM is an international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR. SRTM will be making use of a technique called radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. To get two radar images taken from different locations, the SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle

  8. KSC-99pp0520

    NASA Image and Video Library

    1999-05-13

    Workers inside the Space Station Processing Facility keep watch as an overhead crane begins lifting the Shuttle Radar Topography Mission (SRTM) from the transporter below. The SRTM is being moved to a workstand. The primary payload on mission STS-99, the SRTM consists of a specially modified radar system that will fly onboard the Space Shuttle during the 11-day mission scheduled for launch in September 1999. The objective of this radar system is to obtain the most complete high-resolution digital topographic database of the Earth. It will gather data that will result in the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM is an international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR. SRTM will be making use of a technique called radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. To get two radar images taken from different locations, the SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle

  9. Mechanical Technology Development on A 35-m Deployable Radar Antenna for Monitoring Hurricanes

    NASA Technical Reports Server (NTRS)

    Fang, Houfei; Im, Eastwood

    2006-01-01

    The NEXRAD in Space project develops a novel instrument concept and the associated antenna technologies for a 35-GHz Doppler radar to monitor hurricanes, cyclones, and severe storms from a geostationary orbit. Mechanical challenges of this concept include a 35-m diameter lightweight in space deployable spherical reflector and a feeder scanning mechanism. The feasibility of using shape memory polymer material to develop the large deployable reflector has been investigated by this study. A spiral scanning mechanism concept has been developed and demonstrated by an engineering model.

  10. C-band PARC manual

    NASA Astrophysics Data System (ADS)

    Groot, J. S.

    1992-05-01

    Measurement results of radar cross section, crosstalk level, etc., of a C band Polarimetric Active Radar Calibrator (PARC), which is used to calibrate air and spaceborne radars commonly used in remote sensing, are reported. The results are used to infer guidelines for the use of this PARC. The PARC consists of a high gain amplifier connected between two linearly polarized horn antennas.

  11. Ground penetrating radar survey of pavement thickness on Mn/Road sections : final report

    DOT National Transportation Integrated Search

    1994-11-01

    The research shows that highway speed horn antenna ground penetrating radar equipment and automated analysis software can accurately measure asphalt thickness. To accurately measure concrete and base thickness, lower speed ground coupled equipment al...

  12. General view looking eastnortheast at western end of array ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    General view looking east-northeast at western end of array - Over-the-Horizon Backscatter Radar Network, Columbia Falls Radar Site Receive Sector Three Antenna Array, At the end of Shadagee Ridge Road, Columbia Falls, Washington County, ME

  13. Feasibility of antenna-to-antenna isolation measurements at S-band in the Facility for Antenna and Radar-cross-section Measurements (FARM)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Brock, Billy C.

    2014-01-01

    Frequency-domain antenna-coupling measurements performed in the compact-range room of the FARM, will actually be dominated by reflected components from the ceiling, floor, walls, etc., not the direct freespace coupling. Consequently, signal processing must be applied to the frequency-domain data to extract the direct free-space coupling. The analysis presented above demonstrates that it is possible to do so successfully.

  14. Intercomparison of attenuation correction algorithms for single-polarized X-band radars

    NASA Astrophysics Data System (ADS)

    Lengfeld, K.; Berenguer, M.; Sempere Torres, D.

    2018-03-01

    Attenuation due to liquid water is one of the largest uncertainties in radar observations. The effects of attenuation are generally inversely proportional to the wavelength, i.e. observations from X-band radars are more affected by attenuation than those from C- or S-band systems. On the other hand, X-band radars can measure precipitation fields in higher temporal and spatial resolution and are more mobile and easier to install due to smaller antennas. A first algorithm for attenuation correction in single-polarized systems was proposed by Hitschfeld and Bordan (1954) (HB), but it gets unstable in case of small errors (e.g. in the radar calibration) and strong attenuation. Therefore, methods have been developed that restrict attenuation correction to keep the algorithm stable, using e.g. surface echoes (for space-borne radars) and mountain returns (for ground radars) as a final value (FV), or adjustment of the radar constant (C) or the coefficient α. In the absence of mountain returns, measurements from C- or S-band radars can be used to constrain the correction. All these methods are based on the statistical relation between reflectivity and specific attenuation. Another way to correct for attenuation in X-band radar observations is to use additional information from less attenuated radar systems, e.g. the ratio between X-band and C- or S-band radar measurements. Lengfeld et al. (2016) proposed such a method based isotonic regression of the ratio between X- and C-band radar observations along the radar beam. This study presents a comparison of the original HB algorithm and three algorithms based on the statistical relation between reflectivity and specific attenuation as well as two methods implementing additional information of C-band radar measurements. Their performance in two precipitation events (one mainly convective and the other one stratiform) shows that a restriction of the HB is necessary to avoid instabilities. A comparison with vertically pointing micro rain radars (MRR) reveals good performance of two of the methods based in the statistical k-Z-relation: FV and α. The C algorithm seems to be more sensitive to differences in calibration of the two systems and requires additional information from C- or S-band radars. Furthermore, a study of five months of radar observations examines the long-term performance of each algorithm. From this study conclusions can be drawn that using additional information from less attenuated radar systems lead to best results. The two algorithms that use this additional information eliminate the bias caused by attenuation and preserve the agreement with MRR observations.

  15. Analysis of the Emitted Wavelet of High-Resolution Bowtie GPR Antennas

    PubMed Central

    Rial, Fernando I.; Lorenzo, Henrique; Pereira, Manuel; Armesto, Julia

    2009-01-01

    Most Ground Penetrating Radars (GPR) cover a wide frequency range by emitting very short time wavelets. In this work, we study in detail the wavelet emitted by two bowtie GPR antennas with nominal frequencies of 800 MHz and 1 GHz. Knowledge of this emitted wavelet allows us to extract as much information as possible from recorded signals, using advanced processing techniques and computer simulations. Following previously published methodology used by Rial et al. [1], which ensures system stability and reliability in data acquisition, a thorough analysis of the wavelet in both time and frequency domain is performed. Most of tests were carried out with air as propagation medium, allowing a proper analysis of the geometrical attenuation factor. Furthermore, we attempt to determine, for each antenna, a time zero in the records to allow us to correctly assign a position to the reflectors detected by the radar. Obtained results indicate that the time zero is not a constant value for the evaluated antennas, but instead depends on the characteristics of the material in contact with the antenna. PMID:22408523

  16. In-situ Calibration Methods for Phased Array High Frequency Radars

    NASA Astrophysics Data System (ADS)

    Flament, P. J.; Flament, M.; Chavanne, C.; Flores-vidal, X.; Rodriguez, I.; Marié, L.; Hilmer, T.

    2016-12-01

    HF radars measure currents through the Doppler-shift of electromagnetic waves Bragg-scattered by surface gravity waves. While modern clocks and digital synthesizers yield range errors negligible compared to the bandwidth-limited range resolution, azimuth calibration issues arise for beam-forming phased arrays. Sources of errors in the phases of the received waves can be internal to the radar system (phase errors of filters, cable lengths, antenna tuning) and geophysical (standing waves, propagation and refraction anomalies). They result in azimuthal biases (which can be range-dependent) and beam-forming side-lobes (which induce Doppler ambiguities). We analyze the experimental calibrations of 17 deployments of WERA HF radars, performed between 2003 and 2012 in Hawaii, the Adriatic, France, Mexico and the Philippines. Several strategies were attempted: (i) passive reception of continuous multi-frequency transmitters on GPS-tracked boats, cars, and drones; (ii) bi-static calibrations of radars in mutual view; (iii) active echoes from vessels of opportunity of unknown positions or tracked through AIS; (iv) interference of unknown remote transmitters with the chirped local oscillator. We found that: (a) for antennas deployed on the sea shore, a single-azimuth calibration is sufficient to correct phases within a typical beam-forming azimuth range; (b) after applying this azimuth-independent correction, residual pointing errors are 1-2 deg. rms; (c) for antennas deployed on irregular cliffs or hills, back from shore, systematic biases appear for some azimuths at large incidence angles, suggesting that some of the ground-wave electromagnetic energy propagates in a terrain-following mode between the sea shore and the antennas; (d) for some sites, fluctuations of 10-25 deg. in radio phase at 20-40 deg. azimuthal period, not significantly correlated among antennas, are omnipresent in calibrations along a constant-range circle, suggesting standing waves or multiple paths in the presence of reflecting structures (buildings, fences), or possibly fractal nature of the wavefronts; (e) amplitudes lack stability in time and azimuth to be usable as a-priori calibrations, confirming the accepted method of re-normalizing amplitudes by the signal of nearby cells prior to beam-forming.

  17. Monitoring internal organ motion with continuous wave radar in CT

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Pfanner, Florian; Maier, Joscha; Allmendinger, Thomas

    Purpose: To avoid motion artifacts in medical imaging or to minimize the exposure of healthy tissues in radiation therapy, medical devices are often synchronized with the patient's respiratory motion. Today's respiratory motion monitors require additional effort to prepare the patients, e.g., mounting a motion belt or placing an optical reflector on the patient's breast. Furthermore, they are not able to measure internal organ motion without implanting markers. An interesting alternative to assess the patient's organ motion is continuous wave radar. The aim of this work is to design, implement, and evaluate such a radar system focusing on application in CT.Methods:more » The authors designed a radar system operating in the 860 MHz band to monitor the patient motion. In the intended application of the radar system, the antennas are located close to the patient's body inside the table of a CT system. One receive and four transmitting antennas are used to avoid the requirement of exact patient positioning. The radar waves propagate into the patient's body and are reflected at tissue boundaries, for example at the borderline between muscle and adipose tissue, or at the boundaries of organs. At present, the authors focus on the detection of respiratory motion. The radar system consists of the hardware mentioned above as well as of dedicated signal processing software to extract the desired information from the radar signal. The system was evaluated using simulations and measurements. To simulate the radar system, a simulation model based on radar and wave field equations was designed and 4D respiratory-gated CT data sets were used as input. The simulated radar signals and the measured data were processed in the same way. The radar system hardware and the signal processing algorithms were tested with data from ten volunteers. As a reference, the respiratory motion signal was recorded using a breast belt simultaneously with the radar measurements.Results: Concerning the measurements of the test persons, there is a very good correlation (ρ= 0.917) between the respiratory motion phases received by the radar system and the external motion monitor. Our concept of using an array of transmitting antennas turned out to be widely insensitive to the positioning of the test persons. A time shift between the respiratory motion curves recorded with the radar system and the motion curves from the external respiratory monitor was observed which indicates a slight difference between internal organ motion and motion detected by the external respiratory monitor. The simulations were in good accordance with the measurements.Conclusions: A continuous wave radar operating in the near field of the antennas can be used to determine the respiratory motion of humans accurately. In contrast to trigger systems used today, the radar system is able to measure motion inside the body. If such a monitor was routinely available in clinical CT, it would be possible optimizing the scan start with respect to the respiratory state of the patient. Breathing commands would potentially widely be avoided, and as far as uncooperative patients or children are concerned, less sedation might be necessary. Further applications of the radar system could be in radiation therapy or interventional imaging for instance.« less

  18. The calibration of an HF radar used for ionospheric research

    NASA Astrophysics Data System (ADS)

    From, W. R.; Whitehead, J. D.

    1984-02-01

    The HF radar on Bribie Island, Australia, uses crossed-fan beams produced by crossed linear transmitter and receiver arrays of 10 elements each to simulate a pencil beam. The beam points vertically when all the array elements are in phase, and is steerable by up to 20 deg off vertical at the central one of the three operating frequencies. Phase and gain changes within the transmitters and receivers are compensated for by an automatic system of adjustment. The 10 transmitting antennas are, as nearly as possible, physically identical as are the 10 receiving antennas. Antenna calibration using high flying aircraft or satellites is not possible. A method is described for using the ionospheric reflections to measure the polar diagram and also to correct for errors in the direction of pointing.

  19. Radar observations of the 2009 eruption of Redoubt Volcano, Alaska: Initial deployment of a transportable Doppler radar system for volcano-monitoring

    NASA Astrophysics Data System (ADS)

    Hoblitt, R. P.; Schneider, D. J.

    2009-12-01

    The rapid detection of explosive volcanic eruptions and accurate determination of eruption-column altitude and ash-cloud movement are critical factors in the mitigation of volcanic risks to aviation and in the forecasting of ash fall on nearby communities. The U.S. Geological Survey (USGS) deployed a transportable Doppler radar during the precursory stage of the 2009 eruption of Redoubt Volcano, Alaska, and it provided valuable information during subsequent explosive events. We describe the capabilities of this new monitoring tool and present data that it captured during the Redoubt eruption. The volcano-monitoring Doppler radar operates in the C-band (5.36 cm) and has a 2.4-m parabolic antenna with a beam width of 1.6 degrees, a transmitter power of 330 watts, and a maximum effective range of 240 km. The entire disassembled system, including a radome, fits inside a 6-m-long steel shipping container that has been modified to serve as base for the antenna/radome, and as a field station for observers and other monitoring equipment. The radar was installed at the Kenai Municipal Airport, 82 km east of Redoubt and about 100 km southwest of Anchorage. In addition to an unobstructed view of the volcano, this secure site offered the support of the airport staff and the City of Kenai. A further advantage was the proximity of a NEXRAD Doppler radar operated by the Federal Aviation Administration. This permitted comparisons with an established weather-monitoring radar system. The new radar system first became functional on March 20, roughly a day before the first of nineteen explosive ash-producing events of Redoubt between March 21 and April 4. Despite inevitable start-up problems, nearly all of the events were observed by the radar, which was remotely operated from the Alaska Volcano Observatory office in Anchorage. The USGS and NEXRAD radars both detected the eruption columns and tracked the directions of drifting ash clouds. The USGS radar scanned a 45-degree sector centered on the volcano while NEXRAD scanned a full 360 degrees. The sector strategy scanned the volcano more frequently than the 360-degree strategy. Consequently, the USGS system detected event onset within less than a minute, while the NEXRAD required about 4 minutes. The observed column heights were as high as 20 km above sea level and compared favorably to those from NEXRAD. NEXRAD tracked ash clouds to greater distances than the USGS system. This experience shows that Doppler radar is a valuable complement to traditional seismic and satellite monitoring of explosive eruptions.

  20. MAARSY - The new MST radar on Andøya: System description and first results

    NASA Astrophysics Data System (ADS)

    Latteck, Ralph; Zecha, Marius; Rapp, Markus; Stober, Gunter; Singer, Werner; Renkwitz, Toralf

    2012-07-01

    In 2011 the Leibniz-Institute of Atmospheric Physics in Kühlungsborn completed the installation of the Middle Atmosphere Alomar Radar System ({MAARSY}) on the North-Norwegian island Andøya. MAARSY is a 53.5 MHz monostatic radar with an active phased array antenna consisting of 433 Yagi antennas. The 3-element Yagi antennas are arranged in an equilateral triangular grid forming a circular aperture of approximately 6300 m^2. Each individual antenna is connected to its own transceiver with independent phase control and a scalable power output of up to 2 kW. This arrangement provides very high flexibility of beam forming and beam steering with a symmetric radar beam of a minimum beam width of 3.6°. The system allows classical beam swinging operation as well as experiments with simultaneous multiple beams and the use of interferometric applications for improved studies of the Arctic atmosphere from the troposphere up to the lower thermosphere with high spatio-temporal resolution. Standard observations of tropospheric winds and polar mesosphere summer echoes started immediately with an initial stage of expansion in spring 2010. Meteor head echo experiments and 3D observations of polar mesospheric winter echoes were conducted after an upgrade of the system in December 2010. Multi-beam experiments using up to 97 beams quasi-simultaneously in the mesosphere have been carried out during campaigns in summer 2011 with the completed system. We present a system description of MAARSY including beam pattern validation and show initial results from various campaigns obtained during the first 2 years of operation.

  1. MIMO radar waveform design with peak and sum power constraints

    NASA Astrophysics Data System (ADS)

    Arulraj, Merline; Jeyaraman, Thiruvengadam S.

    2013-12-01

    Optimal power allocation for multiple-input multiple-output radar waveform design subject to combined peak and sum power constraints using two different criteria is addressed in this paper. The first one is by maximizing the mutual information between the random target impulse response and the reflected waveforms, and the second one is by minimizing the mean square error in estimating the target impulse response. It is assumed that the radar transmitter has knowledge of the target's second-order statistics. Conventionally, the power is allocated to transmit antennas based on the sum power constraint at the transmitter. However, the wide power variations across the transmit antenna pose a severe constraint on the dynamic range and peak power of the power amplifier at each antenna. In practice, each antenna has the same absolute peak power limitation. So it is desirable to consider the peak power constraint on the transmit antennas. A generalized constraint that jointly meets both the peak power constraint and the average sum power constraint to bound the dynamic range of the power amplifier at each transmit antenna is proposed recently. The optimal power allocation using the concept of waterfilling, based on the sum power constraint, is the special case of p = 1. The optimal solution for maximizing the mutual information and minimizing the mean square error is obtained through the Karush-Kuhn-Tucker (KKT) approach, and the numerical solutions are found through a nested Newton-type algorithm. The simulation results show that the detection performance of the system with both sum and peak power constraints gives better detection performance than considering only the sum power constraint at low signal-to-noise ratio.

  2. KSC-99pp0776

    NASA Image and Video Library

    1999-06-19

    In the Space Station Processing Facility, the STS-99 crew pose in front of the Shuttle Radar Topography Mission, the payload for their mission. From left are Mission Specialists Mamoru Mohri of Japan, Janet Lynn Kavandi (Ph.D.), and Janice Voss (Ph.D.); Commander Kevin R. Kregel; Mission Specialist Gerhard Thiele of Germany; and Pilot Dominic L. Pudwill Gorie. Mohri represents the National Space Development Agency of Japan and Thiele represents the European Space Agency. An international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR, the SRTM consists of a specially modified radar system that will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. The SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle. STS-99 is scheduled to launch Sept. 16 at 8:47 a.m. from Launch Pad 39A

  3. Interferometric inverse synthetic aperture radar imaging for space targets based on wideband direct sampling using two antennas

    NASA Astrophysics Data System (ADS)

    Tian, Biao; Liu, Yang; Xu, Shiyou; Chen, Zengping

    2014-01-01

    Interferometric inverse synthetic aperture radar (InISAR) imaging provides complementary information to monostatic inverse synthetic aperture radar (ISAR) imaging. This paper proposes a new InISAR imaging system for space targets based on wideband direct sampling using two antennas. The system is easy to realize in engineering since the motion trajectory of space targets can be known in advance, which is simpler than that of three receivers. In the preprocessing step, high speed movement compensation is carried out by designing an adaptive matched filter containing speed that is obtained from the narrow band information. Then, the coherent processing and keystone transform for ISAR imaging are adopted to reserve the phase history of each antenna. Through appropriate collocation of the system, image registration and phase unwrapping can be avoided. Considering the situation not to be satisfied, the influence of baseline variance is analyzed and compensation method is adopted. The corresponding size can be achieved by interferometric processing of the two complex ISAR images. Experimental results prove the validity of the analysis and the three-dimensional imaging algorithm.

  4. Temperate Ice Depth-Sounding Radar

    NASA Astrophysics Data System (ADS)

    Jara-Olivares, V. A.; Player, K.; Rodriguez-Morales, F.; Gogineni, P.

    2008-12-01

    Glaciers in several parts of the world are reported to be retreating and thinning rapidly over the last decade. Radar instruments can be used to provide a wealth of information regarding the internal and basal conditions of large and small ice masses. These instruments typically operate in the VHF and UHF regions of the electromagnetic spectrum. For temperate-ice sounding, however, the high water content produces scattering and attenuation in propagating radar waves at VHF and UHF frequencies, which significantly reduce the penetration depths. Radars operating in the HF band are better suited for systematic surveys of the thickness and sub-glacial topography of temperate-ice regions. We are developing a dual-frequency Temperate-Ice-Depth Sounding Radar (TIDSoR) that can penetrate through water pockets, thus providing more accurate measurements of temperate ice properties such as thickness and basal conditions. The radar is a light-weight, low power consumption portable system for surface-based observations in mountainous terrain or aerial surveys. TIDSoR operates at two different center frequencies: 7.7 MHz and 14 MHz, with a maximum output peak power of 20 W. The transmit waveform is a digitally generated linear frequency-modulated chirp with 1 MHz bandwidth. The radar can be installed on aircrafts such as the CReSIS UAV [1], DCH-6 (Twin Otter), or P-3 Orion for aerial surveys, where it could be supported by the airplane power system. For surface based experiments, TIDSoR can operate in a backpack configuration powered by a compact battery system. The system can also be installed on a sled towed by a motorized vehicle, in which case the power supply can be replaced by a diesel generator. The radar consists of three functional blocks: the digital section, the radio-frequency (RF) section, and the antenna, and is designed to weigh less than 2 kg, excluding the power supply. The digital section generates the transmit waveforms as well as timing and control signals. It also digitizes the output signal from the receiver and stores the data in binary format using a portable computer. The RF-section consists of a high- power transmitter and a low-noise receiver with digitally controlled variable gain. The antenna is time-shared between the transmitter and receiver by means of a transmit/receive (T/R) switch. In regards to the antenna, we have made a survey study of various electrically small antennas (ESA) to choose the most suitable radiating structure for this application. Among the different alternatives that provide a good trade-off between electrical performance and small size, we have adopted an ESA dipole configuration for airborne platforms and a half-wavelength radiator for the surface-based version. The airborne antenna solution is given after studying the geometry of the aerial vehicle and its fuselage contribution to the antenna radiation pattern. Dipoles are made of 11.6 mm diameter cables (AWG 0000) or printed patches embedded into the aircraft fuselage, wings, or both. The system is currently being integrated and tested. TIDSoR is expected to be deployed during the spring 2008 either in Alaska or Greenland for surface based observations. In this paper, we will discuss our design considerations and current progress towards the development of this radar system. [1] Center for Remote Sensing of Ice Sheets (Cresis), Sept 2008, [Online]. Available: http://www.cresis.ku.edu

  5. Through-the-Wall Localization of a Moving Target by Two Independent Ultra Wideband (UWB) Radar Systems

    PubMed Central

    Kocur, Dušan; Švecová, Mária; Rovňáková, Jana

    2013-01-01

    In the case of through-the-wall localization of moving targets by ultra wideband (UWB) radars, there are applications in which handheld sensors equipped only with one transmitting and two receiving antennas are applied. Sometimes, the radar using such a small antenna array is not able to localize the target with the required accuracy. With a view to improve through-the-wall target localization, cooperative positioning based on a fusion of data retrieved from two independent radar systems can be used. In this paper, the novel method of the cooperative localization referred to as joining intersections of the ellipses is introduced. This method is based on a geometrical interpretation of target localization where the target position is estimated using a properly created cluster of the ellipse intersections representing potential positions of the target. The performance of the proposed method is compared with the direct calculation method and two alternative methods of cooperative localization using data obtained by measurements with the M-sequence UWB radars. The direct calculation method is applied for the target localization by particular radar systems. As alternative methods of cooperative localization, the arithmetic average of the target coordinates estimated by two single independent UWB radars and the Taylor series method is considered. PMID:24021968

  6. Through-the-wall localization of a moving target by two independent ultra wideband (UWB) radar systems.

    PubMed

    Kocur, Dušan; Svecová, Mária; Rovňáková, Jana

    2013-09-09

    In the case of through-the-wall localization of moving targets by ultra wideband (UWB) radars, there are applications in which handheld sensors equipped only with one transmitting and two receiving antennas are applied. Sometimes, the radar using such a small antenna array is not able to localize the target with the required accuracy. With a view to improve through-the-wall target localization, cooperative positioning based on a fusion of data retrieved from two independent radar systems can be used. In this paper, the novel method of the cooperative localization referred to as joining intersections of the ellipses is introduced. This method is based on a geometrical interpretation of target localization where the target position is estimated using a properly created cluster of the ellipse intersections representing potential positions of the target. The performance of the proposed method is compared with the direct calculation method and two alternative methods of cooperative localization using data obtained by measurements with the M-sequence UWB radars. The direct calculation method is applied for the target localization by particular radar systems. As alternative methods of cooperative localization, the arithmetic average of the target coordinates estimated by two single independent UWB radars and the Taylor series method is considered.

  7. Performance prediction of high Tc superconducting small antennas using a two-fluid-moment method model

    NASA Astrophysics Data System (ADS)

    Cook, G. G.; Khamas, S. K.; Kingsley, S. P.; Woods, R. C.

    1992-01-01

    The radar cross section and Q factors of electrically small dipole and loop antennas made with a YBCO high Tc superconductor are predicted using a two-fluid-moment method model, in order to determine the effects of finite conductivity on the performances of such antennas. The results compare the useful operating bandwidths of YBCO antennas exhibiting varying degrees of impurity with their copper counterparts at 77 K, showing a linear relationship between bandwidth and impurity level.

  8. Reconstruction of Vertical Profile of Permittivity of Layered Media which is Probed Using Vertical Differential Antenna

    NASA Astrophysics Data System (ADS)

    Pochanin, Gennadiy P.; Poyedinchuk, Anatoliy Y.; Varianytsia-Roshchupkina, Liudmyla A.; Pochanina, Iryna Ye.

    2016-04-01

    Results of this research are intended to use at GPR investigations of layered media (for example, at roads' inspection) for the processing of collected data and reconstruction of dependence of permittivity on the depth. Recently, an antenna system with a vertical differential configuration of receiving module (Patent UA81652) for GPR was suggested and developed The main advantage of the differential antennas in comparison with bistatic antennas is a high electromagnetic decoupling between the transmitting and receiving modules. The new vertical differential configuration has an additional advantage because it allows collecting GPR data reflected by layered media without any losses of information about these layers [1] and, potentially, it is a more accurate instrument for the layers thickness measurements [2]. The developed antenna system is tested in practice with the GPR at asphalt thickness measurements [3] and shown an accuracy which is better than 0.5 cm. Since this antenna system is good for sounding from above the surface (air coupled technique), the mobile laboratory was equipped with the developed GPR [3]. In order to process big set of GPR data that collected during probing at long routes of the roads, for the data processing it was tested new algorithm of the inverse problem solution. It uses a fast algorithm for calculation of electromagnetic wave diffraction by non-uniform anisotropic layers [4]. The algorithm is based on constructing a special case solution to the Riccati equation for the Cauchy problem and enables a qualitative description of the wave diffraction by the electromagnetic structure of the type within a unitary framework. At this stage as initial data we used synthetic GPR data that were obtained as results of the FDTD simulation of the problem of UWB electromagnetic impulse diffraction on layered media. Differential and bistatic antenna configurations were tested at several different profiles of permittivity. Meanings of permittivity of each of layers were reconstructed successfully. Corresponding results are given in the presentation. Acknowledgement The authors acknowledge COST for funding Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar", supporting this work. References 1. L. Gurel, and U. Oguz, "Three-Dimensional FDTD modeling of a ground penetrating radar" IEEE Trans. Geosci. Remote Sensing, vol. 38, no. 4, pp. 1513-1521, 2000. 2. L. Varianytsia-Roshchupkina, Pochanin G., Pochanina I., Masalov Proc. of the 8th Int. Workshop on Advanced Ground Penetrating Radar (IWAGPR 15), Florence, Italy, July 2015. 3. Pochanin, G. P., Ruban, V. P., Kholod, P. V., Shuba, A. A., Pochanin, A. G., Orlenko, A.A., Batrakov, D. O., and Batrakova, A. G. GPR for pavement monitoring., Journal of Radio Electronics. No.1. 2013, Moscow, http://jre.cplire.ru/alt/jan13/8/text.pdf. 4. A. V. Brovenko, P. N. Melezhik, A. Y. Poyedinchuk A numerical analytical method for solving problems of electromagnetic wave diffraction by non-uniform anisotropic layers. Radiophysics and Electronics, Vol.19, No. 4. 2014. pp.12-20.

  9. Monopulse azimuth measurement in the ATC Radar Beacon System

    DOT National Transportation Integrated Search

    1971-12-01

    A review is made of the application of sum-difference beam : techniques to the ATC Radar Beacon System. A detailed error analysis : is presented for the case of a monopulse azimuth measurement based : on the existing beacon antenna with a modified fe...

  10. Goldstone Radar Images of Asteroid 2013 ET

    NASA Image and Video Library

    2013-03-18

    This sequence of radar images of asteroid 2013 ET was obtained on Mar. 10, 2013, by NASA scientists using the 230-foot 70-meter DSN antenna at Goldstone, CA, when the asteroid was about 693,000 mi 1.1 million km from Earth.

  11. GEOS-C altimeter attitude bias error correction. [gate-tracking radar

    NASA Technical Reports Server (NTRS)

    Marini, J. W.

    1974-01-01

    A pulse-limited split-gate-tracking radar altimeter was flown on Skylab and will be used aboard GEOS-C. If such an altimeter were to employ a hypothetical isotropic antenna, the altimeter output would be independent of spacecraft orientation. To reduce power requirements the gain of the altimeter antenna proposed is increased to the point where its beamwidth is only a few degrees. The gain of the antenna consequently varies somewhat over the pulse-limited illuminated region of the ocean below the altimeter, and the altimeter output varies with antenna orientation. The error introduced into the altimeter data is modeled empirically, but close agreements with the expected errors was not realized. The attitude error effects expected with the GEOS-C altimeter are modelled using a form suggested by an analytical derivation. The treatment is restricted to the case of a relatively smooth sea, where the height of the ocean waves are small relative to the spatial length (pulse duration times speed of light) of the transmitted pulse.

  12. Effects of line-of-sight velocity on spaced-antenna measurements, part 3.5A

    NASA Technical Reports Server (NTRS)

    Royrvik, O.

    1984-01-01

    Horizontal wind velocities in the upper atmosphere, particularly the mesosphere, have been measured using a multitude of different techniques. Most techniques are based on stated or unstated assumptions about the wind field that may or may not be true. Some problems with the spaced antenna drifts (SAD) technique that usually appear to be overlooked are investigated. These problems are not unique to the SAD technique; very similar considerations apply to measurement of horizontal wind using multiple-beam Doppler radars as well. Simply stated, the SAD technique relies on scattering from multiple scatterers within an antenna beam of fairly large beam width. The combination of signals with random phase gives rise to an interference pattern on the ground. This pattern will drift across the ground with a velocity twice that of the ionospheric irregularities from which the radar signals are scattered. By using spaced receivers and measuring time delays of the signal fading in different antennas, it is possible to estimate the horizontal drift velocities.

  13. TRMM Precipitation Radar Reflectivity Profiles Compared to High-Resolution Airborne and Ground-Based Radar Measurements

    NASA Technical Reports Server (NTRS)

    Heymsfield, G. M.; Geerts, B.; Tian, L.

    1999-01-01

    In this paper, TRMM (Tropical Rainfall Measuring Mission Satellite) Precipitation Radar (PR) products are evaluated by means of simultaneous comparisons with data from the high-altitude ER-2 Doppler Radar (EDOP), as well as ground-based radars. The comparison is aimed primarily at the vertical reflectivity structure, which is of key importance in TRMM rain type classification and latent heating estimation. The radars used in this study have considerably different viewing geometries and resolutions, demanding non-trivial mapping procedures in common earth-relative coordinates. Mapped vertical cross sections and mean profiles of reflectivity from the PR, EDOP, and ground-based radars are compared for six cases. These cases cover a stratiform frontal rainband, convective cells of various sizes and stages, and a hurricane. For precipitating systems that are large relative to the PR footprint size, PR reflectivity profiles compare very well to high-resolution measurements thresholded to the PR minimum reflectivity, and derived variables such as bright band height and rain types are accurate, even at high PR incidence angles. It was found that for, the PR reflectivity of convective cells small relative to the PR footprint is weaker than in reality. Some of these differences can be explained by non-uniform beam filling. For other cases where strong reflectivity gradients occur within a PR footprint, the reflectivity distribution is spread out due to filtering by the PR antenna illumination pattern. In these cases, rain type classification may err and be biased towards the stratiform type, and the average reflectivity tends to be underestimated. The limited sensitivity of the PR implies that the upper regions of precipitation systems remain undetected and that the PR storm top height estimate is unreliable, usually underestimating the actual storm top height. This applies to all cases but the discrepancy is larger for smaller cells where limited sensitivity is compounded by incomplete beam filling. Users of level three TRMM PR products should be aware of this scale dependency.

  14. Pedestrian recognition using automotive radar sensors

    NASA Astrophysics Data System (ADS)

    Bartsch, A.; Fitzek, F.; Rasshofer, R. H.

    2012-09-01

    The application of modern series production automotive radar sensors to pedestrian recognition is an important topic in research on future driver assistance systems. The aim of this paper is to understand the potential and limits of such sensors in pedestrian recognition. This knowledge could be used to develop next generation radar sensors with improved pedestrian recognition capabilities. A new raw radar data signal processing algorithm is proposed that allows deep insights into the object classification process. The impact of raw radar data properties can be directly observed in every layer of the classification system by avoiding machine learning and tracking. This gives information on the limiting factors of raw radar data in terms of classification decision making. To accomplish the very challenging distinction between pedestrians and static objects, five significant and stable object features from the spatial distribution and Doppler information are found. Experimental results with data from a 77 GHz automotive radar sensor show that over 95% of pedestrians can be classified correctly under optimal conditions, which is compareable to modern machine learning systems. The impact of the pedestrian's direction of movement, occlusion, antenna beam elevation angle, linear vehicle movement, and other factors are investigated and discussed. The results show that under real life conditions, radar only based pedestrian recognition is limited due to insufficient Doppler frequency and spatial resolution as well as antenna side lobe effects.

  15. Integrity inspection of main access tunnel using ground penetrating radar

    NASA Astrophysics Data System (ADS)

    Ismail, M. A.; Abas, A. A.; Arifin, M. H.; Ismail, M. N.; Othman, N. A.; Setu, A.; Ahmad, M. R.; Shah, M. K.; Amin, S.; Sarah, T.

    2017-11-01

    This paper discusses the Ground Penetrating Radar (GPR) survey performed to determine the integrity of wall of tunnel at a hydroelectric power generation facility. GPR utilises electromagnetic waves that are transmitted into the medium of survey. Any reflectors in the medium will reflect the transmitted waves and picked up by the GPR antenna. The survey was done using MALA GeoScience RAMAC CUII with 250MHz antenna. Survey was done on the left, the crown and the right walls of the underground tunnels. Distance was measured using wheel encoders. The results of the survey is discussed in this paper.

  16. Radar Interferometer for Topographic Mapping of Glaciers and Ice Sheets

    NASA Technical Reports Server (NTRS)

    Moller, Delwyn K.; Sadowy, Gregory A.; Rignot, Eric J.; Madsen, Soren N.

    2007-01-01

    A report discusses Ka-band (35-GHz) radar for mapping the surface topography of glaciers and ice sheets at high spatial resolution and high vertical accuracy, independent of cloud cover, with a swath-width of 70 km. The system is a single- pass, single-platform interferometric synthetic aperture radar (InSAR) with an 8-mm wavelength, which minimizes snow penetration while remaining relatively impervious to atmospheric attenuation. As exhibited by the lower frequency SRTM (Shuttle Radar Topography Mission) AirSAR and GeoSAR systems, an InSAR measures topography using two antennas separated by a baseline in the cross-track direction, to view the same region on the ground. The interferometric combination of data received allows the system to resolve the pathlength difference from the illuminated area to the antennas to a fraction of a wavelength. From the interferometric phase, the height of the target area can be estimated. This means an InSAR system is capable of providing not only the position of each image point in along-track and slant range as with a traditional SAR but also the height of that point through interferometry. Although the evolution of InSAR to a millimeter-wave center frequency maximizes the interferometric accuracy from a given baseline length, the high frequency also creates a fundamental problem of swath coverage versus signal-to-noise ratio. While the length of SAR antennas is typically fixed by mass and stowage or deployment constraints, the width is constrained by the desired illuminated swath width. As the across-track beam width which sets the swath size is proportional to the wavelength, a fixed swath size equates to a smaller antenna as the frequency is increased. This loss of antenna size reduces the two-way antenna gain to the second power, drastically reducing the signal-to-noise ratio of the SAR system. This fundamental constraint of high-frequency SAR systems is addressed by applying digital beam-forming (DBF) techniques to synthesize multiple simultaneous receive beams in elevation while maintaining a broad transmit illumination. Through this technique, a high antenna gain on receive is preserved, thereby reducing the required transmit power and thus enabling high-frequency SARs and high-precision InSAR from a single spacecraft.

  17. Ground-Truthing a Next Generation Snow Radar

    NASA Astrophysics Data System (ADS)

    Yan, S.; Brozena, J. M.; Gogineni, P. S.; Abelev, A.; Gardner, J. M.; Ball, D.; Liang, R.; Newman, T.

    2016-12-01

    During the early spring of 2016 the Naval Research Laboratory (NRL) performed a test of a next generation airborne snow radar over ground truth data collected on several areas of fast ice near Barrow, AK. The radar was developed by the Center for Remote Sensing of Ice Sheets (CReSIS) at the University of Kansas, and includes several improvements compared to their previous snow radar. The new unit combines the earlier Ku-band and snow radars into a single unit with an operating frequency spanning the entire 2-18 GHz, an enormous bandwidth which provides the possibility of snow depth measurements with 1.5 cm range resolution. Additionally, the radar transmits on dual polarizations (H and V), and receives the signal through two orthogonally polarized Vivaldi arrays, each with 128 phase centers. The 8 sets of along-track phase centers are combined in hardware to improve SNR and narrow the beamwidth in the along-track, resulting in 8 cross-track effective phase centers which are separately digitized to allow for beam sharpening and forming in post-processing. Tilting the receive arrays 30 degrees from the horizontal also allows the formation of SAR images and the potential for estimating snow-water equivalent (SWE). Ground truth data (snow depth, density, salinity and SWE) were collected over several 60 m wide swaths that were subsequently overflown with the snow radar mounted on a Twin Otter. The radar could be operated in nadir (by beam steering the receive antennas to point beneath the aircraft) or side-looking modes. Results from the comparisons will be shown.

  18. Effects of antenna orientation on 3-D ground penetrating radar surveys: an archaeological perspective

    NASA Astrophysics Data System (ADS)

    Lualdi, Maurizio; Lombardi, Federico

    2014-02-01

    This paper investigates the impact that the GPR antenna orientation, or survey direction, has on migrated image resulting from 3-D georadar acquisitions carried out on heterogeneous and anisotropic subsurface. This feature is related to the directional dependency of wave propagation effects, such as dispersion, absorption, depolarization, and scattering phenomena. We provide a proof of this with two field examples, demonstrating that a 3-D survey performed along a single direction could bring weak results in terms of target detection and reconstruction. To overcome this risk, we show the improvements that the combination of GPR 3-D data acquired along different directions on the same area can obtain: an enhancement of target detection probability and the practical advantage for the end-user of looking through a single image. Further on, we develop a stacking scheme that employs a threshold associated with amplitude comparison to adaptively handle the combination of georadar data volumes.

  19. Reduced-size spiral antenna design using dielectric overlay loading for use in ground penetrating radar and design of alternative antennas using Vivaldi radiators

    NASA Astrophysics Data System (ADS)

    Paolino, Donald D.; Neel, Michael M.; Franck, Charmaine C.

    2002-08-01

    Spiral antennas are one of the common radiators used in ground penetrating radar (GPR). Mine detection is generally performed in a frequency band of interest between 500 MHz to 4 GHz. This paper discusses technical recommendations and R&D performed by Naval Air Warfare Center (NAWC), China Lake, CA , resulting in our best effort spiral design emphasizing highest low band gain while maintaining overall axial ratio purity. This design consisted of a spiral printed on a high dielectric substrate that allowed the antenna to be used at lower frequencies then conventional plastic substrate based two arm spirals of the same diameter. A graded dielectric overlay scheme was employed to facilitate matching to free space on one side, and absorber lined cavity on the other. Test data is given in terms of match and free space patterns using spin linear sources to obtain antenna axial ratios. The low-end gain was improved from -17 dBi to -5 dBi. Two Vivaldi slot antennas (star junction fed and an antipodal construction) are discussed as alternative antennas offering broadband high gain and economical construction. Both designs produced good patterns with a +5 dBi average gain over the band. Patterns for the log spiral and Archimedean spiral, together with recommendations for future improvements are provided.

  20. Radar transponder antenna pattern analysis for the space shuttle

    NASA Technical Reports Server (NTRS)

    Radcliff, Roger

    1989-01-01

    In order to improve tracking capability, radar transponder antennas will soon be mounted on the Shuttle solid rocket boosters (SRB). These four antennas, each being identical cavity-backed helices operating at 5.765 GHz, will be mounted near the top of the SRB's, adjacent to the intertank portion of the external tank. The purpose is to calculate the roll-plane pattern (the plane perpendicular to the SRB axes and containing the antennas) in the presence of this complex electromagnetic environment. The large electrical size of this problem mandates an optical (asymptotic) approach. Development of a specific code for this application is beyond the scope of a summer fellowship; thus a general purpose code, the Numerical Electromagnetics Code - Basic Scattering Code, was chosen as the computational tool. This code is based on the modern Geometrical Theory of Diffraction, and allows computation of scattering of bodies composed of canonical problems such as plates and elliptic cylinders. Apertures mounted on a curved surface (the SRB) cannot be accomplished by the code, so an antenna model consisting of wires excited by a method of moments current input was devised that approximated the actual performance of the antennas. The improvised antenna model matched well with measurements taken at the MSFC range. The SRB's, the external tank, and the shuttle nose were modeled as circular cylinders, and the code was able to produce what is thought to be a reasonable roll-plane pattern.

  1. View of the RMS end effector touching the SIR-B antenna during STS 41-G

    NASA Image and Video Library

    1984-10-05

    41G-03-008 (5-13 Oct. 1984) --- The end effector of the space shuttle Challenger's remote manipulator system (RMS) taps against the shuttle imaging radar's (SIR-B) antenna to secure it during NASA's 41-G mission. Photo credit: NASA

  2. A 60 Meter Delay Stabilized Microwave Fiber Optic Link for 5.3 GHz Reference Signal Distribution on the Shuttle Radar Topography Mapper

    NASA Technical Reports Server (NTRS)

    Lutes, G.; Tu, M.; McWatters, D.

    1999-01-01

    The Photonic Systems for Antenna Applications Symposium (PSAA) is the primary conference devoted exclusively to the exchange of information on the technology and application of photonics in antenna, phased array, and sensor systems.

  3. High-resolution imaging using a wideband MIMO radar system with two distributed arrays.

    PubMed

    Wang, Dang-wei; Ma, Xiao-yan; Chen, A-Lei; Su, Yi

    2010-05-01

    Imaging a fast maneuvering target has been an active research area in past decades. Usually, an array antenna with multiple elements is implemented to avoid the motion compensations involved in the inverse synthetic aperture radar (ISAR) imaging. Nevertheless, there is a price dilemma due to the high level of hardware complexity compared to complex algorithm implemented in the ISAR imaging system with only one antenna. In this paper, a wideband multiple-input multiple-output (MIMO) radar system with two distributed arrays is proposed to reduce the hardware complexity of the system. Furthermore, the system model, the equivalent array production method and the imaging procedure are presented. As compared with the classical real aperture radar (RAR) imaging system, there is a very important contribution in our method that the lower hardware complexity can be involved in the imaging system since many additive virtual array elements can be obtained. Numerical simulations are provided for testing our system and imaging method.

  4. Middle Atmosphere Program. Handbook for MAP. Volume 14: URSI/SCOSTEP Workshop on Technical Aspects of MST Radar

    NASA Technical Reports Server (NTRS)

    Bowhill, S. A. (Editor); Edwards, B. (Editor)

    1984-01-01

    Various topics relative to middle atmosphere research were discussed. meteorological and aeronomical requirements for mesosphere-stratosphere-troposphere (MST) radar networks, general circulation of the middle atmosphere, the interpretation of radar returns from clear air, spaced antenna and Doppler techniques for velocity measurement, and techniques for the study of gravity waves and turbulence are among the topics discussed.

  5. Mathematical modeling and SAR simulation multifunction SAR technology efforts

    NASA Technical Reports Server (NTRS)

    Griffin, C. R.; Estes, J. M.

    1981-01-01

    The orbital SAR (synthetic aperture radar) simulation data was used in several simulation efforts directed toward advanced SAR development. Efforts toward simulating an operational radar, simulation of antenna polarization effects, and simulation of SAR images at serveral different wavelengths are discussed. Avenues for improvements in the orbital SAR simulation and its application to the development of advanced digital radar data processing schemes are indicated.

  6. Ferroelectric/Semiconductor Tunable Microstrip Patch Antenna Developed

    NASA Technical Reports Server (NTRS)

    Romanofsky, Robert R.

    2001-01-01

    A lithographically printed microwave antenna that can be switched and tuned has been developed. The structure consists of a rectangular metallic "patch" radiator patterned on a thin ferroelectric film that was grown on high-resistivity silicon. Such an antenna may one day enable a single-phased array aperture to transmit and receive signals at different frequencies, or it may provide a simple way to reconfigure fractal arrays for communications and radar applications.

  7. Manufacture of a conformal multilayer rf antenna substrate using excimer mask imaging technology and a 6-axis robot

    NASA Astrophysics Data System (ADS)

    Charrier, Michel; Everett, Daniel; Fieret, Jim; Karrer, Tobias; Rau, Sven; Valard, Jean-Luc

    2001-06-01

    A novel method is presented to produce a high precision pattern of copper tracks on both sides of a 4-layer conformal radar antenna made of PEI polymer and shaped as a truncated pseudo-parabolic cylinder. The antenna is an active emitter-receiver so that an accuracy of a fraction of the wavelength of the microwave radiation is required. After 2D layer design in Allegro, the resulting Gerber file-format circuits are wrapped around the antenna shape, resulting in a cutter-path file which provides the input for a postprocessor that outputs G-code for robot- and laser control. A rules file contains embedded information such as laser parameters and mask aperture related to the Allegro symbols. The robot consists of 6 axes that manipulate the antenna, and 2 axes for the mask plate. The antenna can be manipulated to an accuracy of +/- 20 micrometers over its full dimensions of 200x300x50 mm. The four layers are constructed by successive copper coating, resist coating, laser ablation, copper etching, resist removal, insulation polyimide film lamination and laser dielectric drilling for microvia holes and through-holes drilling. Applications are in space and aeronautical communication and radar detection systems, with possible extensions to automotive and mobile hand-sets, and land stations.

  8. Real-Time Atmospheric Phase Fluctuation Correction Using a Phased Array of Widely Separated Antennas: X-Band Results and Ka-Band Progress

    NASA Astrophysics Data System (ADS)

    Geldzahler, B.; Birr, R.; Brown, R.; Grant, K.; Hoblitzell, R.; Miller, M.; Woods, G.; Argueta, A.; Ciminera, M.; Cornish, T.; D'Addario, L.; Davarian, F.; Kocz, J.; Lee, D.; Morabito, D.; Tsao, P.; Jakeman-Flores, H.; Ott, M.; Soloff, J.; Denn, G.; Church, K.; Deffenbaugh, P.

    2016-09-01

    NASA is pursuing a demonstration of coherent uplink arraying at 7.145-7.190 GHz (X-band) and 30-31 GHz (Kaband) using three 12m diameter COTS antennas separated by 60m at the Kennedy Space Center in Florida. In addition, we have used up to three 34m antennas separated by 250m at the Goldstone Deep Space Communication Complex in California at X-band 7.1 GHz incorporating real-time correction for tropospheric phase fluctuations. Such a demonstration can enable NASA to design and establish a high power, high resolution, 24/7 availability radar system for (a) tracking and characterizing observations of Near Earth Objects (NEOs), (b) tracking, characterizing and determining the statistics of small-scale (≤10cm) orbital debris, (c) incorporating the capability into its space communication and navigation tracking stations for emergency spacecraft commanding in the Ka band era which NASA is entering, and (d) fielding capabilities of interest to other US government agencies. We present herein the results of our phased array uplink combining at near 7.17 and 8.3 GHz using widely separated antennas demonstrations at both locales, the results of a study to upgrade from a communication to a radar system, and our vision for going forward in implementing a high performance, low lifecycle cost multi-element radar array.

  9. Distributed MIMO chaotic radar based on wavelength-division multiplexing technology.

    PubMed

    Yao, Tingfeng; Zhu, Dan; Ben, De; Pan, Shilong

    2015-04-15

    A distributed multiple-input multiple-output chaotic radar based on wavelength-division multiplexing technology (WDM) is proposed and demonstrated. The wideband quasi-orthogonal chaotic signals generated by different optoelectronic oscillators (OEOs) are emitted by separated antennas to gain spatial diversity against the fluctuation of a target's radar cross section and enhance the detection capability. The received signals collected by the receive antennas and the reference signals from the OEOs are delivered to the central station for joint processing by exploiting WDM technology. The centralized signal processing avoids precise time synchronization of the distributed system and greatly simplifies the remote units, which improves the localization accuracy of the entire system. A proof-of-concept experiment for two-dimensional localization of a metal target is demonstrated. The maximum position error is less than 6.5 cm.

  10. Investigation of the extended use of Ground Penetrating Radar (GPR) for measuring in-situ material quality characteristics : final report.

    DOT National Transportation Integrated Search

    2008-09-01

    This report tests the application of Ground Penetrating Radar (GPR) as a non-destructive tool for highway infrastructure assessment. Multiple antennas with different frequency ranges were used on a variety infrastructure projects. This report highlig...

  11. Technology Development for 3-D Wide Swath Imaging Supporting ACE

    NASA Technical Reports Server (NTRS)

    Racette, Paul; Heymsfield, Gerry; Li, Lihua; Mclinden, Matthew; Park, Richard; Cooley, Michael; Stenger, Pete; Hand, Thomas

    2014-01-01

    The National Academy of Sciences Decadal Survey (DS) Aerosol-Cloud-Ecosystems Mission (ACE) aims to advance our ability to observe and predict changes to the Earth's hydrological cycle and energy balance in response to climate forcing, especially those changes associated with the effects of aerosol on clouds and precipitation. ACE is focused on obtaining measurements to reduce the uncertainties in current climate models arising from the lack in understanding of aerosol-cloud interactions. As part of the mission instrument suite, a dual-frequency radar comprised of a fixed-beam 94 gigahertz (W-band) radar and a wide-swath 35 gigahertz (Ka-band) imaging radar has been recommended by the ACE Science Working Group.In our 2010 Instrument Incubator Program project, we've developed a radar architecture that addresses the challenge associated with achieving the measurement objectives through an innovative, shared aperture antenna that allows dual-frequency radar operation while achieving wide-swath (100 kilometers) imaging at Ka-band. The antenna system incorporates 2 key technologies; a) a novel dual-band reflectorreflectarray and b) a Ka-band Active Electronically Scanned Array (AESA) feed module. The dual-band antenna is comprised of a primary cylindrical reflectorreflectarray surface illuminated by a point-focus W-band feed (compatible with a quasi-optical beam waveguide feed, such as that employed on CloudSat); the Ka-band AESA line feed provides wide-swath across-track scanning. The benefits of this shared-aperture approach include significant reductions in ACE satellite payload size, weight, and cost, as compared to a two aperture approach. Four objectives were addressed in our project. The first entailed developing the tools for the analysis and design of reflectarray antennas, assessment of candidate reflectarray elements, and validation using test coupons. The second objective was to develop a full-scale aperture design utilizing the reflectarray surface and to detail specific requirements and trades for the Ka-band AESA line feed. As part of the third objective a subscale antenna, similar to the full-scale aperture design, was developed, integrated, and flown with the Cloud Radar System during the 2014 Integrated Precipitation and Hydrology Experiment. The fourth and ongoing objective entails developing a GaN MMIC (Gallium Nitride Monolithic Microwave Integrated Circuits) power amplifier for use in the Ka-band AESA. An overview of the progress made on this project and a look ahead at the 2013 IIP (Instrument Incubator Program) award selection will be presented.

  12. Development of Radar Control system for Multi-mode Active Phased Array Radar for atmospheric probing

    NASA Astrophysics Data System (ADS)

    Yasodha, Polisetti; Jayaraman, Achuthan; Thriveni, A.

    2016-07-01

    Modern multi-mode active phased array radars require highly efficient radar control system for hassle free real time radar operation. The requirement comes due to the distributed architecture of the active phased array radar, where each antenna element in the array is connected to a dedicated Transmit-Receive (TR) module. Controlling the TR modules, which are generally few hundreds in number, and functioning them in synchronisation, is a huge task during real time radar operation and should be handled with utmost care. Indian MST Radar, located at NARL, Gadanki, which is established during early 90's, as an outcome of the middle atmospheric program, is a remote sensing instrument for probing the atmosphere. This radar has a semi-active array, consisting of 1024 antenna elements, with limited beam steering, possible only along the principle planes. To overcome the limitations and difficulties, the radar is being augmented into fully active phased array, to accomplish beam agility and multi-mode operations. Each antenna element is excited with a dedicated 1 kW TR module, located in the field and enables to position the radar beam within 20° conical volume. A multi-channel receiver makes the radar to operate in various modes like Doppler Beam Swinging (DBS), Spaced Antenna (SA), Frequency Domain Interferometry (FDI) etc. Present work describes the real-time radar control (RC) system for the above described active phased array radar. The radar control system consists of a Spartan 6 FPGA based Timing and Control Signal Generator (TCSG), and a computer containing the software for controlling all the subsystems of the radar during real-time radar operation and also for calibrating the radar. The main function of the TCSG is to generate the control and timing waveforms required for various subsystems of the radar. Important components of the RC system software are (i) TR module configuring software which does programming, controlling and health parameter monitoring of the TR modules, (ii) radar operation software which facilitates experimental parameter setting and operating the radar in different modes, (iii) beam steering software which computes the amplitude co-efficients and phases required for each TR module, for forming the beams selected for radar operation with the desired shape and (iv) Calibration software for calibrating the radar by measuring the differential insertion phase and amplitudes in all 1024 Transmit and Receive paths and correcting them. The TR module configuring software is a major task as it needs to control 1024 TR modules, which are located in the field about 150 m away from the RC system in the control room. Each TR module has a processor identified with a dedicated IP address, along with memory to store the instructions and parameters required for radar operation. A communication link is designed using Gigabit Ethernet (GbE) switches to realise 1 to 1024 way switching network. RC system computer communicates with the each processor using its IP address and establishes connection, via 1 to 1024 port GbE switching network. The experimental parameters data are pre-loaded parallely into all the TR modules along with the phase shifter data required for beam steering using this network. A reference timing pulse is sent to all the TR modules simultaneously, which indicates the start of radar operation. RC system also monitors the status parameters from the TR modules indicating their health during radar operation at regular intervals, via GbE switching network. Beam steering software generates the phase shift required for each TR module for the beams selected for operation. Radar operational software calls the phase shift data required for beam steering and adds it to the calibration phase obtained through calibration software and loads the resultant phase data into TR modules. Timed command/data transfer to/from subsystems and synchronisation of subsystems is essential for proper real-time operation of the active phased array radar and the RC system ensures that the commands/experimental parameter data are properly transferred to all subsystems especially to TR modules. In case of failure of any TR module, it is indicated to the user for further rectification. Realisation of the RC system is at an advanced stage. More details will be presented in the conference.

  13. User’s Guide for the VTRPE (Variable Terrain Radio Parabolic Equation) Computer Model

    DTIC Science & Technology

    1991-10-01

    propagation effects and antenna characteristics in radar system performance calculations. the radar transmission equation is oiten employed. Fol- lowing Kerr.2...electromagnetic wave equations for the complex electric and magnetic radiation fields. The model accounts for the effects of nonuniform atmospheric refractivity...mission equation, that is used in the performance prediction and analysis of radar and communication systems. Optimized fast Fourier transform (FFT

  14. The SIR-B science investigations plan

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Shuttle Imaging Radar-B (SIR-B) is the second synthetic aperture radar (SAR) to be flown on the National Aeronautics and Space Administration's Space Transportation System (Shuttle). It is the first spaceborne SAR to feature an antenna that allows acquisition of multiincidence angle imagery. An international team of scientists will use SIR-B to conduct investigations in a wide range of disciplines. The radar, the mission, and the investigations are described.

  15. Analysis of Transient Electromagnetic Scattering from Three Dimensional Cavities

    DTIC Science & Technology

    2014-01-01

    New York, 2002. [24] J. Jin and J. L. Volakis, A hybrid finite element method for scattering and radiation by micro strip patch antennas and arrays...applications such as the design of cavity-backed conformal antennas and the deliberate control in the form of enhancement or reduction of radar cross...electromagnetic scattering analysis, IEEE Trans. Antennas Propagat., 50 (2002), pp. 1192–1202. [22] J. Jin, Electromagnetic scattering from large, deep, and

  16. 47 CFR 15.256 - Operation of level probing radars within the bands 5.925-7.250 GHz, 24.05-29.00 GHz, and 75-85 GHz.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... than 8 degrees. (j) Antenna side lobe gain. LPR devices operating under the provisions of this section must limit the side lobe antenna gain relative to the main beam gain for off-axis angles from the main beam of greater than 60 degrees to the levels provided in Table 2. Table 2—Antenna Side Lobe Gain...

  17. KSC-99pp0999

    NASA Image and Video Library

    1999-07-28

    KENNEDY SPACE CENTER, FLA. -- In the Orbiter Processing Facility, STS-99 Mission Specialists Janet Lynn Kavandi (Ph.D.) and Gerhard P.J. Thiele look over part of the Shuttle Radar Topography Mission (SRTM), primary payload for their mission, as part of a Crew Equipment Interface Test (CEIT). Also taking part in the CEIT are Commander Kevin R. Kregel, Pilot Dominic L. Pudwill Gorie, and Mission Specialists Janice Voss (Ph.D.) and Mamoru Mohri. Mohri is with the National Space Development Agency (NASDA) of Japan, and Thiele is with the European Space Agency. The CEIT provides an opportunity for crew members to check equipment and facilities that will be aboard the orbiter during their mission. The SRTM is a specially modified radar system that will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. The SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle. STS-99 is scheduled to launch Sept. 16 at 8:47 a.m. from Launch Pad 39A

  18. KSC-99pp0998

    NASA Image and Video Library

    1999-07-28

    KENNEDY SPACE CENTER, FLA. -- In the Orbiter Processing Facility, STS-99 Mission Specialists Gerhard P.J. Thiele and Janet Lynn Kavandi (Ph.D.) look over part of the Shuttle Radar Topography Mission (SRTM), primary payload for their mission, as part of a Crew Equipment Interface Test (CEIT). Also taking part in the CEIT are Commander Kevin R. Kregel, Pilot Dominic L. Pudwill Gorie, and Mission Specialists Janice Voss (Ph.D.) and Mamoru Mohri. Mohri is with the National Space Development Agency (NASDA) of Japan, and Thiele is with the European Space Agency. The CEIT provides an opportunity for crew members to check equipment and facilities that will be aboard the orbiter during their mission. The SRTM is a specially modified radar system that will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. The SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle. STS-99 is scheduled to launch Sept. 16 at 8:47 a.m. from Launch Pad 39A

  19. KSC-99pp0774

    NASA Image and Video Library

    1999-06-19

    In the Space Station Processing Facility, STS-99 crew members inspect the Shuttle Radar Topography Mission (SRTM), the payload for their mission. At left is Commander Kevin R. Kregel talking to Mission Specialist Janice Voss (Ph.D.); and Mission Specialists Gerhard Thiele of Germany and Mamoru Mohri of Japan farther back. In the foreground (back to camera) is Mission Specialist Janet Lynn Kavandi (Ph.D.). The final crew member (not shown) is Pilot Dominic L. Pudwill Gorie. Thiele represents the European Space Agency and Mohri represents the National Space Agency of Japan. An international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR, the SRTM consists of a specially modified radar system that will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. The SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle. STS-99 is scheduled to launch Sept. 16 at 8:47 a.m. from Launch Pad 39A

  20. KSC-99pp0775

    NASA Image and Video Library

    1999-06-19

    In the Space Station Processing Facility, STS-99 crew members take part in a simulated flight check of the Shuttle Radar Topography Mission (SRTM), above and behind them. The SRTM is the payload for their mission. The crew members are Commander Kevin R. Kregel, Pilot Dominic L. Pudwill Gorie, and Mission Specialists Janet Lynn kavandi (Ph.D.), Janice Voss (Ph.D.), Mamoru Mohri of Japan and Gerhard Thiele of Germany. Mohri represents the National Space Development Agency of Japan and Thiele represents the European Space Agency. An international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR, the SRTM consists of a specially modified radar system that will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. The SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle. STS-99 is scheduled to launch Sept. 16 at 8:47 a.m. from Launch Pad 39A

  1. KSC-99pp0997

    NASA Image and Video Library

    1999-07-28

    KENNEDY SPACE CENTER, FLA. -- In the Orbiter Processing Facility, members of the STS-99 crew look over the Shuttle Radar Topography Mission (SRTM), primary payload for their mission, as part of a Crew Equipment Interface Test (CEIT). Participating are Commander Kevin R. Kregel, Pilot Dominic L. Pudwill Gorie, and Mission Specialists Janet Lynn Kavandi (Ph.D.), Janice Voss (Ph.D), Mamoru Mohri, and Gerhard P.J. Thiele. Mohri is with the National Space Development Agency (NASDA) of Japan, and Thiele is with the European Space Agency. The CEIT provides an opportunity for crew members to check equipment and facilities that will be aboard the orbiter during their mission. The SRTM is a specially modified radar system that will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. The SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle. STS-99 is scheduled to launch Sept. 16 at 8:47 a.m. from Launch Pad 39A

  2. KSC-99pp0996

    NASA Image and Video Library

    1999-07-28

    KENNEDY SPACE CENTER, FLA. -- In the Orbiter Processing Facility (OPF), the STS-99 crew take part in a Crew Equipment Interface Test (CEIT). Facing the camera and pointing is Mission Specialist Gerhard P.J. Thiele, who is with the European Space Agency. Other crew members in the OPF are Commander Kevin R. Kregel, Pilot Dominic L. Pudwill Gorie, and Mission Specialists Janet Lynn Kavandi (Ph.D.), Janice Voss (Ph.D.), and Mamoru Mohri, who is with the National Space Development Agency (NASDA) of Japan. The CEIT provides an opportunity for crew members to check equipment and facilities that will be aboard the orbiter during their mission. The STS-99 mission is the Shuttle Radar Topography Mission (SRTM), a specially modified radar system that will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. The SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle. STS-99 is scheduled to launch Sept. 16 at 8:47 a.m. from Launch Pad 39A

  3. KSC-99pp0778

    NASA Image and Video Library

    1999-06-19

    The STS-99 crew poses in front of the Shuttle Radar Topography Mission (SRTM) in the Space Station Processing Facility. The crew has been checking out the SRTM, which is the payload for their mission. From left are Mission Specialists Janet Lynn Kavandi (Ph.D.), Mamoru Mohri of Japan, and Gerhard Thiele of Germany; Pilot Dominic L. Pudwill Gorie; Mission Specialist Janice Voss (Ph.D.); and Commander Kevin R. Kregel. Mohri represents the National Space Development Agency of Japan and Thiele represents the European Space Agency. An international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR, the SRTM consists of a specially modified radar system that will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. The SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle. STS-99 is scheduled to launch Sept. 16 at 8:47 a.m. from Launch Pad 39A

  4. KSC-99pp0777

    NASA Image and Video Library

    1999-06-19

    In the Space Station Processing Facility, the STS-99 crew looks over the payload for their mission, the Shuttle Radar Topography Mission (SRTM). Pointing to the SRTM are Commander Kevin R. Kregel and Mission Specialist Gerhard Thiele of Germany. Behind them are (left to right) Pilot Dominic L. Pudwill Gorie and Mission Specialists Mamoru Mohri of Japan and Janet Lynn Kavandi (Ph.D.) The remaining crew member (not shown) is Mission Specialist Janice Voss (Ph.D.) Mohri represents the National Space Development Agency of Japan and Thiele represents the European Space Agency. An international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR, the SRTM consists of a specially modified radar system that will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. The SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle. STS-99 is scheduled to launch Sept. 16 at 8:47 a.m. from Launch Pad 39A

  5. Design and Performance of the WISDOM Antenna System aboard the ExoMars Rover

    NASA Astrophysics Data System (ADS)

    Plettemeier, D.; Ciarletti, V.; Hamran, S.; Corbel, C.; Linke, S.; Benedix, W.

    2009-04-01

    A full polarimetric antenna system on board the ExoMars rover is part of the Experiment "Water Ice and Subsurface Deposit Observations on Mars" (WISDOM). The WISDOM-Experiment is a Ground Penetrating Radar (GPR) selected to be part of the Pasteur payload aboard the rover of the ExoMars mission. The Pasteur Panoramic Instruments (wide angle camera PANCAM, infrared spectrometer MIMA and WISDOM) will perform large-scale scientific investigations at the sites the Rover will visit. Among these instruments, WISDOM is the only one that can provide a view of the subsurface structure prior to drilling. WISDOM is the first space borne GPR aboard a rover and has been designed to characterize the shallow subsurface structure of Mars. WISDOM will give for the first time access to the geological structure, electromagnetic nature, and, possibly, of hydrological state of the shallow subsurface by retrieving the layering and properties of the buried reflectors. It will address some important related science questions regarding the planet present state and past evolution. The measured data will also be used to determine the most promising locations at which to obtain underground samples with the drilling system mounted on board the rover. The instrument objective for WISDOM is to get high-resolution measurements down to 2-meters depth in the Martian crust. The radar is a gated step frequency system covering the frequency range from 500 MHz to 3 GHz. The radar is fully polarimetric and makes use of four ultra wideband Vivaldi antennas. This poster describes the requirements, the design and the realization of the WISDOM antenna system accommodated on the ExoMars rover. Simulated antenna performance and measured antenna parameters as well as preliminary antenna test measurements performed in the lab and in permafrost regions on earth will be discussed in this poster presentation. The main design requirements of the WISDOM antenna system are driven one hand by the required science return of the Experiment and on the other hand by the specific GPR configuration and accommodation on the Mars Rover. The resolution of a few centimetres and a penetration depth of more than two meters results in a bandwidth of 2.5 GHz. To be able to study depolarization effects in the subsurface a fully polarimetric antenna system is required. To realize the best radar performance the antenna system is equipped with two perpendicular linear polarized transmitting antennas and two co- and cross-polar oriented antennas for reception. Usually GPR antennas are placed on ground or accommodated in a close-by ground configuration with respect to the wavelength. Considering the requirements for the design of the ExoMars rover the GPR antenna system has to have a ground clearance of about 30 cm, which is equal to 3 wavelengths for the highest operating frequency. Taking into account that the GPR antennas on the rover are not able to use the advantages of a close-by ground arrangement and that due to mass, volume and planetary protection requirements the application of absorbing material and reflectors are not appropriate, the antenna pattern of each single antenna element should be directed towards ground and should provide a large forward to backward ratio. The radiation pattern should be wide in rover path direction, so that a visibility of point reflectors for long distance is possible. The across path pattern should be narrow. These and other constraints like EMC requirements as well as pattern deformation due to radiation coupling effects with the rover structure led to an antenna design that is based on two perpendicular oriented Vivaldi structures for each antenna. The antennas will be covered by thin dielectric foil to protect the sensitive parts from Martian dust particles. The overall size of the dual polarized transmitting and receiving antenna is less than 20 cm x 20 cm x 20 cm. The total mass for a whole antenna unit is about 200 g. Taking into account all the requirements, a very powerful space qualified broad band antenna system is developed and successfully tested in different environments.

  6. Ultrawideband radar; Proceedings of the Meeting, Los Angeles, CA, Jan. 22, 23, 1992

    NASA Astrophysics Data System (ADS)

    Lahaie, Ivan J.

    1992-05-01

    The present conference discusses a canonical representation of the radar range equation in the time domain, two-way beam patterns fron ultrawideband arrays, modeling of ultrawideband sea clutter, the analysis of time-domain ultrawideband radar signals, a frequency-agile ultrawideband microwave source, and the performance of ultrawideband antennas. Also discussed are the diffraction of ultrawideband radar pulses, sea-clutter measurements with an ultrawideband X-band radar having variable resolution, results from a VHF-impulse SAR, an ultrawideband differential radar, the development of 2D target images from ultrawideband radar systems, ultrawideband generators, and the radiated waveform of a monolithic photoconductive GaAs pulser. (For individual items see A93-28202 to A93-28223)

  7. Radar systems for a polar mission, volume 1

    NASA Technical Reports Server (NTRS)

    Moore, R. K.; Claassen, J. P.; Erickson, R. L.; Fong, R. K. T.; Komen, M. J.; Mccauley, J.; Mcmillan, S. B.; Parashar, S. K.

    1977-01-01

    The application of synthetic aperture radar (SAR) in monitoring and managing earth resources is examined. Synthetic aperture radars form a class of side-looking airborne radar, often referred to as coherent SLAR, which permits fine-resolution radar imagery to be generated at long operating ranges by the use of signal processing techniques. By orienting the antenna beam orthogonal to the motion of the spacecraft carrying the radar, a one-dimensional imagery ray system is converted into a two-dimensional or terrain imaging system. The radar's ability to distinguish - or resolve - closely spaced transverse objects is determined by the length of the pulse. The transmitter components receivers, and the mixer are described in details.

  8. Radar research at University of Oklahoma (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Zhang, Yan R.; Weber, Mark E.

    2017-05-01

    This abstract is for the academic institution profiles session This presentation will focus on radar research programs at the University of Oklahoma, the radar research in OU has more than 50 years history of collaboration with NOAA, and has been through tremendous growth since early 2000. Before 2010, the focus was weather radar and weather surveillance, and since the Defense, Security and Intelligence (DSI) initiative in 2011, there have many new efforts on the defense and military radar applications. This presentation will focus on the following information: (1) The history, facilities and instrumentations of Advanced Radar Research Center, (2) Focus area of polarimetric phased array systems, (3) Focus area of airborne and spaceborne radars, (4) Intelligent radar information processing, (5) Innovative antenna and components.

  9. Basalt-flow imaging using a high-resolution directional borehole radar

    USGS Publications Warehouse

    Moulton, C.W.; Wright, D.L.; Hutton, S.R.; Smith, D.V.G.; Abraham, J.D.

    2002-01-01

    A new high-resolution directional borehole radar-logging tool (DBOR tool) was used to log three wells at the Idaho National Engineering and Environmental Laboratory (INEEL). The radar system uses identical directional cavity-backed monopole transmitting and receiving antennas that can be mechanically rotated while the tool is stationary or moving slowly in a borehole. Faster reconnaissance logging with no antenna rotation was also done to find zones of interest. The microprocessor-controlled motor/encoder in the tool can rotate the antennas azimuthally, to a commanded angle, accurate to a within few degrees. The three logged wells in the unsaturated zone at the INEEL had been cored with good core recovery through most zones. After coring, PVC casing was installed in the wells. The unsaturated zone consists of layered basalt flows that are interbedded with thin layers of coarse-to-fine grained sediments. Several zones were found that show distinctive signatures consistent with fractures in the basalt. These zones may correspond to suspected preferential flow paths. The DBOR data were compared to core, and other borehole log information to help provide better understanding of hydraulic flow and transport in preferential flow paths in the unsaturated zone basalts at the INEEL.

  10. First Results from the Telescope Array RAdar (TARA) Detector

    NASA Astrophysics Data System (ADS)

    Myers, Isaac

    2014-03-01

    The TARA cosmic ray detector has been in operation for about a year and a half. This bi-static radar detector was designed with the goal of detecting cosmic rays in coincidence with Telescope Array (TA). A new high power (25 kW, 5 MW effective radiated power) transmitter and antenna array and 250 MHz fPGA-based DAQ have been operational since August 2013. The eight-Yagi antenna array broadcasts a 54.1 MHz tone across the TA surface detector array toward our receiver station 50 km away at the Long Ridge fluorescence detector. Receiving antennas feed an intelligent DAQ that self-adjusts to the fluctuating radio background and which employs a bank of matched filters that search in real-time for chirp radar echoes. Millions of triggers have been collected in this mode. A second mode is a forced trigger scheme that uses the trigger status of the fluorescence telescope. Of those triggers collected in FD-triggered mode, about 800 correspond with well-reconstructed TA events. I will describe recent advancements in calibrating key components in the transmitter and receiver RF chains and the analysis of FD-triggered data. Work supported by W.M. Keck Foundation and NSF.

  11. Radar systems for the water resources mission. Volume 4: Appendices E-I

    NASA Technical Reports Server (NTRS)

    Moore, R. K.; Claassen, J. P.; Erickson, R. L.; Fong, R. K. T.; Hanson, B. C.; Komen, M. J.; Mcmillan, S. B.; Parashar, S. K.

    1976-01-01

    The use of a scanning antenna beam for a synthetic aperture system was examined. When the resolution required was modest, the radar did not use all the time the beam was passing a given point on the ground to build a synthetic aperture, so time was available to scan the beam to other positions and build several images at different ranges. The scanning synthetic-aperture radar (SCANSAR) could achieve swathwidths of well over 100 km with modest antenna size. Design considerations for a SCANSAR for hydrologic parameter observation are presented. Because of the high sensitivity to soil moisture at angles of incidence near vertical, a 7 to 22 deg swath was considered for that application. For snow and ice monitoring, a 22 to 37 deg scan was used. Frequencies from X-band to L-band were used in the design studies, but the proposed system operated in C-band at 4.75 GHz. It achieved an azimuth resolution of about 50 meters at all angles, with a range resolution varying from 150 meters at 7 deg to 31 meters at 37 deg. The antenna required an aperture of 3 x 4.16 meters, and the average transmitter power was under 2 watts.

  12. An Autonomous Cryobot Synthetic Aperture Radar for Subsurface Exploration of Europa

    NASA Astrophysics Data System (ADS)

    Pradhan, O.; Gasiewski, A. J.

    2015-12-01

    We present the design and field testing of a forward-looking end-fire synthetic aperture radar (SAR) for the 'Very deep Autonomous Laser-powered Kilowatt-class Yo-yoing Robotic Ice Explorer' (VALKYRIE) ice-penetrating cryobot. This design demonstrates critical technologies that will support an eventual landing and ice penetrating mission to Jupiter's icy moon, Europa. Results proving the feasibility of an end-fire SAR system for vehicle guidance and obstacle avoidance in a sub-surface ice environment will be presented. Data collected by the SAR will also be used for constructing sub-surface images of the glacier which can be used for: (i) mapping of englacial features such as crevasses, moulins, and embedded liquid water and (ii) ice-depth and glacier bed analysis to construct digital elevation models (DEM) that can help in the selection of crybot trajectories and future drill sites for extracting long-term climate records. The project consists of three parts, (i) design of an array of four conformal cavity-backed log-periodic folded slot dipole array (LPFSA) antennas that form agile radiating elements, (ii) design of a radar system that includes RF signal generation, 4x4 transmit-receive antenna switching and isolation and digital SAR data processing and (iii) field testing of the SAR in melt holes. The antennas have been designed, fabricated, and lab tested at the Center for Environmental Technology (CET) at CU-Boulder. The radar system was also designed and integrated at CET utilizing rugged RF components and FPGA based digital processing. Field testing was performed in conjunction with VALKYRIE tests by Stone Aerospace in June, 2015 on Matanuska Glacier, Alaska. The antennas are designed to operate inside ice while being immersed in a thin layer of surrounding low-conductivity melt water. Small holes in the corners of the cavities allow flooding of these cavities with the same melt-water thus allowing for quarter-wavelength cavity-backed reflection. Testing of the antenna array was first carried out by characterizing their operation inside a large ice block at the Stone Aerospace facility in Austin, TX. The complete radar system was then tested on the Matanuska glacier in Alaska, which is an effective Earth analog to Europan sub-surface exploration.

  13. Halloween Asteroid Rotation

    NASA Image and Video Library

    2015-11-03

    The 230-foot 70-meter DSS-14 antenna at Goldstone, Ca. obtained these radar images of asteroid 2015 TB145 on Oct. 31, 2015. Asteroid 2015 TB145 is depicted in eight individual radar images collected on Oct. 31, 2015 between 5:55 a.m. PDT (8:55 a.m. EDT) and 6:08 a.m. PDT (9:08 a.m. EDT). At the time the radar images were taken, the asteroid was between 440,000 miles (710,000 kilometers) and about 430,000 miles (690,000 kilometers) distant. Asteroid 2015 TB145 safely flew past Earth on Oct. 31, at 10:00 a.m. PDT (1 p.m. EDT) at about 1.3 lunar distances (300,000 miles, 480,000 kilometers). To obtain the radar images, the scientists used the 230-foot (70-meter) DSS-14 antenna at Goldstone, California, to transmit high power microwaves toward the asteroid. The signal bounced of the asteroid, and their radar echoes were received by the National Radio Astronomy Observatory's 100-meter (330-foot) Green Bank Telescope in West Virginia. The images achieve a spatial resolution of about 13 feet (4 meters) per pixel. http://photojournal.jpl.nasa.gov/catalog/PIA20043

  14. UAVSAR Instrument: Current Operations and Planned Upgrades

    NASA Technical Reports Server (NTRS)

    Lou, Yunling; Hensley, Scott; Chao, Roger; Chapin, Elaine; Heavy, Brandon; Jones, Cathleen; Miller, Timothy; Naftel, Chris; Fratello, David

    2011-01-01

    The Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) instrument is a pod-based Lband polarimetric synthetic aperture radar (SAR), specifically designed to acquire airborne repeat track SAR data for differential interferometric measurements. This instrument is currently installed on the NASA Gulfstream- III (G-III) aircraft with precision real-time Global Positioning System (GPS) and a sensor-controlled flight management system for precision repeat-pass data acquisitions. UAVSAR has conducted engineering and preliminary science data flights since October 2007 on the G-III. We are porting the radar to the Global Hawk Unmanned Airborne Vehicle (UAV) to enable long duration/long range data campaigns. We plan to install two radar pods (each with its own active array antenna) under the wings of the Global Hawk to enable the generation of precision topographic maps and single pass polarimetric-interferometry (SPI) providing vertical structure of ice and vegetation. Global Hawk's range of 8000 nm will enable regional surveys with far fewer sorties as well as measurements of remote locations without the need for long and complicated deployments. We are also developing P-band polarimetry and Ka-band single-pass interferometry capabilities on UAVSAR by replacing the radar antenna and front-end electronics to operate at these

  15. KSC-99pp1001

    NASA Image and Video Library

    1999-07-28

    KENNEDY SPACE CENTER, FLA. -- In the Orbiter Processing Facility, STS-99 Mission Specialists Mamoru Mohri (left center), who is with the National Space Development Agency (NASDA) of Japan, and Janice Voss (Ph.D.) look over equipment during a Crew Equipment Interface Test (CEIT). The CEIT provides an opportunity for crew members to check equipment and facilities that will be aboard the orbiter during their mission. Others taking part are Commander Kevin R. Kregel, Pilot Dominic L. Pudwill Gorie, and Mission Specialists Janet Lynn Kavandi (Ph.D.) and Gerhard P.J. Thiele, who is with the European Space Agency. The SRTM is a specially modified radar system that will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. The SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle. STS-99 is scheduled to launch Sept. 16 at 8:47 a.m. from Launch Pad 39A

  16. Development of Stiff and Extendible Electromagnetic Sensors for Space Missions

    NASA Astrophysics Data System (ADS)

    Kasaba, Y.; Kumamoto, A.; Ishisaka, K.; Kojima, H.; Higuchi, K.; Watanabe, A.; Watanabe, K.

    2010-05-01

    We developed three types of stiff and extendible electromagnetic sensors in rigid monopole antenna, loop antenna, and Yagi-Uda antenna for future space missions. They are based on carbon fiber reinforced plastic (CFRP) technologies, in order to fulfill severe requirements, i.e. enough stiffness, light mass, compact storage, safe extension, and reasonable test efforts. One of them, rigid monopole antennas, coupled with an inflatable actuator system, was successfully used in the JAXA S-520-23 sounding rocket experiment in September 2007. Applications of those antennas are expected in space plasma missions including the SCOPE program, sounding rocket experiments, planetary radar remote sensing, and landing radio measurements.

  17. Development of Spaceborne Radar Simulator by NICT and JAXA using JMA Cloud-resolving Model

    NASA Astrophysics Data System (ADS)

    Kubota, T.; Eito, H.; Aonashi, K.; Hashimoto, A.; Iguchi, T.; Hanado, H.; Shimizu, S.; Yoshida, N.; Oki, R.

    2009-12-01

    We are developing synthetic spaceborne radar data toward a simulation of the Dual-frequency Precipitation Radar (DPR) aboard the Global Precipitation Measurement (GPM) core-satellite. Our purposes are a production of test-bed data for higher level DPR algorithm developers, in addition to a diagnosis of a cloud resolving model (CRM). To make the synthetic data, we utilize the CRM by the Japan Meteorological Agency (JMA-NHM) (Ikawa and Saito 1991, Saito et al. 2006, 2007), and the spaceborne radar simulation algorithm by the National Institute of Information and Communications Technology (NICT) and the Japan Aerospace Exploration Agency (JAXA) named as the Integrated Satellite Observation Simulator for Radar (ISOSIM-Radar). The ISOSIM-Radar simulates received power data in a field of view of the spaceborne radar with consideration to a scan angle of the radar (Oouchi et al. 2002, Kubota et al. 2009). The received power data are computed with gaseous and hydrometeor attenuations taken into account. The backscattering and extinction coefficients are calculated assuming the Mie approximation for all species. The dielectric constants for solid particles are computed by the Maxwell-Garnett model (Bohren and Battan 1982). Drop size distributions are treated in accordance with those of the JMA-NHM. We assume a spherical sea surface, a Gaussian antenna pattern, and 49 antenna beam directions for scan angles from -17 to 17 deg. in the PR. In this study, we report the diagnosis of the JMA-NHM with reference to the TRMM Precipitation Radar (PR) and CloudSat Cloud Profiling Radar (CPR) using the ISOSIM-Radar from the view of comparisons in cloud microphysics schemes of the JMA-NHM. We tested three kinds of explicit bulk microphysics schemes based on Lin et al. (1983), that is, three-ice 1-moment scheme, three-ice 2-moment scheme (Eito and Aonashi 2009), and newly developed four-ice full 2-moment scheme (Hashimoto 2008). The hydrometeor species considered here are rain, graupel, snow, cloud water, cloud ice and hail (4-ice scheme only). We examined a case of an intersection with the TRMM PR and the CloudSat CPR on 6th April 2008 over sea surface in the south of Kyushu Island of Japan. In this work, observed rainfall systems are simulated with one-way double nested domains having horizontal grid sizes of 5 km (outer) and 2 km (inner). Data used here are from the inner domain only. Results of the PR indicated better performances of 2-moment bulk schemes. It suggests that prognostic number concentrations of frozen hydrometeors are more effective in high altitudes and constant number concentrations can lead to the overestimation of the snow there. For three-ice schemes, simulated received power data overestimated above freezing levels with reference to the observed data. In contrast, the overestimation of frozen particles was heavily reduced for the four-ice scheme.

  18. Environmental projects. Volume 15: Environmental assessment: Proposed 1-megawatt radar transmitter at the Mars site

    NASA Technical Reports Server (NTRS)

    1992-01-01

    The Goldstone Deep Space Communications Complex (GDSCC), located in the Mojave Desert about 64.5 km (40 mi) north of Barstow, California. and about 258 km (160 mi) northeast of Pasadena, California, is part of the National Aeronautics and Space Administration's (NASA's) Deep Space Network (DSN), one of the world's larger and more sensitive scientific telecommunications and radio navigation networks. The Goldstone Complex is managed, technically directed, and operated for NASA by the Jet Propulsion Laboratory (JPL) of the California Institute of Technology in Pasadena, California. Activities at the GDSCC support the operation of six parabolic dish antennas located at five separate sites called Deep Space Stations (DSS's). Four sites, named Echo, Mars, Uranus, and Apollo, are operational for space missions, while the remaining Venus Site is devoted to research and development activities. The Mars Site at the GDSCC contains two antennas: the Uranus antenna (DSS 15, 34 m) and the Mars antenna (DSS 14, 70 m). This present volume deals solely with the DSS-14 Mars antenna. The Mars antenna not only can act as a sensitive receiver to detect signals from spacecraft, but it also can be used in radar astronomy as a powerful transmitter to send out signals to probe the solar system. At present, the Mars antenna operates as a continuous-wave microwave system at a frequency of 8.51 GHz at a power level of 0.5 MW. JPL has plans to upgrade the Mars antenna to a power level of 1 MW. Because of the anticipated increase in the ambient levels of radio frequency radiation (RFR), JPL retained Battelle Pacific Northwest Laboratories (BPNL), Richland, Washington, to conduct an environmental assessment with respect to this increased RFR. This present volume is a JPL-expanded version of the BPNL report titled Environmental Assessment of the Goldstone Solar System Radar, which was submitted to JPL in Nov. 1991. This BPNL report concluded that the operation of the upgraded Mars antenna at the GDSCC, with its increased potential electromagnetic radiation hazards and interferences, would have no significantly adverse biological, physical, or socioeconomic effects on the environment. Thus, a Finding of No Significant Impact (FONSI) is appropriate in accordance with local, State, Federal, and NASA environmental rules and regulations.

  19. Radar Transponder Antenna Systems Evaluation Handbook

    DTIC Science & Technology

    2006-07-01

    Poincare Sphere Usage. The plane geometry... Poincare Sphere any coupling factor is numerically equal to the cosine of half the distance between states on the spherical surface. 5-52 Then in...Erhcp, Elhcp) on the Poincare sphere (Paragraph 5.14.1). As such, any antenna whose polarization lies on this plane receives the same

  20. On Ambiguities in SAR Design

    NASA Technical Reports Server (NTRS)

    Freeman, Anthony

    2006-01-01

    Ambiguities are an aliasing effect caused by the periodic sampling of the scene backscatter inherent to pulsed radar systems such as Synthetic Aperture radar (SAR). In this paper we take a fresh look at the relationship between SAR range and azimuth ambiguity constraints on the allowable pulse repetition frequency (PRF) and the antenna length. We show that for high squint angles smaller antennas may be feasible in some cases. For some applications, the ability to form a synthetic aperture at high squint angles is desirable, but the size of the antenna causes problems in the design of systems capable of such operation. This is because the SAR system design is optimized for a side-looking geometry. In two examples design examples we take a suboptimum antenna size and examine the performance in terms of azimuth resolution and swath width as a function of squint angle. We show that for stripmap SARs, the swath width is usually worse for off-boresight squint angles, because it is severely limited by range walk, except in cases where we relax the spatial resolution. We consider the implications for the design of modest-resolution, narrow swath, scanning SAR scatterometers .

  1. Buried nonmetallic object detection using bistatic ground penetrating radar with variable antenna elevation angle and height

    NASA Astrophysics Data System (ADS)

    Zhang, Yu; Orfeo, Dan; Burns, Dylan; Miller, Jonathan; Huston, Dryver; Xia, Tian

    2017-04-01

    Ground penetrating radar (GPR) has been shown to be an effective device for detecting buried objects that have little or no metal content, such as plastic, ceramic, and concrete pipes. In this paper, buried non-metallic object detection is evaluated for different antenna elevation angles and heights using a bistatic air-launched GPR. Due to the large standoff distance between antennas and the ground surface, the air-launched GPR has larger spreading loss than the hand-held GPR and vehicle-mounted GPR. Moreover, nonmetallic objects may have similar dielectric property to the buried medium, which results in further difficulty for accurate detection using air-launched GPR. To study such effects, both GPR simulations and GPR laboratory experiments are performed with various setups where antennas are placed at different heights and angles. In the experiments, the test surface areas are configured with and without rocks in order to examine surface clutter effect. The experimental results evaluate the feasibility and effectiveness of bistatic air-launched GPR for detecting buried nonmetallic objects, which provide valuable insights for subsurface scanning with unmanned aerial vehicle (UAV) mounted GPR.

  2. Artist concept of Magellan spacecraft above Venusian surface

    NASA Technical Reports Server (NTRS)

    1988-01-01

    Artist concept shows Magellan spacecraft in cruise configuration oriented above Venusian surface, during data collection and radar mapping sequence. Solar panels are deployed and low-gain and high gain antennas, altimeter antenna, thermal control louvers, forward equipment module, equipment bus with thermal control louvers, and control rocket engine module are visible. The continued quest for detailed topographic measurements of Venus will again be undertaken in April 1989 by Magellan, named after the 16th century Portuguese explorer. Magellan will orbit Venus about once every three hours, acquiring radar data for 37 minutes of each orbit when it is closest to the surface. Using an advanced instrument called a synthetic aperature radar (SAR), it will map more than 90 per cent of the surface with resolution ten times better than the best prior spacecraft. Magellan is managed by the Jet Propulsion Laboratory (JPL); Martin Marietta is developing the spacecraft and Hughes Aircraft Company,

  3. Short pulse radar used to measure sea surface wind speed and SWH. [Significant Wave Height

    NASA Technical Reports Server (NTRS)

    Hammond, D. L.; Mennella, R. A.; Walsh, E. J.

    1977-01-01

    A joint airborne measurement program is being pursued by NRL and NASA Wallops Flight Center to determine the extent to which wind speed and sea surface significant wave height (SWH) can be measured quantitatively and remotely with a short pulse (2 ns), wide-beam (60 deg), nadir-looking 3-cm radar. The concept involves relative power measurements only and does not need a scanning antenna, Doppler filters, or absolute power calibration. The slopes of the leading and trailing edges of the averaged received power for the pulse limited altimeter are used to infer SWH and surface wind speed. The interpretation is based on theoretical models of the effects of SWH on the leading edge shape and rms sea-surface slope on the trailing-edge shape. The models include the radar system parameters of antenna beam width and pulsewidth.

  4. Parametric dependence of ocean wave-radar modulation transfer functions

    NASA Technical Reports Server (NTRS)

    Plant, W. J.; Keller, W. C.; Cross, A.

    1983-01-01

    Microwave techniques at X and L band were used to determine the dependence of ocean-wave radar modulation transfer functions (MTFs) on various environmental and radar parameters during the Marine Remote Sensing experiment of 1979 (MARSEN 79). These MIF are presented, as are coherence functions between the AM and FM parts of the backscattered microwave signal. It is shown that they both depend on several of these parameters. Besides confirming many of the properties of transfer functions reported by previous authors, indications are found that MTFs decrease with increasing angle between wave propagation and antenna-look directions but are essentially independent of small changes in air-sea temperature difference. However, coherence functions are much smaller when the antennas are pointed perpendicular to long waves. It is found that X band transfer functions measured with horizontally polarized microwave radiation have larger magnitudes than those obtained by using vertical polarization.

  5. The INAF contribution to the ASI Space Debris program: observational activities.

    NASA Astrophysics Data System (ADS)

    Pupillo, G.; Salerno, E.; Bartolini, M.; Di Martino, M.; Mattana, A.; Montebugnoli, S.; Portelli, C.; Pluchino, S.; Schillirò, F.; Konovalenko, A.; Nabatov, A.; Nechaeva, M.

    Space debris are man made objects orbiting around Earth that pose a serious hazard for both present and future human activities in space. Since 2007 the Istituto Nazionale di Astrofisica (INAF) carried out a number of radar campaigns in the framework of the ASI ``Space Debris'' program. The observations were performed by using bi- and multi-static radars, composed of the INAF 32-m Italian radiotelescopes located at Medicina and Noto (used as receivers) and the 70-m parabolic antenna at Evpatoria (Ukraine) used as transmitter. The 32 m Ventspils antenna in Latvia also participated in the last campaign at the end of June 2010. Several kinds of objects in various orbital regions (radar calibrators, rocket upper stages, debris of different sizes) were observed and successfully detected. Some unknown objects were also discovered in LEO during the beam-park sessions. In this paper we describe some results of the INAF-ASI space debris research activity.

  6. Detection and Tracking of Moving Targets Behind Cluttered Environments Using Compressive Sensing

    NASA Astrophysics Data System (ADS)

    Dang, Vinh Quang

    Detection and tracking of moving targets (target's motion, vibration, etc.) in cluttered environments have been receiving much attention in numerous applications, such as disaster search-and-rescue, law enforcement, urban warfare, etc. One of the popular techniques is the use of stepped frequency continuous wave radar due to its low cost and complexity. However, the stepped frequency radar suffers from long data acquisition time. This dissertation focuses on detection and tracking of moving targets and vibration rates of stationary targets behind cluttered medium such as wall using stepped frequency radar enhanced by compressive sensing. The application of compressive sensing enables the reconstruction of the target space using fewer random frequencies, which decreases the acquisition time. Hardware-accelerated parallelization on GPU is investigated for the Orthogonal Matching Pursuit reconstruction algorithm. For simulation purpose, two hybrid methods have been developed to calculate the scattered fields from the targets through the wall approaching the antenna system, and to convert the incoming fields into voltage signals at terminals of the receive antenna. The first method is developed based on the plane wave spectrum approach for calculating the scattered fields of targets behind the wall. The method uses Fast Multiple Method (FMM) to calculate scattered fields on a particular source plane, decomposes them into plane wave components, and propagates the plane wave spectrum through the wall by integrating wall transmission coefficients before constructing the fields on a desired observation plane. The second method allows one to calculate the complex output voltage at terminals of a receiving antenna which fully takes into account the antenna effects. This method adopts the concept of complex antenna factor in Electromagnetic Compatibility (EMC) community for its calculation.

  7. Model studies of surface noise interference in ground-probing radar

    NASA Astrophysics Data System (ADS)

    Arcone, S. A.; Delaney, A. J.

    1985-11-01

    Ground-probing radar can be an effective tool for exploring the top 10 to 20 m of ground, especially in cold regions where the freezing of water decreases signal absorption. However, the large electrical variability of the surface, combined with the short wavelengths used, can often cause severe ground clutter that can mask a desired, deeper return. In this study a model facility was constructed consisting of a metallic reflector covered by sand. Troughs of saturated sand were emplaced at the surface to carry surface electrical properties and to act as a noise source to interfere with the bottom reflections. Antenna polarization and height, and signal stacking in both static (antennas stationary) and dynamic (antennas moving) modes were then investigated as methods for reducing the surface clutter. Polarization parallel to the profile direction (perpendicular to the troughs' axes) gave profiles superior to the perpendicular case because of the dimensional sensitivity of the antenna radiation. Dynamic stacking greatly improved the signal-to-noise ratio because noise sources were averaged as the antennas moved, while the desired reflector, buried at constant depth, was enhanced. Raising the antennas above the surface also reduced noise because the surface area over which reflections were integrated increased. All three noise reduction techniques could be effective in surveys for reflectors at nearly constant depth such as groundwater tables or ice/water interfaces.

  8. Radar image of Rio Sao Francisco, Brazil

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This radar image acquired by SRTM shows an area south of the Sao Francisco River in Brazil. The area is predominantly scrub forest. Areas such as these are difficult to map by traditional methods because of frequent cloud cover and local inaccessibility. Image brightness differences in this image are caused by differences in vegetation type and density. Tributaries of the Sao Francisco are visible in the upper right. The Sao Francisco River is a major source of water for irrigation and hydroelectric power. Mapping such regions will allow scientists to better understand the relationships between flooding cycles, forestation and human influences on ecosystems.

    This radar image was obtained by the Shuttle Radar Topography Mission as part of its mission to map the Earth's topography. The image was acquired by just one of SRTM's two antennas, and consequently does not show topographic data but only the strength of the radar signal reflected from the ground. This signal, known as radar backscatter, provides insight into the nature of the surface, including its roughness, vegetation cover, and urbanization.

    The Shuttle Radar Topography Mission (SRTM), launched on February 11, 2000, uses the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. The mission is designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, an additional C-band imaging antenna and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Imagery and Mapping Agency (NIMA) and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Earth Science Enterprise, Washington, DC.

  9. Monitoring controlled graves representing common burial scenarios with ground penetrating radar

    NASA Astrophysics Data System (ADS)

    Schultz, John J.; Martin, Michael M.

    2012-08-01

    Implementing controlled geophysical research is imperative to understand the variables affecting detection of clandestine graves during real-life forensic searches. This study focused on monitoring two empty control graves (shallow and deep) and six burials containing a small pig carcass (Sus scrofa) representing different burial forensic scenarios: a shallow buried naked carcass, a deep buried naked carcass, a deep buried carcass covered by a layer of rocks, a deep buried carcass covered by a layer of lime, a deep buried carcass wrapped in an impermeable tarpaulin and a deep buried carcass wrapped in a cotton blanket. Multi-frequency, ground penetrating radar (GPR) data were collected monthly over a 12-month monitoring period. The research site was a cleared field within a wooded area in a humid subtropical environment, and the soil consisted of a Spodosol, a common soil type in Florida. This study compared 2D GPR reflection profiles and horizontal time slices obtained with both 250 and 500 MHz dominant frequency antennae to determine the utility of both antennae for grave detection in this environment over time. Overall, a combination of both antennae frequencies provided optimal detection of the targets. Better images were noted for deep graves, compared to shallow graves. The 250 MHz antenna provided better images for detecting deep graves, as less non-target anomalies were produced with lower radar frequencies. The 250 MHz antenna also provided better images detecting the disturbed ground. Conversely, the 500 MHz antenna provided better images when detecting the shallow pig grave. The graves that contained a pig carcass with associated grave items provided the best results, particularly the carcass covered with rocks and the carcass wrapped in a tarpaulin. Finally, during periods of increased soil moisture levels, there was increased detection of graves that was most likely related to conductive decompositional fluid from the carcasses.

  10. Ground-penetrating radar calibration at the Virginia Smart Road and signal analysis to improve prediction of flexible pavement layer thicknesses.

    DOT National Transportation Integrated Search

    2005-01-01

    A ground-penetrating radar (GPR) system was used to collect data over the different pavement sections of the Virginia Smart Road from June 1999 until December 2002. Three antennae at different frequencies were used for this research. The collected da...

  11. Imaging tree roots with borehole radar

    Treesearch

    John R. Butnor; Kurt H. Johnsen; Per Wikstrom; Tomas Lundmark; Sune Linder

    2006-01-01

    Ground-penetrating radar has been used to de-tect and map tree roots using surface-based antennas in reflection mode. On amenable soils these methods can accurately detect lateral tree roots. In some tree species (e.g. Pinus taeda, Pinus palustris), vertically orientated tap roots directly beneath the tree, comprise most of the root mass. It is...

  12. 37. View of detection radar environmental display (DRED) console for ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    37. View of detection radar environmental display (DRED) console for middle DR 2 (structure no. 736) antenna, located in MWOC facility. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  13. SAR Processing Based On Two-Dimensional Transfer Function

    NASA Technical Reports Server (NTRS)

    Chang, Chi-Yung; Jin, Michael Y.; Curlander, John C.

    1994-01-01

    Exact transfer function, ETF, is two-dimensional transfer function that constitutes basis of improved frequency-domain-convolution algorithm for processing synthetic-aperture-radar, SAR data. ETF incorporates terms that account for Doppler effect of motion of radar relative to scanned ground area and for antenna squint angle. Algorithm based on ETF outperforms others.

  14. Comparing Vesta's Surface Roughness to the Moon Using Bistatic Radar Observations by the Dawn Mission

    NASA Astrophysics Data System (ADS)

    Palmer, E. M.; Heggy, E.; Kofman, W. W.; Moghaddam, M.

    2015-12-01

    The first orbital bistatic radar (BSR) observations of a small body have been conducted opportunistically by NASA's Dawn spacecraft at Asteroid Vesta using the telecommunications antenna aboard Dawn to transmit and the Deep Space Network 70-meter antennas on Earth to receive. Dawn's high-gain communications antenna continuously transmitted right-hand circularly polarized radio waves (4-cm wavelength), and due to the opportunistic nature of the experiment, remained in a fixed orientation pointed toward Earth throughout each BSR observation. As a consequence, Dawn's transmitted radio waves scattered from Vesta's surface just before and after each occultation of the Dawn spacecraft behind Vesta, resulting in surface echoes at highly oblique incidence angles of greater than 85 degrees, and a small Doppler shift of ~2 Hz between the carrier signal and surface echoes from Vesta. We analyze the power and Doppler spreading of Vesta's surface echoes to assess surface roughness, and find that Vesta's area-normalized radar cross section ranges from -8 to -17 dB, which is notably much stronger than backscatter radar cross section values reported for the Moon's limbs (-20 to -35 dB). However, our measurements correspond to the forward scattering regime--such that at high incidence, radar waves are expected to scatter more weakly from a rough surface in the backscatter direction than that which is scattered forward. Using scattering models of rough surfaces observed at high incidence, we report on the relative roughness of Vesta's surface as compared to the Moon and icy Galilean satellites. Through this, we assess the dominant processes that have influenced Vesta's surface roughness at centimeter and decimeter scales, which are in turn applicable to assisting future landing, sampling and orbital missions of other small bodies.

  15. Ultrawideband radar clutter measurements and analysis

    NASA Astrophysics Data System (ADS)

    Tuley, Michael T.; Sheen, David M.; Collins, H. D.; Sager, Earl V.; Schultheis, A. C.

    1993-05-01

    This paper reports the results of ultrawideband radar clutter measurements made by Battelle- Pacific Northwest Laboratories and the System Planning Corporation near Sequim, WA. The measurement area is a mountainous coniferous forest with occasional roads and clear-cut areas. Local grazing angles range from near zero to approximately 40 degree(s). Very limited data are also presented from measurements made in a desert-type terrain near Richland, WA. Two ultrawideband radar systems were employed in the data collection. An impulse system providing an approximate one nanosecond monocycle pulse (bandwidth of 300 MHz - 1000 MHz) acquired data over a 0.7 km2 area (121,000 resolution cells). A step chirp radar with the same total bandwidth as the impulse system collected data over a 6.2 km2 area (780,000 resolution cells), including the area sampled by the impulse system. Wideband TEM horn antennas (log-periodic antennas for the step chirp system) deployed on a 19 m horizontally scanned aperture were used for transmission and reception, providing a 1.5 degree(s) azimuth resolution at 300 MHz for both systems.

  16. Development of Bread Board Model of TRMM precipitation radar

    NASA Astrophysics Data System (ADS)

    Okamoto, Ken'ichi; Ihara, Toshio; Kumagai, Hiroshi

    The active array radar was selected as a reliable candidate for the TRMM (Tropical Rainfall Measuring Mission) precipitation radar after the trade off studies performed by Communications Research Laboratory (CRL) in the US-Japan joint feasibility study of TRMM in 1987-1988. Main system parameters and block diagram for TRMM precipitation radar are shown as the result of feasibility study. CRL developed key devices for the active array precipitation radar such as 8-element slotted waveguide array antenna, the 5 bit PIN diode phase shifters, solid state power amplifiers and low noise amplifiers in 1988-1990. Integration of these key devices was made to compose 8-element Bread Board Model of TRMM precipitation radar.

  17. Antenna Characterization for the Wideband Instrument for Snow Measurements

    NASA Technical Reports Server (NTRS)

    Lambert, Kevin M.; Miranda, Felix A.; Romanofsky, Robert R.; Durham, Timothy E.; Vanhille, Kenneth J.

    2015-01-01

    Experimental characterization of the antenna for the Wideband Instrument for Snow Measurements (WISM) under development for the NASA Earth Science Technology Office (ESTO) Instrument Incubator Program (IIP), is discussed. A current sheet antenna, consisting of a small, 6x6 element, dual-linear polarized array with integrated beamformer, feeds an offset parabolic reflector, enabling WISM operation over an 8 to 40 GHz frequency band. An overview of the test program implemented for both the feed and the reflector antenna is given along with select results for specific frequencies utilized by the radar and radiometric sensors of the WISM.

  18. Antenna Characterization for the Wideband Instrument for Snow Measurements (WISM)

    NASA Technical Reports Server (NTRS)

    Lambert, Kevin M.; Miranda, Felix A.; Romanofsky, Robert R.; Durham, Timothy E.; Vanhille, Kenneth J.

    2015-01-01

    Experimental characterization of the antenna for the Wideband Instrument for Snow Measurement (WISM) under development for the NASA Earth Science Technology Office (ESTO) Instrument Incubator Program (IIP), is discussed. A current sheet antenna, consisting of a small, 6x6 element, dual-linear polarized array with integrated beamformer, feeds an offset parabolic reflector, enabling WISM operation over an 8 to 40 GHz frequency band. An overview of the test program implemented for both the feed and the reflector antenna is given along with select results for specific frequencies utilized by the radar and radiometric sensors of the WISM.

  19. Monostatic ultra-wideband GPR antenna for through wall detection

    NASA Astrophysics Data System (ADS)

    Ali, Jawad; Abdullah, Noorsaliza; Yahya, Roshayati; Naeem, Taimoor

    2017-11-01

    The aim of this paper is to present a monostatic arc-shaped ultra-wideband (UWB) printed monopole antenna system with 3-16 GHz frequency bandwidth suitable for through-wall detection. Ground penetrating radar (GPR) technique is used for detection with the gain of 6.2 dB achieved for the proposed antenna using defected ground structure (DGS) method. To serve the purpose, a simulation experiment of through-wall detection model is constructed which consists of a monostatic antenna act as transmitter and receiver, concrete wall and human skin model. The time domain reflection of obtained result is then analysed for target detection.

  20. An Estimation Of The Geoelectric Features Of Planetary Shallow Subsurfaces With TAPIR Antennae

    NASA Astrophysics Data System (ADS)

    Le Gall, A.; Reineix, A.; Ciarletti, V.; Jean-Jacques, B.; Ney, R.; Dolon, F.; Corbel, C.

    2005-12-01

    Exploring the interior of Mars and searching for water reservoirs, either in the form of ice or of liquid water, was one of the main scientific objectives of the NETLANDER project. In that frame, the CETP (Centre d'Etude des Environnements Terrestre et Planetaires) has developed an imaging ground penetrating radar (GPR), called TAPIR (Terrestrial And Planetary Investigation by Radar). Operating from a fixed position and at low frequencies (from 2 to 4MHz), this instrument allows to retrieve not only the distance but also the inclination of deep subsurface reflectors by measuring the two horizontal electrical components and the three magnetic components of the reflected waves. In 2004, ground tests have been successfully carried out on the Antarctic Continent; the bedrock, lying under a thick layer of ice (until 1200m), was detected and part of its relief was revealed. Yet, knowing the electric parameters of the close subsurface is required to correctly process the measured electric and magnetic components of the echoes and deduce their propagation vector. In addition, these electric parameters can bring a very interesting piece of information on the nature of the material in the shallow underground. We have therefore looked for a possible method (appropriate for a planetary mission) to evaluate them using a special mode of operation of the radar. This method relies on the fact that the electrical characteristics of the transmitting electric antennas (current along the antenna, driving-point impedance.) depend on the nature of the ground on which the radar is lying. If this dependency is significant enough, geological parameters of the subsurface can be deduced from the analysis of specific measurements. We have thus performed a detailed experimental and theoretical study of the TAPIR resistively loaded electrical dipoles to get a precise understanding of the radar transmission and assess the role of the electric parameters of the underground. In this poster, we will analytically prove the sensitivity of TAPIR antennae to subsurface nature. Besides, a numerical code, based on the FDTD method, has been built to simulate with accuracy radar operation and its coupling with the environment. Results from simulations will be then compared to in-situ measurements collected in three different sites. Eventually, we will see that the inferred geoelectrical values characterize only a thin layer of the subsurface.

  1. Analysis of Fully Polarimetric Laboratory Measurements Performed with the WISDOM Radar

    NASA Astrophysics Data System (ADS)

    Plettemeier, D.; Ciarletti, V.; Cais, P.; Benedix, W.-S.; Zhang, H.; Hamran, S.-E.; Clifford, S.

    2012-04-01

    The Ground Penetrating Radar WISDOM (Water Ice Subsurface Deposit Observation on Mars) is one of the instruments selected to be part of the Pasteur payload of ESA's ExoMars Rover mission. The main scientific objectives of the Pasteur payload are to search for evidence of past and present life on Mars and to characterize the nature of the shallow subsurface. WISDOM is capable to obtain subsurface information along the rover path and to explore the first 3 meters of the soil with a vertical resolution of a few centimeters. WISDOM will help identify the location of sedimentary layers, where organic molecules are most likely to be found. By investigating geometry, location and properties of buried reflectors, WISDOM will contribute to the understanding of the 3D geological structure, electromagnetic nature, and, possibly, the state of water and ice in the shallow subsurface. WISDOM measurements will be performed 1) by conducting periodic soundings along the Rover traverse, which will provide a coarse, non-uniform, but positionally well-determined investigation of the landing site and 2) by selected high-resolution surveys of areas of strong scientific interest, which are identified for potential investigation and sampling by the Rover's drill. Such surveys will generally be conducted by acquiring a number of closely spaced parallel profiles. Supported by specific hardware features, like the arrangement of the fully polarimetric antenna system, an interpolated 3-D subsurface map of the local stratigraphy can be constructed from these radar measurements. Laboratory measurements are performed on a planar scanner in the anechoic chamber to simulate the closely spaced parallel profiles of selected high-resolution surveys. To characterize the performance of the radar and to be able to analyze the influence of radiation coupling effects between the rover and the antennas, the fully polarimetric WISDOM antenna system was mounted on a simple rover-like mockup. Calibration algorithms were applied to reduce the interference from radiation coupling and cross-talk between transmitting and receiving antenna. The analysis of the laboratory measurement will show features of the fully polarimetric radar system and quantify most of the important performance parameters. Synthetic aperture processing is implemented to increase the azimuth resolution of radar. The three dimensional reconstruction of the positioning of an arrangement of discrete objects will be shown.

  2. Microwave Imaging Radar Reflectometer System Utilizing Digital Beam Forming

    NASA Astrophysics Data System (ADS)

    Hu, Fengqi; Li, Meijiao; Domier, Calvin W.; Liu, Xiaoguang; Luhmann, Neville C., Jr.

    2016-10-01

    Microwave Imaging Reflectometry is a radar-like technique developed to measure the electron density fluctuations in fusion plasmas. Phased Antenna Arrays can serve as electronically controlled ``lenses'' that can generate the required wavefronts by phase shifting and amplitude scaling, which is being realized in the digital domain with higher flexibility and faster processing speed. In the transmitter, the resolution of the phase control is 1.4 degrees and the amplitude control is 0.5 dB/ step. A V-band double-sided, printed bow tie antenna which exhibits 49% bandwidth (46 - 76 GHz) is employed. The antenna is fed by a microstrip transmission line for easy impedance matching. The simple structure and the small antenna are suitable for low cost fabrication, easy circuit integration, and phased antenna array multi-frequency applications. In the receiver part, a sub-array of 32 channels with 200 mil spacing is used to collect the scattered reflected signal from one unit spot on the plasma cutoff surface. Pre-amplification is used to control the noise level of the system and wire bondable components are used to accommodate the small spacing between each channel. After down converting, base band signals are digitized and processed in an FPGA module. U.S. Department of Energy Grant No. DE-FG02-99ER54531.

  3. Evaluation of clay content in soils for pavement engineering applications using GPR

    NASA Astrophysics Data System (ADS)

    Tosti, Fabio; Patriarca, Claudio; Benedetto, Andrea; Slob, Evert C.; Lambot, Sébastien

    2013-04-01

    Clay content significantly influences the mechanical behavior of soils, thereby playing an important role in many fields of applications such as civil engineering, geology and agriculture. In the area of pavement engineering, clay content in structural bearing courses of pavement frequently causes damages and defects, such as transversal and longitudinal cracks, or other faults. The main consequence is a lowering of both the road safety and operability, with the number of expected accidents increasing. In this study, ground-penetrating radar (GPR) laboratory tests were carried out to predict the clay amount in pavement structural layers under different clay and moisture conditions. GPR data processing is performed using two different methods. The first method is based on the Fresnel theory and focuses on the Rayleigh scattering of the radar waves. The approach is based on a different scattering of the various components of the frequency spectrum, mostly depending on both the soil texture and variation in soil moisture content. For the application of this method, we used a pulse radar with ground-coupled, 500 MHz centre-frequency antennas in a common offset, bistatic configuration. The transmitter and receiver were linked by optic fiber electronic modules. The second method is based on full-waveform inversion of the ultra wideband radar data. In particular, a specific radar-antenna electromagnetic model is used to filter out antenna effects and antenna-medium interactions from the raw radar data and retrieve the response of the soil only, expressed in terms of a layered medium Green's function. To estimate the medium geometrical and electrical values, an optimization inverse problem is formulated. For the application of that second method, we used a vector network analyzer (VNA) as continuous-wave stepped-frequency radar system to acquire data in the 500-3000 MHz frequency range. A doubled-ridged broadband horn antenna operating in far-field conditions was used as transmitter and receiver, and was connected to the radar using a high-quality coaxial cable. Typical road materials for subgrade and sub-base courses were used. In particular, three types of soils classified, respectively, as A1,A2,A3 by AASHTO were used and adequately compacted in electrically and hydraulically isolated boxes. A copper sheet was laid at the bottom of the experimental boxes to control the bottom boundary conditions in the electromagnetic model. Basically, two significant cases were considered for each soil type, taking into account the 0% and the 25% by weight of bentonite clay, respectively. Water was gradually added and GPR measurements were carried out for all moisture steps until the maximum saturation level was reached. Concerning the Rayleigh scattering method, analyses show a high consistency of the results with respect to our expectations. A negative correlation between the shift of the frequency spectrum peaks and the clay amount was demonstrated, by virtue of its strong hygroscopic properties. Similarly, the full-waveform inversion technique allowed to measure reliable electric parameters. Generally, different responses (e.g. electric conductivity and permittivity) of the 0% clay-member cases compared to those of the analogous clayey soil samples highlight the large potentiality of both methods for the detection of clay.

  4. Polar cloud observatory at Ny-Ålesund in GRENE Arctic Climate Change Research Project

    NASA Astrophysics Data System (ADS)

    Yamanouchi, Takashi; Takano, Toshiaki; Shiobara, Masataka; Okamoto, Hajime; Koike, Makoto; Ukita, Jinro

    2016-04-01

    Cloud is one of the main processes in the climate system and especially a large feed back agent for Arctic warming amplification (Yoshimori et al., 2014). From this reason, observation of polar cloud has been emphasized and 95 GHz cloud profiling radar in high precision was established at Ny-Ålesund, Svalbard in 2013 as one of the basic infrastructure in the GRENE (Green Network of Excellence Program) Arctic Climate Change Research Project. The radar, "FALCON-A", is a FM-CW (frequency modulated continuous wave) Doppler radar, developed for Arctic use by Chiba University (PI: T. Takano) in 2012, following its prototype, "FALCON-1" which was developed in 2006 (Takano et al., 2010). The specifications of the radar are, central frequency: 94.84 GHz; antenna power: 1 W; observation height: up to 15 km; range resolution: 48 m; beam width: 0.2 degree (15 m at 5 km); Doppler width: 3.2 m/s; time interval: 10 sec, and capable of archiving high sensitivity and high spatial and time resolution. An FM-CW type radar realizes similar sensitivity with much smaller parabolic antennas separated 1.4 m from each other used for transmitting and receiving the wave. Polarized Micro-Pulse Lidar (PMPL, Sigma Space MPL-4B-IDS), which is capable to measure the backscatter and depolarization ratio, has also been deployed to Ny-Ålesund in March 2012, and now operated to perform collocated measurements with FALCON-A. Simultaneous measurement data from collocated PMPL and FALCON-A are available for synergetic analyses of cloud microphysics. Cloud mycrophysics, such as effective radius of ice particles and ice water content, are obtained from the analysis based on algorithm, which is modified for ground-based measurements from Okamoto's retrieval algorithm for satellite based cloud profiling radar and lidar (CloudSat and CALIPSO; Okamoto et al., 2010). Results of two years will be shown in the presentation. Calibration is a point to derive radar reflectivity (dBZ) from original intensity data. Degradation of transmission power was monitored and sensitivity of receiving system was derived with estimating antenna gain by using radio wave absorber and considering antenna geometry of two antenna system. In order to estimate final results, altitude dependent detection limit curve was also calculated. Original intensity data in real time and calibrated radar reflectivity data are archived on "Arctic Data archive System (ADS)". Other collocated observations were made with fog monitor (particle size distribution), MPS (particle image) for continuous measurements at Zeppelin Mountain, 450 m height a. s. l., and tethered balloon for intense observing period. From these measurements together with aerosol and meteorological monitoring made by collaborating institutes (Stockholm University, University of Florence, AWI, NILU, NCAR and NPI) microphysics of low level cloud and aerosol-cloud interactions are discussed. Ground based remote sensors provide a powerful validation for satellite cloud observations. Radar reflectivity (dBZ) by FALCON-A was compared with that by CPR on CloudSAT during several overpasses around Ny-Ålesund, and though some difference due to the different vertical resolution was seen, overall agreement was confirmed. We are planning to establish Ny-Ålesund observatory as the super site for validation for EarthCARE (JAXA-ESA) mission.

  5. Wimpy Radar Antenna! Grades 6-8.

    ERIC Educational Resources Information Center

    Rushton, Erik; Ryan, Emily; Swift, Charles

    In this activity, students reinforce an antenna tower made from foam insulation so that it can withstand a 480 N-cm bending moment (torque) and a 280 N-cm twisting moment (torque) with minimal deflection. One class period is used to discuss the problem, run the initial bending and torsion tests, and graph the results. The second class is used for…

  6. 77 FR 68742 - 36(b)(1) Arms Sales Notification

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-16

    ... Engagement Control Systems, 30 Antenna Mast Groups, 44 M902 Launching Stations, 246 PATRIOT MIM-104E Guidance... Fire Units, 11 AN/MPQ-65 Radar Sets, 11 AN/ MSQ-132 Engagement Control Systems, 30 Antenna Mast Groups... Letter of Offer Pursuant to Section 36(b)(1) of the Arms Export Control Act, as amended (i) Prospective...

  7. Three-Dimensional Stable Nonorthogonal FDTD Algorithm with Adaptive Mesh Refinement for Solving Maxwell’s Equations

    DTIC Science & Technology

    2013-03-01

    Räisänen. An efficient FDTD algorithm for the analysis of microstrip patch antennas printed on a general anisotropic dielectric substrate. IEEE...applications [3, 21, 22], including antenna , microwave circuits, geophysics, optics, etc. The Ground Penetrating Radar (GPR) is a popular and...IEEE Trans. Antennas Propag., 41:994–999, 1993. 16 [6] S. G. Garcia, T. M. Hung-Bao, R. G. Martin, and B. G. Olmedo. On the application of finite

  8. Artist Concept of Atlantis' new home

    NASA Image and Video Library

    2012-01-18

    CAPE CANAVERAL, Fla. – At NASA’s Kennedy Space Center in Florida, workers are constructing 40-foot-diameter dish antenna arrays for the Ka-Band Objects Observation and Monitoring, or Ka-BOOM system. The antennas will be part of the operations command center facility. The construction site is near the former Vertical Processing Facility, which has been demolished. The Ka-BOOM project is one of the final steps in developing the techniques to build a high power, high resolution radar system capable of becoming a Near Earth Object Early Warning System. While also capable of space communication and radio science experiments, developing radar applications is the primary focus of the arrays. Photo credit: NASA/ Ben Smegelsky

  9. KSC-2009-1084

    NASA Image and Video Library

    2009-01-08

    CAPE CANAVERAL, Fla. -- A replacement weather Doppler radar has been installed on top of this tower in a remote field located west of NASA's Kennedy Space Center in Florida. The radome houses the rotating antenna and pedestal and protects them from the elements. The tower is 100 feet high; the radome is 22 feet in diameter, the antenna 14 feet in diameter. It rotates at 6 rpm. The structure can withstand 130 mph winds. It is undergoing initial testing and expected to become operational in the summer. The weather radar is essential in issuing lightning and other severe weather warnings and vital in evaluating lightning launch commit criteria for space shuttle and rocket launches. Photo credit: NASA/Troy Cryder

  10. KSC-2009-1082

    NASA Image and Video Library

    2009-01-08

    CAPE CANAVERAL, Fla. -- A replacement weather Doppler radar has been installed on top of this tower in a remote field located west of NASA's Kennedy Space Center in Florida. The radome houses the rotating antenna and pedestal and protects them from the elements. The tower is 100 feet high; the radome is 22 feet in diameter, the antenna 14 feet in diameter. It rotates at 6 rpm. The structure can withstand 130 mph winds. It is undergoing initial testing and expected to become operational in the summer. The weather radar is essential in issuing lightning and other severe weather warnings and vital in evaluating lightning launch commit criteria for space shuttle and rocket launches. Photo credit: NASA/Troy Cryder

  11. KSC-2009-1081

    NASA Image and Video Library

    2009-01-08

    CAPE CANAVERAL, Fla. -- A replacement weather Doppler radar has been installed in the radome on top of this tower in a remote field located west of NASA's Kennedy Space Center in Florida. The dome houses the rotating antenna and pedestal and protects them from the elements. The tower is 100 feet high; the radome is 22 feet in diameter, the antenna 14 feet in diameter. It rotates at 6 rpm. The structure can withstand 130 mph winds. It is undergoing initial testing and expected to become operational in the summer. The weather radar is essential in issuing lightning and other severe weather warnings and vital in evaluating lightning launch commit criteria for space shuttle and rocket launches. Photo credit: NASA/Troy Cryder

  12. KSC-2009-1083

    NASA Image and Video Library

    2009-01-08

    CAPE CANAVERAL, Fla. -- A replacement weather Doppler radar has been installed on top of this tower in a remote field located west of NASA's Kennedy Space Center in Florida. The radome houses the rotating antenna and pedestal and protects them from the elements. The tower is 100 feet high; the radome is 22 feet in diameter, the antenna 14 feet in diameter. It rotates at 6 rpm. The structure can withstand 130 mph winds. It is undergoing initial testing and expected to become operational in the summer. The weather radar is essential in issuing lightning and other severe weather warnings and vital in evaluating lightning launch commit criteria for space shuttle and rocket launches. Photo credit: NASA/Troy Cryder

  13. Radar Attitude Sensing System (RASS)

    NASA Technical Reports Server (NTRS)

    1971-01-01

    The initial design and fabrication efforts for a radar attitude sensing system (RASS) are covered. The design and fabrication of the RASS system is being undertaken in two phases, 1B1 and 1B2. The RASS system as configured under phase 1B1 contains the solid state transmitter and local oscillator, the antenna system, the receiving system, and the altitude electronics. RASS employs a pseudo-random coded cw signal and receiver correlation techniques to measure range. The antenna is a planar, phased array, monopulse type, whose beam is electronically steerable using diode phase shifters. The beam steering computer and attitude sensing circuitry are to be included in Phase 1B2 of the program.

  14. EMI survey for maritime satellite 1535-1645-MHz shipboard terminal

    NASA Technical Reports Server (NTRS)

    Taylor, R. E.; Brandel, D. L.; Hill, J. S.

    1977-01-01

    A 15,690-ton commercial container ship was selected as lead ship for an onboard electromagnetic-interference (EMI) survey prior to installation of 1535-1645-MHz (L-Band) shipboard terminals for communication via a maritime satellite. In general, the EMI survey revealed tolerable interference levels on board ship. Radiometer measurements indicate antenna-noise temperatures less than 70 K at elevation angles of 5 deg and greater at 1559 MHz at the output terminals of the 1.2-m diameter parabolic-dish antenna for the L-band shipboard terminal. Other EMI measurements include field intensity from 3-cm and 10-cm wavelength pulse radars, and conducted-emission tests of primary power lines to both onboard radars.

  15. Multi beam observations of cosmic radio noise using a VHF radar with beam forming by a Butler matrix

    NASA Astrophysics Data System (ADS)

    Renkwitz, T.; Singer, W.; Latteck, R.; Rapp, M.

    2011-08-01

    The Leibniz-Institute of Atmospheric Physics (IAP) in Kühlungsborn started to install a new MST radar on the North-Norwegian island Andøya (69.30° N, 16.04° E) in 2009. The new Middle Atmosphere Alomar Radar System (MAARSY) replaces the previous ALWIN radar which has been successfully operated for more than 10 years. The MAARSY radar provides increased temporal and spatial resolution combined with a flexible sequential point-to-point steering of the radar beam. To increase the spatiotemporal resolution of the observations a 16-port Butler matrix has been built and implemented to the radar. In conjunction with 64 Yagi antennas of the former ALWIN antenna array the Butler matrix simultaneously provides 16 individual beams. The beam forming capability of the Butler matrix arrangement has been verified observing the galactic cosmic radio noise of the supernova remnant Cassiopeia A. Furthermore, this multi beam configuration has been used in passive experiments to estimate the cosmic noise absorption at 53.5 MHz during events of enhanced solar and geomagnetic activity as indicators for enhanced ionization at altitudes below 90 km. These observations are well correlated with simultaneous observations of corresponding beams of the co-located imaging riometer AIRIS (69.14° N, 16.02° E) at 38.2 MHz. In addition, enhanced cosmic noise absorption goes along with enhanced electron densities at altitudes below about 90 km as observed with the co-located Saura MF radar using differential absorption and differential phase measurements.

  16. Radar Movie of Asteroid 1999 JD6

    NASA Image and Video Library

    2015-07-31

    This frame from a movie made from radar images of asteroid 1999 JD6 was collected by NASA scientists on July 25, 2015. The images show the rotation of the asteroid, which made its closest approach on July 24 at 9:55 p.m. PDT (12:55 a.m. EDT on July 25) at a distance of about 4.5 million miles (7.2 million kilometers, or about 19 times the distance from Earth to the moon). The asteroid appears to be a contact binary -- an asteroid with two lobes that are stuck together. The radar images show the asteroid is highly elongated, with a length of approximately 1.2 miles (2 kilometers) on its long axis. These images are radar echoes, which are more like a sonogram than a photograph. The views were obtained by pairing NASA's 230-foot-wide (70-meter) Deep Space Network antenna at Goldstone, California, with the 330-foot (100-meter) National Science Foundation Green Bank Telescope in West Virginia. Using this approach, the Goldstone antenna beams a radar signal at an asteroid and Green Bank receives the reflections. The technique, referred to as a bistatic observation, dramatically improves the amount of detail that can be seen in radar images. The new views obtained with the technique show features as small as about 25 feet (7.5 meters) wide. http://photojournal.jpl.nasa.gov/catalog/PIA19646

  17. Instrument concepts and technologies for future spaceborne atmospheric radars

    NASA Astrophysics Data System (ADS)

    Im, Eastwood; Durden, Stephen L.

    2005-01-01

    In conjunction with the implementation of spaceborne atmospheric radar flight missions, NASA is developing advanced instrument concepts and technologies for future spaceborne atmospheric radars, with the over-arching objectives of making such instruments more capable in supporting future science needs, and more cost effective. Two such examples are the Second-Generation Precipitation Radar (PR-2) and the Nexrad-In-Space (NIS). PR-2 is a 14/35-GHz dual-frequency rain radar with a deployable 5-meter, wide-swath scanned membrane antenna, a dual-polarized/dual-frequency receiver, and a real-time digital signal processor. It is intended for Low Earth Orbit (LEO) operations to provide greatly enhanced rainfall profile retrieval accuracy while using only a fraction of the mass of the current TRMM PR. NIS is designed to be a 35-GHz Geostationary Earth Orbiting (GEO) radar with the intent of providing hourly monitoring of the life cycle of hurricanes and tropical storms. It uses a 35-m, spherical, lightweight membrane antenna and Doppler processing to acquire 3-dimensional information on the intensity and vertical motion of hurricane rainfall. Technologies for NIS are synergistic with those for PR-2. During the last two years, several of the technology items associated with these notional instruments have also been prototyped. This paper will give an overview of these instrument design concepts and their associated technologies.

  18. KSC-99pp0995

    NASA Image and Video Library

    1999-07-28

    Under the watchful eyes of a KSC worker (far left), members of the STS-99 crew check out equipment in the Orbiter Processing Facility (OPF) Bay 2. From left are Mission Specialists Mamoru Mohri, Gerhard P.J. Thiele, and Janice Voss (Ph.D.). Mohri represents the National Space Development Agency (NASDA) of Japan, and Thiele the European Space Agency. Other crew members (not shown) are Commander Kevin R. Kregel, Pilot Dominic L. Pudwill Gorie, and Mission Specialist Janet Lynn Kavandi (Ph.D.). The crew are at KSC to take part in a Crew Equipment Interface Test (CEIT), which provides an opportunity for crew members to check equipment and facilities that will be aboard the orbiter during their mission. The STS-99 mission is the Shuttle Radar Topography Mission (SRTM), a specially modified radar system that will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. The SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle. STS-99 is scheduled to launch Sept. 16 at 8:47 a.m. from Launch Pad 39A

  19. KSC-99pp0994

    NASA Image and Video Library

    1999-07-28

    In the Orbiter Processing Facility (OPF) Bay 2, under the watchful eyes of a KSC worker (far left) the STS-99 crew look over equipment as part of a Crew Equipment Interface Test (CEIT). From left (second from right) are Mission Specialists Janet Lynn Kavandi (Ph.D.), Mamoru Mohri, Gerhard P.J. Thiele, and Janice Voss (Ph.D.); behind Voss are Pilot Dominic L. Pudwill Gorie and Commander Kevin R. Kregel. Mohri is with the National Space Development Agency (NASDA) of Japan, and Thiele is with the European Space Agency. The CEIT provides an opportunity for crew members to check equipment and facilities that will be aboard the orbiter during their mission. The STS-99 mission is the Shuttle Radar Topography Mission (SRTM), a specially modified radar system that will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. The SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle. STS-99 is scheduled to launch Sept. 16 at 8:47 a.m. from Launch Pad 39A

  20. Equatorial radar system

    NASA Technical Reports Server (NTRS)

    Rukao, S.; Tsuda, T.; Sato, T.; Kato, S.

    1989-01-01

    A large clear air radar with the sensitivity of an incoherent scatter radar for observing the whole equatorial atmosphere up to 1000 km altitude is now being designed in Japan. The radar, called the Equatorial Radar, will be built in Pontianak, Kalimantan Island, Indonesia (0.03 N, 109.3 E). The system is a 47 MHz monostatic Doppler radar with an active phased array configuration similar to that of the MU radar in Japan, which has been in successful operation since 1983. It will have a PA product of more than 5 x 10(9) sq. Wm (P = average transmitter power, A = effective antenna aperture) with sensitivity more than 10 times that of the MU radar. This system configuration enables pulse-to-pulse beam steering within 25 deg from the zenith. As is the case of the MU radar, a variety of sophisticated operations will be made feasible under the supervision of the radar controller. A brief description of the system configuration is presented.

  1. Imaging Buried Culverts Using Ground Penetrating Radar: Comparing 100 MHZ Through 1 GHZ Antennae

    NASA Astrophysics Data System (ADS)

    Abdul Aziz, A.; Stewart, R. R.; Green, S. L.

    2013-12-01

    *Aziz, A A aabdulaziz@uh.edu Allied Geophysical Lab, Department of Earth and Atmospheric Sciences, University of Houston, TX, USA Stewart, R R rrstewart@uh.edu Allied Geophysical Lab, Department of Earth and Atmospheric Sciences, University of Houston, TX, USA *Green, S L slgreen@yahoo.com Allied Geophysical Lab, Department of Earth and Atmospheric Sciences, University of Houston, TX, USA A 3D ground penetrating radar (GPR) survey, using three different frequency antennae, was undertaken to image buried steel culverts at the University of Houston's La Marque Geophysical Observatory 30 miles south of Houston, Texas. The four culverts, under study, support a road crossing one of the area's bayous. A 32 m by 4.5 m survey grid was designed on the road above the culverts and data were collected with 100 MHz, 250 MHz, and 1 GHz antennae. We used an orthogonal acquisition geometry for the three surveys. Inline sampling was from 1.0 cm to 10 cm (from 1 GHz to 100 MHz antenna) with inline and crossline spacings ranging from 0.2 m to 0.5 m. We used an initial velocity of 0.1 m/ns (from previous CMP work at the site) for the display purposes. The main objective of the study was to analyze the effect of different frequency antennae on the resultant GPR images. We are also interested in the accuracy and resolution of the various images, in addition to developing an optimal processing flow.The data were initially processed with standard steps that included gain enhancement, dewow and temporal-filtering, background suppression, and 2D migration. Various radar velocities were used in the 2D migration and ultimately 0.12 m/ns was used. The data are complicated by multipathing from the surface and between culverts (from modeling). Some of this is ameliorated via deconvolution. The top of each of the four culverts was evident in the GPR images acquired with the 250 MHz and 100 MHz antennas. For 1 GHz, the top of the culvert was not clear due to the signal's attenuation. The 250 MHz shielded antenna provides a vertical resolution of about 0.1 m and is the choice to image the culverts. The 100 MHz antenna provided an increment in depth of penetration, but at the expense of a substantially diminished resolution (0.25 m).

  2. STS-99 crew takes part in CEIT at KSC

    NASA Technical Reports Server (NTRS)

    1999-01-01

    In the Orbiter Processing Facility, STS-99 Mission Specialists Mamoru Mohri (center), who is with the National Space Development Agency (NASDA) of Japan, and Janice Voss (Ph.D.) (right) talk with a KSC worker (left) during a Crew Equipment Interface Test (CEIT). The CEIT provides an opportunity for crew members to check equipment and facilities that will be aboard the orbiter during their mission. Others taking part are Commander Kevin R. Kregel, Pilot Dominic L. Pudwill Gorie, and Mission Specialists Janet Lynn Kavandi (Ph.D.) and Gerhard P.J. Thiele, who is with the European Space Agency. The SRTM is a specially modified radar system that will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. The SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle. STS-99 is scheduled to launch Sept. 16 at 8:47 a.m. from Launch Pad 39A.

  3. KSC-99pp1000

    NASA Image and Video Library

    1999-07-28

    KENNEDY SPACE CENTER, FLA. -- In the Orbiter Processing Facility, STS-99 Mission Specialists Mamoru Mohri (center), who is with the National Space Development Agency (NASDA) of Japan, and Janice Voss (Ph.D.) (right) talk with a KSC worker (left) during a Crew Equipment Interface Test (CEIT). The CEIT provides an opportunity for crew members to check equipment and facilities that will be aboard the orbiter during their mission. Others taking part are Commander Kevin R. Kregel, Pilot Dominic L. Pudwill Gorie, and Mission Specialists Janet Lynn Kavandi (Ph.D.) and Gerhard P.J. Thiele, who is with the European Space Agency. The SRTM is a specially modified radar system that will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM will make use of radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. The SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle. STS-99 is scheduled to launch Sept. 16 at 8:47 a.m. from Launch Pad 39A

  4. Measuring snow water equivalent from common-offset GPR records through migration velocity analysis

    NASA Astrophysics Data System (ADS)

    St. Clair, James; Holbrook, W. Steven

    2017-12-01

    Many mountainous regions depend on seasonal snowfall for their water resources. Current methods of predicting the availability of water resources rely on long-term relationships between stream discharge and snowpack monitoring at isolated locations, which are less reliable during abnormal snow years. Ground-penetrating radar (GPR) has been shown to be an effective tool for measuring snow water equivalent (SWE) because of the close relationship between snow density and radar velocity. However, the standard methods of measuring radar velocity can be time-consuming. Here we apply a migration focusing method originally developed for extracting velocity information from diffracted energy observed in zero-offset seismic sections to the problem of estimating radar velocities in seasonal snow from common-offset GPR data. Diffractions are isolated by plane-wave-destruction (PWD) filtering and the optimal migration velocity is chosen based on the varimax norm of the migrated image. We then use the radar velocity to estimate snow density, depth, and SWE. The GPR-derived SWE estimates are within 6 % of manual SWE measurements when the GPR antenna is coupled to the snow surface and 3-21 % of the manual measurements when the antenna is mounted on the front of a snowmobile ˜ 0.5 m above the snow surface.

  5. Detection of Metallic and Electronic Radar Targets by Acoustic Modulation of Electromagnetic Waves

    DTIC Science & Technology

    2017-07-01

    reradiated wave is captured by the radar’s receive antenna. The presence of measurable EM energy at any discrete multiple of the audio frequency away...the radar receiver (Rx). The presence of measurable EM energy at any discrete multiple of faudio away from the original RF carrier fRF (i.e., at any n

  6. 9. View of back side of radar scanner building no. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. View of back side of radar scanner building no. 106 showing passageway links to other buildings east and west, and DR 3 antenna in background. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  7. 10. View of back side of radar scanner building no. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. View of back side of radar scanner building no. 104 showing passageway links to other building to east and DR 1 antenna in background. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  8. Inflatable Space Structures Technology Development for Large Radar Antennas

    NASA Technical Reports Server (NTRS)

    Freeland, R. E.; Helms, Richard G.; Willis, Paul B.; Mikulas, M. M.; Stuckey, Wayne; Steckel, Gary; Watson, Judith

    2004-01-01

    There has been recent interest in inflatable space-structures technology for possible applications on U.S. Department of Defense (DOD) missions because of the technology's potential for high mechanical-packaging efficiency, variable stowed geometry, and deployment reliability. In recent years, the DOD sponsored Large Radar Antenna (LRA) Program applied this new technology to a baseline concept: a rigidizable/inflatable (RI) perimeter-truss structure supporting a mesh/net parabolic reflector antenna. The program addressed: (a) truss concept development, (b) regidizable materials concepts assessment, (c) mesh/net concept selection and integration, and (d) developed potential mechanical-system performance estimates. Critical and enabling technologies were validated, most notably the orbital radiation durable regidized materials and the high modulus, inflatable-deployable truss members. These results in conjunction with conclusions from previous mechanical-packaging studies by the U.S. Defense Advanced Research Projects Agency (DARPA) Special Program Office (SPO) were the impetus for the initiation of the DARPA/SPO Innovative Space-based Antenna Technology (ISAT) Program. The sponsor's baseline concept consisted of an inflatable-deployable truss structure for support of a large number of rigid, active radar panels. The program's goal was to determine the risk associated with the application of these new RI structures to the latest in radar technologies. The approach used to define the technology maturity level of critical structural elements was to: (a) develop truss concept baseline configurations (s), (b) assess specific inflatable-rigidizable materials technologies, and (c) estimate potential mechanical performance. The results of the structures portion of the program indicated there was high risk without the essential materials technology flight experiments, but only moderate risk if the appropriate on-orbit demonstrations were performed. This paper covers both programs (LRA and ISAT) in two sections, Parts 1 and 2 respectively. Please note that the terms strut, tube, and column are all used interchangeably and refer to the basic strut element of a truss. Also, the paper contains a mix of English and metric dimensional descriptions that reflect prevailing technical discipline conventions and common usage.

  9. Real-time multiple-look synthetic aperture radar processor for spacecraft applications

    NASA Technical Reports Server (NTRS)

    Wu, C.; Tyree, V. C. (Inventor)

    1981-01-01

    A spaceborne synthetic aperture radar (SAR) having pipeline multiple-look data processing is described which makes use of excessive azimuth bandwidth in radar echo signals to produce multiple-looking images. Time multiplexed single-look image lines from an azimuth correlator go through an energy analyzer which analyzes the mean energy in each separate look to determine the radar antenna electric boresight for use in generating the correct reference functions for the production of high quality SAR images. The multiplexed single look image lines also go through a registration delay to produce multi-look images.

  10. Radar systems for the water resources mission, volume 2

    NASA Technical Reports Server (NTRS)

    Moore, R. K.; Claassen, J. P.; Erickson, R. L.; Fong, R. K. T.; Hanson, B. C.; Komen, M. J.; Mcmillan, S. B.; Parashar, S. K.

    1976-01-01

    The application of synthetic aperture radar (SAR) in monitoring and managing earth resources was examined. The function of spaceborne radar is to provide maps and map imagery to be used for earth resource and oceanographic applications. Spaceborne radar has the capability of mapping the entire United States regardless of inclement weather; however, the imagery must have a high degree of resolution to be meaningful. Attaining this resolution is possible with the SAR system. Imagery of the required quality must first meet mission parameters in the following areas: antenna patterns, azimuth and range ambiguities, coverage, and angle of incidence.

  11. Noninvasive biosignal detection radar system using circular polarization.

    PubMed

    Lee, Jee-Hoon; Hwang, Jung Man; Choi, Dong Hyuk; Park, Seong-Ook

    2009-05-01

    This paper proposes an integrated hypersensitive Doppler radar system through a circular polarization characteristic. Through the idea of a reverse sense of rotation when the reflecting surface is perfectly conducting, it is shown that the detecting property of the system can be effectively improved by using antennas that have a reverse polarization. This bistatic radar system can be used in noninvasively sensing biosignals such as respiration and heart rates with the periodic movement of skin and muscle near the heart. The operating frequency of the system is in the X-band and the radar size is 95 x50 x13 mm(3).

  12. Whole-machine calibration approach for phased array radar with self-test

    NASA Astrophysics Data System (ADS)

    Shen, Kai; Yao, Zhi-Cheng; Zhang, Jin-Chang; Yang, Jian

    2017-06-01

    The performance of the missile-borne phased array radar is greatly influenced by the inter-channel amplitude and phase inconsistencies. In order to ensure its performance, the amplitude and the phase characteristics of radar should be calibrated. Commonly used methods mainly focus on antenna calibration, such as FFT, REV, etc. However, the radar channel also contains T / R components, channels, ADC and messenger. In order to achieve on-based phased array radar amplitude information for rapid machine calibration and compensation, we adopt a high-precision plane scanning test platform for phase amplitude test. A calibration approach for the whole channel system based on the radar frequency source test is proposed. Finally, the advantages and the application prospect of this approach are analysed.

  13. UAVSAR: Airborne L-band Radar for Repeat Pass Interferometry

    NASA Technical Reports Server (NTRS)

    Moes, Timothy R.

    2009-01-01

    The primary objectives of the UAVSAR Project were to: a) develop a miniaturized polarimetric L-band synthetic aperture radar (SAR) for use on an unmanned aerial vehicle (UAV) or piloted vehicle. b) develop the associated processing algorithms for repeat-pass differential interferometric measurements using a single antenna. c) conduct measurements of geophysical interest, particularly changes of rapidly deforming surfaces such as volcanoes or earthquakes. Two complete systems were developed. Operational Science Missions began on February 18, 2009 ... concurrent development and testing of the radar system continues.

  14. Limits to Clutter Cancellation in Multi-Aperture GMTI Data

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Doerry, Armin W.; Bickel, Douglas L.

    2015-03-01

    Multi-aperture or multi-subaperture antennas are fundamental to Ground Moving Target Indicator (GMTI) radar systems in order to detect slow-moving targets with Doppler characteristics similar to clutter. Herein we examine the performance of several subaperture architectures for their clutter cancelling performance. Significantly, more antenna phase centers isn’t always better, and in fact is sometimes worse, for detecting targets.

  15. IRCI-Free MIMO-OFDM SAR Using Circularly Shifted Zadoff-Chu Sequences

    NASA Astrophysics Data System (ADS)

    Cao, Yun-He; Xia, Xiang-Gen

    2015-05-01

    Cyclic prefix (CP) based MIMO-OFDM radar has been recently proposed for distributed transmit antennas, where there is no inter-range-cell interference (IRCI). It can collect full spatial diversity and each transmitter transmits signals with the same frequency band, i.e., the range resolution is not reduced. However, it needs to transmit multiple OFDM pulses consecutively to obtain range profiles for a single swath, which may be too long in time for a reasonable swath width. In this letter, we propose a CP based MIMO-OFDM synthetic aperture radar (SAR) system, where each transmitter transmits only a single OFDM pulse to obtain range profiles for a swath and has the same frequency band, thus the range resolution is not reduced. It is IRCI free and can collect the full spatial diversity if the transmit antennas are distributed. Our main idea is to use circularly shifted Zadoff-Chu sequences as the weighting coefficients in the OFDM pulses for different transmit antennas and apply spatial filters with multiple receive antennas to divide the whole swath into multiple subswaths, and then each subswath is reconstructed/imaged using our proposed IRCI free range reconstruction method.

  16. Electromagnetic Vortex-Based Radar Imaging Using a Single Receiving Antenna: Theory and Experimental Results

    PubMed Central

    Yuan, Tiezhu; Wang, Hongqiang; Cheng, Yongqiang; Qin, Yuliang

    2017-01-01

    Radar imaging based on electromagnetic vortex can achieve azimuth resolution without relative motion. The present paper investigates this imaging technique with the use of a single receiving antenna through theoretical analysis and experimental results. Compared with the use of multiple receiving antennas, the echoes from a single receiver cannot be used directly for image reconstruction using Fourier method. The reason is revealed by using the point spread function. An additional phase is compensated for each mode before imaging process based on the array parameters and the elevation of the targets. A proof-of-concept imaging system based on a circular phased array is created, and imaging experiments of corner-reflector targets are performed in an anechoic chamber. The azimuthal image is reconstructed by the use of Fourier transform and spectral estimation methods. The azimuth resolution of the two methods is analyzed and compared through experimental data. The experimental results verify the principle of azimuth resolution and the proposed phase compensation method. PMID:28335487

  17. STS-99 Shuttle Radar Topography Mission Stability and Control

    NASA Technical Reports Server (NTRS)

    Hamelin, Jennifer L.; Jackson, Mark C.; Kirchwey, Christopher B.; Pileggi, Roberto A.

    2001-01-01

    The Shuttle Radar Topography Mission (SRTM) flew aboard Space Shuttle Endeavor February 2000 and used interferometry to map 80% of the Earth's landmass. SRTM employed a 200-foot deployable mast structure to extend a second antenna away from the main antenna located in the Shuttle payload bay. Mapping requirements demanded precision pointing and orbital trajectories from the Shuttle on-orbit Flight Control System (PCS). Mast structural dynamics interaction with the FCS impacted stability and performance of the autopilot for attitude maneuvers and pointing during mapping operations. A damper system added to ensure that mast tip motion remained with in the limits of the outboard antenna tracking system while mapping also helped to mitigate structural dynamic interaction with the FCS autopilot. Late changes made to the payload damper system, which actually failed on-orbit, required a redesign and verification of the FCS autopilot filtering schemes necessary to ensure rotational control stability. In-flight measurements using three sensors were used to validate models and gauge the accuracy and robustness of the pre-mission notch filter design.

  18. Waveform Optimization for Target Estimation by Cognitive Radar with Multiple Antennas.

    PubMed

    Yao, Yu; Zhao, Junhui; Wu, Lenan

    2018-05-29

    A new scheme based on Kalman filtering to optimize the waveforms of an adaptive multi-antenna radar system for target impulse response (TIR) estimation is presented. This work aims to improve the performance of TIR estimation by making use of the temporal correlation between successive received signals, and minimize the mean square error (MSE) of TIR estimation. The waveform design approach is based upon constant learning from the target feature at the receiver. Under the multiple antennas scenario, a dynamic feedback loop control system is established to real-time monitor the change in the target features extracted form received signals. The transmitter adapts its transmitted waveform to suit the time-invariant environment. Finally, the simulation results show that, as compared with the waveform design method based on the MAP criterion, the proposed waveform design algorithm is able to improve the performance of TIR estimation for extended targets with multiple iterations, and has a relatively lower level of complexity.

  19. Broadband Ground Penetrating Radar with conformal antennas for subsurface imaging from a rover

    NASA Astrophysics Data System (ADS)

    Stillman, D. E.; Oden, C. P.; Grimm, R. E.; Ragusa, M.

    2015-12-01

    Ground-Penetrating Radar (GPR) allows subsurface imaging to provide geologic context and will be flown on the next two martian rovers (WISDOM on ExoMars and RIMFAX on Mars 2020). The motivation of our research is to minimize the engineering challenges of mounting a GPR antenna to a spacecraft, while maximizing the scientific capabilities of the GPR. The scientific capabilities increase with the bandwidth as it controls the resolution. Furthermore, ultra-wide bandwidth surveys allow certain mineralogies and rock units to be discriminated based on their frequency-dependent EM or scattering properties. We have designed and field-tested a prototype GPR that utilizes bi-static circularly polarized spiral antennas. Each antenna has a physical size of 61 x 61 x 4 cm, therefore two antennas could be mounted to the underbelly of a MSL-class rover. Spiral antennas were chosen because they have an inherent broadband response and provide a better low frequency response compared with similarly sized linearly polarized antennas. A horizontal spiral radiator emits energy both upward and downward directions. After the radiator is mounted to a metal surface (i.e. the underside of a rover), a cavity is formed that causes the upward traveling energy to reverberate and cause unwanted interference. This interference is minimized by 1) using a high metallization ratio on the spiral to reduce cavity emissions, and 2) placing absorbing material inside the cavity. The resulting antennas provide high gain (0 to 8 dBi) from 200 to 1000 MHz. The low frequency response can be improved by increasing the antenna thickness (i.e., cavity depth). In an initial field test, the antennas were combined with impulse GPR electronics that had ~140 dB of dynamic range (not including antennas) and a sand/clay interface 7 feet deep was detected. To utilize the full bandwidth the antennas, a gated Frequency Modulated Continuous Waveform system will be developed - similar to RIMFAX. The goal is to reach a total system dynamic range of 180 dB in order to provide significant penetration.

  20. Dual-band microstrip patch antenna based on metamaterial refractive surface

    NASA Astrophysics Data System (ADS)

    Salhi, Ridha; Labidi, Mondher; Boujemaa, Mohamed Ali; Choubani, Fethi

    2017-06-01

    In this paper, we present a new design of microstrip patch antenna based on metamaterial refractive surface (MRS). By optimizing the air gap between the MRS layer and the patch antenna to be 7 mm, the band width and the gain of the proposed antenna are significantly enhanced. The proposed prototype presents a dual band antenna. The center frequency for the first band is 2.44 GHz and the generated bandwidth is 25 MHz. The second band has a center frequency of 2.8 GHz and with a bandwidth of 50 MHz. The simulation results are analyzed and discussed in terms of return loss, gain and radiation pattern using electromagnetic simulator software. Finally, the designed dual band antenna is fabricated and different measurement results are performed and compared with simulation results in order to validate its performances. The proposed antenna supports WiBro (wireless broadband), ISM, WiFi, Bluetooth, WiMAX and radars services.

  1. Impulse radar with swept range gate

    DOEpatents

    McEwan, Thomas E.

    1998-09-08

    A radar range finder and hidden object locator is based on ultra-wide band radar with a high resolution swept range gate. The device generates an equivalent time amplitude scan with a typical range of 4 inches to 20 feet, and an analog range resolution as limited by a jitter of on the order of 0.01 inches. A differential sampling receiver is employed to effectively eliminate ringing and other aberrations induced in the receiver by the near proximity of the transmit antenna (10), so a background subtraction is not needed, simplifying the circuitry while improving performance. Techniques are used to reduce clutter in the receive signal, such as decoupling the receive (24) and transmit cavities (22) by placing a space between them, using conductive or radiative damping elements on the cavities, and using terminating plates on the sides of the openings. The antennas can be arranged in a side-by-side parallel spaced apart configuration or in a coplanar opposed configuration which significantly reduces main bang coupling.

  2. Nuclear reactor power for a space-based radar. SP-100 project

    NASA Technical Reports Server (NTRS)

    Bloomfield, Harvey; Heller, Jack; Jaffe, Leonard; Beatty, Richard; Bhandari, Pradeep; Chow, Edwin; Deininger, William; Ewell, Richard; Fujita, Toshio; Grossman, Merlin

    1986-01-01

    A space-based radar mission and spacecraft, using a 300 kWe nuclear reactor power system, has been examined, with emphasis on aspects affecting the power system. The radar antenna is a horizontal planar array, 32 X 64 m. The orbit is at 61 deg, 1088 km. The mass of the antenna with support structure is 42,000 kg; of the nuclear reactor power system, 8,300 kg; of the whole spacecraft about 51,000 kg, necessitating multiple launches and orbital assembly. The assembly orbit is at 57 deg, 400 km, high enough to provide the orbital lifetime needed for orbital assembly. The selected scenario uses six Shuttle launches to bring the spacecraft and a Centaur G upper-stage vehicle to assembly orbit. After assembly, the Centaur places the spacecraft in operational orbit, where it is deployed on radio command, the power system started, and the spacecraft becomes operational. Electric propulsion is an alternative and allows deployment in assembly orbit, but introduces a question of nuclear safety.

  3. Impulse radar with swept range gate

    DOEpatents

    McEwan, T.E.

    1998-09-08

    A radar range finder and hidden object locator is based on ultra-wide band radar with a high resolution swept range gate. The device generates an equivalent time amplitude scan with a typical range of 4 inches to 20 feet, and an analog range resolution as limited by a jitter of on the order of 0.01 inches. A differential sampling receiver is employed to effectively eliminate ringing and other aberrations induced in the receiver by the near proximity of the transmit antenna, so a background subtraction is not needed, simplifying the circuitry while improving performance. Techniques are used to reduce clutter in the receive signal, such as decoupling the receive and transmit cavities by placing a space between them, using conductive or radiative damping elements on the cavities, and using terminating plates on the sides of the openings. The antennas can be arranged in a side-by-side parallel spaced apart configuration or in a coplanar opposed configuration which significantly reduces main bang coupling. 25 figs.

  4. Navigator alignment using radar scan

    DOEpatents

    Doerry, Armin W.; Marquette, Brandeis

    2016-04-05

    The various technologies presented herein relate to the determination of and correction of heading error of platform. Knowledge of at least one of a maximum Doppler frequency or a minimum Doppler bandwidth pertaining to a plurality of radar echoes can be utilized to facilitate correction of the heading error. Heading error can occur as a result of component drift. In an ideal situation, a boresight direction of an antenna or the front of an aircraft will have associated therewith at least one of a maximum Doppler frequency or a minimum Doppler bandwidth. As the boresight direction of the antenna strays from a direction of travel at least one of the maximum Doppler frequency or a minimum Doppler bandwidth will shift away, either left or right, from the ideal situation.

  5. Multi-channel Ice Penetrating Radar Traverse for Estimates of Firn Density in the Percolation Zone, Western Greenland Ice Sheet

    NASA Astrophysics Data System (ADS)

    Meehan, T.; Osterberg, E. C.; Lewis, G.; Overly, T. B.; Hawley, R. L.; Bradford, J.; Marshall, H. P.

    2016-12-01

    To better predict the response of the Greenland Ice Sheet (GrIS) to future warming, leading edge Regional Climate Models (RCM) must be calibrated with in situ measurements of recent accumulation and melt. Mass balance estimates averaged across the entire Greenland Ice Sheet (GrIS) vary between models by more than 30 percent, and regional comparisons of mass balance reconstructions in Greenland vary by 100 percent or more. Greenland Traverse for Accumulation and Climate Studies (GreenTrACS) is a multi-year and multi-disciplinary 1700 km science traverse from Raven/Dye2 in SW Greenland, to Summit Station. Multi-offset radar measurements can provide high accuracy electromagnetic (EM) velocity estimates of the firn to within (+-) 0.002 to 0.003 m/ns. EM velocity, in turn, can be used to estimate bulk firn density. Using a mixing equation such as the CRIM Equation we use the measured EM velocity, along with the known EM velocity in air and ice, to estimate bulk density. During spring 2016, we used multi-channel 500MHz radar in a multi-offset configuration to survey more than 800 km from Raven towards summit. Preliminary radar-derived snow density estimates agree with density estimates from a firn core measurement ( 50 kg/m3), despite the lateral heterogeneity of the firn across the length of the antenna array (12 m).

  6. Detecting defects in conifers with ground penetrating radar: applications and challenges

    Treesearch

    J.R. Butnor; M.L. Pruyn; D.C. Shaw; M.E. Harmon; A.N. Mucciardi; M.G. Ryan

    2009-01-01

    Our objective was to test ground penetrating radar (GPR) to non-destructively estimate decay volumes in living coniferous trees. GPR is geophysical tool which uses an antenna to propagate short bursts of electromagnetic energy in solid materials and measure the two-way travel time and amplitude of reflected signals. We compared estimates hof bole decay from data...

  7. Middle Atmosphere Program. Handbook for MAP, volume 20

    NASA Technical Reports Server (NTRS)

    Bowhill, S. A. (Editor); Edwards, B. (Editor)

    1986-01-01

    Various topics related to investigations of the middle atmosphere are discussed. Numerical weather prediction, performance characteristics of weather profiling radars, determination of gravity wave and turbulence parameters, case studies of gravity-wave propagation, turbulence and diffusion due to gravity waves, the climatology of gravity waves, mesosphere-stratosphere-troposphere radar, antenna arrays, and data management techniques are among the topics discussed.

  8. Interferometric synthetic aperture radar (InSAR)—its past, present and future

    USGS Publications Warehouse

    Lu, Zhong; Kwoun, Oh-Ig; Rykhus, R.P.

    2007-01-01

    Very simply, interferometric synthetic aperture radar (InSAR) involves the use of two or more synthetic aperture radar (SAR) images of the same area to extract landscape topography and its deformation patterns. A SAR system transmits electromagnetic waves at a wavelength that can range from a few millimeters to tens of centimeters and therefore can operate during day and night under all-weather conditions. Using SAR processing technique (Curlander and McDonough, 1991), both the intensity and phase of the reflected (or backscattered) radar signal of each ground resolution element (a few meters to tens of meters) can be calculated in the form of a complex-valued SAR image that represents the reflectivity of the ground surface. The amplitude or intensity of the SAR image is determined primarily by terrain slope, surface roughness, and dielectric constants, whereas the phase of the SAR image is determined primarily by the distance between the satellite antenna and the ground targets. InSAR imaging utilizes the interaction of electromagnetic waves, referred to as interference, to measure precise distances between the satellite antenna and ground resolution elements to derive landscape topography and its subtle change in elevation.

  9. Ka Band Objects: Observation and Monitoring (KaBOOM)

    NASA Astrophysics Data System (ADS)

    Geldzahler, B.

    2012-09-01

    NASA has embarked on a path that will enable the implementation of a high power, high resolution X/Ka band radar system using widely spaced 12m antennas to better track and characterize near Earth objects and orbital debris. This radar system also has applications for cost effective space situational awareness. We shall demonstrate Ka band coherent uplink arraying with real-time atmospheric compensation using three 12m antennas at the Kennedy Space Center (KSC). Our proposed radar system can complement and supplement the activities of the Space Fence. The proposed radar array has the advantages of filling the gap between dusk and dawn and offers the possibility of high range resolution (4 cm) and high spatial resolution (?10 cm at GEO) when used in a VLBI mode. KSC was chosen because [a] of reduced implementation costs, [b] there is a lot of water vapor in the air (not Ka band friendly), and [c] the test satellites have a low elevation adding more attenuation and turbulence to the demonstration. If Ka band coherent uplink arraying can be made to work at KSC, it will work anywhere. We expect to rebaseline X-band in 2013, and demonstrate Ka band uplink arraying in 2014.

  10. Vital Sign Monitoring Through the Back Using an UWB Impulse Radar With Body Coupled Antennas.

    PubMed

    Schires, Elliott; Georgiou, Pantelis; Lande, Tor Sverre

    2018-04-01

    Radar devices can be used in nonintrusive situations to monitor vital sign, through clothes or behind walls. By detecting and extracting body motion linked to physiological activity, accurate simultaneous estimations of both heart rate (HR) and respiration rate (RR) is possible. However, most research to date has focused on front monitoring of superficial motion of the chest. In this paper, body penetration of electromagnetic (EM) wave is investigated to perform back monitoring of human subjects. Using body-coupled antennas and an ultra-wideband (UWB) pulsed radar, in-body monitoring of lungs and heart motion was achieved. An optimised location of measurement in the back of a subject is presented, to enhance signal-to-noise ratio and limit attenuation of reflected radar signals. Phase-based detection techniques are then investigated for back measurements of vital sign, in conjunction with frequency estimation methods that reduce the impact of parasite signals. Finally, an algorithm combining these techniques is presented to allow robust and real-time estimation of both HR and RR. Static and dynamic tests were conducted, and demonstrated the possibility of using this sensor in future health monitoring systems, especially in the form of a smart car seat for driver monitoring.

  11. Finite difference time domain modeling of spiral antennas

    NASA Technical Reports Server (NTRS)

    Penney, Christopher W.; Beggs, John H.; Luebbers, Raymond J.

    1992-01-01

    The objectives outlined in the original proposal for this project were to create a well-documented computer analysis model based on the finite-difference, time-domain (FDTD) method that would be capable of computing antenna impedance, far-zone radiation patterns, and radar cross-section (RCS). The ability to model a variety of penetrable materials in addition to conductors is also desired. The spiral antennas under study by this project meet these requirements since they are constructed of slots cut into conducting surfaces which are backed by dielectric materials.

  12. 89. View of DR 2 antenna (structure no. 736) at ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    89. View of DR 2 antenna (structure no. 736) at 65 percent completion showing erection process. Antenna system designed and factory construction by D.S. Kennedy & Company., Comasset, MA, 1958. Note scanner radar building in background. Official photograph BMEWS Project by unknown photographer, 11 July, 1960, Photographic Services, Riverton, NJ, BMEWS, clear as negative no. A-824. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  13. Interleaved array antenna technology development

    NASA Technical Reports Server (NTRS)

    1985-01-01

    This is the third phase of a program to establish an antenna concept for shuttle and free flying spacecraft earth resources experiments using Synthetic Aperture Radar. The feasibility of a plated graphite epoxy waveguide for a space antenna was evaluated. A quantity of flat panels and waveguides were developed, procured, and tested for electrical and mechanical properties. In addition, processes for the assembly of a unique waveguide array were investigated. Finally, trades between various configurations that would allow elevation (range) electronic scanning and that would minimize feed complexity for various RF bandwidths were made.

  14. Airborne polarimetric Doppler weather radar: trade-offs between various engineering specifications

    NASA Astrophysics Data System (ADS)

    Vivekanandan, Jothiram; Loew, Eric

    2018-01-01

    NCAR EOL is investigating potential configurations for the next-generation airborne phased array radar (APAR) that is capable of retrieving dynamic and microphysical characteristics of clouds and precipitation. The APAR will operate at C band. The APAR will use the electronic scanning (e-scan) feature to acquire the optimal number of independent samples for recording research-quality measurements. Since the airborne radar has only a limited time for collecting measurements over a specified region (moving aircraft platform ˜ 100 m s-1), beam multiplexing will significantly enhance its ability to collect high-resolution, research-quality measurements. Beam multiplexing reduces errors in radar measurements while providing rapid updates of scan volumes. Beamwidth depends on the size of the antenna aperture. Beamwidth and directivity of elliptical, circular, and rectangular antenna apertures are compared and radar sensitivity is evaluated for various polarimetric configurations and transmit-receive (T/R) elements. In the case of polarimetric measurements, alternate transmit with alternate receive (single-channel receiver) and simultaneous reception (dual-channel receiver) is compared. From an overall architecture perspective, element-level digitization of T/R module versus digital sub-array is considered with regard to flexibility in adaptive beamforming, polarimetric performance, calibration, and data quality. Methodologies for calibration of the radar and removing bias in polarimetric measurements are outlined. The above-mentioned engineering options are evaluated for realizing an optimal APAR system suitable for measuring the high temporal and spatial resolutions of Doppler and polarimetric measurements of precipitation and clouds.

  15. Improved Coal-Thickness Measurement

    NASA Technical Reports Server (NTRS)

    Barr, T. A.

    1984-01-01

    Summed signals and dielectric-filled antenna improve measurement. Improved FM radar for measuring thickness of coal seam eliminates spectrum splitting and reduces magnitude of echo from front coal surface.

  16. Rascal Air-to-Ground Guided Missiles

    DTIC Science & Technology

    1947-04-30

    versions of antennas in a comparatively short time. Their present test equipment Is limited to X, S , and the lower frequency bands . They specialise...system (assuming power supply of 28 volts d.c, and cles 115 volts a.c.). a final report showing in detail the study, work, s and...research program: Subject Discussed Radar Relay K- Band Rapid Scan System Clearances Search Antenna Ultrasonic Trainers Free Flight Symposium

  17. A SEASAT-A synthetic aperture imaging radar system

    NASA Technical Reports Server (NTRS)

    Jordan, R. L.; Rodgers, D. H.

    1975-01-01

    The SEASAT, a synthetic aperture imaging radar system is the first radar system of its kind designed for the study of ocean wave patterns from orbit. The basic requirement of this system is to generate continuous radar imagery with a 100 km swath with 25m resolution from an orbital altitude of 800 km. These requirements impose unique system design problems. The end to end data system described including interactions of the spacecraft, antenna, sensor, telemetry link, and data processor. The synthetic aperture radar system generates a large quantity of data requiring the use of an analog link with stable local oscillator encoding. The problems associated in telemetering the radar information with sufficient fidelity to synthesize an image on the ground is described as well as the selected solutions to the problems.

  18. Integrated Lens Antennas for Multi-Pixel Receivers

    NASA Technical Reports Server (NTRS)

    Lee, Choonsup; Chattopadhyay, Goutam

    2011-01-01

    Future astrophysics and planetary experiments are expected to require large focal plane arrays with thousands of detectors. Feedhorns have excellent performance, but their mass, size, fabrication challenges, and expense become prohibitive for very large focal plane arrays. Most planar antenna designs produce broad beam patterns, and therefore require additional elements for efficient coupling to the telescope optics, such as substrate lenses or micromachined horns. An antenna array with integrated silicon microlenses that can be fabricated photolithographically effectively addresses these issues. This approach eliminates manual assembly of arrays of lenses and reduces assembly errors and tolerances. Moreover, an antenna array without metallic horns will reduce mass of any planetary instrument significantly. The design has a monolithic array of lens-coupled, leaky-wave antennas operating in the millimeter- and submillimeter-wave frequencies. Electromagnetic simulations show that the electromagnetic fields in such lens-coupled antennas are mostly confined in approximately 12 15 . This means that one needs to design a small-angle sector lens that is much easier to fabricate using standard lithographic techniques, instead of a full hyper-hemispherical lens. Moreover, this small-angle sector lens can be easily integrated with the antennas in an array for multi-pixel imager and receiver implementation. The leaky antenna is designed using double-slot irises and fed with TE10 waveguide mode. The lens implementation starts with a silicon substrate. Photoresist with appropriate thickness (optimized for the lens size) is spun on the substrate and then reflowed to get the desired lens structure. An antenna array integrated with individual lenses for higher directivity and excellent beam profile will go a long way in realizing multi-pixel arrays and imagers. This technology will enable a new generation of compact, low-mass, and highly efficient antenna arrays for use in multi-pixel receivers and imagers for future planetary and astronomical instruments. These antenna arrays can also be used in radars and imagers for contraband detection at stand-off distances. This will be enabling technology for future balloon-borne, smaller explorer class mission (SMEX), and other missions, and for a wide range of proposed planetary sounders and radars for planetary bodies.

  19. Radar cross section lectures

    NASA Astrophysics Data System (ADS)

    Fuhs, A. E.

    A comprehensive account is given of the principles that can be applied in military aircraft configuration studies to minimize the radar cross section (RCS) that will be presented by the resulting design to advanced radars under various mission circumstances. It is noted that, while certain ECM techniques can be nullified by improved enemy electronics in a very short time, RCS reductions may require as much as a decade of radar development before prior levels of detectability can be reestablished by enemy defenses. Attention is given to RCS magnitude determinants, inverse scattering, the polarization and scattering matrix, the RCSs of flat plates and conducting cylinders, and antenna geometry and beam patterns.

  20. Light Detection and Ranging (LIDAR) From Space - Laser Altimeters

    NASA Technical Reports Server (NTRS)

    Sun, Xiaoli

    2016-01-01

    Light detection and ranging, or lidar, is like radar but atoptical wavelengths. The principle of operation and theirapplications in remote sensing are similar. Lidars havemany advantages over radars in instrument designs andapplications because of the much shorter laser wavelengthsand narrower beams. The lidar transmitters and receiveroptics are much smaller than radar antenna dishes. Thespatial resolution of lidar measurement is much finer thanthat of radar because of the much smaller footprint size onground. Lidar measurements usually give a better temporalresolution because the laser pulses can be much narrowerthan radio frequency (RF) signals. The major limitation oflidar is the ability to penetrate clouds and ground surfaces.

  1. A Vehicular Mobile Standard Instrument for Field Verification of Traffic Speed Meters Based on Dual-Antenna Doppler Radar Sensor

    PubMed Central

    Du, Lei; Sun, Qiao; Cai, Changqing; Bai, Jie; Fan, Zhe; Zhang, Yue

    2018-01-01

    Traffic speed meters are important legal measuring instruments specially used for traffic speed enforcement and must be tested and verified in the field every year using a vehicular mobile standard speed-measuring instrument to ensure speed-measuring performances. The non-contact optical speed sensor and the GPS speed sensor are the two most common types of standard speed-measuring instruments. The non-contact optical speed sensor requires extremely high installation accuracy, and its speed-measuring error is nonlinear and uncorrectable. The speed-measuring accuracy of the GPS speed sensor is rapidly reduced if the amount of received satellites is insufficient enough, which often occurs in urban high-rise regions, tunnels, and mountainous regions. In this paper, a new standard speed-measuring instrument using a dual-antenna Doppler radar sensor is proposed based on a tradeoff between the installation accuracy requirement and the usage region limitation, which has no specified requirements for its mounting distance and no limitation on usage regions and can automatically compensate for the effect of an inclined installation angle on its speed-measuring accuracy. Theoretical model analysis, simulated speed measurement results, and field experimental results compared with a GPS speed sensor with high accuracy showed that the dual-antenna Doppler radar sensor is effective and reliable as a new standard speed-measuring instrument. PMID:29621142

  2. A low cost, low power, S-band radar for atmospheric turbulence studies

    NASA Astrophysics Data System (ADS)

    Farrell, Thomas C.

    2015-05-01

    We present a frequency modulated continuous wave (FMCW) radar capable of measuring atmospheric turbulence profiles within the Earth's surface layer. Due to the low cost and easily automated design, a number of units may be built and deployed to sites of interest around the world. Each unit would be capable of collecting turbulence strength, as a function of altitude, with a range of about 50 meters above the antenna plane. Such data is valuable to developers of directed energy, laser communications, imaging, and other optical systems, where good engineering design is based on an understanding of the details of the turbulence in which those systems will have to operate. The radar is based on the MIT "coffee can" design1,2. It is FCC compliant, operating in the 2.4 GHz instrumentation, science, and medical (ISM) band with less than 1 watt effective isotropic radiated power (EIRP). It is expected to cost less than $1000 per unit and is built from commercial off the shelf parts, along with easily constructed horn antennas. Major modifications to the design in 1,2 are the inclusion of horn antennas for directivity, and a straight forward processing software change that increases integration times to the order of tens of seconds to a minute. Here, a prototype system is described and preliminary data is presented.

  3. A Vehicular Mobile Standard Instrument for Field Verification of Traffic Speed Meters Based on Dual-Antenna Doppler Radar Sensor.

    PubMed

    Du, Lei; Sun, Qiao; Cai, Changqing; Bai, Jie; Fan, Zhe; Zhang, Yue

    2018-04-05

    Traffic speed meters are important legal measuring instruments specially used for traffic speed enforcement and must be tested and verified in the field every year using a vehicular mobile standard speed-measuring instrument to ensure speed-measuring performances. The non-contact optical speed sensor and the GPS speed sensor are the two most common types of standard speed-measuring instruments. The non-contact optical speed sensor requires extremely high installation accuracy, and its speed-measuring error is nonlinear and uncorrectable. The speed-measuring accuracy of the GPS speed sensor is rapidly reduced if the amount of received satellites is insufficient enough, which often occurs in urban high-rise regions, tunnels, and mountainous regions. In this paper, a new standard speed-measuring instrument using a dual-antenna Doppler radar sensor is proposed based on a tradeoff between the installation accuracy requirement and the usage region limitation, which has no specified requirements for its mounting distance and no limitation on usage regions and can automatically compensate for the effect of an inclined installation angle on its speed-measuring accuracy. Theoretical model analysis, simulated speed measurement results, and field experimental results compared with a GPS speed sensor with high accuracy showed that the dual-antenna Doppler radar sensor is effective and reliable as a new standard speed-measuring instrument.

  4. A scheme for a high-power, low-cost transmitter for deep space applications

    NASA Astrophysics Data System (ADS)

    Scheffer, L. K.

    2005-10-01

    Applications such as planetary radars and spacecraft communications require transmitters with extremely high effective isotropic radiated power. Until now, this has been done by combining a high-power microwave source with a large reflective antenna. However, this arrangement has a number of disadvantages. It is costly, since the steerable reflector alone is quite expensive, and for spacecraft communications, the need to transmit hurts the receive performance. For planetary radars, the utilization is very low since the antenna must be shared with other applications such as radio astronomy or spacecraft communications. This paper describes a potential new way of building such transmitters with lower cost, greater versatility, higher reliability, and potentially higher power. The basic idea is a phased array with a very large number of low-power elements, built with mass production techniques that have been optimized for consumer markets. The antennas are built en mass on printed circuit boards and are driven by chips, built with consumer complementary metal-oxide-semiconductor technology, that adjust the phase of each element. Assembly and maintenance should be comparatively inexpensive since the boards need only be attached to large, flat, unmoving, ground-level infrastructure. Applications to planetary radar and spacecraft communications are examined. Although we would be unlikely to use such a facility in this way, an implication for Search for Extraterrestrial Intelligence (SETI) is that high-power beacons are easier to build than had been thought.

  5. Conformal fractal antenna and FSS for low-RCS applications

    NASA Astrophysics Data System (ADS)

    Varadan, Vijay K.; Vinoy, K. J.; Jose, K. A.; Varadan, Vasundara V.

    2000-06-01

    On many situations the reduction of radar cross section (RCS) is of continued strategic interest, especially with aircraft and missiles. Once the overall RCS of the vehicle is reduced, the reflections from the antennas can dominate. The commonly known approaches to RCS reduction may not be applicable for antennas, and hence special techniques are followed. These include configuring the antennas completely conformal, and using band pass frequency selective surfaces. The use fractal patterns have shown to result in such band pass characteristics. The overall RCS of a typical target body is experimentally found to be reduced when these screens are used. The paper presents the experimental result on the transmission and backscatter characteristics of a fractal FSS screen.

  6. Antenna analysis using properties of metamaterials

    NASA Astrophysics Data System (ADS)

    Mitra, Atindra K.; Hu, Colin; Maxwell, Kasandra

    2010-04-01

    As part of the Student Internship Programs at Wright-Patterson Air Force Base, including the AFRL Wright Scholar Program for High School Students and the AFRL STEP Program, sample results from preliminary investigation and analysis of integrated antenna structures are reported. Investigation of these novel integrated antenna geometries can be interpreted as a continuation of systems analysis under the general topic area of potential integrated apertures for future software radar/radio solutions [1] [2]. Specifically, the categories of novel integrated aperture geometries investigated in this paper include slotted-fractal structures on microstrip rectangular patch antenna models in tandem with the analysis of exotic substrate materials comprised of a type of synthesized electromagnetic structure known as metamaterials [8] - [10].

  7. Ground-penetrating radar methods used in surface-water discharge measurements

    USGS Publications Warehouse

    Haeni, F.P.; Buursink, Marc L.; Costa, John E.; Melcher, Nick B.; Cheng, Ralph T.; Plant, William J.

    2000-01-01

    In 1999, an experiment was conducted to see if a combination of complementary radar methods could be used to calculate the discharge of a river without having any of the measuring equipment in the water. The cross-sectional area of the 183-meter wide Skagit River in Washington State was measured using a ground-penetrating radar (GPR) system with a single 100-MHz antenna. A van-mounted, side-looking pulsed-Doppler radar system was used to collect water-surface velocity data across the same section of the river. The combined radar data sets were used to calculate the river discharge and the results compared closely to the discharge measurement made by using the standard in-water measurement techniques.

  8. 2. View toward east, west face ("D" wall) of perimeter ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. View toward east, west face ("D" wall) of perimeter acquisition radar building with subterranean power plants diesel engine intake (the smaller column) and exhaust seen in foreground. Behind the globe is the very low frequency (VLP) antenna - Stanley R. Mickelsen Safeguard Complex, Perimeter Acquisition Radar Building, Limited Access Area, between Limited Access Patrol Road & Service Road A, Nekoma, Cavalier County, ND

  9. Windshear detection radar signal processing studies

    NASA Technical Reports Server (NTRS)

    Baxa, Ernest G., Jr.

    1993-01-01

    This final report briefly summarizes research work at Clemson in the Radar Systems Laboratory under the NASA Langley Research Grant NAG-1-928 in support of the Antenna and Microwave Branch, Guidance and Control Division, program to develop airborne sensor technology for the detection of low altitude windshear. A bibliography of all publications generated by Clemson personnel is included. An appendix provides abstracts of all publications.

  10. Geological Interpretations of the Topography of Selected Regions of Venus from Arecibo to Goldstone Radar Interferometry

    NASA Technical Reports Server (NTRS)

    Jurgens, R. F.; Margot, J-L.; Simons, M.; Pritchard, M. E.; Slade, M. A.

    2002-01-01

    Radar interferometry using Arecibo to transmit and three antennas at the Goldstone to receive was conducted on 14 dates in Spring, 2001. This data has been used so far to generate DEMs (digital elevation models) for several of the dates with pixel resolution of 0.5-1.0 km. Additional information is contained in the original extended abstract.

  11. Integrated source and channel encoded digital communication system design study

    NASA Technical Reports Server (NTRS)

    Huth, G. K.; Udalov, S.

    1974-01-01

    This study investigated the configuration and integration of a wideband communication system with a Ku-band rendezvous radar system. The goal of the study was to provide as much commonality between the two systems as possible. The antenna design was described with the only change being the requirement for dual polarization (linear for the radar system and circular for the communication system).

  12. An algorithm for automatic target recognition using passive radar and an EKF for estimating aircraft orientation

    NASA Astrophysics Data System (ADS)

    Ehrman, Lisa M.

    2005-07-01

    Rather than emitting pulses, passive radar systems rely on "illuminators of opportunity," such as TV and FM radio, to illuminate potential targets. These systems are attractive since they allow receivers to operate without emitting energy, rendering them covert. Until recently, most of the research regarding passive radar has focused on detecting and tracking targets. This dissertation focuses on extending the capabilities of passive radar systems to include automatic target recognition. The target recognition algorithm described in this dissertation uses the radar cross section (RCS) of potential targets, collected over a short period of time, as the key information for target recognition. To make the simulated RCS as accurate as possible, the received signal model accounts for aircraft position and orientation, propagation losses, and antenna gain patterns. An extended Kalman filter (EKF) estimates the target's orientation (and uncertainty in the estimate) from velocity measurements obtained from the passive radar tracker. Coupling the aircraft orientation and state with the known antenna locations permits computation of the incident and observed azimuth and elevation angles. The Fast Illinois Solver Code (FISC) simulates the RCS of potential target classes as a function of these angles. Thus, the approximated incident and observed angles allow the appropriate RCS to be extracted from a database of FISC results. Using this process, the RCS of each aircraft in the target class is simulated as though each is executing the same maneuver as the target detected by the system. Two additional scaling processes are required to transform the RCS into a power profile (magnitude only) simulating the signal in the receiver. First, the RCS is scaled by the Advanced Refractive Effects Prediction System (AREPS) code to account for propagation losses that occur as functions of altitude and range. Then, the Numerical Electromagnetic Code (NEC2) computes the antenna gain pattern, further scaling the RCS. A Rician likelihood model compares the scaled RCS of the illuminated aircraft with those of the potential targets. To improve the robustness of the result, the algorithm jointly optimizes over feasible orientation profiles and target types via dynamic programming.

  13. First Measurements of Polar Mesospheric Summer Echoes by a Tri-static Radar System

    NASA Astrophysics Data System (ADS)

    La Hoz, C.

    2015-12-01

    Polar Mesospheric Summer Echoes (PMSE) have been observed for the first time by a tri-static radar system comprising the EISCAT VHF (224 MHz, 0.67 m Bragg wavelength) active radar in Tromso (Norway) and passive receiving stations in Kiruna, (Sweden) and Sodankyla (Finland). The antennas at the receiving stations, originally part of the EISCAT tri-static UHF radar system at 930 MHz, have been refitted with new feeder systems at the VHF frequency of the transmitter in Tromso. The refitted radar system opens new opportunities to study PMSE for its own sake and as a tracer of the dynamics of the polar mesosphere, a region that is difficult to investigate by other means. The measurements show that very frequently both remote receiving antennas detect coherent signals that are much greater than the regular incoherent scattering due to thermal electrons and coinciding in time and space with PMSE measured by the transmitter station in Tromso. This represents further evidence that PMSE is not aspect sensitive, as was already indicated by a less sensitive radar system in a bi-static configuration, and implying that the underlying atmospheric turbulence, at least at sub-meter scales, is isotropic in agreement with Kolmogorov's hypothesis. Measurements also show that the vertical rate of fall of persistent features of PMSE is the same as the vertical line of sight velocity inferred from the doppler shift of the PMSE signals. This equivalence forms the basis for using PMSE as a tracer of the dynamics of the background mesosphere. Thus, it is possible to measure the 3-dimensional velocity field in the PMSE layer over the intersection volume of the three antennas. Since the signals have large signal-to-noise ratios (up to 30 dB), the inferred velocities have high accuracies and good time resolutions. This affords the possibility to make estimates of momentum flux in the mesosphere deposited by overturning gravity waves. Gravity wave momentum flux is believed to be the engine of a gigantic refrigerator that cools the polar mesospheres in summer. Momentum flux investigations will be the subject of a separate report.

  14. Sensitivity Analysis of Sampling Number on Quality of Polarmetric Measurements from S-band Dual-Polarization Radar

    NASA Astrophysics Data System (ADS)

    KIM, H.; Suk, M. K.; Jung, S. A.; Park, J. S.; Ko, J. S.

    2016-12-01

    The data quality of dual-polarimetric weather radar is subject to radar scanning strategies such as pulse length, pulse repetition frequency (PRF), antenna scan speed, and sampling number. In terms of sampling number, the quality of radar moment data increases with the increasing of sampling number at the given PRF and pulse length while the feasible number of elevation angles decreases for the given time or the time required for radar volume scan increases with the relatively high sampling number. For operational weather radar, the sampling number is subjectively determined by the proficient radar operator. The determination of suitable sampling number is still challengeable for operational dual-polarimetric weather radar.In this study, we analyzed the sensitivity of polarimetric measurements to sampling number based on special radar experiment for rainfall and snowfall events using S-band dual-polarimetric radar (YIT) at Yong-In test bed. For this experiment, YIT radar transmitted a simultaneously polarized beam in horizontal and vertical with pulse length of 1.0 μs and single PRF of 600Hz. The beam width and gate size were 1.0° and 250m, respectively. The volume scan was composed of three PPI scans with three sampling numbers (antenna scan speed) of 40 (15°s-1), 60(10°s-1), and 85(7°s-1) at same elevation angle (=0.2°). We first investigated the spatial fluctuation of the polarimetric measurements according to three sampling numbers using radial texture. As the sampling number increases, the radial fluctuations of polarimetric measurements decrease. Second, we also examined the sensitivity to fuzzy logic based quality control algorithm for dual-polarimetric radar (Ye et al. 2015). The probability density functions (PDFs) of fuzzy logic feature parameters between ground clutter and meteorological echo area were compared. For overlapping area in both PDFs between ground clutter and meteorological echo increases with decreasing the sampling number. As the overlapping area increases, the classification of ground clutter (or meteorological echo) in fuzzy logic classifier is more difficult due to similar characteristics between ground clutter and meteorological echoes.

  15. A Phased Array of Widely Separated Antennas for Space Communication and Planetary Radar

    NASA Astrophysics Data System (ADS)

    Geldzahler, B.; Bershad, C.; Brown, R.; Cox, R.; Hoblitzell, R.; Kiriazes, J.; Ledford, B.; Miller, M.; Woods, G.; Cornish, T.; D'Addario, L.; Davarian, F.; Lee, D.; Morabito, D.; Tsao, P.; Soloff, J.; Church, K.; Deffenbaugh, P.; Abernethy, K.; Anderson, W.; Collier, J.; Wellen, G.

    NASA has successfully demonstrated coherent uplink arraying with real time compensation for atmospheric phase fluctuations at 7.145-7.190 GHz (X-band) and is pursuing a similar demonstration 30-31 GHz (Ka-band) using three 12m diameter COTS antennas separated by 60m at the Kennedy Space Center in Florida. In addition, we have done the same demonstration with up to three 34m antennas separated by 250m at the Goldstone Deep Space Communication Complex in California at X-band 7.1 GHz. We have begun to infuse the capability at Goldstone into the Deep Space Network to provide a quasi-operational system. Such a demonstration can enable NASA to design and establish a high power (10 PW) high resolution (<10 cm), 24/7 availability radar system for (a) tracking and characterizing observations of Near Earth Objects (NEOs), (b) tracking, characterizing and determining the statistics of small-scale (≤10cm) orbital debris, (c) incorporating the capability into its space communication and navigation tracking stations for emergency spacecraft commanding in the Ka band era which NASA is entering, and (d) fielding capabilities of interest to other US government agencies. We present herein the results of our phased array uplink combining at near 7.17 and 8.3 GHz using widely separated antennas demonstrations, our moderately successful attempts to rescue the STEREO-B spacecraft (distance 2 astronomical units (185,000,000 miles), the first two attempts at imaging and ranging of near Earth asteroids, and progress in developing telescopes that are fully capable at radio and optical frequencies. And progress toward the implementation of our vision for going forward in implementing a high performance, low lifecycle cost multi-element radar array.

  16. The Born approximation, multiple scattering, and the butterfly algorithm

    NASA Astrophysics Data System (ADS)

    Martinez, Alejandro F.

    Radar works by focusing a beam of light and seeing how long it takes to reflect. To see a large region the beam is pointed in different directions. The focus of the beam depends on the size of the antenna (called an aperture). Synthetic aperture radar (SAR) works by moving the antenna through some region of space. A fundamental assumption in SAR is that waves only bounce once. Several imaging algorithms have been designed using that assumption. The scattering process can be described by iterations of a badly behaving integral. Recently a method for efficiently evaluating these types of integrals has been developed. We will give a detailed implementation of this algorithm and apply it to study the multiple scattering effects in SAR using target estimates from single scattering algorithms.

  17. Low-index-metamaterial for gain enhancement of planar terahertz antenna

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhang, Qing-Le; Si, Li-Ming, E-mail: lms@bit.edu.cn; Lv, Xin

    2014-03-15

    We theoretically present a high gain planar antenna at terahertz (THz) frequencies by combing a conventional log-periodic antenna (LPA) with a low-index-metamaterial (LIM, |n| < 1). The LIM is realized by properly designing a fishnet metamaterial using full-wave finite-element simulation. Owing to the impedance matching, the LIM can be placed seamlessly on the substrate of the LPA without noticeable reflection. The effectiveness of using LIM for antenna gain enhancement is confirmed by comparing the antenna performance with and without LIM, where significantly improved half-power beam-width (3-dB beam-width) and more than 4 dB gain enhancement are seen within a certain frequencymore » range. The presented LIM-enhanced planar THz antenna is compact, flat, low profile, and high gain, which has extensive applications in THz systems, including communications, radar, and spectroscopy.« less

  18. The Goldstone solar system radar: A science instrument for planetary research

    NASA Technical Reports Server (NTRS)

    Dvorsky, J. D.; Renzetti, N. A.; Fulton, D. E.

    1992-01-01

    The Goldstone Solar System Radar (GSSR) station at NASA's Deep Space Communications Complex in California's Mojave Desert is described. A short chronological account of the GSSR's technical development and scientific discoveries is given. This is followed by a basic discussion of how information is derived from the radar echo and how the raw information can be used to increase understanding of the solar system. A moderately detailed description of the radar system is given, and the engineering performance of the radar is discussed. The operating characteristics of the Arcibo Observatory in Puerto Rico are briefly described and compared with those of the GSSR. Planned and in-process improvements to the existing radar, as well as the performance of a hypothetical 128-m diameter antenna radar station, are described. A comprehensive bibliography of referred scientific and engineering articles presenting results that depended on data gathered by the instrument is provided.

  19. World War II Radar and Early Radio Astronomy

    NASA Astrophysics Data System (ADS)

    Smith, G.

    2005-08-01

    The pattern of radio astronomy which developed in Europe and Australia followed closely the development of metre wave radar in World War II. The leading pioneers, Ryle, Lovell, Hey and Pawsey, were all in radar research establishments in the UK and Australia. They returned to universities, recruited their colleagues into research groups and immediately started on some basic observations of solar radio waves, meteor echoes, and the galactic background. There was at first little contact with conventional astronomers. This paper traces the influence of the radar scientists and of several types of radar equipment developed during WW II, notably the German Wurzburg, which was adapted for radio research in several countries. The techniques of phased arrays and antenna switching were used in radar and aircraft installations. The influence of WW II radar can be traced at least up to 10 years after the War, when radio astronomy became accepted as a natural discipline within astronomy.

  20. Radar/radiometer facilities for precipitation measurements

    NASA Technical Reports Server (NTRS)

    Hodge, D. B.; Taylor, R. C.

    1973-01-01

    The OSU ElectroScience Laboratory Radar/Radiometer Facilities are described. This instrumentation includes a high-resolution radar/radiometer system, a fully automated low-resolution radar system, and a small surveillance radar system. The high-resolution radar/radiometer system operates at 3, 9, and 15 GHz using two 9.1 m and one 4.6 m parabolic antennas, respectively. The low-resolution and surveillance radars operate at 9 and 15 GHz, respectively. Both the high- and low-resolution systems are interfaced to real-time digital processing and recording systems. This capability was developed for the measurement of the temporal and spatial characteristics of precipitation in conjunction with millimeter wavelength propagation studies utilizing the Advanced Technology Satellites. Precipitation characteristics derived from these measurements could also be of direct benefit in such diverse areas as: the atmospheric sciences, meteorology, water resources, flood control and warning, severe storm warning, agricultural crop studies, and urban and regional planning.

  1. Ground-Based Radar (GBR): Environmental Assessment.

    DTIC Science & Technology

    1989-03-01

    control of the antenna’s radiation pattern, the narrow, pencil-shaped main beam can be directed essentially instantaneously at incoming targets in any...Public Law 99-239: Compact of Free Association Act of 1M, January 14. 108. U.S. Department of Defense, Office of Economic Adjustment, 1984. Ecnomic ...may be directed essentially instantaneously at incoming targets. Phased-Array Technology The GBR will use a phased-array antenna for radiating the

  2. Radar based technology for non-contact monitoring of accumulation of blood in the head: A numerical study.

    PubMed

    Oziel, Moshe; Korenstein, Rafi; Rubinsky, Boris

    2017-01-01

    This theoretical study examines the use of radar to continuously monitor "accumulation of blood in the head" (ACBH) non-invasively and from a distance, after the location of a hematoma or hemorrhage in the brain was initially identified with conventional medical imaging. Current clinical practice is to monitor ABCH with multiple, subsequent, conventional medical imaging. The radar technology introduced in this study could provide a lower cost and safe alternative to multiple conventional medical imaging monitoring for ACBH. The goal of this study is to evaluate the feasibility of using radar to monitor changes in blood volume in the brain through a numerical simulation of ACBH monitoring from remote, with a directional spiral slot antennae, in 3-D models of the brain. The focus of this study is on evaluating the effect of frequencies on the antennae reading. To that end we performed the calculations for frequencies of 100 MHz, 500 MHz and 1 GHz. The analysis shows that the ACBH can be monitored with radar and the monitoring resolution improves with an increase in frequency, in the range studied. However, it also appears that when typical clinical dimensions of hematoma and hemorrhage are used, the variable ratio of blood volume radius and radar wavelength can bring the measurements into the Mie and Rayleigh regions of the radar cross section. In these regions there is an oscillatory change in signal with blood volume size. For some frequencies there is an increase in signal with an increase in volume while in others there is a decrease. While radar can be used to monitor ACBH non-invasively and from a distance, the observed Mie region dependent oscillatory relation between blood volume size and wavelength requires further investigation. Classifiers, multifrequency algorithms or ultra-wide band radar are possible solutions that should be explored in the future.

  3. Radar based technology for non-contact monitoring of accumulation of blood in the head: A numerical study

    PubMed Central

    Korenstein, Rafi; Rubinsky, Boris

    2017-01-01

    Background This theoretical study examines the use of radar to continuously monitor “accumulation of blood in the head” (ACBH) non-invasively and from a distance, after the location of a hematoma or hemorrhage in the brain was initially identified with conventional medical imaging. Current clinical practice is to monitor ABCH with multiple, subsequent, conventional medical imaging. The radar technology introduced in this study could provide a lower cost and safe alternative to multiple conventional medical imaging monitoring for ACBH. Materials and methods The goal of this study is to evaluate the feasibility of using radar to monitor changes in blood volume in the brain through a numerical simulation of ACBH monitoring from remote, with a directional spiral slot antennae, in 3-D models of the brain. The focus of this study is on evaluating the effect of frequencies on the antennae reading. To that end we performed the calculations for frequencies of 100 MHz, 500 MHz and 1 GHz. Results and discussion The analysis shows that the ACBH can be monitored with radar and the monitoring resolution improves with an increase in frequency, in the range studied. However, it also appears that when typical clinical dimensions of hematoma and hemorrhage are used, the variable ratio of blood volume radius and radar wavelength can bring the measurements into the Mie and Rayleigh regions of the radar cross section. In these regions there is an oscillatory change in signal with blood volume size. For some frequencies there is an increase in signal with an increase in volume while in others there is a decrease. Conclusions While radar can be used to monitor ACBH non-invasively and from a distance, the observed Mie region dependent oscillatory relation between blood volume size and wavelength requires further investigation. Classifiers, multifrequency algorithms or ultra-wide band radar are possible solutions that should be explored in the future. PMID:29023544

  4. SAR Tomography for Terrestrial Snow Stratigraphy

    NASA Astrophysics Data System (ADS)

    Lei, Y.; Xu, X.; Baldi, C.; Bleser, J. W. D.; Yueh, S. H.; Elder, K.

    2017-12-01

    Traditional microwave observation of snowpack includes brightness temperature and backscatter. The single baseline configuration and loss of phase information hinders the retrieval of snow stratigraphy information from microwave observations. In this paper, we are investigating the tomography of polarimetric SAR to measure snow stratigraphy. In the past two years, we have developed a homodyne frequency modulated continuous wave radar (FMCW), operation at three earth exploration satellite bands within the X-band and Ku-band spectrums (centered at 9.6 GHz, 13.5 GHz, and 17.2 GHz) at Jet Propulsion Laboratory. The transceiver is mounted to a dual-axis planar scanner (60cm in each direction), which translates the antenna beams across the target area creating a tomographic baseline in two directions. Dual-antenna architecture was implemented to improve the isolation between the transmitter and receiver. This technique offers a 50 dB improvement in signal-to-noise ratio versus conventional single-antenna FMCW radar systems. With current setting, we could have around 30cm vertical resolution. The system was deployed on a ground based tower at the Fraser Experimental Forest (FEF) Headquarters, near Fraser, CO, USA (39.847°N, 105.912°W) from February 1 to April 30, 2017 and run continuously with some gaps for required optional supports. FEF is a 93-km2 research watershed in the heart of the central Rocky Mountains approximately 80-km West of Denver. During the campaign, in situ measurements of snow depth and other snowpack properties were performed every week for comparison with the remotely sensed data. A network of soil moisture sensors, time-lapse cameras, acoustic depth sensors, laser depth sensor and meteorological instruments was installed next to the site to collect in situ measurements of snow, weather, and soil conditions. Preliminary tomographic processing of ground based SAR data of snowpack at X- and Ku- band has revealed the presence of multiple layers within the snowpack and clear melting/refrozen cycle, which is consistant with the in-situ measurement.

  5. Design of a C- Band Circular Polarization Microstrip Antenna

    NASA Astrophysics Data System (ADS)

    Yohandri; Jumiah, Yusna; Tetuko Sri Sumantyo, Josaphat

    2018-04-01

    The development of circularly polarized microstrip antenna is an interesting topic in current research, due to its superiority in various applications. In this work, the design of a circular polarization antenna that will be operated in the C-band range will be described. The developed antenna is intended to be used for Synthetic Aperture Radar (SAR) applications. Through this application, various targets or areas on the surface of the earth, such as buildings, soil and land can be observed. To get the ideal antenna characteristic, in this research the various parameters in antenna design will be simulated. A software CST Studio will be operated in this simulation. Based on the simulation results, the optimum parameters are obtained in term of reflection coefficient, VSWR, axial ratio, and gain. The reflection coefficient of the antenna (S11) is obtained at -19.75 dB and VSWR of 1.23. Meanwhile, the axial ratio and gain of the antenna were obtained at 2.66 dB and 2.1 dBi, respectively. Based on this simulated results, antenna design is potential to be developed and fabricated for SAR sensor applications.

  6. Improving the detectability and imaging capability of ground penetrating radar using novel antenna concepts

    NASA Astrophysics Data System (ADS)

    Koyadan Koroth, Ajith; Bhattacharya, Amitabha

    2017-04-01

    Antennas are key components of Ground Penetrating Radar (GPR) instrumentation. A carefully designed antenna can improve the detectability and imaging capability of a GPR to a great extent without changing the other instrumentations. In this work, we propose four different types of antennas for GPR. They are modifications of a conventional bowtie antenna with great improvement in performance parameters. The designed antennas has also been tested in a stepped frequency type GPR and two dimensional scan images of various targets are presented. Bowtie antennas have been traditionally employed in GPR for its wide impedance bandwidth and radiation properties. The researchers proposed resistive loading to improve the bandwidth of the bowtie antenna and for low ringing pulse radiation. But this method was detrimental for antenna gain and efficiency. Bowtie antennas have a very wide impedance bandwidth. But the useful bandwidth of the antenna has been limited by the radiation pattern bandwidth. The boresight gain of bowtie antennas are found to be unstable beyond a 4:1 bandwidth. In this work, these problems have been addressed and maximum usable bandwidth for the bowtie antennas has been achieved. In this work, four antennas have been designed: namely, 1.) RC loaded bowtie antennas, 2.) RC loaded bowtie with metamaterial lens, 3.) Loop loaded bowtie, 4.) Loop loaded bowtie with directors. The designed antennas were characterized for different parameters like impedance bandwidth, radiation pattern and, gain. In antenna 1, a combined resistive-capacitive loading has been applied by periodic slot cut on the arms of the bowtie and pasting a planar graphite sheet over it. Graphite having a less conductance compared to copper acts as resistive loading. This would minimize the losses compared to lumped resistive loading. The antenna had a 10:1 impedance bandwidth and, a 5:1 pattern bandwidth. In antenna 2, a metamaterial lens has been designed to augment the antenna 1, to improve the forward gain. This antenna had the same impedance bandwidth of 10:1 while pattern bandwidth has been raised to 7:1. In antenna 3, a loop loaded bowtie antenna has been designed. This antenna do not employ any kind of resistive loading, yet achieves an impedance bandwidth of 11:1 and also a usable bandwidth of 11:1. The antenna 4 employs concentric offset loops which acts as directors to improve the directivity. This antenna achieved an impedance bandwidth and a pattern bandwidth of 13:1. All the antennas have a maximum size of about 0.3λ at lowest operating frequency. An experimental stepped frequency type GPR has been constructed to study the suitability of the fabricated antennas in detecting buried targets. Four experiments have been conducted viz. 1.) To detect a metallic pipe of 1in diameter, 2.) To detect a metallic pipe of 2in diameter 3.) To detect dry bamboo, 3.) To detect rebar in concrete. The detectability and imaging capability of GPR has been found to be improving from antenna 1 to 4.

  7. NASA Soil Moisture Mapper Takes First SMAPshots

    NASA Image and Video Library

    2015-03-09

    Fresh off the recent successful deployment of its 20-foot (6-meter) reflector antenna and associated boom arm, NASA's new Soil Moisture Active Passive (SMAP) observatory has successfully completed a two-day test of its science instruments. On Feb. 27 and 28, SMAP's radar and radiometer instruments were successfully operated for the first time with SMAP's antenna in a non-spinning mode. The test was a key step in preparation for the planned spin-up of SMAP's antenna to approximately 15 revolutions per minute in late March. The spin-up will be performed in a two-step process after additional tests and maneuvers adjust the observatory to its final science orbit over the next couple of weeks. Based on the data received, mission controllers at NASA's Jet Propulsion Laboratory, Pasadena, California; and NASA's Goddard Space Flight Center, Greenbelt, Maryland; concluded that the radar and radiometer performed as expected. SMAP launched Jan. 31 on a minimum three-year mission to map global soil moisture and detect whether soils are frozen or thawed. The mission will help scientists understand the links in Earth's water, energy and carbon cycles, help reduce uncertainties in predicting weather and climate, and enhance our ability to monitor and predict natural hazards such as floods and droughts The first test image illustrates the significance of SMAP's spinning instrument design. For this initial test with SMAP's antenna not yet spinning, the observatory's measurement swath width -- the strips observed on Earth in the image -- was limited to 25 miles (40 kilometers). When fully spun up and operating, SMAP's antenna will measure a 620-mile-wide (1,000-kilometer) swath of the ground as it flies above Earth at an altitude of 426 miles (685 kilometers). This will allow SMAP to map the entire globe with high-resolution radar data every two to three days, filling in all of the land surface detail that is not available in this first image. The radar data illustrated in the upper panel of the image show a clear contrast between land and ocean surfaces. The Amazon and Congo forests in South America and Africa, respectively, produced strong radar echoes due to their large biomass and water content. Areas with no vegetation and low soil moisture, such as the Sahara Desert, yielded weaker radar echoes. As expected, the dry snow zone in central Greenland, the largest zone of the Greenland ice sheet where snow does not melt year-round, produced weaker radar echoes. Surrounding areas in Greenland's percolation zone, where some meltwater penetrates down into glaciers and refreezes, had strong radar echoes due to ice lens and glands within the ice sheet. Ice lenses form when moisture that is diffused within soil or rock accumulates in a localized zone. Ice glands are columns of ice in the granular snow at the top of glaciers. The test shows that SMAP's radiometer is performing well. The radiometer's brightness temperature data are illustrated in the lower panel. Brightness temperature is a measurement of how much natural microwave radiant energy is traveling up from Earth's surface to the satellite. The contrast between land and ocean surface brightness temperatures is clear, as they are in the radar image. The Sahara Desert has high brightness temperatures because it is so hot and has low soil moisture content. The India subcontinent is currently in its dry season and therefore also has high brightness temperatures. Some regions, such as the northeast corner of Australia, showed low brightness temperatures, likely due to the high moisture content of the soil after heavy rainfall from Cyclone Marcia in late February. http://photojournal.jpl.nasa.gov/catalog/PIA19236

  8. Compound Radar Approach for Breast Imaging.

    PubMed

    Byrne, Dallan; Sarafianou, Mantalena; Craddock, Ian J

    2017-01-01

    Multistatic radar apertures record scattering at a number of receivers when the target is illuminated by a single transmitter, providing more scattering information than its monostatic counterpart per transmission angle. This paper considers the well-known problem of detecting tumor targets within breast phantoms using multistatic radar. To accurately image potentially cancerous targets size within the breast, a significant number of multistatic channels are required in order to adequately calibrate-out unwanted skin reflections, increase the immunity to clutter, and increase the dynamic range of a breast radar imaging system. However, increasing the density of antennas within a physical array is inevitably limited by the geometry of the antenna elements designed to operate with biological tissues at microwave frequencies. A novel compound imaging approach is presented to overcome these physical constraints and improve the imaging capabilities of a multistatic radar imaging modality for breast scanning applications. The number of transmit-receive (TX-RX) paths available for imaging are increased by performing a number of breast scans with varying array positions. A skin calibration method is presented to reduce the influence of skin reflections from each channel. Calibrated signals are applied to receive a beamforming method, compounding the data from each scan to produce a microwave radar breast profile. The proposed imaging method is evaluated with experimental data obtained from constructed phantoms of varying complexity, skin contour asymmetries, and challenging tumor positions and sizes. For each imaging scenario outlined in this study, the proposed compound imaging technique improves skin calibration, clearly detects small targets, and substantially reduces the level of undesirable clutter within the profile.

  9. Ultra-Wideband UHF Microstrip Array for GeoSAR Application

    NASA Technical Reports Server (NTRS)

    Thomas, Robert F.; Huang, John

    1998-01-01

    GeoSAR is a program sponsored by DARPA (Defense Advanced Research Projects Agency) and NASA (National Aeronautics and Space Administration) to develop an airborne, radar- based, commercial terrain mapping system for identification of geologic, seismic, and environmental information, it has two (dual-band at X and UHF) state-of-the-art interferometric synthetic aperture radar (SAR) ground mapping systems. The UHF interferometric system is utilized to penetrate the vegetation canopy and obtain true ground surface height information, while the Xband system will provide capability of mapping the top foliage surface. This paper presents the UHF antenna system where the required center frequency is 350 MHz with a 160 MHz of bandwidth (46% from 270 MHz to 430 MHz). The antenna is required to have dual-linear polarization with a peak gain of 10 dB at the center frequency and a minimum gain of 8 dB toward two ends of the frequency band. One of the most challenging tasks, in addition to achieving the 46% bandwidth, is to develop an antenna with small enough size to fit in the wing-tip pod of a Gulfstream II aircraft.

  10. KSC-04PD-2705

    NASA Technical Reports Server (NTRS)

    2004-01-01

    KENNEDY SPACE CENTER, FLA. Members of the STS-114 crew pose for a photo with workers installing the 30-foot-diameter C-band antenna (above them) and a smaller X-band antenna north of the Haulover Canal. The astronauts at left are Commander Eileen Collins; Mission Specialists Stephen Robinson, Soichi Noguchi, Wendy Lawrence and Charles Camarda (in center). At far right is Pilot James Kelly. The antennas are being tested during the launch of a Delta II rocket carrying NASAs MESSENGER spacecraft bound for the planet Mercury that will work together to create an image of the Delta rocket in flight. The test will evaluate the use of the radars as part of NASAs Return to Flight program for the Space Shuttle to observe possible debris coming from the Shuttle during launch. If successful, the radar configuration could be used on ships downrange, including on one of the solid rocket booster retrieval ships. And it may enable the return to launching Space Shuttles at night. The launch window for Return to Flight mission STS-114 is May 12 through June 3, 2005.

  11. Electromagnetic approaches to wall characterization, wall mitigation, and antenna design for through-the-wall radar systems

    NASA Astrophysics Data System (ADS)

    Thajudeen, Christopher

    Through-the-wall imaging (TWI) is a topic of current interest due to its wide range of public safety, law enforcement, and defense applications. Among the various available technologies such as, acoustic, thermal, and optical imaging, which can be employed to sense and image targets of interest, electromagnetic (EM) imaging, in the microwave frequency bands, is the most widely utilized technology and has been at the forefront of research in recent years. The primary objectives for any Through-the-Wall Radar Imaging (TWRI) system are to obtain a layout of the building and/or inner rooms, detect if there are targets of interest including humans or weapons, determine if there are countermeasures being employed to further obscure the contents of a building or room of interest, and finally to classify the detected targets. Unlike conventional radar scenarios, the presence of walls, made of common construction materials such as brick, drywall, plywood, cinder block, and solid concrete, adversely affects the ability of any conventional imaging technique to properly image targets enclosed within building structures as the propagation through the wall can induce shadowing effects on targets of interest which may result in image degradation, errors in target localization, and even complete target masking. For many applications of TWR systems, the wall ringing signals are strong enough to mask the returns from targets not located a sufficient distance behind the wall, beyond the distance of the wall ringing, and thus without proper wall mitigation, target detection becomes extremely difficult. The results presented in this thesis focus on the development of wall parameter estimation, and intra-wall and wall-type characterization techniques for use in both the time and frequency domains as well as analysis of these techniques under various real world scenarios such as reduced system bandwidth scenarios, various wall backing scenarios, the case of inhomogeneous walls, presence of ground reflections, and situations where they may be applied to the estimation of the parameters associated with an interior wall. It is demonstrated through extensive computer simulations and laboratory experiments that, by proper exploitation of the electromagnetic characteristics of walls, one can efficiently extract the constitutive parameters associated with unknown wall(s) as well as to characterize and image the intra-wall region. Additionally, it is possible, to a large extent, to remove the negative wall effects, such as shadowing and incorrect target localization, as well as to enhance the imaging and classification of targets behind walls. In addition to the discussion of post processing the radar data to account for wall effects, the design of antenna elements used for transmit (Tx) and receive (Rx) operations in TWR radars is also discussed but limited to antennas for mobile, handheld, or UAV TWR systems which impose design requirements such as low profiles, wide operational bands, and in most cases lend themselves to fabrication using surface printing techniques. A new class of wideband antennas, formed though the use of printed metallic paths in the form of Peano and Hilbert space-filling curves (SFC) to provide top-loading properties that miniaturize monopole antenna elements, has been developed for applications in conformal and/or low profile antennas systems, such as mobile platforms for TWRI and communication systems. Additionally, boresight gain enhancements of a stair-like antenna geometry, through the addition of parasitic self-similar patches and gate like ground plane structures, are presented.

  12. Development of an Ultra-Wideband Circularly Polarized Multiple Layer Dielectric Rod Antenna Design

    NASA Astrophysics Data System (ADS)

    Wainwright, Gregory D.

    This dissertations focuses on the development of a novel Ultra-Wideband (UWB) circularly polarized dielectric rod antenna (CPDRA) which yields a constant gain, pattern, and phase center. These properties are important in many applications. Within radar systems a constant phase center is desirable to avoid errors within downrange and crossrange measurements. In a reflector antenna the illumination, spillover, and phase efficiencies will remain the same over an ultra-wideband. Lastly, near field probes require smooth amplitude and phase patterns over frequency to avoid errors during the calibration process of the antenna under test. In this dissertation a novel CP feeding network has been developed for an ultra-wideband dielectric rod antenna. Circularly-polarized antennas have a major advantage over its linearly-polarized counterpart in that the polarization mismatch loss caused by misalignment between the polarizations of the incident fields and antenna can be avoided. This is important in satellite communications and broadcasts where signal propagation through the ionosphere can experience Faraday Rotation. A circularly polarized antenna is also helpful in mobile radar and communication systems where the receiving antennas orientation is not fixed. Previous research on UWB dielectric rod antenna designs has focused on Dual linear feeds. Each polarization within the dual linear feed is excited by a pair of linear launcher arms fed with a 0°-180° hybrid balun. The proposed CPDRA design does not require the 0°-180° hybrid baluns or 0°-90° hybrid for achieving CP operation. These hybrids will increase the antennas size, weight, cost, and reduce operational bandwidth. A design technique has been developed for an UWB multilayer dielectric waveguide used in a CPDRA antenna. This design technique uses near-field Electric field data from inside the waveguide, in conjunction with a genetic algorithm optimization to yield a wideband waveguide with a near field amplitude distribution that scales with frequency. A multilayered dielectric waveguide presents many fabrication challenges. The thermal expansion rates, moisture absorption rates, and vibration properties differ within the various dielectric materials used. Therefore, the development of a wideband waveguide using one material with a low dielectric constant would be advantages since 3-D printing technology can be utilized. In this dissertation novel TE01 and TM01 mode suppressors have been developed using only a single dielectric material.

  13. Millimeter wave front-end figure of merit, part 2

    NASA Astrophysics Data System (ADS)

    Silberman, Gabriel G.

    1995-09-01

    This report presents a practical approach for defining and calculating a meaningful figure of merit for frequency modulated continuous wave radar systems with separate receive and transmit (bistatic) antennas.

  14. Detectability of underground electrical cables junction with a ground penetrating radar: electromagnetic simulation and experimental measurements

    NASA Astrophysics Data System (ADS)

    Liu, Xiang; serhir, mohammed; kameni, abelin; lambert, marc; pichon, lionel

    2016-04-01

    For a company like Electricity De France (EDF), being able to detect accurately using non-destructive methods the position of the buried junction between two underground cables is a crucial issue. The junction is the linking part where most maintenance operations are carried out. The challenge of this work is to conduct a feasibility study to confirm or deny the relevance of Ground Penetrating Radar (GPR) to detect these buried junctions in their actual environment against clutter. Indeed, the cables are buried in inhomogeneous medium at around 80cm deep. To do this, the study is conducted in a numerical environment. We use the 3D simulation software CST MWS to model a GPR scenario. In this simulation, we place the already optimized bowtie antennas operating in the frequency band [0.5 GHz - 3 GHz] in front of wet soil (dispersive) and dry soil where the underground cable is placed at 80cm deep. We collect the amplitude and phase of the reflected waves in order to detect the contrast provoked by the geometric dimensions variation of the cable [1] (diameter of the cable is 48mm and the diameter of the junction 74mm). The use of an ultra-wideband antenna is necessary to reconcile resolution and penetration of electromagnetic waves in the medium to be characterized. We focus on the performance of the GPR method according to the characteristics of the surrounding medium in which the electric cables are buried, the polarization of the Tx and Rx antennas. The experimental measurement collected in the EDF site will be presented. The measured data are processed using the clutter reduction method based on digital filtering [2]. We aim at showing that using the developed bowtie antennas that the GPR technique is well adapted for the cable junction localization even in cluttered environment. References [1] D. J. Daniels, "Surface-Penetrating Radar", London, IEE 1996. [2] Potin, D.; Duflos, E.; Vanheeghe, P., "Landmines Ground-Penetrating Radar Signal Enhancement by Digital Filtering," in Geoscience and Remote Sensing, IEEE Transactions on , vol.44, no.9, pp.2393-2406, Sept. 2006 .

  15. Asteroid 1999 JD6

    NASA Image and Video Library

    2015-07-31

    This collage of radar images of near-Earth asteroid 1999 JD6 was collected by NASA scientists on July 25, 2015. The images show the rotation of the asteroid, which made its closest approach on July 24 at 9:55 p.m. PDT (12:55 a.m. EDT on July 25) at a distance of about 4.5 million miles (7.2 million kilometers, or about 19 times the distance from Earth to the moon). The asteroid appears to be a contact binary -- an asteroid with two lobes that are stuck together. These views, which are radar echoes, were obtained by pairing NASA's 230-foot-wide (70-meter) Deep Space Network antenna at Goldstone, California, with the 330-foot (100-meter) National Science Foundation Green Bank Telescope in West Virginia. Using this approach, the Goldstone antenna beams a radar signal at an asteroid and Green Bank receives the reflections. The technique, referred to as a bistatic observation, dramatically improves the amount of detail that can be seen in radar images. The new views obtained with the technique show features as small as about 25 feet (7.5 meters) wide. The images show the asteroid is highly elongated, with a length of approximately 1.2 miles (2 kilometers) on its long axis. http://photojournal.jpl.nasa.gov/catalog/PIA19647

  16. Electromagnetic absorption properties of spacecraft and space debris

    NASA Astrophysics Data System (ADS)

    Micheli, D.; Santoni, F.; Giusti, A.; Delfini, A.; Pastore, R.; Vricella, A.; Albano, M.; Arena, L.; Piergentili, F.; Marchetti, M.

    2017-04-01

    Aim of the work is to present a method to evaluate the electromagnetic absorption properties of spacecraft and space debris. For these objects, the radar detection ability depends mainly on volume, shape, materials type and other electromagnetic reflecting behaviour of spacecraft surface components, such as antennas or thermal blankets, and of metallic components in space debris. The higher the electromagnetic reflection coefficient of such parts, the greater the radar detection possibility. In this research an electromagnetic reverberation chamber is used to measure the absorption cross section (ACS) of four objects which may represent space structure operating components as well as examples of space debris: a small satellite, a composite antenna dish, a Thermal Protection System (TPS) tile and a carbon-based composite missile shell. The ACS mainly depends on geometrical characteristics like apertures, face numbers and bulk porosity, as well as on the type of the material itself. The ACS, which is an electromagnetic measurement, is expressed in squared meters and thus can be compared with the objects geometrical cross section. A small ACS means a quite electromagnetic reflective tendency, which is beneficial for radar observations; on the contrary, high values of ACS indicate a strong absorption of the electromagnetic field, which in turn can result a critical hindering of radar tracking.

  17. A 24-GHz Front-End Integrated on a Multilayer Cellulose-Based Substrate for Doppler Radar Sensors.

    PubMed

    Alimenti, Federico; Palazzi, Valentina; Mariotti, Chiara; Virili, Marco; Orecchini, Giulia; Bonafoni, Stefania; Roselli, Luca; Mezzanotte, Paolo

    2017-09-12

    This paper presents a miniaturized Doppler radar that can be used as a motion sensor for low-cost Internet of things (IoT) applications. For the first time, a radar front-end and its antenna are integrated on a multilayer cellulose-based substrate, built-up by alternating paper, glue and metal layers. The circuit exploits a distributed microstrip structure that is realized using a copper adhesive laminate, so as to obtain a low-loss conductor. The radar operates at 24 GHz and transmits 5 mW of power. The antenna has a gain of 7.4 dBi and features a half power beam-width of 48 degrees. The sensor, that is just the size of a stamp, is able to detect the movement of a walking person up to 10 m in distance, while a minimum speed of 50 mm/s up to 3 m is clearly measured. Beyond this specific result, the present paper demonstrates that the attractive features of cellulose, including ultra-low cost and eco-friendliness (i.e., recyclability and biodegradability), can even be exploited for the realization of future high-frequency hardware. This opens opens the door to the implementation on cellulose of devices and systems which make up the "sensing layer" at the base of the IoT ecosystem.

  18. Numerical and Experimental Investigation on Electromagnetic Attenuation by Semi-Ellipsoidal Shaped Plasma

    NASA Astrophysics Data System (ADS)

    He, Xiang; Chen, Jianping; Zhang, Yachun; Chen, Yudong; Zeng, Xiaojun; Tang, Chunmei

    2015-10-01

    Some reports presented that the radar cross section (RCS) from the radar antenna of military airplanes can be reduced by using a low-temperature plasma screen. This paper gives a numerical and experimental analysis of this RCS-reduction method. The shape of the plasma screen was designed as a semi-ellipsoid in order to make full use of the space in the radar dome. In simulations, we discussed the scattering of the electromagnetic (EM) wave by a perfect electric conductor (PEC) covered with this plasma screen using the finite-difference-time-domain (FDTD) method. The variations of their return loss as a function of wave frequency, plasma density profile, and collision frequency were presented. In the experiments, a semi-ellipsoidal shaped plasma screen was produced. Electromagnetic attenuation of 1.5 GHz EM wave was measured for a radio frequency (RF) power of 5 kW at an argon pressure of 200-1150 Pa. A good agreement is found between simulated and experimental results. It can be confirmed that the plasma screen is useful in applications for stealth of radar antenna. supported by National Natural Science Foundation of China (No. 51107033) and the Fundamental Research Funds for the Central Universities, China (No. 2013B33614)

  19. Searching for Survivors through Random Human-Body Movement Outdoors by Continuous-Wave Radar Array

    PubMed Central

    Liu, Miao; Li, Zhao; Liang, Fulai; Jing, Xijing; Lu, Guohua; Wang, Jianqi

    2016-01-01

    It is a major challenge to search for survivors after chemical or nuclear leakage or explosions. At present, biological radar can be used to achieve this goal by detecting the survivor’s respiration signal. However, owing to the random posture of an injured person at a rescue site, the radar wave may directly irradiate the person’s head or feet, in which it is difficult to detect the respiration signal. This paper describes a multichannel-based antenna array technology, which forms an omnidirectional detection system via 24-GHz Doppler biological radar, to address the random positioning relative to the antenna of an object to be detected. Furthermore, since the survivors often have random body movement such as struggling and twitching, the slight movements of the body caused by breathing are obscured by these movements. Therefore, a method is proposed to identify random human-body movement by utilizing multichannel information to calculate the background variance of the environment in combination with a constant-false-alarm-rate detector. The conducted outdoor experiments indicate that the system can realize the omnidirectional detection of random human-body movement and distinguish body movement from environmental interference such as movement of leaves and grass. The methods proposed in this paper will be a promising way to search for survivors outdoors. PMID:27073860

  20. Searching for Survivors through Random Human-Body Movement Outdoors by Continuous-Wave Radar Array.

    PubMed

    Li, Chuantao; Chen, Fuming; Qi, Fugui; Liu, Miao; Li, Zhao; Liang, Fulai; Jing, Xijing; Lu, Guohua; Wang, Jianqi

    2016-01-01

    It is a major challenge to search for survivors after chemical or nuclear leakage or explosions. At present, biological radar can be used to achieve this goal by detecting the survivor's respiration signal. However, owing to the random posture of an injured person at a rescue site, the radar wave may directly irradiate the person's head or feet, in which it is difficult to detect the respiration signal. This paper describes a multichannel-based antenna array technology, which forms an omnidirectional detection system via 24-GHz Doppler biological radar, to address the random positioning relative to the antenna of an object to be detected. Furthermore, since the survivors often have random body movement such as struggling and twitching, the slight movements of the body caused by breathing are obscured by these movements. Therefore, a method is proposed to identify random human-body movement by utilizing multichannel information to calculate the background variance of the environment in combination with a constant-false-alarm-rate detector. The conducted outdoor experiments indicate that the system can realize the omnidirectional detection of random human-body movement and distinguish body movement from environmental interference such as movement of leaves and grass. The methods proposed in this paper will be a promising way to search for survivors outdoors.

  1. Stand-off explosive detection utilizing low power stimulated emission nuclear quadrupole resonance detection and subwavelength focusing wideband super lens

    NASA Astrophysics Data System (ADS)

    Apostolos, John; Mouyos, William; Feng, Judy; Chase, Walter

    2015-05-01

    The need for advanced techniques to detect improvised explosive devices (IED) at stand-off distances greater than ten (10) meters has driven AMI Research and Development (AMI) to develop a solution to detect and identify the threat utilizing a forward looking Synthetic Aperture Radar (SAR) combined with our CW radar technology Nuclear Quadrupole Resonance (NQR) detection system. The novel features include a near-field sub-wavelength focusing antenna, a wide band 300 KHz to 300 MHz rapidly scanning CW radar facilitated by a high Q antenna/tuner, and an advanced processor utilizing Rabi transitions where the nucleus oscillates between states under the time dependent incident electromagnetic field and alternately absorbs energy from the incident field while emitting coherent energy via stimulated emission. AMI's Sub-wavelength Focusing Wide Band Super Lens uses a Near-Field SAR, making detection possible at distances greater than ten (10) meters. This super lens is capable of operating on the near-field and focusing electromagnetic waves to resolutions beyond the diffraction limit. When applied to the case of a vehicle approaching an explosive hazard the methodologies of synthetic aperture radar is fused with the array based super resolution and the NQR data processing detecting the explosive hazard.

  2. AgRISTARS. Supporting research: MARS x-band scatterometer

    NASA Technical Reports Server (NTRS)

    Ulaby, F. T. (Principal Investigator); Gabel, P. F., Jr.; Brunfeldt, D. R.

    1981-01-01

    The design, construction, and data collection procedures of the mobile agricultural radar sensor (MARS) x band scatterometer are described. This system is an inexpensive, highly mobile, truck mounted FM-CW radar operating at a center frequency of 10.2 GHz. The antennas, which allow for VV and VH polarizations, are configured in a side looking mode that allows for drive by data collection. This configuration shortens fieldwork time considerably while increasing statistical confidence in the data. Both internal calibration, via a delay line, and external calibration with a Luneberg lens are used to calibrate the instrument in terms of sigma(o). The radar scattering cross section per unit area, sigma(o), is found using the radar equation.

  3. Photographic fireball networks

    NASA Technical Reports Server (NTRS)

    Ceplecha, Z.

    1987-01-01

    Long term radar observations of any meteor shower yield good data for a study of the features of its cross section structure in detail. The hourly rates of meteor echoes represent usually the basic data from which shower characteristics are derived. Unfortunately, the hourly rate does not depend only on the activity of the shower in question but also on the position of the shower radiant, on the mutual radiant antenna position, and on the parameters of the radar system. It is known that the knowledge of the response function of the radar is necessary for good interpretation of the hourly echo counts. A method of long term radar shower data analysis is discussed along with preliminary results.

  4. Nonprincipal plane scattering of flat plates and pattern control of horn antennas

    NASA Technical Reports Server (NTRS)

    Balanis, Constantine A.; Polka, Lesley A.; Liu, Kefeng

    1989-01-01

    Using the geometrical theory of diffraction, the traditional method of high frequency scattering analysis, the prediction of the radar cross section of a perfectly conducting, flat, rectangular plate is limited to principal planes. Part A of this report predicts the radar cross section in nonprincipal planes using the method of equivalent currents. This technique is based on an asymptotic end-point reduction of the surface radiation integrals for an infinite wedge and enables nonprincipal plane prediction. The predicted radar cross sections for both horizontal and vertical polarizations are compared to moment method results and experimental data from Arizona State University's anechoic chamber. In part B, a variational calculus approach to the pattern control of the horn antenna is outlined. The approach starts with the optimization of the aperture field distribution so that the control of the radiation pattern in a range of directions can be realized. A control functional is thus formulated. Next, a spectral analysis method is introduced to solve for the eigenfunctions from the extremal condition of the formulated functional. Solutions to the optimized aperture field distribution are then obtained.

  5. A diagnostic technique used to obtain cross range radiation centers from antenna patterns

    NASA Technical Reports Server (NTRS)

    Lee, T. H.; Burnside, W. D.

    1988-01-01

    A diagnostic technique to obtain cross range radiation centers based on antenna radiation patterns is presented. This method is similar to the synthetic aperture processing of scattered fields in the radar application. Coherent processing of the radiated fields is used to determine the various radiation centers associated with the far-zone pattern of an antenna for a given radiation direction. This technique can be used to identify an unexpected radiation center that creates an undesired effect in a pattern; on the other hand, it can improve a numerical simulation of the pattern by identifying other significant mechanisms. Cross range results for two 8' reflector antennas are presented to illustrate as well as validate that technique.

  6. The Great Astronomical Ear.

    ERIC Educational Resources Information Center

    Hiatt, Blanchard

    1980-01-01

    Presents a description of the world's largest radio/radar antenna, the Areciba Observatory in Puerto Rico. Activities at the observatory are discussed as well as the scientific research in the field of radio astronomy. (SA)

  7. High Temperature Superconductivity Applications for Electronic Warfare and Microwave Systems

    DTIC Science & Technology

    1990-05-01

    instantaneous frequency measurement (IFM), as well as, switched delay lines for EW radar range deception and low loss, high resolution MMIC phase...Junction (JJ). This device has been demonstrated in LTSC and is used in very stable ( low noise ), frequency selective, oscillators and very low noise ...following HTSC components: 1) MMIC Filters 2) MMIC Delay Lines/Phase Shifters 3) Microwave Resonators 4) Antenna Feed Networks 5) Low Frequency Antennas 1

  8. Breast Cancer Nodes Detection Using Ultrasonic Microscale Subarrayed MIMO RADAR

    PubMed Central

    Siwamogsatham, Siwaruk; Pomalaza-Ráez, Carlos

    2014-01-01

    This paper proposes the use of ultrasonic microscale subarrayed MIMO RADARs to estimate the position of breast cancer nodes. The transmit and receive antenna arrays are divided into subarrays. In order to increase the signal diversity each subarray is assigned a different waveform from an orthogonal set. High-frequency ultrasonic transducers are used since a breast is considered to be a superficial structure. Closed form expressions for the optimal Neyman-Pearson detector are derived. The combination of the waveform diversity present in the subarrayed deployment and traditional phased-array RADAR techniques provides promising results. PMID:25309591

  9. Design of a large dual polarized Ku band reflectarray for space borne radar altimeter

    NASA Technical Reports Server (NTRS)

    Hodges, Richard E.; Zawadzki, Mark

    2004-01-01

    We describe the design of a large dual-beam, dual polarized reflectarray designed for a space-based radar altimeter. This application requires a 2.16 X 0.35 m aperture that can be folded for launch stowage. Low mass and >50% efficiency are also required. A reflectarray antenna offers the best approach but also presents unique technical challenges since a reflectarry has never been used in a space based radar application. In what follows, we describe the design, analysis and measurements of a breadboard test array built to demonstrate the reflectarray concept.

  10. Criteria for site selection and frequency allocation (keynote paper), part 5

    NASA Technical Reports Server (NTRS)

    Rottger, J.

    1985-01-01

    Technical aspects of mesosphere-stratosphere-troposphere (MST) Radar on site and frequency selection were discussed. Recommendations on site selections are presented. Tests of interference will be conducted before selecting a site. A small directional antenna may be suitable to simulate sidelobe sensitivity of radars however, sophisticated data-processing methods make system sensitivity extremely good. The use of the complete data system to look for interference is recommended. There is the difficulty of allocation of frequencies -- almost continuous use by these radars will be made when the band 40 to 60 MHz is allocated to other services.

  11. Contents of payload bay of the STS-68 Space Shuttle Endeavour

    NASA Image and Video Library

    1994-09-30

    STS068-267-079 (30 September-11 October 1994) --- The rear windows of the Space Shuttle Endeavour reflect sunlight in this view of part of the cargo bay, 115 nautical miles above the Earth. The Space Radar Laboratory (SRL-2) Multipurpose Experiment Support Structure (MPESS) is seen at bottom frame. Also partially seen are other experiments including other components of the primary payload. They are the antenna for the Spaceborne Imaging Radar (SIR-C), the X-band Synthetic Aperture Radar (X-SAR), the device for Measurement of Air Pollution from Satellites (MAPS) and some Getaway Special (GAS) canisters.

  12. Contents of payload bay of the STS-68 Space Shuttle Endeavour

    NASA Image and Video Library

    1994-09-30

    STS068-272-075 (30 September-11 October 1994) --- The darkness of space forms the backdrop for this scene of the Space Shuttle Endeavour's cargo bay, 115 nautical miles above a cloud covered Indian Ocean. The Space Radar Laboratory (SRL-2) Multipurpose Experiment Support Structure (MPESS) is seen at bottom frame. Also partially seen are other experiments including other components of the primary payload. They are the antenna for the Spaceborne Imaging Radar (SIR-C), the X-band Synthetic Aperture Radar (X-SAR), the device for Measurement of Air Pollution from Satellites (MAPS) and some Getaway Special (GAS) canisters.

  13. Validation of Airborne FMCW Radar Measurements of Snow Thickness Over Sea Ice in Antarctica

    NASA Technical Reports Server (NTRS)

    Galin, Natalia; Worby, Anthony; Markus, Thorsten; Leuschen, Carl; Gogineni, Prasad

    2012-01-01

    Antarctic sea ice and its snow cover are integral components of the global climate system, yet many aspects of their vertical dimensions are poorly understood, making their representation in global climate models poor. Remote sensing is the key to monitoring the dynamic nature of sea ice and its snow cover. Reliable and accurate snow thickness data are currently a highly sought after data product. Remotely sensed snow thickness measurements can provide an indication of precipitation levels, predicted to increase with effects of climate change in the polar regions. Airborne techniques provide a means for regional-scale estimation of snow depth and distribution. Accurate regional-scale snow thickness data will also facilitate an increase in the accuracy of sea ice thickness retrieval from satellite altimeter freeboard estimates. The airborne data sets are easier to validate with in situ measurements and are better suited to validating satellite algorithms when compared with in situ techniques. This is primarily due to two factors: better chance of getting coincident in situ and airborne data sets and the tractability of comparison between an in situ data set and the airborne data set averaged over the footprint of the antennas. A 28-GHz frequency modulated continuous wave (FMCW) radar loaned by the Center for Remote Sensing of Ice Sheets to the Australian Antarctic Division is used to measure snow thickness over sea ice in East Antarctica. Provided with the radar design parameters, the expected performance parameters of the radar are summarized. The necessary conditions for unambiguous identification of the airsnow and snowice layers for the radar are presented. Roughnesses of the snow and ice surfaces are found to be dominant determinants in the effectiveness of layer identification for this radar. Finally, this paper presents the first in situ validated snow thickness estimates over sea ice in Antarctica derived from an FMCW radar on a helicopterborne platform.

  14. The Telecommunications and Data Acquisition Report

    NASA Technical Reports Server (NTRS)

    Posner, E. C. (Editor)

    1989-01-01

    Deep Space Network advanced systems, very large scale integration architecture for decoders, radar interface and control units, microwave time delays, microwave antenna holography, and a radio frequency interference survey are among the topics discussed.

  15. Wide band stepped frequency ground penetrating radar

    DOEpatents

    Bashforth, M.B.; Gardner, D.; Patrick, D.; Lewallen, T.A.; Nammath, S.R.; Painter, K.D.; Vadnais, K.G.

    1996-03-12

    A wide band ground penetrating radar system is described embodying a method wherein a series of radio frequency signals is produced by a single radio frequency source and provided to a transmit antenna for transmission to a target and reflection therefrom to a receive antenna. A phase modulator modulates those portions of the radio frequency signals to be transmitted and the reflected modulated signal is combined in a mixer with the original radio frequency signal to produce a resultant signal which is demodulated to produce a series of direct current voltage signals, the envelope of which forms a cosine wave shaped plot which is processed by a Fast Fourier Transform Unit 44 into frequency domain data wherein the position of a preponderant frequency is indicative of distance to the target and magnitude is indicative of the signature of the target. 6 figs.

  16. A view of the SRTM's 200 ft. boom deployed from OV-105 during STS-99

    NASA Image and Video Library

    2000-02-12

    S99-E-5033 (12 February 2000) --- The 200 ft.-long mast supporting the Shuttle Radar Topography Mission juts into space from the Space Shuttle Endeavour (out of frame at left). The giant structure was deployed earlier today and the antennae on it quickly went to work mapping parts of Earth. By the time members of Endeavour's Red Team had reached lunchtime on this first full day in space for the SRTM, the radar antennae in the payload bay and at the end of long mast had mapped about 1.7 million square miles (4.5 million square kilometers) of the Earth's surface, or the equivalent of about half the area of the United States. This photograph was taken with an electronic still camera (ESC) by a crew member inside Endeavour's cabin.

  17. Surveying glacier bedrock topography with a helicopter-borne dual-polarization ground-penetrating radar system

    NASA Astrophysics Data System (ADS)

    Langhammer, L.; Rabenstein, L.; Schmid, L.; Bauder, A.; Schaer, P.; Maurer, H.

    2017-12-01

    Glacier mass estimations are crucial for future run-off projections in the Swiss Alps. Traditionally, ice thickness modeling approaches and ground-based radar transects have been the tools of choice for estimating glacier volume in high mountain areas, but these methods either contain high uncertainties or are logistically expensive and offer mostly only sparse subsurface information. We have developed a helicopter-borne dual-polarization ground-penetrating radar (GPR) system, which enhances operational feasibility in rough, high-elevation terrain and increases the data output per acquisition campaign significantly. Our system employs a prototype pulseEKKO device with two broadside 25-MHz antenna pairs fixed to a helicopter-towed wooden frame. Additionally attached to the system are a laser altimeter for measuring the flight height above ground, three GPS receivers for accurate positioning and a GoPro camera for obtaining visual images of the surface. Previous investigations have shown the significant impact of the antenna dipole orientation on the detectability of the bedrock reflection. For optimal results, the dipoles of the GPR should be aligned parallel to the strike direction of the surrounding mountain walls. In areas with a generally unknown bedrock topography, such as saddle areas or diverging zones, a dual-polarization system is particularly useful. This could be demonstrated with helicopter-borne GPR profiles acquired on more than 25 glaciers in the Swiss Alps. We observed significant differences in ice-bedrock interface visibility depending on the orientation of the antennas.

  18. C-SIDE: The control-structure interaction demonstration experiment

    NASA Technical Reports Server (NTRS)

    Mohl, James B.; Davis, Hugh W.

    1993-01-01

    The Control-Structure Interaction Demonstration Experiment (C-SIDE) is sponsored by the Electro-Optics and Cryogenics Division of Ball Aerospace Systems Group. Our objective is to demonstrate methods of solution to structure control problems utilizing currently available hardware in a system that is an extension of our corporate experience. The larger space structures with which Ball has been associated are the SEASAT radar antenna, Shuttle Imaging Radar (SIR) -A, -B and -C antennas and the Radarsat spacecraft. The motivation for the C-SIDE configuration is to show that integration of active figure control in the radar's system-level design can relieve antenna mechanical design constraints. This presentation is primarily an introduction to the C-SIDE testbed. Its physical and functional layouts, and major components are described. The sensor is of special interest as it enables direct surface figure measurements from a remote location. The Remote Attitude Measurement System (RAMS) makes high-rate, unobtrusive measurements of many locations, several of which may be collocated easily with actuators. The control processor is a 386/25 executing a reduced order model-based algorithm with provision for residual mode filters to compensate for structure interaction. The actuators for the ground demonstration are non-contacting, linear force devices. Results presented illustrate some basic characteristics of control-structure interaction with this hardware. The testbed will be used for evaluation of current technologies and for research in several areas. A brief indication of the evolution of the C-SIDE is given at the conclusion.

  19. Status of a UAVSAR designed for repeat pass interferometry for deformation measurements

    NASA Technical Reports Server (NTRS)

    Hensley, Scott; Wheeler, Kevin; Sadowy, Greg; Miller, Tim; Shaffer, Scott; Muellerschoen, Ron; Jones, Cathleen; Zebker, Howard; Madsen, Soren; Paul, Rose

    2005-01-01

    NASA's Jet Propulsion Laboratory is currently implementing a reconfigurable polarimetric L-band synthetic aperture radar (SAR), specifically designed to acquire airborne repeat track interferometric (RTI) SAR data, also known as differential interferometric measurements. Differential interferometry can provide key deformation measurements, important for the scientific studies of Earthquakes and volcanoes. Using precision real-time GPS and a sensor controlled flight management system, the system will be able to fly predefined paths with great precision. The expected performance of the flight control system will constrain the flight path to be within a 10 m diameter tube about the desired flight track. The radar wilI be designed to operate on a UAV (Unpiloted Aria1 Vehicle) but will initially be demonstrated on a minimally piloted vehicle (MPV), such as the Proteus buitt by Scaled Composites or on a NASA Gulfstream III. The radar design is a fully polarimetric with an 80 MHz bandwidth (2 m range resolution) and 16 km range swath. The antenna is an electronically steered along track to assure that the actual antenna pointing can be controlled independent of the wind direction and speed. Other features supported by the antenna include an elevation monopulse option and a pulse-to-pulse resteering capability that will enable some novel modes of operation. The system will nominally operate at 45,000 ft (13800 m). The program began out as an Instrument Incubator Project (IIP) funded by NASA Earth Science and Technology Office (ESTO).

  20. Fundamental studies of radar scattering from water surfaces: The Lake Washington experiment

    NASA Technical Reports Server (NTRS)

    Salam, A.; Bush, D.; Gogineni, S.; Zaide, A.

    1991-01-01

    The University of Kansas and the University of Washington conducted a series of experiments during July and August of 1989, and July and August of 1990, to study the effects of various geophysical parameters on radar backscatter. The experiments were conducted from a platform in Lake Washington. Measurements of backscattered power and radar range were made by the University of Kansas, and environmental data such as wind speed, wind direction, and air and water temperature were measured by the University of Washington. Results of preliminary data processing are described. Radar data were acquired using two radars, one that operated at C and X bands and another at Ka band. Measurements were made at W and HH antenna polarizations, at different angles of incidence and under various wind conditions. Plots of backscattered power, normalized radar cross section, and wave height, and the Modulation Transfer Functions of selected data are presented.

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