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Sample records for printed high-frequency phased-array

  1. Fully Printed High-Frequency Phased-Array Antenna on Flexible Substrate

    NASA Technical Reports Server (NTRS)

    Chen, Yihong; Lu, Xuejun

    2010-01-01

    To address the issues of flexible electronics needed for surface-to-surface, surface-to-orbit, and back-to-Earth communications necessary for manned exploration of the Moon, Mars, and beyond, a room-temperature printing process has been developed to create active, phased-array antennas (PAAs) on a flexible Kapton substrate. Field effect transistors (FETs) based on carbon nanotubes (CNTs), with many unique physical properties, were successfully proven feasible for phased-array antenna systems. The carrier mobility of an individual CNT is estimated to be at least 100,000 sq cm/V(dot)s. The CNT network in solution has carrier mobility as high as 46,770 sq cm/V(dot)s, and has a large current-density carrying capacity of approx. 1,000 mA/sq cm , which corresponds to a high carrying power of over 2,000 mW/ sq cm. Such high carrier mobility, and large current carrying capacity, allows the achievement of high-speed (>100 GHz), high-power, flexible electronic circuits that can be monolithically integrated on NASA s active phasedarray antennas for various applications, such as pressurized rovers, pressurized habitats, and spacesuits, as well as for locating beacon towers for lunar surface navigation, which will likely be performed at S-band and attached to a mobile astronaut. A fully printed 2-bit 2-element phasedarray antenna (PAA) working at 5.6 GHz, incorporating the CNT FETs as phase shifters, is demonstrated. The PAA is printed out at room temperature on 100-mm thick Kapton substrate. Four CNT FETs are printed together with microstrip time delay lines to function as a 2-bit phase shifter. The FET switch exhibits a switching speed of 0.2 ns, and works well for a 5.6-GHz RF signal. The operating frequency is measured to be 5.6 GHz, versus the state-of-the-art flexible FET operating frequency of 52 MHz. The source-drain current density is measured to be over 1,000 mA/sq cm, while the conventional organic FETs, and single carbon nanotube-based FETs, are typically in the m

  2. Acoustic trapping with a high frequency linear phased array.

    PubMed

    Zheng, Fan; Li, Ying; Hsu, Hsiu-Sheng; Liu, Changgeng; Tat Chiu, Chi; Lee, Changyang; Ham Kim, Hyung; Shung, K Kirk

    2012-11-19

    A high frequency ultrasonic phased array is shown to be capable of trapping and translating microparticles precisely and efficiently, made possible due to the fact that the acoustic beam produced by a phased array can be both focused and steered. Acoustic manipulation of microparticles by a phased array is advantageous over a single element transducer since there is no mechanical movement required for the array. Experimental results show that 45 μm diameter polystyrene microspheres can be easily and accurately trapped and moved to desired positions by a 64-element 26 MHz phased array.

  3. Acoustic trapping with a high frequency linear phased array

    PubMed Central

    Zheng, Fan; Li, Ying; Hsu, Hsiu-Sheng; Liu, Changgeng; Tat Chiu, Chi; Lee, Changyang; Ham Kim, Hyung; Shung, K. Kirk

    2012-01-01

    A high frequency ultrasonic phased array is shown to be capable of trapping and translating microparticles precisely and efficiently, made possible due to the fact that the acoustic beam produced by a phased array can be both focused and steered. Acoustic manipulation of microparticles by a phased array is advantageous over a single element transducer since there is no mechanical movement required for the array. Experimental results show that 45 μm diameter polystyrene microspheres can be easily and accurately trapped and moved to desired positions by a 64-element 26 MHz phased array. PMID:23258939

  4. Fully Printed, Flexible, Phased Array Antenna for Lunar Surface Communication

    NASA Technical Reports Server (NTRS)

    Subbaraman, Harish; Hen, Ray T.; Lu, Xuejun; Chen, Maggie Yihong

    2013-01-01

    NASAs future exploration missions focus on the manned exploration of the Moon, Mars, and beyond, which will rely heavily on the development of a reliable communications infrastructure from planetary surface-to-surface, surface-to-orbit, and back to Earth. Flexible antennas are highly desired in many scenarios. Active phased array antennas (active PAAs) with distributed control and processing electronics at the surface of an antenna aperture offer numerous advantages for radar communications. Large-area active PAAs on flexible substrates are of particular interest in NASA s space radars due to their efficient inflatable package that can be rolled up during transportation and deployed in space. Such an inflatable package significantly reduces stowage volume and mass. Because of these performance and packaging advantages, large-area inflatable active PAAs are highly desired in NASA s surface-to-orbit and surface-to-relay communications. To address the issues of flexible electronics, a room-temperature printing process of active phased-array antennas on a flexible Kapton substrate was developed. Field effect transistors (FETs) based on carbon nanotubes (CNTs), with many unique physical properties, were successfully proved feasible for the PAA system. This innovation is a new type of fully inkjet-printable, two-dimensional, high-frequency PAA on a flexible substrate at room temperature. The designed electronic circuit components, such as the FET switches in the phase shifter, metal interconnection lines, microstrip transmission lines, etc., are all printed using a special inkjet printer. Using the developed technology, entire 1x4, 2x2, and 4x4 PAA systems were developed, packaged, and demonstrated at 5.3 GHz. Several key solutions are addressed in this work to solve the fabrication issues. The source/drain contact is developed using droplets of silver ink printed on the source/drain areas prior to applying CNT thin-film. The wet silver ink droplets allow the silver to

  5. Design and development of high frequency matrix phased-array ultrasonic probes

    NASA Astrophysics Data System (ADS)

    Na, Jeong K.; Spencer, Roger L.

    2012-05-01

    High frequency matrix phased-array (MPA) probes have been designed and developed for more accurate and repeatable assessment of weld conditions of thin sheet metals commonly used in the auto industry. Unlike the line focused ultrasonic beam generated by a linear phased-array (LPA) probe, a MPA probe can form a circular shaped focused beam in addition to the typical beam steering capabilities of phased-array probes. A CIVA based modeling and simulation method has been used to design the probes in terms of various probe parameters such as number of elements, element size, overall dimensions, frequency etc. Challenges associated with the thicknesses of thin sheet metals have been resolved by optimizing these probe design parameters. A further improvement made on the design of the MPA probe proved that a three-dimensionally shaped matrix element can provide a better performing probe at a much lower probe manufacturing cost by reducing the total number of elements and lowering the operational frequency. This three dimensional probe naturally matches to the indentation shape of the weld on the thin sheet metals and hence a wider inspection area with the same level of spatial resolution obtained by a twodimensional flat MPA probe operating at a higher frequency. The two aspects, a wider inspection area and a lower probe manufacturing cost, make this three-dimensional MPA sensor more attractive to auto manufacturers demanding a quantitative nondestructive inspection method.

  6. PMN-PT single-crystal high-frequency kerfless phased array.

    PubMed

    Chen, Ruimin; Cabrera-Munoz, Nestor E; Lam, Kwok Ho; Hsu, Hsiu-sheng; Zheng, Fan; Zhou, Qifa; Shung, K Kirk

    2014-06-01

    This paper reports the design, fabrication, and characterization of a miniature high-frequency kerfless phased array prepared from a PMN-PT single crystal for forward-looking intravascular or endoscopic imaging applications. After lapping down to around 40 μm, the PMN-PT material was utilized to fabricate 32-element kerfless phased arrays using micromachining techniques. The aperture size of the active area was only 1.0 × 1.0 mm. The measured results showed that the array had a center frequency of 40 MHz, a bandwidth of 34% at -6 dB with a polymer matching layer, and an insertion loss of 20 dB at the center frequency. Phantom images were acquired and compared with simulated images. The results suggest that the feasibility of developing a phased array mounted at the tip of a forward-looking intravascular catheter or endoscope. The fabricated array exhibits much higher sensitivity than PZT ceramic-based arrays and demonstrates that PMN-PT is well suited for this application.

  7. PMN-PT Single-Crystal High-Frequency Kerfless Phased Array

    PubMed Central

    Chen, Ruimin; Cabrera-Munoz, Nestor E.; Lam, Kwok Ho; Hsu, Hsiu-sheng; Zheng, Fan; Zhou, Qifa; Shung, K. Kirk

    2015-01-01

    This paper reports the design, fabrication, and characterization of a miniature high-frequency kerfless phased array prepared from a PMN-PT single crystal for forward-looking intravascular or endoscopic imaging applications. After lapping down to around 40 μm, the PMN-PT material was utilized to fabricate 32-element kerfless phased arrays using micromachining techniques. The aperture size of the active area was only 1.0 × 1.0 mm. The measured results showed that the array had a center frequency of 40 MHz, a bandwidth of 34% at −6 dB with a polymer matching layer, and an insertion loss of 20 dB at the center frequency. Phantom images were acquired and compared with simulated images. The results suggest that the feasibility of developing a phased array mounted at the tip of a forward-looking intravascular catheter or endoscope. The fabricated array exhibits much higher sensitivity than PZT ceramic-based arrays and demonstrates that PMN-PT is well suited for this application. PMID:24859667

  8. Scan blindness in infinite phased arrays of printed dipoles

    NASA Technical Reports Server (NTRS)

    Pozar, D. M.; Schaubert, D. H.

    1984-01-01

    A comprehensive study of infinite phased arrays of printed dipole antennas is presented, with emphasis on the scan blindness phenomenon. A rigorous and efficient moment method procedure is used to calculate the array impedance versus scan angle. Data are presented for the input reflection coefficient for various element spacings and substrate parameters. A simple theory, based on coupling from Floquet modes to surface wave modes on the substrate, is shown to predict the occurrence of scan blindness. Measurements from a waveguide simulator of a blindness condition confirm the theory.

  9. Demonstration of Two-Way Extremely High Frequency (EHF) Satellite Communication (SATCOM) Using Submarine-Survivable Phased Arrays

    DTIC Science & Technology

    2009-01-01

    successfully using both the Military Strategic and Tactical Relay (MILSTAR) and Ultra High Frequency Follow-On ( UFO ) military satellites. The antennas...a Navy-qualified submarine FOT and High Power Amplifier (HPA) system, toward a MILSTAR or UFO EHF satellite. FULL-DUPLEX STATIC TESTING...both the K & Q band phased arrays. Both the MILSTAR and UFO satellites were used for this testing, based on availability. Using the Type 8 Mod 3

  10. High frequency GaAlAs modulator and photodetector for phased array antenna applications

    NASA Technical Reports Server (NTRS)

    Claspy, P. C.; Chorey, C. M.; Hill, S. M.; Bhasin, K. B.

    1989-01-01

    A waveguide Mach-Zehnder electro-optic modulator and an interdigitated photoconductive detector designed to operate at 820 nm, fabricated on different GaAlAs/GaAs heterostructure materials, are being investigated for use in optical interconnects in phased array antenna systems. Measured optical attenuation effects in the modulator are discussed and the observed modulation performance up to 1 GHz is presented. Measurements of detector frequency response are described and results presented.

  11. High frequency GaAlAs modulator and photodetector for phased array antenna applications

    NASA Technical Reports Server (NTRS)

    Claspy, P. C.; Chorey, C. M.; Hill, S. M.; Bhasin, K. B.

    1988-01-01

    A waveguide Mach-Zehnder electro-optic modulator and an interdigitated photoconductive detector designed to operate at 820 nm, fabricated on different GaAlAs/GaAs heterostructure materials, are being investigated for use in optical interconnects in phased array antenna systems. Measured optical attenuation effects in the modulator are discussed and the observed modulation performance up to 1 GHz is presented. Measurements of detector frequency response are described and results presented.

  12. Fabrication and performance of a miniaturized 64-element high-frequency endoscopic phased array.

    PubMed

    Bezanson, Andre; Adamson, Rob; Brown, Jeremy

    2014-01-01

    We have developed a 40-MHz, 64-element phased-array transducer packaged in a 2.5 x 3.1 mm endoscopic form factor. The array is a forward-looking semi-kerfed design based on a 0.68Pb(Mg(1/3)Nb(2/3))O(3) - 0.32PbTiO3 (PMN-32%PT) single-crystal wafer with an element-to-element pitch of 38 µm. To achieve a miniaturized form factor, a novel technique of wire bonding the array elements to a polyimide flexible circuit board oriented parallel to the forward looking ultrasound beam and perpendicular to the array was developed. A technique of partially dicing into the back of the array was also implemented to improve the directivity of the array elements. The array was fabricated with a single-layer P(VDF-TrFE)-copolymer matching layer and a polymethylpentene (TPX) lens for passive elevation focusing to a depth of 7 mm. The two-way -6-dB pulse bandwidth was measured to be 55% and the average electromechanical coupling (k(eff)) for the individual elements was measured to be 0.62. The one-way -6-dB directivities from several array elements were measured to be ±20°, which was shown to be an improvement over an identical kerfless array. The -3-dB elevation focus resulting from the TPX lens was measured to be 152 µm at the focal depth, and the focused lateral resolution was measured to be 80 µm at a steering angle of 0°. To generate beam profiles and images, the probe was connected to a commercial ultrasound imaging platform which was reprogrammed to allow for phased array transmit beamforming and receive data collection. The collected RF data were then processed offline using a numerical computing script to generate sector images. The radiation pattern for the beamformed transmit pulse was collected along with images of wire phantoms in water and tissue-equivalent medium with a dynamic range of 60 dB. Finally, ex vivo tissue images were generated of porcine brain tissue.

  13. A Sub-Nyquist, Variable Sampling, High-Frequency Phased Array Beamformer.

    PubMed

    Samson, Christopher A; Bezanson, Andre; Brown, Jeremy A

    2017-03-01

    A digital receive beamformer implementing a "one sample per pixel" variable sampling technique is described. The sampling method reduces the required sampling rates by a factor of 3, and reduces the data capture rate by a factor of 2, in comparison with the previous systems based on variable sampling. The sampling method is capable of estimating broadband pulse envelopes accurate for bandwidths up to 83.0%. This beamforming method has been implemented on a field-programmable gate array with maximum transmit and receive delay errors measured to be less than ±1.0 ns. The beamformer was tested and verified on a previously described 45-MHz 64-element phased array. The system generates images with 128 lines, 512 pixels per RF line, and 2 transmit focal zones. The system generates images with approximately 55 dB of dynamic range and was tested by imaging wire targets submersed in a water bath, wire targets embedded in a tissue phantom, and real-time in vivo imaging of a human wrist.

  14. Cobalt Nanoparticle Inks for Printed High Frequency Applications on Polycarbonate

    NASA Astrophysics Data System (ADS)

    Nelo, Mikko; Myllymäki, Sami; Juuti, Jari; Uusimäki, Antti; Jantunen, Heli

    2015-12-01

    In this work the high frequency properties of low curing temperature cobalt nanoparticle inks printed on polycarbonate substrates were investigated. The inks consisted of 30-70 vol.% metallic cobalt nanoparticles and poly (methylene methacrylate) polymer, having excellent adhesion on polycarbonate and a curing temperature of 110°C. The influence of binder material content on the electromagnetic properties of the ink was investigated using the shorted microstrip transmission-line perturbation method. Changes in mechanical properties were evaluated with adhesion tests using the pull-out strength test and the ASTM D 3359-B cross-hatch tape peel test. The microstructure of the printed patterns was investigated with field emission scanning electron microscopy (FESEM). The inks remained mechanically durable with metal contents up to 60 vol.%, achieving pull-off strength of up to 5.2 MPa and the highest marks in adhesion of the tape peel test. The inks obtained a relative permeability of 1.5-3 in the 45 MHz-10 GHz band with a magnetic loss tangent of 0.01-0.06. The developed inks can be utilized in various printed electronics applications such as antenna miniaturization, antenna substrates and magnetic sensors or sensing.

  15. X-band printed phased array antennas using high-performance CNT/ion gel/Ag transistors

    NASA Astrophysics Data System (ADS)

    Grubb, Peter M.; Bidoky, Fazel; Mahajan, Ankit; Subbaraman, Harish; Li, Wentao; Frisbie, Daniel; Chen, Ray T.

    2016-05-01

    This paper reports a fully printed phased array antenna developed on a 125 micron thick flexible Kapton substrate. Switching for the phase delay lines is accomplished using printed carbon nanotube transistors with ion gel dielectric layers. Design of each element of the phased array antenna is reported, including a low loss constant impedance power divider, a phase shifter network, and patch antenna design. Steering of an X-band PAA operating at 10GHz from 0 degrees to 22.15 degrees is experimentally demonstrated. In order to completely package the array with electrical interconnects, a single substrate interconnect scheme is also investigated.

  16. Active aperture phased arrays

    NASA Astrophysics Data System (ADS)

    Shenoy, R. P.

    1989-04-01

    Developments towards the realization of active aperture phased arrays are reviewed. The technology and cost aspects of the power amplifier and phase shifter subsystems are discussed. Consideration is given to research concerning T/R modules, MESFETs, side lobe control, beam steering, optical control techniques, and printed circuit antennas. Methods for configuring the array are examined, focusing on the tile and brick configurations. It is found that there is no technological impediment for introducing active aperture phased arrays.

  17. Printed silver nanowire antennas with low signal loss at high-frequency radio.

    PubMed

    Komoda, Natsuki; Nogi, Masaya; Suganuma, Katsuaki; Kohno, Kazuo; Akiyama, Yutaka; Otsuka, Kanji

    2012-05-21

    Silver nanowires are printable and conductive, and are believed to be promising materials in the field of printed electronics. However, the resistivity of silver nanowire printed lines is higher than that of metallic particles or flakes even when sintered at high temperatures of 100-400 °C. Therefore, their applications have been limited to the replacement of transparent electrodes made from high-resistivity materials, such as doped metallic oxides, conductive polymers, carbon nanotubes, or graphenes. Here we report that using printed silver nanowire lines, signal losses obtained in the high-frequency radio were lower than those obtained using etched copper foil antennas, because their surfaces were much smoother than those of etched copper foil antennas. This was the case even though the resistivity of silver nanowire lines was 43-71 μΩ cm, which is much higher than that of etched copper foil (2 μΩ cm). When printed silver nanowire antennas were heated at 100 °C, they achieved signal losses that were much lower than those of silver paste antennas comprising microparticles, nanoparticles, and flakes. Furthermore, using a low temperature process, we succeeded in remotely controlling a commercialized radio-controlled car by transmitting a 2.45 GHz signal via a silver nanowire antenna printed on a polyethylene terephthalate film.

  18. Printed silver nanowire antennas with low signal loss at high-frequency radio

    NASA Astrophysics Data System (ADS)

    Komoda, Natsuki; Nogi, Masaya; Suganuma, Katsuaki; Kohno, Kazuo; Akiyama, Yutaka; Otsuka, Kanji

    2012-05-01

    Silver nanowires are printable and conductive, and are believed to be promising materials in the field of printed electronics. However, the resistivity of silver nanowire printed lines is higher than that of metallic particles or flakes even when sintered at high temperatures of 100-400 °C. Therefore, their applications have been limited to the replacement of transparent electrodes made from high-resistivity materials, such as doped metallic oxides, conductive polymers, carbon nanotubes, or graphenes. Here we report that using printed silver nanowire lines, signal losses obtained in the high-frequency radio were lower than those obtained using etched copper foil antennas, because their surfaces were much smoother than those of etched copper foil antennas. This was the case even though the resistivity of silver nanowire lines was 43-71 μΩ cm, which is much higher than that of etched copper foil (2 μΩ cm). When printed silver nanowire antennas were heated at 100 °C, they achieved signal losses that were much lower than those of silver paste antennas comprising microparticles, nanoparticles, and flakes. Furthermore, using a low temperature process, we succeeded in remotely controlling a commercialized radio-controlled car by transmitting a 2.45 GHz signal via a silver nanowire antenna printed on a polyethylene terephthalate film.Silver nanowires are printable and conductive, and are believed to be promising materials in the field of printed electronics. However, the resistivity of silver nanowire printed lines is higher than that of metallic particles or flakes even when sintered at high temperatures of 100-400 °C. Therefore, their applications have been limited to the replacement of transparent electrodes made from high-resistivity materials, such as doped metallic oxides, conductive polymers, carbon nanotubes, or graphenes. Here we report that using printed silver nanowire lines, signal losses obtained in the high-frequency radio were lower than those

  19. Optically interconnected phased arrays

    NASA Technical Reports Server (NTRS)

    Bhasin, Kul B.; Kunath, Richard R.

    1988-01-01

    Phased-array antennas are required for many future NASA missions. They will provide agile electronic beam forming for communications and tracking in the range of 1 to 100 GHz. Such phased arrays are expected to use several hundred GaAs monolithic integrated circuits (MMICs) as transmitting and receiving elements. However, the interconnections of these elements by conventional coaxial cables and waveguides add weight, reduce flexibility, and increase electrical interference. Alternative interconnections based on optical fibers, optical processing, and holography are under evaluation as possible solutions. In this paper, the current status of these techniques is described. Since high-frequency optical components such as photodetectors, lasers, and modulators are key elements in these interconnections, their performance and limitations are discussed.

  20. Pad-printed thick-film transducers for high-frequency and high-power applications

    NASA Astrophysics Data System (ADS)

    Wolny, Wanda W.; Ketterling, Jeffrey A.; Levassort, Franck; Lou-Moeller, Rasmus; Filoux, Erwan; Mamou, Jonathan; Silverman, Ronald H.; Lethiecq, Marc

    2011-03-01

    High-frequency-ultrasound transducers are widely used but are typically based either on planar piezoceramic sections that are lapped down to smaller thicknesses or on piezopolymers that may be deformed into more complex geometries. Piezoceramics then require dicing to obtain arrays or can be fractured into spherical geometries to achieve focusing. Piezopolymers are not as efficient for very small element sizes and are normally available only in discrete thicknesses. Thick-film (TF) transducers provide a means of overcoming these limits because the piezoelectric film is deposited with the required thickness, size and geometry, thus avoiding any subsequent machining. Thick-film transducers offer the potential of a wide range of geometries such as single-elements and annular or linear arrays. Here, a single-element focused transducer was developed using a piezoceramic composition adapted to high-power operation which is commonly used at standard MHz frequencies. After fabrication, the transducer was characterized. Using specific transmit-receive electronics and a water tank adapted to high-frequency devices, the transducer was excited using a short pulse to evaluate its bandwidth and imaging capabilities. Finally, it was excited by a one-period sine wave using several power levels to evaluate its capacity to produce high-intensity focused ultrasound at frequencies over 20 MHz.

  1. Printed circuit-mounted surge suppressor matched to characteristic impedance of high frequency transmission line

    SciTech Connect

    Bird, A.O.

    1994-01-11

    A surge suppressor for a high frequency transmission line contains a microstrip architecture comprising a dielectric sheet on a first side of which a signal conductor stripe layer is formed and on a second side of which a ground plane conductor layer is formed. The strip layer is disposed along a generally central linear region of the first surface, so as to facilitate direct connection to the center conductor of a pair of end connectors, such as type F coaxial connectors. The ground plane conductor layer is attached to the shield layer of the coaxial connectors. A gas discharge tube is coupled between a first location of the stripe layer and the ground plane layer. The discharge device may be mounted on the first side of the microstrip structure and is connected to the ground plane layer on the opposite surface by way of a plated through hole. The ground plane layer has an aperture of a prescribed area in mutual alignment with the stripe layer so as to effectively remove the distributed capacitance between the stripe layer and the ground plane along a defined length of the stripe. This decrease in the distributed microstrip capacitance coupled with the fact that the removal of ground plane metal leaves the overlying section of the center conductor as a length of inductance compensate for the alteration of the characteristic impedance by the connection of the discharge device between the stripe conductor layer and the ground plane layer. 8 figs.

  2. Adaptive ground implemented phase array

    NASA Technical Reports Server (NTRS)

    Spearing, R. E.

    1973-01-01

    The simulation of an adaptive ground implemented phased array of five antenna elements is reported for a very high frequency system design that is tolerant to the radio frequency interference environment encountered by a tracking data relay satellite. Signals originating from satellites are received by the VHF ring array and both horizontal and vertical polarizations from each of the five elements are multiplexed and transmitted down to ground station. A panel on the transmitting end of the simulation chamber contains up to 10 S-band RFI sources along with the desired signal to simulate the dynamic relationship between user and TDRS. The 10 input channels are summed, and desired and interference signals are separated and corrected until the resultant sum signal-to-interference ratio is maximized. Testing performed with this simulation equipment demonstrates good correlation between predicted and actual results.

  3. Phased array ghost elimination

    PubMed Central

    Kellman, Peter; McVeigh, Elliot R.

    2007-01-01

    Parallel imaging may be applied to cancel ghosts caused by a variety of distortion mechanisms, including distortions such as off-resonance or local flow, which are space variant. Phased array combining coefficients may be calculated that null ghost artifacts at known locations based on a constrained optimization, which optimizes SNR subject to the nulling constraint. The resultant phased array ghost elimination (PAGE) technique is similar to the method known as sensitivity encoding (SENSE) used for accelerated imaging; however, in this formulation is applied to full field-of-view (FOV) images. The phased array method for ghost elimination may result in greater flexibility in designing acquisition strategies. For example, in multi-shot EPI applications ghosts are typically mitigated by the use of an interleaved phase encode acquisition order. An alternative strategy is to use a sequential, non-interleaved phase encode order and cancel the resultant ghosts using PAGE parallel imaging. Cancellation of ghosts by means of phased array processing makes sequential, non-interleaved phase encode acquisition order practical, and permits a reduction in repetition time, TR, by eliminating the need for echo-shifting. Sequential, non-interleaved phase encode order has benefits of reduced distortion due to off-resonance, in-plane flow and EPI delay misalignment. Furthermore, the use of EPI with PAGE has inherent fat-water separation and has been used to provide off-resonance correction using a technique referred to as lipid elimination with an echo-shifting N/2-ghost acquisition (LEENA), and may further generalized using the multi-point Dixon method. Other applications of PAGE include cancelling ghosts which arise due to amplitude or phase variation during the approach to steady state. Parallel imaging requires estimates of the complex coil sensitivities. In vivo estimates may be derived by temporally varying the phase encode ordering to obtain a full k-space dataset in a scheme

  4. Nonlinear phased array imaging

    NASA Astrophysics Data System (ADS)

    Croxford, Anthony J.; Cheng, Jingwei; Potter, Jack N.

    2016-04-01

    A technique is presented for imaging acoustic nonlinearity within a specimen using ultrasonic phased arrays. Acoustic nonlinearity is measured by evaluating the difference in energy of the transmission bandwidth within the diffuse field produced through different focusing modes. The two different modes being classical beam forming, where delays are applied to different element of a phased array to physically focus the energy at a single location (parallel firing) and focusing in post processing, whereby one element at a time is fired and a focused image produced in post processing (sequential firing). Although these two approaches are linearly equivalent the difference in physical displacement within the specimen leads to differences in nonlinear effects. These differences are localized to the areas where the amplitude is different, essentially confining the differences to the focal point. Direct measurement at the focal point are however difficult to make. In order to measure this the diffuse field is used. It is a statistical property of the diffuse field that it represents the total energy in the system. If the energy in the diffuse field for both the sequential and parallel firing case is measured then the difference between these, within the input signal bandwidth, is largely due to differences at the focal spot. This difference therefore gives a localized measurement of where energy is moving out of the transmission bandwidth due to nonlinear effects. This technique is used to image fatigue cracks and other damage types undetectable with conventional linear ultrasonic measurements.

  5. Large phased-array radars

    SciTech Connect

    Brookner, D.E.

    1988-12-15

    Large phased-array radars can play a very important part in arms control. They can be used to determine the number of RVs being deployed, the type of targeting of the RVs (the same or different targets), the shape of the deployed objects, and possibly the weight and yields of the deployed RVs. They can provide this information at night as well as during the day and during rain and cloud covered conditions. The radar can be on the ground, on a ship, in an airplane, or space-borne. Airborne and space-borne radars can provide high resolution map images of the ground for reconnaissance, of anti-ballistic missile (ABM) ground radar installations, missile launch sites, and tactical targets such as trucks and tanks. The large ground based radars can have microwave carrier frequencies or be at HF (high frequency). For a ground-based HF radar the signal is reflected off the ionosphere so as to provide over-the-horizon (OTH) viewing of targets. OTH radars can potentially be used to monitor stealth targets and missile traffic.

  6. Multibeam Phased Array Antennas

    NASA Technical Reports Server (NTRS)

    Popovic, Zoya; Romisch, Stefania; Rondineau, Sebastien

    2004-01-01

    In this study, a new architecture for Ka-band multi-beam arrays was developed and demonstrated experimentally. The goal of the investigation was to demonstrate a new architecture that has the potential of reducing the cost as compared to standard expensive phased array technology. The goals of this specific part of the project, as stated in the yearly statement of work in the original proposal are: 1. Investigate bounds on performance of multi-beam lens arrays in terms of beamwidths, volume (size), isolation between beams, number of simultaneous beams, etc. 2. Design a small-scale array to demonstrate the principle. The array will be designed for operation around 3OGHz (Ka-band), with two 10-degree beamwidth beams. 3. Investigate most appropriate way to accomplish fine-tuning of the beam pointing within 5 degrees around the main beam pointing angle.

  7. Octave Bandwidth Printed Circuit Phased Array Element

    DTIC Science & Technology

    2005-12-01

    superstrate layer over the antenna was also tried in the computer models, it would provide protection from weather, and was found to also improve the...element feed impedance match if the superstrate has a very low dielectric constant such as εr = 1.4 or less. The superstrate does not need any etching...or vias. The best superstrate thickness was about lambda/4 at the top of the band. Syntactic Foam Spacer with Plated-Thru Via Holes The modeling

  8. Optically controlled phased-array technology for space communication systems

    NASA Technical Reports Server (NTRS)

    Kunath, Richard R.; Bhasin, Kul B.

    1988-01-01

    Using MMICs in phased-array applications above 20 GHz requires complex RF and control signal distribution systems. Conventional waveguide, coaxial cable, and microstrip methods are undesirable due to their high weight, high loss, limited mechanical flexibility and large volume. An attractive alternative to these transmission media, for RF and control signal distribution in MMIC phased-array antennas, is optical fiber. Presented are potential system architectures and their associated characteristics. The status of high frequency opto-electronic components needed to realize the potential system architectures is also discussed. It is concluded that an optical fiber network will reduce weight and complexity, and increase reliability and performance, but may require higher power.

  9. Modeling of phased array transducers.

    PubMed

    Ahmad, Rais; Kundu, Tribikram; Placko, Dominique

    2005-04-01

    Phased array transducers are multi-element transducers, where different elements are activated with different time delays. The advantage of these transducers is that no mechanical movement of the transducer is needed to scan an object. Focusing and beam steering is obtained simply by adjusting the time delay. In this paper the DPSM (distributed point source method) is used to model the ultrasonic field generated by a phased array transducer and to study the interaction effect when two phased array transducers are placed in a homogeneous fluid. Earlier investigations modeled the acoustic field for conventional transducers where all transducer points are excited simultaneously. In this research, combining the concepts of delayed firing and the DPSM, the phased array transducers are modeled semi-analytically. In addition to the single transducer modeling the ultrasonic fields from two phased array transducers placed face to face in a fluid medium is also modeled to study the interaction effect. The importance of considering the interaction effect in multiple transducer modeling is discussed, pointing out that neighboring transducers not only act as ultrasonic wave generators but also as scatterers.

  10. Cabling design for phased arrays

    NASA Technical Reports Server (NTRS)

    Kruger, I. D.; Turkiewicz, L.

    1972-01-01

    The ribbon-cabling system used for the AEGIS phased array which provides minimum cable bulk, complete EMI shielding, rugged mechanical design, repeatable electrical characteristics, and ease of assembly and maintenance is described. The ribbon cables are 0.040-inch thick, and in widths up to 2 1/2 inches. Their terminations are molded connectors that can be grouped in a three-tier arrangement, with cable branching accomplished by a matrix-welding technique.

  11. Active membrane phased array radar

    NASA Technical Reports Server (NTRS)

    Moussessian, Alina; Del Castillo, Linda; Huang, John; Sadowy, Greg; Hoffman, James; Smith, Phil; Hatake, Toshiro; Derksen, Chuck; Lopez, Bernardo; Caro, Ed

    2005-01-01

    We have developed the first membrane-based active phased array in L-band (1.26GHz). The array uses membrane compatible Transmit/Receive (T/R) modules (membrane T/R) for each antenna element. We use phase shifters within each T/R module for electronic beam steering. We will discuss the T/R module design and integration with the membrane, We will also present transmit and receive beam-steering results for the array.

  12. Airborne electronically steerable phased array

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The results are presented of the second stage of a program for the design and development of a phased array capable of simultaneous and separate transmission and reception of radio frequency signals at S-band frequencies. The design goals of this stage were the development of three major areas of interest required for the final prototype model. These areas are the construction and testing of the low-weight, full-scale 128-element array of antenna elements, the development of the RF manifold feed system, and the construction and testing of a working module containing diplexer and transmit and receive circuits.

  13. Distributed phased array architecture study

    NASA Technical Reports Server (NTRS)

    Bourgeois, Brian

    1987-01-01

    Variations in amplifiers and phase shifters can cause degraded antenna performance, depending also on the environmental conditions and antenna array architecture. The implementation of distributed phased array hardware was studied with the aid of the DISTAR computer program as a simulation tool. This simulation provides guidance in hardware simulation. Both hard and soft failures of the amplifiers in the T/R modules are modeled. Hard failures are catastrophic: no power is transmitted to the antenna elements. Noncatastrophic or soft failures are modeled as a modified Gaussian distribution. The resulting amplitude characteristics then determine the array excitation coefficients. The phase characteristics take on a uniform distribution. Pattern characteristics such as antenna gain, half power beamwidth, mainbeam phase errors, sidelobe levels, and beam pointing errors were studied as functions of amplifier and phase shifter variations. General specifications for amplifier and phase shifter tolerances in various architecture configurations for C band and S band were determined.

  14. Optical phased-array ladar.

    PubMed

    Montoya, Juan; Sanchez-Rubio, Antonio; Hatch, Robert; Payson, Harold

    2014-11-01

    We demonstrate a ladar with 0.5 m class range resolution obtained by integrating a continuous-wave optical phased-array transmitter with a Geiger-mode avalanche photodiode receiver array. In contrast with conventional ladar systems, an array of continuous-wave sources is used to effectively pulse illuminate a target by electro-optically steering far-field fringes. From the reference frame of a point in the far field, a steered fringe appears as a pulse. Range information is thus obtained by measuring the arrival time of a pulse return from a target to a receiver pixel. This ladar system offers a number of benefits, including broad spectral coverage, high efficiency, small size, power scalability, and versatility.

  15. EHF multifunction phased array antenna

    NASA Astrophysics Data System (ADS)

    Solbach, Klaus

    1986-07-01

    The design of a low cost demonstration EHF multifunction-phased array antenna is described. Both, the radiating elements and the phase-shifter circuits are realized on microstrip substrate material in order to allow photolithographic batch fabrication. Self-encapsulated beam-lead PIN-diodes are employed as the electronic switch elements to avoid expensive hermetic encapsulation of the semiconductors or complete circuits. A space-feed using a horn-radiator to illuminate the array from the front-side is found to be the simplest and most inexpensive feed. The phased array antenna thus operates as a reflect-array, the antenna elements employed in a dual role for the collection of energy from the feed-horn and for the re-radiation of the phase-shifted waves (in transmit-mode). The antenna is divided into modules containing the radiator/phase-shifter plate plus drive- and BITE-circuitry at the back. Both drive- and BITE-components use gate-array integrated circuits especially designed for the purpose. Several bus-systems are used to supply bias and logical data flows to the modules. The beam-steering unit utilizes several signal processors and high-speed discrete adder circuits to combine the pointing, frequency and beam-shape information from the radar system computer with the stored phase-shift codes for the array elements. Since space, weight and power consumption are prime considerations only the most advanced technology is used in the design of both the microwave and the digital/drive circuitry.

  16. Quantitative ultrasonic phased array imaging

    NASA Astrophysics Data System (ADS)

    Engle, Brady J.; Schmerr, Lester W., Jr.; Sedov, Alexander

    2014-02-01

    When imaging with ultrasonic phased arrays, what do we actually image? What quantitative information is contained in the image? Ad-hoc delay-and-sum methods such as the synthetic aperture focusing technique (SAFT) and the total focusing method (TFM) fail to answer these questions. We have shown that a new quantitative approach allows the formation of flaw images by explicitly inverting the Thompson-Gray measurement model. To examine the above questions, we have set up a software simulation test bed that considers a 2-D scalar scattering problem of a cylindrical inclusion with the method of separation of variables. It is shown that in SAFT types of imaging the only part of the flaw properly imaged is the front surface specular response of the flaw. Other responses (back surface reflections, creeping waves, etc.) are improperly imaged and form artifacts in the image. In the case of TFM-like imaging the quantity being properly imaged is an angular integration of the front surface reflectivity. The other, improperly imaged responses are also averaged, leading to a reduction in some of the artifacts present. Our results have strong implications for flaw sizing and flaw characterization with delay-and-sum images.

  17. Proceedings: EPRI Second Phased Array Inspection Seminar

    SciTech Connect

    2001-11-01

    The Second EPRI Phased Array Inspection Seminar focused on industrial applications of phased array technology that have been achieved to date or are planned for the near future. Presentations were made by developers of inspection techniques, inspection services vendors, and utility personnel who have performed inspections using arrays.

  18. Delamination Detection Using Guided Wave Phased Arrays

    NASA Technical Reports Server (NTRS)

    Tian, Zhenhua; Yu, Lingyu; Leckey, Cara

    2016-01-01

    This paper presents a method for detecting multiple delaminations in composite laminates using non-contact phased arrays. The phased arrays are implemented with a non-contact scanning laser Doppler vibrometer (SLDV). The array imaging algorithm is performed in the frequency domain where both the guided wave dispersion effect and direction dependent wave properties are considered. By using the non-contact SLDV array with a frequency domain imaging algorithm, an intensity image of the composite plate can be generated for delamination detection. For the proof of concept, a laboratory test is performed using a non-contact phased array to detect two delaminations (created through quasi-static impact test) at different locations in a composite plate. Using the non-contact phased array and frequency domain imaging, the two impact-induced delaminations are successfully detected. This study shows that the non-contact phased array method is a potentially effective method for rapid delamination inspection in large composite structures.

  19. Method for Fabricating and Packaging an M.Times.N Phased-Array Antenna

    NASA Technical Reports Server (NTRS)

    Subbaraman, Harish (Inventor); Xu, Xiaochuan (Inventor); Chen, Yihong (Inventor); Chen, Ray T. (Inventor)

    2017-01-01

    A method for fabricating an M.times.N, P-bit phased-array antenna on a flexible substrate is disclosed. The method comprising ink jet printing and hardening alignment marks, antenna elements, transmission lines, switches, an RF coupler, and multilayer interconnections onto the flexible substrate. The substrate of the M.times.N, P-bit phased-array antenna may comprise an integrated control circuit of printed electronic components such as, photovoltaic cells, batteries, resistors, capacitors, etc. Other embodiments are described and claimed.

  20. Phased Array Ultrasonic Inspection of Titanium Forgings

    SciTech Connect

    Howard, P.; Klaassen, R.; Kurkcu, N.; Barshinger, J.; Chalek, C.; Nieters, E.; Sun, Zongqi; Fromont, F. de

    2007-03-21

    Aerospace forging inspections typically use multiple, subsurface-focused sound beams in combination with digital C-scan image acquisition and display. Traditionally, forging inspections have been implemented using multiple single element, fixed focused transducers. Recent advances in phased array technology have made it possible to perform an equivalent inspection using a single phased array transducer. General Electric has developed a system to perform titanium forging inspection based on medical phased array technology and advanced image processing techniques. The components of that system and system performance for titanium inspection will be discussed.

  1. A phased array tracking antenna for vehicles

    NASA Technical Reports Server (NTRS)

    Ohmori, Shingo; Mano, Kazukiko; Tanaka, Kenji; Matsunaga, Makoto; Tsuchiya, Makio

    1990-01-01

    An antenna system including antenna elements and a satellite tracking method is considered a key technology in implementing land mobile satellite communications. In the early stage of land mobile satellite communications, a mechanical tracking antenna system is considered the best candidate for vehicles, however, a phased array antenna will replace it in the near future, because it has many attractive advantages such as a low and compact profile, high speed tracking, and potential low cost. Communications Research Laboratory is now developing a new phased array antenna system for land vehicles based on research experiences of the airborne phased array antenna, which was developed and evaluated in satellite communication experiments using the ETS-V satellite. The basic characteristics of the phased array antenna for land vehicles are described.

  2. Microwave properties of sphere-, flake-, and disc-shaped BaFe12O19 nanoparticle inks for high-frequency applications on printed electronics

    NASA Astrophysics Data System (ADS)

    Myllymäki, S.; Maček Kržmanc, M.; Sloma, M.; Juuti, J.; Nelo, M.; Teirikangas, M.; Jakubowska, M.; Suvorov, D.; Jantunen, H.

    2016-12-01

    Spherical (diameter 50-200 nm), flake- (diameter 40-200 nm), and disc-shaped (diameter 10-20 nm) BaFe12O19 nanoparticles were synthesized with a wet chemical method, and their permittivity, electric loss tangent, permeability, and magnetic loss tangent were measured in the 0.045-10 GHz range. The materials were prepared using a solution of 12% PMMA resin in a butyldiglycol solvent for 10-50 wt% filling content. Microstrip transmission-line perturbation was used to measure complex permeability and the split post dielectric resonator method was employed to measure dielectric properties. The frequency dependence of the permeability and permittivity spectra of the composites was affected by their shape and filling fraction. The composites made with spherical particles had higher permeability values (1.4-1.75) at 1 GHz than the composites made with flake (1.25-1.6) or disc particles (1.1-1.3), but the spherical particles caused more losses. The flake particle composite provided permeability and magnetic loss characteristics at both 1 GHz and 7 GHz superior to those of the sphere particle composite in low-loss RF applications. The magnetic loss tangent of PMMA/BaFe12O19 was 0.2-0.3 at 1 GHz, being lower than that of state-of-the-art PANI/BaFe12O19 composites. The sphere composite inks showed permeability values less than 1 at 1-4 GHz ferromagnetic resonance (FMR); they could be used as a tunable material in microwave applications. The sphere and flake composite inks also had sufficient printing quality for the screen-printing fabrication method.

  3. Basis of Ionospheric Modification by High-Frequency Waves

    DTIC Science & Technology

    2007-06-01

    for conducting ionospheric heating experiments in Gakona, Alaska, as part of the High Frequency Active Auroral Research Program ( HAARP ) [5], is being...upgraded. The upgraded HAARP HF transmitting system will be a phased-array antenna of 180 elements. Each element is a cross dipole, which radiates a...supported by the High Frequency Active Auroral Research Program ( HAARP ), the Air Force Research Laboratory at Hanscom Air Force Base, MA, and by the Office

  4. Large-scale nanophotonic phased array.

    PubMed

    Sun, Jie; Timurdogan, Erman; Yaacobi, Ami; Hosseini, Ehsan Shah; Watts, Michael R

    2013-01-10

    Electromagnetic phased arrays at radio frequencies are well known and have enabled applications ranging from communications to radar, broadcasting and astronomy. The ability to generate arbitrary radiation patterns with large-scale phased arrays has long been pursued. Although it is extremely expensive and cumbersome to deploy large-scale radiofrequency phased arrays, optical phased arrays have a unique advantage in that the much shorter optical wavelength holds promise for large-scale integration. However, the short optical wavelength also imposes stringent requirements on fabrication. As a consequence, although optical phased arrays have been studied with various platforms and recently with chip-scale nanophotonics, all of the demonstrations so far are restricted to one-dimensional or small-scale two-dimensional arrays. Here we report the demonstration of a large-scale two-dimensional nanophotonic phased array (NPA), in which 64 × 64 (4,096) optical nanoantennas are densely integrated on a silicon chip within a footprint of 576 μm × 576 μm with all of the nanoantennas precisely balanced in power and aligned in phase to generate a designed, sophisticated radiation pattern in the far field. We also show that active phase tunability can be realized in the proposed NPA by demonstrating dynamic beam steering and shaping with an 8 × 8 array. This work demonstrates that a robust design, together with state-of-the-art complementary metal-oxide-semiconductor technology, allows large-scale NPAs to be implemented on compact and inexpensive nanophotonic chips. In turn, this enables arbitrary radiation pattern generation using NPAs and therefore extends the functionalities of phased arrays beyond conventional beam focusing and steering, opening up possibilities for large-scale deployment in applications such as communication, laser detection and ranging, three-dimensional holography and biomedical sciences, to name just a few.

  5. Optically controlled phased-array antenna technology for space communication systems

    NASA Technical Reports Server (NTRS)

    Kunath, Richard R.; Bhasin, Kul B.

    1988-01-01

    Using MMICs in phased-array applications above 20 GHz requires complex RF and control signal distribution systems. Conventional waveguide, coaxial cable, and microstrip methods are undesirable due to their high weight, high loss, limited mechanical flexibility and large volume. An attractive alternative to these transmission media, for RF and control signal distribution in MMIC phased-array antennas, is optical fiber. Presented are potential system architectures and their associated characteristics. The status of high frequency opto-electronic components needed to realize the potential system architectures is also discussed. It is concluded that an optical fiber network will reduce weight and complexity, and increase reliability and performance, but may require higher power.

  6. 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.

  7. Improved Phased Array Imaging of a Model Jet

    NASA Technical Reports Server (NTRS)

    Dougherty, Robert P.; Podboy, Gary G.

    2010-01-01

    An advanced phased array system, OptiNav Array 48, and a new deconvolution algorithm, TIDY, have been used to make octave band images of supersonic and subsonic jet noise produced by the NASA Glenn Small Hot Jet Acoustic Rig (SHJAR). The results are much more detailed than previous jet noise images. Shock cell structures and the production of screech in an underexpanded supersonic jet are observed directly. Some trends are similar to observations using spherical and elliptic mirrors that partially informed the two-source model of jet noise, but the radial distribution of high frequency noise near the nozzle appears to differ from expectations of this model. The beamforming approach has been validated by agreement between the integrated image results and the conventional microphone data.

  8. An experimental X band phased array

    NASA Astrophysics Data System (ADS)

    Rao, N. P. R.; Limaye, K. U.; Ramalingam, R. P.; Gangadharan, T. S.; Bhandopadhyay, G.; Deshpande, P. A.

    1983-10-01

    The details of an X band experimental 11 x 11 element Phased Array Antenna of phased lens configuration with a monopulse space feed developed at LRDE are presented. The studies carried and the results obtained on collimation, beam steering, pattern variation with scan, array operation in two-dimensional search, dedicated track and track while scan (TWS) are also given.

  9. Proposed Functional Description for Phased Arrays

    NASA Technical Reports Server (NTRS)

    Jackson, Deborah

    1996-01-01

    Generally speaking, many photonic engineers, while working in a systems development mode, still focus on presenting the unique physical details of the optical elements, instead of using functional representation to describe the system. The purpose of this presentation is to introduce symbols that can be used to represent the functional intent of most of the phased array architecture.

  10. Ultrasonic fingerprinting by phased array transducer

    NASA Astrophysics Data System (ADS)

    Sednev, D.; Kataeva, O.; Abramets, V.; Pushenko, P.; Tverdokhlebova, T.

    2016-06-01

    Increasing quantity of spent nuclear fuel that must be under national and international control requires a novel approach to safeguard techniques and equipment. One of the proposed approaches is utilize intrinsic features of casks with spent fuel. In this article an application of a phased array ultrasonic method is considered. This study describes an experimental results on ultrasonic fingerprinting of austenitic steel seam weld.

  11. Optical signal processing of phased array radar

    NASA Astrophysics Data System (ADS)

    Weverka, Robert T.

    This thesis develops optical processors that scale to very high processing speed. Optical signal processing is often promoted on the basis of smaller size, lower weight and lower power consumption as well as higher signal processing speed. While each of these requirements has applications, it is the ones that require processing speed beyond that available in electronics that are most compelling. Thirty years ago, optical processing was the only method fast enough to process Synthetic Aperture Radar (SAR), one of the more demanding signal processing tasks at this time. Since that time electronic processing speed has improved sufficiently to tackle that problem. We have sought out the problems that require significantly higher processing speed and developed optical processors that tackle these more difficult problems. The components that contribute to high signal processing speed are high input signal bandwidth, a large number of parallel input channels each with this high bandwidth, and a large number of parallel operations required on each input channel. Adaptive signal processing for phased array radar has all of these factors. The processors developed for this task scale well in three dimensions, which allows them to maximize parallelism for high speed. This thesis explores an example of a negative feedback adaptive phased array processor and an example of a positive feedback phased array processor. The negative feedback processor uses and array of inputs in up to two dimensions together with the time history of the signal in the third dimension to adapt the array pattern to null out incoming jammer signals. The positive feedback processor uses the incoming signals and assumptions about the radar scene to correct for position errors in a phased array. Discovery and analysis of these new processors are facilitated by an original volume holographic analysis technique developed in the thesis. The thesis includes a new acoustooptic Bragg cell geometry developed with

  12. Control of the necrosed tissue volume during noninvasive ultrasound surgery using a 16-element phased array.

    PubMed

    Fan, X; Hynynen, K

    1995-03-01

    Focused high-power ultrasound beams are well suited for noninvasive local destruction of deep target volumes. In order to avoid cavitation and to utilize only thermal tissue damage, high frequencies (1-5 MHz) are used in ultrasonic surgery. However, the focal spots generated by sharply focused transducers become so small that only small tumors can be treated in a reasonable time. Phased array ultrasound transducers can be employed to electronically scan a focal spot or to produce multiple foci in the desired region to increase the treated volume. In this article, theoretical and experimental studies of spherically curved square-element phased arrays for use in ultrasonic surgery were performed. The simulation results were compared with experimental results from a 16-element array. It was shown that the phased array could control the necrosed tissue volume by using closely spaced multiple foci. The phased array can also be used to enlarge a necrosed tissue volume in only one direction at a time, i.e., lateral or longitudinal. The spherically curved 16 square-element phased array can produce useful results by varying the phase and amplitude setting. Four focal points can be easily generated with a distance of two or four wavelengths between the two closest peaks. The maximum necrosed tissue volume generated by the array can be up to sixteen times the volume induced by a similar spherical transducer. Therefore the treatment time could be reduced compared with single transducer treatment.

  13. MSAT-X electronically steered phased array antenna system

    NASA Technical Reports Server (NTRS)

    Chung, H. H.; Foy, W.; Schaffner, G.; Pagels, W.; Vayner, M.; Nelson, J.; Peng, S. Y.

    1988-01-01

    A low profile electronically steered phased array was successfully developed for the Mobile Satellite Experiment Program (MSAT-X). The newly invented cavity-backed printed crossed-slot was used as the radiating element. The choice of this element was based on its low elevation angle gain coverage and low profile. A nineteen-way radial type unequal power divider and eighteen three-bit diode phase shifters constitute the beamformer module which is used to scan the beams electronically. A complete hybrid mode pointing system was also developed. The major features of the antenna system are broad coverage, low profile, and fast acquisition and tracking performance, even under fading conditions. Excellent intersatellite isolation (better than 26 dB) was realized, which will provide good quality mobile satellite communication in the future.

  14. Development of a C-Scan phased array ultrasonic imaging system using a 64-element 35MHz transducer

    NASA Astrophysics Data System (ADS)

    Zheng, Fan; Hu, Changhong; Zhang, Lequan; Snook, Kevin; Liang, Yu; Hackenberger, Wesley S.; Liu, Ruibin; Geng, Xuecang; Jiang, Xiaoning; Shung, K. Kirk

    2011-04-01

    Phased array imaging systems provide the features of electronic beam steering and dynamic depth focusing that cannot be obtained with conventional linear array systems. This paper presents a system design of a digital ultrasonic imaging system, which is capable of handling a 64-element 35MHz center frequency phased array transducer. The system consists of 5 parts: an analog front-end, a data digitizer, a DSP based beamformer, a computer controlled motorized linear stage, and a computer for post image processing and visualization. Using a motorized linear stage, C-scan images, parallel to the surface of scanned objects may be generated. This digital ultrasonic imaging system in combination a 35 MHz phased array appears to be a promising tool for NDT applications with high spatial resolution. It may also serve as an excellent research platform for high frequency phased array design and testing as well as ultrasonic array signal algorithm developing using system's raw RF data acquisition function.

  15. Ka-Band Phased Array System Characterization

    NASA Technical Reports Server (NTRS)

    Acosta, R.; Johnson, S.; Sands, O.; Lambert, K.

    2001-01-01

    Phased Array Antennas (PAAs) using patch-radiating elements are projected to transmit data at rates several orders of magnitude higher than currently offered with reflector-based systems. However, there are a number of potential sources of degradation in the Bit Error Rate (BER) performance of the communications link that are unique to PAA-based links. Short spacing of radiating elements can induce mutual coupling between radiating elements, long spacing can induce grating lobes, modulo 2 pi phase errors can add to Inter Symbol Interference (ISI), phase shifters and power divider network introduce losses into the system. This paper describes efforts underway to test and evaluate the effects of the performance degrading features of phased-array antennas when used in a high data rate modulation link. The tests and evaluations described here uncover the interaction between the electrical characteristics of a PAA and the BER performance of a communication link.

  16. Photorefractive processing for large adaptive phased arrays

    NASA Astrophysics Data System (ADS)

    Weverka, Robert T.; Wagner, Kelvin; Sarto, Anthony

    1996-03-01

    An adaptive null-steering phased-array optical processor that utilizes a photorefractive crystal to time integrate the adaptive weights and null out correlated jammers is described. This is a beam-steering processor in which the temporal waveform of the desired signal is known but the look direction is not. The processor computes the angle(s) of arrival of the desired signal and steers the array to look in that direction while rotating the nulls of the antenna pattern toward any narrow-band jammers that may be present. We have experimentally demonstrated a simplified version of this adaptive phased-array-radar processor that nulls out the narrow-band jammers by using feedback-correlation detection. In this processor it is assumed that we know a priori only that the signal is broadband and the jammers are narrow band. These are examples of a class of optical processors that use the angular selectivity of volume holograms to form the nulls and look directions in an adaptive phased-array-radar pattern and thereby to harness the computational abilities of three-dimensional parallelism in the volume of photorefractive crystals. The development of this processing in volume holographic system has led to a new algorithm for phased-array-radar processing that uses fewer tapped-delay lines than does the classic time-domain beam former. The optical implementation of the new algorithm has the further advantage of utilization of a single photorefractive crystal to implement as many as a million adaptive weights, allowing the radar system to scale to large size with no increase in processing hardware.

  17. A Phased Array Magnetometer for Sensing IED

    DTIC Science & Technology

    2008-02-04

    of information is estimated to average 1 tiour per response, including the time for reviewing instructions, searching existing data sources, gathering...Device Organization (JIEDDO) (Contract No: FA9550-07- 1 -0107) Program Dr. Byung-Lip "Les" Lee Manager Project Title A Phased Array...Los Angeles, CA 90095-1597 Voice: 310-825-6030 Fax:310-206-2302 1 . OVERALL OBJECTIVE The objective of this project was to develop the fundamental

  18. Technology Development for Millimeter Wave Phased Arrays.

    DTIC Science & Technology

    1987-05-01

    design would use the technology of integration-the same technology that has brought us computing power at such a low cost. The integrated phased array ...circuitry and/or the feed network, which can degrade sidelobe levels or polarization. A Two Layer Substrate Figure 2.8 shows a possible two-layer design ...feed substrates. Coupling is again through aper- tures in the ground plane of the antenna substrate. This design also allows the use of a low dielectric

  19. RADIATION CHARACTERISTICS OF A GENERALIZED PHASED ARRAY

    NASA Technical Reports Server (NTRS)

    Acosta, R. J.

    1994-01-01

    The phased array has become a key component in the design of advanced antenna systems. This computer program was developed to examine the radiation characteristics of a generalized phased array antenna. Using a very efficient numerical technique, this program calculates the array's radiated power and its directivity. The results can be used to determine the radiation pattern of a generalized phased array at near- or far-field observation points. This program is a key research tool at the NASA Lewis Research Center for analyzing advanced space communication antenna systems. Results from this program compare favorably with experimental Lewis results for arrays of 2x2 and 3x3 elements. Given the array geometry and element characteristics, generalized phased array attributes can be broken into two areas: 1) the power radiated and its directivity at any given point, and 2) the co- and cross-polarization field components. This program allows arbitrarily located source elements with an analytically described cosine pattern. The formulation is based on a Romberg integration scheme and takes into account arbitrary element polarization, E and H plane element patterns, and mutual coupling. The input consists of the array geometry; phase, amplitude, linear and circular polarization of each source element; and the cosine functions of the element pattern. The output is a series of observation angles with their associated field magnitude and polarizations. Total radiated power and peak directivity are also calculated. This program is written in FORTRAN IV for batch execution and has been implemented on an IBM 370 computer operating under TSS with a central memory requirement of approximately 22K of 8 bit bytes. The IBM Scientific Subroutine Package (SSP) is required to run the program. This program was developed in 1986.

  20. A MRI rotary phased array head coil.

    PubMed

    Li, Bing Keong; Weber, Ewald; Crozier, Stuart

    2013-08-01

    A new rotary phased array (RPA) head coil that can provide homogenous brain images comparable to volumetric radiofrequency coils is proposed for magnetic resonance brain imaging applications. The design of the RPA head coil is a departure from conventional circumferential array design method, as coil elements of the RPA head coil have a "paddle-like" structure consisting of a pair of main conductors located on opposite sides, inserted equi-angularly around and over the head. A prototype 2T receive-only 4-element RPA head coil was constructed and experimentally tested against a conventional receive-only 4-element phased array head coil and a commercial receive-only quadrature birdcage head coil. Homogenous phantom images acquired by the RPA head coil show that signal intensity deep at the center of the phantom was improved as compared to the conventional phased array head coil and this improvement allow the RPA head coil to acquire homogenous brain images similar to brain images acquired with the birdcage head coil. In addition, partial parallel imaging was used in conjunction with the RPA head coil to enable rapid imaging.

  1. Phased array-fed antenna configuration study

    NASA Technical Reports Server (NTRS)

    Crosswell, W. F.; Ball, D. E.; Taylor, R. C.

    1983-01-01

    The scope of this contract entails a configuration study for a phased array fed transmit antenna operating in the frequency band of 17.7 to 20.2 GHz. This initial contract provides a basis for understanding the design limitations and advantages of advanced phased array and cluster feeds (both utilizing intergral MMIC modules) illuminating folded reflector optics (both near field and focused types). Design parametric analyses are performed utilizing as constraints the objective secondary performance requirements of the Advanced Communications Technology Satellite (Table 1.0). The output of the study provides design information which serves as a data base for future active phased array fed antenna studies such as detailed designs required to support the development of a ground tested breadboard. In general, this study is significant because it provides the antenna community with an understanding of the basic principles which govern near field phased scanned feed effects on secondary reflector system performance. Although several articles have been written on analysis procedures and results for these systems, the authors of this report have observed phenomenon of near field antenna systems not previously documented. Because the physical justification for the exhibited performance is provided herein, the findings of this study add a new dimension to the available knowledge of the subject matter.

  2. Proceedings of the Third EPRI Phased Array Ultrasound Seminar

    SciTech Connect

    2003-12-01

    Phased array technology for ultrasonic examination is providing innovative solutions for nuclear in-service examination applications. EPRI has been a prime mover in the development and deployment of phased array ultrasound applications in the domestic nuclear market over the past decade. As part of this strategic effort, EPRI has hosted a series of seminars on phased array technology and its applications.

  3. Design of a K-Band Transmit Phased Array For Low Earth Orbit Satellite Communications

    NASA Technical Reports Server (NTRS)

    Watson, Thomas; Miller, Stephen; Kershner, Dennis; Anzic, Godfrey

    2000-01-01

    The design of a light weight, low cost phased array antenna is presented. Multilayer printed wiring board (PWB) technology is utilized for Radio Frequencies (RF) and DC/Logic manifold distribution. Transmit modules are soldered on one side and patch antenna elements are on the other, allowing the use of automated assembly processes. The 19 GHz antenna has two independently steerable beams, each capable of transferring data at 622 Mbps. A passive, self-contained phase change thermal management system is also presented.

  4. Phased array antenna matching: Simulation and optimization of a planar phased array of circular waveguide elements

    NASA Technical Reports Server (NTRS)

    Dudgeon, J. E.

    1972-01-01

    A computerized simulation of a planar phased array of circular waveguide elements is reported using mutual coupling and wide angle impedance matching in phased arrays. Special emphasis is given to circular polarization. The aforementioned computer program has as variable inputs: frequency, polarization, grid geometry, element size, dielectric waveguide fill, dielectric plugs in the waveguide for impedance matching, and dielectric sheets covering the array surface for the purpose of wide angle impedance matching. Parameter combinations are found which produce reflection peaks interior to grating lobes, while dielectric cover sheets are successfully employed to extend the usable scan range of a phased array. The most exciting results came from the application of computer aided optimization techniques to the design of this type of array.

  5. Wide Angle Liquid Crystal Optical Phased Array

    NASA Technical Reports Server (NTRS)

    Wang, Xing-Hua; Wang, Bin; Bos, Philip J.; Anderson, James E.; Pouch, John J.; Miranda, Felix A.; McManamon, Paul F.

    2004-01-01

    Accurate modeling of a high resolution, liquid crystal (LC) based, optical phased array (OPA) is shown. The simulation shows excellent agreement with a test 2-D LC OPA. The modeling method is extendable to cases where the array element size is close to the wavelength of light. The fringing fields of such a device are first studied, and subsequently reduced. This results in a device that demonstrates plus or minus 7.4 degrees of continuous beam steering at a wavelength of 1550 nm, and a diffraction efficiency (DE) higher than 72%.

  6. Phased array performance evaluation with photoelastic visualization

    SciTech Connect

    Ginzel, Robert; Dao, Gavin

    2014-02-18

    New instrumentation and a widening range of phased array transducer options are affording the industry a greater potential. Visualization of the complex wave components using the photoelastic system can greatly enhance understanding of the generated signals. Diffraction, mode conversion and wave front interaction, together with beam forming for linear, sectorial and matrix arrays, will be viewed using the photoelastic system. Beam focus and steering performance will be shown with a range of embedded and surface targets within glass samples. This paper will present principles and sound field images using this visualization system.

  7. An Optical Phased Array for LIDAR

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Wu, M. C.

    2016-11-01

    We have previously demonstrated the development of an Optical Phased Array (OPA) micromechanical system (MEMS) used for beam steering, which shows great advantages over previous mechanisms such as opto-mechanical, acousto-optical (AO) or electro-optical (EO). We aim to integrate the OPA MEMS system into the application of automobile navigation, which is currently primarily dominated by opto-mechanical scanning based systems. Opto-mechanical scanning devices are usually bulky and relatively slow, while competing technologies (AO, EO) utilize devices that while small in size, cannot provide the steering speeds and versatility necessary for many applications. In drawing from phased array concepts that revolutionized RADAR technology by providing a compact, agile alternative to mechanically steered technology, the OPA based LIDAR program seeks to integrate thousands of closely packed optical emitting facets, precise relative electronic phase control of these facets, and all within a very small form factor. Comparing with other competing LIDAR system, the OPA based LIDAR system will have multiple degrees of freedom for phase control which enables not only agile beam steering but also beam forming and multiple beam generation, greatly expanding the diversity of applications.

  8. High frequency reference electrode

    DOEpatents

    Kronberg, James W.

    1994-01-01

    A high frequency reference electrode for electrochemical experiments comprises a mercury-calomel or silver-silver chloride reference electrode with a layer of platinum around it and a layer of a chemically and electrically resistant material such as TEFLON around the platinum covering all but a small ring or "halo" at the tip of the reference electrode, adjacent to the active portion of the reference electrode. The voltage output of the platinum layer, which serves as a redox electrode, and that of the reference electrode are coupled by a capacitor or a set of capacitors and the coupled output transmitted to a standard laboratory potentiostat. The platinum may be applied by thermal decomposition to the surface of the reference electrode. The electrode provides superior high-frequency response over conventional electrodes.

  9. High frequency reference electrode

    DOEpatents

    Kronberg, J.W.

    1994-05-31

    A high frequency reference electrode for electrochemical experiments comprises a mercury-calomel or silver-silver chloride reference electrode with a layer of platinum around it and a layer of a chemically and electrically resistant material such as TEFLON around the platinum covering all but a small ring or halo' at the tip of the reference electrode, adjacent to the active portion of the reference electrode. The voltage output of the platinum layer, which serves as a redox electrode, and that of the reference electrode are coupled by a capacitor or a set of capacitors and the coupled output transmitted to a standard laboratory potentiostat. The platinum may be applied by thermal decomposition to the surface of the reference electrode. The electrode provides superior high-frequency response over conventional electrodes. 4 figs.

  10. [High frequency ultrasound].

    PubMed

    Sattler, E

    2015-07-01

    Diagnostic ultrasound has become a standard procedure in clinical dermatology. Devices with intermediate high frequencies of 7.5-15 MHz are used in dermato-oncology for the staging and postoperative care of skin tumor patients and in angiology for improved vessel diagnostics. In contrast, the high frequency ultrasound systems with 20-100 MHz probes offer a much higher resolution, yet with a lower penetration depth of about 1 cm. The main indications are the preoperative measurements of tumor thickness in malignant melanoma and other skin tumors and the assessment of inflammatory and soft tissue diseases, offering information on the course of these dermatoses and allowing therapy monitoring. This article gives an overview on technical principles, devices, mode of examination, influencing factors, interpretation of the images, indications but also limitations of this technique.

  11. Optimizing an ELF/VLF Phased Array at HAARP

    NASA Astrophysics Data System (ADS)

    Fujimaru, S.; Moore, R. C.

    2013-12-01

    The goal of this study is to maximize the amplitude of 1-5 kHz ELF/VLF waves generated by ionospheric HF heating and measured at a ground-based ELF/VLF receiver. The optimization makes use of experimental observations performed during ELF/VLF wave generation experiments at the High-frequency Active Auroral Research Program (HAARP) Observatory in Gakona, Alaska. During these experiments, the amplitude, phase, and propagation delay of the ELF/VLF waves were carefully measured. The HF beam was aimed at 15 degrees zenith angle in 8 different azimuthal directions, equally spaced in a circle, while broadcasting a 3.25 MHz (X-mode) signal that was amplitude modulated (square wave) with a linear frequency-time chirp between 1 and 5 kHz. The experimental observations are used to provide reference amplitudes, phases, and propagation delays for ELF/VLF waves generated at these specific locations. The presented optimization accounts for the trade-off between duty cycle, heated area, and the distributed nature of the source region in order to construct a "most efficient" phased array. The amplitudes and phases generated by modulated heating at each location are combined in post-processing to find an optimal combination of duty cycle, heating location, and heating order.

  12. Quantitative flaw characterization with ultrasonic phased arrays

    NASA Astrophysics Data System (ADS)

    Engle, Brady John

    Ultrasonic nondestructive evaluation (NDE) is a critical diagnostic tool in many industries. It is used to characterize potentially dangerous flaws in critical components for aerospace, automotive, and energy applications. The use of phased array transducers allows for the extension of traditional techniques and the introduction of new methods for quantitative flaw characterization. An equivalent flaw sizing technique for use in time-of-flight diffraction setups is presented that provides an estimate of the size and orientation of isolated cracks, surface-breaking cracks, and volumetric flaws such as voids and inclusions. Experimental validation is provided for the isolated crack case. A quantitative imaging algorithm is developed that corrects for system effects and wave propagation, making the images formed directly related to the properties of the scatterer present. Simulated data is used to form images of cylindrical and spherical inclusions. The contributions of different signals to the image formation process are discussed and examples of the quantitative nature of the images are shown.

  13. A Phased Array Approach to Rock Blasting

    SciTech Connect

    Leslie Gertsch; Jason Baird

    2006-07-01

    A series of laboratory-scale simultaneous two-hole shots was performed in a rock simulant (mortar) to record the shock wave interference patterns produced in the material. The purpose of the project as a whole was to evaluate the usefulness of phased array techniques of blast design, using new high-precision delay technology. Despite high-speed photography, however, we were unable to detect the passage of the shock waves through the samples to determine how well they matched the expected interaction geometry. The follow-up mine-scale tests were therefore not conducted. Nevertheless, pattern analysis of the vectors that would be formed by positive interference of the shockwaves from multiple charges in an ideal continuous, homogeneous, isotropic medium indicate the potential for powerful control of blast design, given precise characterization of the target rock mass.

  14. PHASED ARRAY FEED CALIBRATION, BEAMFORMING, AND IMAGING

    SciTech Connect

    Landon, Jonathan; Elmer, Michael; Waldron, Jacob; Jones, David; Stemmons, Alan; Jeffs, Brian D.; Warnick, Karl F.; Richard Fisher, J.; Norrod, Roger D.

    2010-03-15

    Phased array feeds (PAFs) for reflector antennas offer the potential for increased reflector field of view and faster survey speeds. To address some of the development challenges that remain for scientifically useful PAFs, including calibration and beamforming algorithms, sensitivity optimization, and demonstration of wide field of view imaging, we report experimental results from a 19 element room temperature L-band PAF mounted on the Green Bank 20 Meter Telescope. Formed beams achieved an aperture efficiency of 69% and a system noise temperature of 66 K. Radio camera images of several sky regions are presented. We investigate the noise performance and sensitivity of the system as a function of elevation angle with statistically optimal beamforming and demonstrate cancelation of radio frequency interference sources with adaptive spatial filtering.

  15. Photonic Multitasking Interleaved Si Nanoantenna Phased Array.

    PubMed

    Lin, Dianmin; Holsteen, Aaron L; Maguid, Elhanan; Wetzstein, Gordon; Kik, Pieter G; Hasman, Erez; Brongersma, Mark L

    2016-12-14

    Metasurfaces provide unprecedented control over light propagation by imparting local, space-variant phase changes on an incident electromagnetic wave. They can improve the performance of conventional optical elements and facilitate the creation of optical components with new functionalities and form factors. Here, we build on knowledge from shared aperture phased array antennas and Si-based gradient metasurfaces to realize various multifunctional metasurfaces capable of achieving multiple distinct functions within a single surface region. As a key point, we demonstrate that interleaving multiple optical elements can be accomplished without reducing the aperture of each subelement. Multifunctional optical elements constructed from Si-based gradient metasurface are realized, including axial and lateral multifocus geometric phase metasurface lenses. We further demonstrate multiwavelength color imaging with a high spatial resolution. Finally, optical imaging functionality with simultaneous color separation has been obtained by using multifunctional metasurfaces, which opens up new opportunities for the field of advanced imaging and display.

  16. Wavelet Analysis for Acoustic Phased Array

    NASA Astrophysics Data System (ADS)

    Kozlov, Inna; Zlotnick, Zvi

    2003-03-01

    Wavelet spectrum analysis is known to be one of the most powerful tools for exploring quasistationary signals. In this paper we use wavelet technique to develop a new Direction Finding (DF) Algorithm for the Acoustic Phased Array (APA) systems. Utilising multi-scale analysis of libraries of wavelets allows us to work with frequency bands instead of individual frequency of an acoustic source. These frequency bands could be regarded as features extracted from quasistationary signals emitted by a noisy object. For detection, tracing and identification of a sound source in a noisy environment we develop smart algorithm. The essential part of this algorithm is a special interacting procedure of the above-mentioned DF-algorithm and the wavelet-based Identification (ID) algorithm developed in [4]. Significant improvement of the basic properties of a receiving APA pattern is achieved.

  17. Multiband Photonic Phased-Array Antenna

    NASA Technical Reports Server (NTRS)

    Tang, Suning

    2015-01-01

    A multiband phased-array antenna (PAA) can reduce the number of antennas on shipboard platforms while offering significantly improved performance. Crystal Research, Inc., has developed a multiband photonic antenna that is based on a high-speed, optical, true-time-delay beamformer. It is capable of simultaneously steering multiple independent radio frequency (RF) beams in less than 1,000 nanoseconds. This high steering speed is 3 orders of magnitude faster than any existing optical beamformer. Unlike other approaches, this technology uses a single controlling device per operation band, eliminating the need for massive optical switches, laser diodes, and fiber Bragg gratings. More importantly, only one beamformer is needed for all antenna elements.

  18. 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.

  19. COMPOSITE CERAMIC ARMOR DEFECT ANALYSIS USING PHASED ARRAY ULTRASOUND

    DTIC Science & Technology

    2011-01-30

    background variation. Such an approximation applied to the FFT results of Conclusion Phased - array ultrasonic inspection methods have been...SNR values above 2.55) were statistically defective either. CONCLUSION Phased - array ultrasonic inspection methods have been successfully applied to...4 G.P. Singh and J. W. Davies, “Multiple Transducer Ultrasonic Techniques: Phased Arrays ” In Nondestructive Testing Handbook, 2nd Ed., 7, pp. 284

  20. MMIC devices for active phased array antennas

    NASA Technical Reports Server (NTRS)

    Mittra, R.

    1985-01-01

    Considerable progress has been made in the calculation and measurement of the scattering parameters of printed circuit discontinuities. These discontinuities occur in a variety of structures, such as transitions between rectangular waveguide and printed circuits, junctions between circuits of different dielectric constants, and filters and impedance matching circuits. Because of the variety of devices in which these discontinuities occur, it is very useful to understand them in as great a detail as possible. Both theoretical and experimental studies of discontinuities were considered. The theoretical studies have focused on finding ways to predict the scattering from discontinuities. The experimental studies have concentrated on developing measurement techniques for determining the scattering parameters of these discontinuities.

  1. Development of a 20-MHz wide-bandwidth PMN-PT single crystal phased-array ultrasound transducer.

    PubMed

    Wong, Chi-Man; Chen, Yan; Luo, Haosu; Dai, Jiyan; Lam, Kwok-Ho; Chan, Helen Lai-Wa

    2017-01-01

    In this study, a 20-MHz 64-element phased-array ultrasound transducer with a one-wavelength pitch is developed using a PMN-30%PT single crystal and double-matching layer scheme. High piezoelectric (d33>1000pC/N) and electromechanical coupling (k33>0.8) properties of the single crystal with an optimized fabrication process involving the photolithography technique have been demonstrated to be suitable for wide-bandwidth (⩾70%) and high-sensitivity (insertion loss ⩽30dB) phased-array transducer application. A -6dBbandwidth of 91% and an insertion loss of 29dBfor the 20-MHz 64-element phased-array transducer were achieved. This result shows that the bandwidth is improved comparing with the investigated high-frequency (⩾20MHz) ultrasound transducers using piezoelectric ceramic and single crystal materials. It shows that this phased-array transducer has potential to improve the resolution of biomedical imaging, theoretically. Based on the hypothesis of resolution improvement, this phased-array transducer is capable for small animal (i.e. mouse and zebrafish) studies.

  2. MMIC Phased Array Demonstrations with ACTS

    NASA Technical Reports Server (NTRS)

    Raquet, Charles A. (Compiler); Martzaklis, Konstantinos (Compiler); Zakrajsek, Robert J. (Compiler); Andro, Monty (Compiler); Turtle, John P.

    1996-01-01

    Over a one year period from May 1994 to May 1995, a number of demonstrations were conducted by the NASA Lewis Research Center (LeRC) in which voice, data, and/or video links were established via NASA's advanced communications technology satellite (ACTS) between the ACTS link evaluation terminal (LET) in Cleveland, OH, and aeronautical and mobile or fixed Earth terminals having monolithic microwave integrated circuit (MMIC) phased array antenna systems. This paper describes four of these. In one, a duplex voice link between an aeronautical terminal on the LeRC Learjet and the ACTS was achieved. Two others demonstrated duplex voice (and in one case video as well) links between the ACTS and an Army vehicle. The fourth demonstrated a high data rate downlink from ACTS to a fixed terminal. Array antenna systems used in these demonstrations were developed by LeRC and featured LeRC and Air Force experimental arrays using gallium arsenide MMIC devices at each radiating element for electronic beam steering and distributed power amplification. The single 30 GHz transmit array was developed by NASA/LeRC and Texas Instruments. The three 20 GHz receive arrays were developed in a cooperative effort with the Air Force Rome Laboratory, taking advantage of existing Air Force array development contracts with Boeing and Lockheed Martin. The paper describes the four proof-of-concept arrays and the array control system. The system configured for each of the demonstrations is described, and results are discussed.

  3. Phased Array Transmit Antenna for a Satellite

    NASA Technical Reports Server (NTRS)

    Huggins, R. W.; Heisen, P. T.; Miller, G. E.; McMeen, D. J.; Perko, K. L.

    1999-01-01

    Active phased array antennas with electronically scanned beams offer advantages over high gain parabolic dish antennas currently used on spacecraft. Benefits include the elimination of deployable structures, no moving parts, and no torque disturbances that moving antennas impart to the spacecraft. The latter results in the conservation of spacecraft power, and the ability to take precision optical data while transmitting data. Such an antenna has been built under a contract from NASA Goddard Space Flight Center for the New Millennium Program EO- 1 satellite where it will act as the primary highspeed scientific data communication link. The antenna operates at X-band, has an integral controller and power conditioner, communicates with the spacecraft over a 1773 optical data bus, and is space qualified for low earth orbit (705 Km altitude). The nominal mission length is one year, and the operational requirement is for one 10 minute transmission a day over Spitsbergen, Norway. Details of the antenna and its performance will be described in the following paper.

  4. Ultrasonic phased array transducers for nondestructive evaluation of steel structures

    NASA Astrophysics Data System (ADS)

    Song, Sung-Jin; Shin, Hyeon Jae; Jang, You Hyun

    2000-05-01

    An ultrasonic phased array transducer has been developed and demonstrated for the nondestructive evaluation of steel structures. The number of array elements is 64 and the center frequency is about 5 MHz. This phased array transducer is designed to use with the phased array system that does steering, transmission focusing and dynamic receive focusing. Each of the array elements is individually excited according to the focal laws and steering angles. Measurements of ultrasonic beam profiles for the array transducer in a reference steel block are presented and compared with theoretical predictions. Some of the phased array transducer design concepts for the application in steel structures are discussed. The two-dimensional ultrasonic images of the sample steel block including flat bottom holes and side drilled holes are presented. Experimental and theoretical results demonstrate excellent feasibility of the utility of the phased array transducer in imaging and detection of defects in steel structures.

  5. Phased-Array Study of Dual-Flow Jet Noise: Effect of Nozzles and Mixers

    NASA Technical Reports Server (NTRS)

    Soo Lee, Sang; Bridges, James

    2006-01-01

    A 16-microphone linear phased-array installed parallel to the jet axis and a 32-microphone azimuthal phased-array installed in the nozzle exit plane have been applied to identify the noise source distributions of nozzle exhaust systems with various internal mixers (lobed and axisymmetric) and nozzles (three different lengths). Measurements of velocity were also obtained using cross-stream stereo particle image velocimetry (PIV). Among the three nozzle lengths tested, the medium length nozzle was the quietest for all mixers at high frequency on the highest speed flow condition. Large differences in source strength distributions between nozzles and mixers occurred at or near the nozzle exit for this flow condition. The beamforming analyses from the azimuthal array for the 12-lobed mixer on the highest flow condition showed that the core flow and the lobe area were strong noise sources for the long and short nozzles. The 12 noisy spots associated with the lobe locations of the 12-lobed mixer with the long nozzle were very well detected for the frequencies 5 KHz and higher. Meanwhile, maps of the source strength of the axisymmetric splitter show that the outer shear layer was the most important noise source at most flow conditions. In general, there was a good correlation between the high turbulence regions from the PIV tests and the high noise source regions from the phased-array measurements.

  6. Extremely high frequency RF effects on electronics.

    SciTech Connect

    Loubriel, Guillermo Manuel; Vigliano, David; Coleman, Phillip Dale; Williams, Jeffery Thomas; Wouters, Gregg A.; Bacon, Larry Donald; Mar, Alan

    2012-01-01

    The objective of this work was to understand the fundamental physics of extremely high frequency RF effects on electronics. To accomplish this objective, we produced models, conducted simulations, and performed measurements to identify the mechanisms of effects as frequency increases into the millimeter-wave regime. Our purpose was to answer the questions, 'What are the tradeoffs between coupling, transmission losses, and device responses as frequency increases?', and, 'How high in frequency do effects on electronic systems continue to occur?' Using full wave electromagnetics codes and a transmission-line/circuit code, we investigated how extremely high-frequency RF propagates on wires and printed circuit board traces. We investigated both field-to-wire coupling and direct illumination of printed circuit boards to determine the significant mechanisms for inducing currents at device terminals. We measured coupling to wires and attenuation along wires for comparison to the simulations, looking at plane-wave coupling as it launches modes onto single and multiconductor structures. We simulated the response of discrete and integrated circuit semiconductor devices to those high-frequency currents and voltages, using SGFramework, the open-source General-purpose Semiconductor Simulator (gss), and Sandia's Charon semiconductor device physics codes. This report documents our findings.

  7. High-frequency ECG

    NASA Technical Reports Server (NTRS)

    Tragardh, Elin; Schlegel, Todd T.

    2006-01-01

    The standard ECG is by convention limited to 0.05-150 Hz, but higher frequencies are also present in the ECG signal. With high-resolution technology, it is possible to record and analyze these higher frequencies. The highest amplitudes of the high-frequency components are found within the QRS complex. In past years, the term "high frequency", "high fidelity", and "wideband electrocardiography" have been used by several investigators to refer to the process of recording ECGs with an extended bandwidth of up to 1000 Hz. Several investigators have tried to analyze HF-QRS with the hope that additional features seen in the QRS complex would provide information enhancing the diagnostic value of the ECG. The development of computerized ECG-recording devices that made it possible to record ECG signals with high resolution in both time and amplitude, as well as better possibilities to store and process the signals digitally, offered new methods for analysis. Different techniques to extract the HF-QRS have been described. Several bandwidths and filter types have been applied for the extraction as well as different signal-averaging techniques for noise reduction. There is no standard method for acquiring and quantifying HF-QRS. The physiological mechanisms underlying HF-QRS are still not fully understood. One theory is that HF-QRS are related to the conduction velocity and the fragmentation of the depolarization wave in the myocardium. In a three-dimensional model of the ventricles with a fractal conduction system it was shown that high numbers of splitting branches are associated with HF-QRS. In this experiment, it was also shown that the changes seen in HF-QRS in patients with myocardial ischemia might be due to the slowing of the conduction velocity in the region of ischemia. This mechanism has been tested by Watanabe et al by infusing sodium channel blockers into the left anterior descending artery in dogs. In their study, 60 unipolar ECGs were recorded from the entire

  8. Coplanar waveguide feeds for phased array antennas

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Lee, Richard Q.

    1992-01-01

    The design and performance of the following coplanar waveguide (CPW) microwave distribution networks for linear as well as circularly polarized microstrip patches and printed dipole arrays is presented: (1) CPW/microstrip line feed; (2) CPW/balanced stripline feed; (3) CPW/slotline feed; (4) grounded CPW (GCPW)/balanced coplanar stripline feed; and (5) CPW/slot coupled feed. Typical measured radiation patterns are presented, and their relative advantages and disadvantages are compared.

  9. Simulation of Temperature Field Induced by 8-Element Phased Array HIFU Transducer with Concave Spherical Surface

    NASA Astrophysics Data System (ADS)

    Sun, Wujun; Zhang, Ping; Zhang, Xiaojing; Jian, Xiqi; Li, Zhihua

    2011-09-01

    Multi-element High Intensity Focused Ultrasound (HIFU) transducers can change their focal lengths and form multi-foci. In this paper the Westervelt formula and Pennes bio-heat transfer equation have been used along, with the Finite Difference Time Domain (FDTD) method, to study the temperature distribution induced by an 8-element phased array HIFU transducer inside the human body. We evaluated the effects of the gap in the arc between two rings, the frequency of excitation function and pre-focal length on the temperature field. For HIFU therapy, skin burns were caused by high frequency, small pre-focal length, or a big gap between two rings. The focal region may be no longer an ellipsoid due to high frequency. In addition, the actual focal length is slightly different from the pre-focal length.

  10. S-band antenna phased array communications system

    NASA Technical Reports Server (NTRS)

    Delzer, D. R.; Chapman, J. E.; Griffin, R. A.

    1975-01-01

    The development of an S-band antenna phased array for spacecraft to spacecraft communication is discussed. The system requirements, antenna array subsystem design, and hardware implementation are examined. It is stated that the phased array approach offers the greatest simplicity and lowest cost. The objectives of the development contract are defined as: (1) design of a medium gain active phased array S-band communications antenna, (2) development and test of a model of a seven element planar array of radiating elements mounted in the appropriate cavity matrix, and (3) development and test of a breadboard transmit/receive microelectronics module.

  11. Phased array ultrasonic inspection of Friction Stir Weldments

    NASA Astrophysics Data System (ADS)

    Lamarre, André; Moles, Michael; Lupien, Vincent

    2000-05-01

    Phased array ultrasonic inspection methods have been developed for the rapid inspection of Friction Stir Weldments (FSW) on Delta rocket cryogenic tanks. A comprehensive review was performed to identify NDE methods that are suitable for the detection of defects in this new welding process. The search included a review of traditional and advanced NDE methods that were capable of demonstrating both the sensitivity and inspection rates required for this examination. This paper will discuss the theory behind phased array techniques, fundamentals of several probe designs for FSW configurations, and the advantages of using phased arrays over conventional NDE methods for this applications.

  12. Cracks measurement using fiber-phased array laser ultrasound generation

    NASA Astrophysics Data System (ADS)

    Pei, Cuixiang; Demachi, Kazuyuki; Fukuchi, Tetsuo; Koyama, Kazuyoshi; Uesaka, Mitsuru

    2013-04-01

    A phased array laser ultrasound generation system by using fiber optic delivery and a custom-designed focusing objective lens has been developed for crack inspection. The enhancement of crack tip diffraction by using phased array laser ultrasound is simulated with finite element method and validated by experiment. A non-contact and non-destructive measurement of inner-surface cracks by time-of-flight diffraction method using fiber-phased array laser ultrasound generation and electromagnetic acoustic transducer detection has been studied.

  13. An inkjet vision measurement technique for high-frequency jetting.

    PubMed

    Kwon, Kye-Si; Jang, Min-Hyuck; Park, Ha Yeong; Ko, Hyun-Seok

    2014-06-01

    Inkjet technology has been used as manufacturing a tool for printed electronics. To increase the productivity, the jetting frequency needs to be increased. When using high-frequency jetting, the printed pattern quality could be non-uniform since the jetting performance characteristics including the jetting speed and droplet volume could vary significantly with increases in jet frequency. Therefore, high-frequency jetting behavior must be evaluated properly for improvement. However, it is difficult to measure high-frequency jetting behavior using previous vision analysis methods, because subsequent droplets are close or even merged. In this paper, we present vision measurement techniques to evaluate the drop formation of high-frequency jetting. The proposed method is based on tracking target droplets such that subsequent droplets can be excluded in the image analysis by focusing on the target droplet. Finally, a frequency sweeping method for jetting speed and droplet volume is presented to understand the overall jetting frequency effects on jetting performance.

  14. An inkjet vision measurement technique for high-frequency jetting

    SciTech Connect

    Kwon, Kye-Si Jang, Min-Hyuck; Park, Ha Yeong; Ko, Hyun-Seok

    2014-06-15

    Inkjet technology has been used as manufacturing a tool for printed electronics. To increase the productivity, the jetting frequency needs to be increased. When using high-frequency jetting, the printed pattern quality could be non-uniform since the jetting performance characteristics including the jetting speed and droplet volume could vary significantly with increases in jet frequency. Therefore, high-frequency jetting behavior must be evaluated properly for improvement. However, it is difficult to measure high-frequency jetting behavior using previous vision analysis methods, because subsequent droplets are close or even merged. In this paper, we present vision measurement techniques to evaluate the drop formation of high-frequency jetting. The proposed method is based on tracking target droplets such that subsequent droplets can be excluded in the image analysis by focusing on the target droplet. Finally, a frequency sweeping method for jetting speed and droplet volume is presented to understand the overall jetting frequency effects on jetting performance.

  15. MMIC devices for active phased array antennas

    NASA Technical Reports Server (NTRS)

    Mittra, R.

    1984-01-01

    The study of printed circuit discontinuities is necessary in order to design, for example, transitions between rectangular waveguides and printed circuits. New developments with respect to the analytical approaches to this problem are discussed. A summary of the progress in the experimental approach is presented. The accurate solution for the modes in various millimeter-wave waveguides is essential in the analysis of many integrated circuit components, such as filters and impedance transformers. Problems associated with the numerical computation of these modes in two frequently used waveguide forms, namely, the finline and microstrip, are presented. The spectral domain method of formulation, with a moment method solution, is considered. This approach can be readily extended to analyze an arbitrary configuration of dielectric and metallized regions in a shielded enclosure. Galerkin's method is used, where the testing and basic functions are the same. It is shown that the mode functions, or eigenfunctions, are more sensitive to errors than the phase constants, or eigenvalues. The approximate mode functions do not satisfy the orthogonality relationship well, resulting in difficulties when these modal solutions are used to form an approximate Green's function or are used in a mode matching analysis.

  16. Phased-array sources based on nonlinear metamaterial nanocavities

    SciTech Connect

    Wolf, Omri; Campione, Salvatore; Benz, Alexander; Ravikumar, Arvind P.; Liu, Sheng; Luk, Ting S.; Kadlec, Emil Andrew; Shaner, Eric A.; Klem, John Frederick; Sinclair, Michael B.; Brener, Igal

    2015-07-01

    Coherent superposition of light from subwavelength sources is an attractive prospect for the manipulation of the direction, shape and polarization of optical beams. This phenomenon constitutes the basis of phased arrays, commonly used at microwave and radio frequencies. Here we propose a new concept for phased-array sources at infrared frequencies based on metamaterial nanocavities coupled to a highly nonlinear semiconductor heterostructure. Optical pumping of the nanocavity induces a localized, phase-locked, nonlinear resonant polarization that acts as a source feed for a higher-order resonance of the nanocavity. Varying the nanocavity design enables the production of beams with arbitrary shape and polarization. As an example, we demonstrate two second harmonic phased-array sources that perform two optical functions at the second harmonic wavelength (~5 μm): a beam splitter and a polarizing beam splitter. As a result, proper design of the nanocavity and nonlinear heterostructure will enable such phased arrays to span most of the infrared spectrum.

  17. [Modeling and simulation of responses from ultrasonic linear phased array].

    PubMed

    He, Wenjing; Zhu, Yuanzhong; Wang, Yufeng; He, Lingli; Lai, Siyu

    2012-10-01

    Phased array transducers are very attractive because the beam generated by the arrays can be electronically focused and steered. The present work characterizes far-field 2D properties of phased array system by functions that are deduced from rectangle source, rectangle line array and phased array based on point source. Results are presented for the distribution of ultrasound intensity on plane xoz and on x-axis by simulation using numerical calculation. It is shown that the shape of response of rectangle line array is modulated by the single array element. It is also demonstrated that the delay time of phased array is the key to steer the beam, sacrificing the value of main lobe and increasing the number of side lobes.

  18. Laser-scanning photoacoustic microscopy with ultrasonic phased array transducer.

    PubMed

    Zheng, Fan; Zhang, Xiangyang; Chiu, Chi Tat; Zhou, Bill L; Shung, K Kirk; Zhang, Hao F; Jiao, Shuliang

    2012-11-01

    In this paper, we report our latest progress on proving the concept that ultrasonic phased array can improve the detection sensitivity and field of view (FOV) in laser-scanning photoacoustic microscopy (LS-PAM). A LS-PAM system with a one-dimensional (1D) ultrasonic phased array was built for the experiments. The 1D phased array transducer consists of 64 active elements with an overall active dimension of 3.2 mm × 2 mm. The system was tested on imaging phantom and mouse ear in vivo. Experiments showed a 15 dB increase of the signal-to-noise ratio (SNR) when beamforming was employed compared to the images acquired with each single element. The experimental results demonstrated that ultrasonic phased array can be a better candidate for LS-PAM in high sensitivity applications like ophthalmic imaging.

  19. Phased-array sources based on nonlinear metamaterial nanocavities.

    PubMed

    Wolf, Omri; Campione, Salvatore; Benz, Alexander; Ravikumar, Arvind P; Liu, Sheng; Luk, Ting S; Kadlec, Emil A; Shaner, Eric A; Klem, John F; Sinclair, Michael B; Brener, Igal

    2015-07-01

    Coherent superposition of light from subwavelength sources is an attractive prospect for the manipulation of the direction, shape and polarization of optical beams. This phenomenon constitutes the basis of phased arrays, commonly used at microwave and radio frequencies. Here we propose a new concept for phased-array sources at infrared frequencies based on metamaterial nanocavities coupled to a highly nonlinear semiconductor heterostructure. Optical pumping of the nanocavity induces a localized, phase-locked, nonlinear resonant polarization that acts as a source feed for a higher-order resonance of the nanocavity. Varying the nanocavity design enables the production of beams with arbitrary shape and polarization. As an example, we demonstrate two second harmonic phased-array sources that perform two optical functions at the second harmonic wavelength (∼5 μm): a beam splitter and a polarizing beam splitter. Proper design of the nanocavity and nonlinear heterostructure will enable such phased arrays to span most of the infrared spectrum.

  20. Phase Noise in Photonic Phased-Array Antenna Systems

    NASA Technical Reports Server (NTRS)

    Logan, Ronald T., Jr.; Maleki, Lute

    1998-01-01

    The total noise of a phased-array antenna system employing a photonic feed network is analyzed using a model for the individual component noise including both additive and multiplicative equivalent noise generators.

  1. Laser-scanning photoacoustic microscopy with ultrasonic phased array transducer

    PubMed Central

    Zheng, Fan; Zhang, Xiangyang; Chiu, Chi Tat; Zhou, Bill L.; Shung, K. Kirk; Zhang, Hao F.; Jiao, Shuliang

    2012-01-01

    In this paper, we report our latest progress on proving the concept that ultrasonic phased array can improve the detection sensitivity and field of view (FOV) in laser-scanning photoacoustic microscopy (LS-PAM). A LS-PAM system with a one-dimensional (1D) ultrasonic phased array was built for the experiments. The 1D phased array transducer consists of 64 active elements with an overall active dimension of 3.2 mm × 2 mm. The system was tested on imaging phantom and mouse ear in vivo. Experiments showed a 15 dB increase of the signal-to-noise ratio (SNR) when beamforming was employed compared to the images acquired with each single element. The experimental results demonstrated that ultrasonic phased array can be a better candidate for LS-PAM in high sensitivity applications like ophthalmic imaging. PMID:23162708

  2. Coherent optical monolithic phased-array antenna steering system

    DOEpatents

    Hietala, Vincent M.; Kravitz, Stanley H.; Vawter, Gregory A.

    1994-01-01

    An optical-based RF beam steering system for phased-array antennas comprising a photonic integrated circuit (PIC). The system is based on optical heterodyning employed to produce microwave phase shifting by a monolithic PIC constructed entirely of passive components. Microwave power and control signal distribution to the antenna is accomplished by optical fiber, permitting physical separation of the PIC and its control functions from the antenna. The system reduces size, weight, complexity, and cost of phased-array antenna systems.

  3. Genetic Algorithms as a Tool for Phased Array Radar Design

    DTIC Science & Technology

    2002-06-01

    NAVAL POSTGRADUATE SCHOOL Monterey, California THESIS Approved for public release; distribution is unlimited. GENETIC ALGORITHMS AS A...REPORT DATE June 2002 3. REPORT TYPE AND DATES COVERED Master’s Thesis 4. TITLE AND SUBTITLE: Genetic Algorithms as a Tool for Phased Array Radar...creative ways to design multi-function phased array radars. This thesis proposes that Genetic Algorithms, computer programs that mimic natural selection

  4. MSAT mobile electronically steered phased array antenna development

    NASA Technical Reports Server (NTRS)

    Schmidt, Fred

    1988-01-01

    The Mobile Satellite Experiment (MSAT-X) breadboard antenna design demonstrates the feasibility of using a phased array in a mobile satellite application. An electronically steerable phased array capable of tracking geosynchronous satellites from anywhere in the Continental United States has been developed. The design is reviewed along with the test data. Cost analysis are presented which indicate that this design can be produced at a cost of $1620 per antenna.

  5. Designing of Phased Array Transducers for Industrial Applications

    NASA Astrophysics Data System (ADS)

    Dumas, Ph.; Poguet, J.; Fleury, G.

    2004-02-01

    By increasing inspection speed, and deflection capabilities of the transducers, Phased-array technology has proved its interest to face new ∂ NDT challenges, and is becoming more and more popular in the main industrial fields of activities. This paper describes the main effects of specifications on transducer performances, and explains how to defined them. The second part speaks about the manufacturing step, showing the influence of component choice on performances. Several Phased-array applications examples illustrating these considerations will be presented.

  6. Optimizing Satellite Communications With Adaptive and Phased Array Antennas

    NASA Technical Reports Server (NTRS)

    Ingram, Mary Ann; Romanofsky, Robert; Lee, Richard Q.; Miranda, Felix; Popovic, Zoya; Langley, John; Barott, William C.; Ahmed, M. Usman; Mandl, Dan

    2004-01-01

    A new adaptive antenna array architecture for low-earth-orbiting satellite ground stations is being investigated. These ground stations are intended to have no moving parts and could potentially be operated in populated areas, where terrestrial interference is likely. The architecture includes multiple, moderately directive phased arrays. The phased arrays, each steered in the approximate direction of the satellite, are adaptively combined to enhance the Signal-to-Noise and Interference-Ratio (SNIR) of the desired satellite. The size of each phased array is to be traded-off with the number of phased arrays, to optimize cost, while meeting a bit-error-rate threshold. Also, two phased array architectures are being prototyped: a spacefed lens array and a reflect-array. If two co-channel satellites are in the field of view of the phased arrays, then multi-user detection techniques may enable simultaneous demodulation of the satellite signals, also known as Space Division Multiple Access (SDMA). We report on Phase I of the project, in which fixed directional elements are adaptively combined in a prototype to demodulate the S-band downlink of the EO-1 satellite, which is part of the New Millennium Program at NASA.

  7. Optoelectronic signal processing for phased-array antennas II; Proceedings of the Meeting, Los Angeles, CA, Jan. 16, 17, 1990

    NASA Astrophysics Data System (ADS)

    Hendrickson, Brian M.; Koepf, Gerhard A.

    Various papers on optoelectronic signal processing for phased-array antennas (PAAs) are presented. Individual topics addressed include: the dynamics of high-frequency lasers, an electrooptic phase modulator for PA applications, a laser mixer for microwave fiber optics, optical control of microwaves with III-V semiconductor optical waveguides, a high-dynamic-range modulator for microwave PAs, the high-modulation-rate potential of surface-emitter laser-diode arrays, an electrooptical switch for antenna beam steering, and adaptive PA radar processing using photorefractive crystals. Also discussed are an optical processor for array antenna beam shaping and steering, an integrated optical Butler matrix for beam forming in PAAs, an acoustooptic/photorefractive processor for adaptive antenna arrays, BER testing of fiber-optic data links for MMIC-based phased-array antennas, and the design of an optically controlled K(a)-band GaAs MMIC PAA.

  8. Full-matrix capture with a customizable phased array instrument

    NASA Astrophysics Data System (ADS)

    Dao, Gavin; Braconnier, Dominique; Gruber, Matt

    2015-03-01

    In recent years, a technique known as Full-Matrix Capture (FMC) has gained some headway in the NDE community for phased array applications. It's important to understand that FMC is the method that the instrumentation acquires the ultrasonic signals, but further post-processing is required in software to create a meaningful image for a particular application. Having a flexible software interface, small form factor, excellent signal-to-noise ratio per acquisition channel on a 64/64 or 128/128 phased array module with FMC capability proves beneficial in both industrial implementation and in further investigation of post-processing techniques. This paper will provide an example of imaging with a 5MHz linear phased array transducer with 128 elements using FMC and a popular post-processing algorithm known as Total-Focus Method (TFM).

  9. Phased Array Radiometer Calibration Using a Radiated Noise Source

    NASA Technical Reports Server (NTRS)

    Srinivasan, Karthik; Limaye, Ashutoch S.; Laymon, Charles A.; Meyer, Paul J.

    2010-01-01

    Electronic beam steering capability of phased array antenna systems offer significant advantages when used in real aperture imaging radiometers. The sensitivity of such systems is limited by the ability to accurately calibrate variations in the antenna circuit characteristics. Passive antenna systems, which require mechanical rotation to scan the beam, have stable characteristics and the noise figure of the antenna can be characterized with knowledge of its physical temperature [1],[2]. Phased array antenna systems provide the ability to electronically steer the beam in any desired direction. Such antennas make use of active components (amplifiers, phase shifters) to provide electronic scanning capability while maintaining a low antenna noise figure. The gain fluctuations in the active components can be significant, resulting in substantial calibration difficulties [3]. In this paper, we introduce two novel calibration techniques that provide an end-to-end calibration of a real-aperture, phased array radiometer system. Empirical data will be shown to illustrate the performance of both methods.

  10. Optical phased arrays with evanescently-coupled antennas

    DOEpatents

    Sun, Jie; Watts, Michael R; Yaacobi, Ami; Timurdogan, Erman

    2015-03-24

    An optical phased array formed of a large number of nanophotonic antenna elements can be used to project complex images into the far field. These nanophotonic phased arrays, including the nanophotonic antenna elements and waveguides, can be formed on a single chip of silicon using complementary metal-oxide-semiconductor (CMOS) processes. Directional couplers evanescently couple light from the waveguides to the nanophotonic antenna elements, which emit the light as beams with phases and amplitudes selected so that the emitted beams interfere in the far field to produce the desired pattern. In some cases, each antenna in the phased array may be optically coupled to a corresponding variable delay line, such as a thermo-optically tuned waveguide or a liquid-filled cell, which can be used to vary the phase of the antenna's output (and the resulting far-field interference pattern).

  11. Phased arrays for satellites and the TDRSS antennas

    NASA Astrophysics Data System (ADS)

    Imbriale, W. A.

    The design and performance of satellite phased-array systems are examined by considering several specific antennas built for spacecraft use. Particular consideration is given to: (1) the JARED (Jammer Reduction Antenna System) antenna, and adaptive phased array which can be used to null jammer signals while providing coverage to specific user areas; (2) the algorithm used in the JARED antenna; and (3) a technique that can be used to detect and locate jammers. The antennas used by the Tracking and Data Relay Satellite System (TDRSS) are then described. A significant aspect of the TDRSS is the multiple access antenna which is a 30-element phased array, providing a single steered beam on transmit and the ability to receive data from 20 simultaneous users. Also included on the TDRSS is a mesh deployable reflector and a C-band and K-band communications system.

  12. A 35 MHz PCMUT phased array for NDE ultrasound

    NASA Astrophysics Data System (ADS)

    Snook, Kevin; Jiang, Xiaoning; Hu, Changhong; Geng, Xuecang; Liu, Ruibin; Welter, John; Shung, Kirk; Hackenberger, Wesley S.

    2009-03-01

    In this paper, the development of a 35 MHz 64-channel Piezoelectric Composite based Micromachined Ultrasound Transducer (PCMUT) phased array for NDE ultrasound application is presented. A 35 MHz PMN-PT single crystal 1-3 composite based PC-MUT phased array was designed with extensive acoustic field and 1D modeling. The initial modeling results demonstrated that the focused detection resolution (10% of -3 dB beam width) could be as small as 30 μm in the azimuth direction. The maximum imaging depth for ceramic samples is around 20 mm. The PC-MUT array being developed will extend the state-of-art NDE phased array technology from approximately 20 MHz to 35 MHz, which will greatly enhance the imaging resolution for a broad range of NDE ultrasound applications.

  13. Reconfigurable Wave Velocity Transmission Lines for Phased Arrays

    NASA Technical Reports Server (NTRS)

    Host, Nick; Chen, Chi-Chih; Volakis, John L.; Miranda, Felix

    2013-01-01

    Phased array antennas showcase many advantages over mechanically steered systems. However, they are also more complex, heavy and most importantly costly. This presentation paper presents a concept which overcomes these detrimental attributes by eliminating all of the phase array backend (including phase shifters). Instead, a wave velocity reconfigurable transmission line is used in a series fed array arrangement to allow phase shifting with one small (100mil) mechanical motion. Different configurations of the reconfigurable wave velocity transmission line are discussed and simulated and experimental results are presented.

  14. Ultrasonic Phased-Array Characterization for NDE Applications

    NASA Technical Reports Server (NTRS)

    Hanley, John J.; Tennis, Richard F.; Pickens, Keith S.

    1995-01-01

    Southwest Research Institute (SwRI) recently fabricated and delivered the 100-channel Ultrasonic Phased-Array Testbed System (UPATS) for NASA's Langley Research Center. NASA prepared the specifications and provided the funding to develop UPATS in order to provide a tool for the improvement of ultrasonic nondestructive evaluation (NDE) and characterization of materials. UPATS incorporates state-of-the-art phased-array concepts such as beam steering, focusing, apodization, and phase-sensitive detection which make it possible to develop more sophisticated testing methodologies. It also can be used to investigate fundamental ultrasonic propagation and detection phenomena such as refraction, diffraction, scattering, and beam broadening.

  15. Microwave power transmitting phased array antenna research project

    NASA Technical Reports Server (NTRS)

    Dickinson, R. M.

    1978-01-01

    An initial design study and the development results of an S band RF power transmitting phased array antenna experiment system are presented. The array was to be designed, constructed and instrumented to permit wireless power transmission technology evaluation measurements. The planned measurements were to provide data relative to the achievable performance in the state of the art of flexible surface, retrodirective arrays, as a step in technically evaluating the satellite power system concept for importing to earth, via microwave beams, the nearly continuous solar power available in geosynchronous orbit. Details of the microwave power transmitting phased array design, instrumentation approaches, system block diagrams, and measured component and breadboard characteristics achieved are presented.

  16. Ka-Band Multibeam Aperture Phased Array Being Developed

    NASA Technical Reports Server (NTRS)

    Reinhart, Richard C.; Kacpura, Thomas J.

    2004-01-01

    Phased-array antenna systems offer many advantages to low-Earth-orbiting satellite systems. Their large scan angles and multibeam capabilities allow for vibration-free, rapid beam scanning and graceful degradation operation for high rate downlink of data to users on the ground. Technology advancements continue to reduce the power, weight, and cost of these systems to make phased arrays a competitive alternative in comparison to the gimbled reflector system commonly used in science missions. One effort to reduce the cost of phased arrays is the development of a Ka-band multibeam aperture (MBA) phased array by Boeing Corporation under a contract jointly by the NASA Glenn Research Center and the Office of Naval Research. The objective is to develop and demonstrate a space-qualifiable dual-beam Ka-band (26.5-GHz) phased-array antenna. The goals are to advance the state of the art in Ka-band active phased-array antennas and to develop and demonstrate multibeam transmission technology compatible with spacecraft in low Earth orbit to reduce the cost of future missions by retiring certain development risks. The frequency chosen is suitable for space-to-space and space-to-ground communication links. The phased-array antenna has a radiation pattern designed by combining a set of individual radiating elements, optimized with the type of radiating elements used, their positions in space, and the amplitude and phase of the currents feeding the elements. This arrangement produces a directional radiation pattern that is proportional to the number of individual radiating elements. The arrays of interest here can scan the main beam electronically with a computerized algorithm. The antenna is constructed using electronic components with no mechanical parts, and the steering is performed electronically, without any resulting vibration. The speed of the scanning is limited primarily by the control electronics. The radiation performance degrades gracefully if a portion of the elements

  17. Phase estimation for a phased array therapeutic interstitial ultrasound probe.

    PubMed

    Yang, Zhenya; Dillenseger, Jean-Louis

    2012-01-01

    This paper deals about high intensity ultrasound interstitial therapy simulation. The simulated phased array ultrasound probe allows a dynamic electronic focusing of the therapeutic beam. In order to maximize the power deposit at the focal point we propose a method which allows to optimally defining the phase shift of the electrical control signal for each individual element.

  18. Guided wave phased array beamforming and imaging in composite plates.

    PubMed

    Yu, Lingyu; Tian, Zhenhua

    2016-05-01

    This paper describes phased array beamforming using guided waves in anisotropic composite plates. A generic phased array algorithm is presented, in which direction dependent guided wave parameters and the energy skew effect are considered. This beamforming at an angular direction is achieved based on the classic delay-and-sum principle by applying phase delays to signals received at array elements and adding up the delayed signals. The phase delays are determined with the goal to maximize the array output at the desired direction and minimize it otherwise. For array characterization, the beam pattern of rectangular grid arrays in composite plates is derived. In addition to the beam pattern, the beamforming factor in terms of wavenumber distribution is defined to provide intrinsic explanations for phased array beamforming. The beamforming and damage detection in a composite plate are demonstrated using rectangular grid arrays made by a non-contact scanning laser Doppler vibrometer. Detection images of the composite plate with multiple surface defects at various directions are obtained. The results show that the guided wave phased array method is a potential effective method for rapid inspection of large composite structures.

  19. Noise correlations and SNR in phased-array MRS.

    PubMed

    Martini, N; Santarelli, M F; Giovannetti, G; Milanesi, M; De Marchi, D; Positano, V; Landini, L

    2010-01-01

    The acquisition of magnetic resonance spectroscopy (MRS) signals by multiple receiver coils can improve the signal-to-noise ratio (SNR) or alternatively can reduce the scan time maintaining a reliable SNR. However, using phased array coils in MRS studies requires efficient data processing and data combination techniques in order to exploit the sensitivity improvement of the phased array coil acquisition method. This paper describes a novel method for the combination of MRS signals acquired by phased array coils, even in presence of correlated noise between the acquisition channels. In fact, although it has been shown that electric and magnetic coupling mechanisms produce correlated noise in the coils, previous algorithms developed for MRS data combination have ignored this effect. The proposed approach takes advantage of a noise decorrelation stage to maximize the SNR of the combined spectra. In particular Principal Component Analysis (PCA) was exploited to project the acquired spectra in a subspace where the noise vectors are orthogonal. In this subspace the SNR weighting method will provide the optimal overall SNR. Performance evaluation of the proposed method is carried out on simulated (1)H-MRS signals and experimental results are obtained on phantom (1)H-MR spectra using a commercially available 8-element phased array coil. Noise correlations between elements were generally low due to the optimal coil design, leading to a fair SNR gain (about 0.5%) in the center of the field of view (FOV). A greater SNR improvement was found in the peripheral FOV regions.

  20. Phased-array sources based on nonlinear metamaterial nanocavities

    PubMed Central

    Wolf, Omri; Campione, Salvatore; Benz, Alexander; Ravikumar, Arvind P.; Liu, Sheng; Luk, Ting S.; Kadlec, Emil A.; Shaner, Eric A.; Klem, John F.; Sinclair, Michael B.; Brener, Igal

    2015-01-01

    Coherent superposition of light from subwavelength sources is an attractive prospect for the manipulation of the direction, shape and polarization of optical beams. This phenomenon constitutes the basis of phased arrays, commonly used at microwave and radio frequencies. Here we propose a new concept for phased-array sources at infrared frequencies based on metamaterial nanocavities coupled to a highly nonlinear semiconductor heterostructure. Optical pumping of the nanocavity induces a localized, phase-locked, nonlinear resonant polarization that acts as a source feed for a higher-order resonance of the nanocavity. Varying the nanocavity design enables the production of beams with arbitrary shape and polarization. As an example, we demonstrate two second harmonic phased-array sources that perform two optical functions at the second harmonic wavelength (∼5 μm): a beam splitter and a polarizing beam splitter. Proper design of the nanocavity and nonlinear heterostructure will enable such phased arrays to span most of the infrared spectrum. PMID:26126879

  1. Coordinated Radar Resource Management for Networked Phased Array Radars

    DTIC Science & Technology

    2014-12-01

    Research and Development Canada Ottawa, Canada K1A 0Z4 Email: Peter.Moo@drdc-rddc.gc.ca Abstract A phased array radar has the ability to rapidly and...search and Development Canada (DRDC) Ottawa to analyse the performance of radar resource management techniques for naval radars operating in a littoral

  2. Phased arrays. Citations from the NTIS data base

    NASA Astrophysics Data System (ADS)

    Reed, W. E.

    1980-04-01

    The design, performance, radiation patterns, and applications of phased arrays are presented in these Federally-sponsored research reports. Applications include communications, radar, optical, spacecraft, and navigational aids. This updated bibliography contains 244 abstracts, 44 of which are new entries to the previous edition.

  3. Code-modulated interferometric imaging system using phased arrays

    NASA Astrophysics Data System (ADS)

    Chauhan, Vikas; Greene, Kevin; Floyd, Brian

    2016-05-01

    Millimeter-wave (mm-wave) imaging provides compelling capabilities for security screening, navigation, and bio- medical applications. Traditional scanned or focal-plane mm-wave imagers are bulky and costly. In contrast, phased-array hardware developed for mass-market wireless communications and automotive radar promise to be extremely low cost. In this work, we present techniques which can allow low-cost phased-array receivers to be reconfigured or re-purposed as interferometric imagers, removing the need for custom hardware and thereby reducing cost. Since traditional phased arrays power combine incoming signals prior to digitization, orthogonal code-modulation is applied to each incoming signal using phase shifters within each front-end and two-bit codes. These code-modulated signals can then be combined and processed coherently through a shared hardware path. Once digitized, visibility functions can be recovered through squaring and code-demultiplexing operations. Pro- vided that codes are selected such that the product of two orthogonal codes is a third unique and orthogonal code, it is possible to demultiplex complex visibility functions directly. As such, the proposed system modulates incoming signals but demodulates desired correlations. In this work, we present the operation of the system, a validation of its operation using behavioral models of a traditional phased array, and a benchmarking of the code-modulated interferometer against traditional interferometer and focal-plane arrays.

  4. Electro-optical processing of phased-array antenna data

    NASA Technical Reports Server (NTRS)

    Casasent, D.; Casasayas, F.

    1975-01-01

    An on-line two-dimensional optical processor has been used to process simulated linear and planar phased-array radar data off-line but at real-time data rates. The input transducer is an electron-beam-addressed KD2PO4 light valve.

  5. NASA Adaptive Multibeam Phased Array (AMPA): An application study

    NASA Technical Reports Server (NTRS)

    Mittra, R.; Lee, S. W.; Gee, W.

    1982-01-01

    The proposed orbital geometry for the adaptive multibeam phased array (AMPA) communication system is reviewed and some of the system's capabilities and preliminary specifications are highlighted. Typical AMPA user link models and calculations are presented, the principal AMPA features are described, and the implementation of the system is demonstrated. System tradeoffs and requirements are discussed. Recommendations are included.

  6. Phased-array sources based on nonlinear metamaterial nanocavities

    DOE PAGES

    Wolf, Omri; Campione, Salvatore; Benz, Alexander; ...

    2015-07-01

    Coherent superposition of light from subwavelength sources is an attractive prospect for the manipulation of the direction, shape and polarization of optical beams. This phenomenon constitutes the basis of phased arrays, commonly used at microwave and radio frequencies. Here we propose a new concept for phased-array sources at infrared frequencies based on metamaterial nanocavities coupled to a highly nonlinear semiconductor heterostructure. Optical pumping of the nanocavity induces a localized, phase-locked, nonlinear resonant polarization that acts as a source feed for a higher-order resonance of the nanocavity. Varying the nanocavity design enables the production of beams with arbitrary shape and polarization.more » As an example, we demonstrate two second harmonic phased-array sources that perform two optical functions at the second harmonic wavelength (~5 μm): a beam splitter and a polarizing beam splitter. As a result, proper design of the nanocavity and nonlinear heterostructure will enable such phased arrays to span most of the infrared spectrum.« less

  7. Looking Below the Surface with Ultrasonic Phased Array

    SciTech Connect

    Cinson, Anthony D.; Crawford, Susan L.

    2010-10-01

    This article is a brief tutorial on the benefits of volumetric ultrasonic phased array line scanning. The article describes the need, the approach, and the methods/practices used to analyze the data for flaw detection and characterization in the nuclear power plant component arena.

  8. Designing of a small wearable conformal phased array antenna for wireless communications

    NASA Astrophysics Data System (ADS)

    Roy, Sayan

    In this thesis, a unique design of a self-adapting conformal phased-array antenna system for wireless communications is presented. The antenna system is comprised of one microstrip antenna array and a sensor circuit. A 1x4 printed microstrip patch antenna array was designed on a flexible substrate with a resonant frequency of 2.47 GHz. However, the performance of the antenna starts to degrade as the curvature of the surface of the substrate changes. To recover the performance of the system, a flexible sensor circuitry was designed. This sensor circuitry uses analog phase shifters, a flexible resistor and operational-amplifier circuitry to compensate the phase of each array element of the antenna. The proposed analytical method for phase compensation has been first verified by designing an RF test platform consisting of a microstrip antenna array, commercially available analog phase shifters, analog voltage attenuators, 4-port power dividers and amplifiers. The platform can be operated through a LabVIEW GUI interface using a 12-bit digital-to-analog converter. This test board was used to design and calibrate the sensor circuitry by observing the behavior of the antenna array system on surfaces with different curvatures. In particular, this phased array antenna system was designed to be used on the surface of a spacesuit or any other flexible prototype. This work was supported in part by the Defense Miroelectronics Activity (DMEA), NASA ND EPSCoR and DARPA/MTO.

  9. Binaural beats at high frequencies.

    PubMed

    McFadden, D; Pasanen, E G

    1975-10-24

    Binaural beats have long been believed to be audible only at low frequencies, but an interaction reminiscent of a binaural beat can sometimes be heard when different two-tone complexes of high frequency are presented to the two ears. The primary requirement is that the frequency separation in the complex at one ear be slightly different from that in the other--that is, that there be a small interaural difference in the envelope periodicities. This finding is in accord with other recent demonstrations that the auditory system is not deaf to interaural time differences at high frequencies.

  10. EMAT phased array: A feasibility study of surface crack detection.

    PubMed

    Isla, J; Cegla, F

    2017-02-14

    Electromagnetic-acoustic transducers (EMATs) consist of a magnet and a coil. They are advantageous in some non-destructive evaluation (NDE) applications because no direct contact with the specimen is needed to send and receive ultrasonic waves. However, EMATs commonly require excitation peak powers greater than 1kW and therefore the driving electronics and the EMAT coils have to be bulky. This has hindered the development of EMAT phased arrays with characteristics similar to those of conventional piezoelectric phased arrays. Phased arrays are widely used in NDE because they offer superior defect characterization in comparison to single-element transducers. In this paper, we report a series of novel techniques and design elements that make it possible to construct an EMAT phased array that performs similarly to conventional piezoelectric arrays used in NDE. One of the key enabling features is the use of coded excitation to reduce the excitation peak power to less than 4.8W (24 Vpp and 200mA) so that racetrack coils with dimensions 3.2×18mm(2) can be employed. Moreover, these racetrack coils are laid out along their shortest dimension so that 1/3 of their area is overlapped. This helps to reduce the crosstalk between the coils, i.e., the array elements, to less than -15dB. We show that an 8-element EMAT phased array operating at a central frequency of 1MHz can be used to detect defects which have a width and a depth of 0.2 and 0.8mm respectively and are located on the surface opposite to the array.

  11. High-frequency broadband transformers

    NASA Astrophysics Data System (ADS)

    London, S. E.; Tomashevich, S. V.

    1981-05-01

    A systematic review of the theory and design principles of high-frequency broadband transformers is presented. It is shown that the transformers of highest performance are those whose coils consist of strips of double-wire and multiwire transmission lines. Such devices are characterized by a wide operating frequency range, and make possible operation at microwave frequencies at high levels of transmitted power.

  12. Ultra-Wideband Phased Array for Millimeter-Wave 5G and ISM

    NASA Technical Reports Server (NTRS)

    Novak, Markus H.; Volakis, John L.; Miranda, Felix A.

    2016-01-01

    Growing mobile data consumption has prompted the exploration of the millimeter-wave spectrum for large bandwidth, high speed communications. However, the allocated bands are spread across a wide swath of spectrum: fifth generation mobile architecture (5G): 28, 38, 39, 64-71 GHz, as well as Industrial, Scientific, and Medical bands (ISM): 24 and 60 GHz. Moreover, high gain phased arrays are required to overcome the significant path loss associated with these frequencies. Further, it is necessary to incorporate several of these applications in a single, small size and low cost platform. To this end, we have developed a scanning, Ultra-Wideband (UWB) array which covers all 5G, ISM, and other mm-W bands from 24-72 GHz. Critically, this is accomplished using mass-production Printed Circuit Board (PCB) fabrication.

  13. A novel serrated columnar phased array ultrasonic transducer

    NASA Astrophysics Data System (ADS)

    Zou, Cheng; Sun, Zhenguo; Cai, Dong; Song, Hongwei; Chen, Qiang

    2016-02-01

    Traditionally, wedges are required to generate transverse waves in a solid specimen and mechanical rotation device is needed for interrogation of a specimen with a hollow bore, such as high speed railway locomotive axles, turbine rotors, etc. In order to eliminate the mechanical rotation process, a novel array pattern of phased array ultrasonic transducers named as serrated columnar phased array ultrasonic transducer (SCPAUT) is designed. The elementary transducers are planar rectangular, located on the outside surface of a cylinder. This layout is aimed to generate electrically rotating transverse waveforms so as to inspect the longitudinal cracks on the outside surface of a specimen which has a hollow bore at the center, such as the high speed railway locomotive axles. The general geometry of the SCPAUT and the inspection system are illustrated. A FEM model and mockup experiment has been carried out. The experiment results are in good agreement with the FEM simulation results.

  14. A design concept for an MMIC microstrip phased array

    NASA Technical Reports Server (NTRS)

    Lee, R. Q.; Smetana, J.; Acosta, R.

    1986-01-01

    A conceptual design for a microstrip phased array with monolithic microwave integrated circuit (MMIC) amplitude and phase controls is described. The MMIC devices used are 20 GHz variable power amplifiers and variable phase shifters recently developed by NASA contractors for applications in future Ka band advanced satellite communication antenna systems. The proposed design concept is for a general NxN element array of rectangular lattice geometry. Subarray excitation is incorporated in the MMIC phased array design to reduce the complexity of the beam forming network and the number of MMIC components required. The proposed design concept takes into consideration the RF characteristics and actual phyical dimensions of the MMIC devices. Also, solutions to spatial constraints and interconnections associated with currently available packaging designs are discussed. Finally, the design of the microstrip radiating elements and their radiation characteristics are examined.

  15. A Phased Array Coil for Human Cardiac Imaging

    PubMed Central

    Constantinides, Chris D.; Westgate, Charles R.; O'Dell, Walter G.; Zerhouni, Elias A.; McVeigh, Elliot R.

    2007-01-01

    A prototype cardiac phased array receiver coil was constructed that comprised a cylindrical array and a separate planar array. Both arrays had two coil loops with the same coil dimensions. Data acquisition with the cylindrical array placed on the human chest, and the planar array placed under the back, yielded an overall enhancement of the signal-to-noise ratio (SNR) over the entire heart by a factor of 1.1–2.85 over a commercially available flexible coil and a commercially available four-loop planar phased array coil. This improvement in SNR can be exploited in cardiac imaging to increase the spatial resolution and reduce the image acquisition time. PMID:7674903

  16. 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.

  17. Robotic inspection of fiber reinforced composites using phased array UT

    NASA Astrophysics Data System (ADS)

    Stetson, Jeffrey T.; De Odorico, Walter

    2014-02-01

    Ultrasound is the current NDE method of choice to inspect large fiber reinforced airframe structures. Over the last 15 years Cartesian based scanning machines using conventional ultrasound techniques have been employed by all airframe OEMs and their top tier suppliers to perform these inspections. Technical advances in both computing power and commercially available, multi-axis robots now facilitate a new generation of scanning machines. These machines use multiple end effector tools taking full advantage of phased array ultrasound technologies yielding substantial improvements in inspection quality and productivity. This paper outlines the general architecture for these new robotic scanning systems as well as details the variety of ultrasonic techniques available for use with them including advances such as wide area phased array scanning and sound field adaptation for non-flat, non-parallel surfaces.

  18. Removing Background Noise with Phased Array Signal Processing

    NASA Technical Reports Server (NTRS)

    Podboy, Gary; Stephens, David

    2015-01-01

    Preliminary results are presented from a test conducted to determine how well microphone phased array processing software could pull an acoustic signal out of background noise. The array consisted of 24 microphones in an aerodynamic fairing designed to be mounted in-flow. The processing was conducted using Functional Beam forming software developed by Optinav combined with cross spectral matrix subtraction. The test was conducted in the free-jet of the Nozzle Acoustic Test Rig at NASA GRC. The background noise was produced by the interaction of the free-jet flow with the solid surfaces in the flow. The acoustic signals were produced by acoustic drivers. The results show that the phased array processing was able to pull the acoustic signal out of the background noise provided the signal was no more than 20 dB below the background noise level measured using a conventional single microphone equipped with an aerodynamic forebody.

  19. Fiber optic signal distribution for phased array antennas

    NASA Astrophysics Data System (ADS)

    Mecherle, G. S.

    1992-03-01

    The use of a 32-GHz phased-array transmitting antenna with fiberoptic signal distribution is considered in the context of a Mars relay satellite for NASA's Space Exploration Initiative. The specifications of the proposed application are assessed with specific attention given to the EIRP requirement of 86 dBW and its ramifications on the phased array, antenna, and photonic architecture. A photonic performance analysis is conducted to study phase-noise and SNR degradations to determine whether phase-locked loop (PLL) complexity is required. SNR and phase noise are examined as a function of the number of optical splits, and the number is shown to be limited to 350. Use of the PLL allows one laser to support 650 elements - as opposed to 250 - showing that only a single laser diode is needed to support the array for the Mars transmitter.

  20. Computation of the radiation characteristics of a generalized phased array

    NASA Technical Reports Server (NTRS)

    Acosta, R. J.

    1986-01-01

    With the advent of monolithic microwave integrated circuit (MMIC) technology, the phased array has become a key component in the design of advanced antenna systems. Array-fed antennas are used extensively in today's multiple beam satellite antennas. A computer program based on a very efficient numerical technique for calculating the radiated power (Romberg integration), directivity, and radiation pattern of a phased array is described. The formulation developed is very general, and takes into account arbitrary element polarization, E- and H-plane element pattern, element location, and complex element excitation. For comparison purposes sample cases have been presented. Excellent agreement has been obtained for all cases. Also included are a user guide and a copy of the computer program.

  1. Ultrasonic Phased Array Simulations of Welded Components at NASA

    NASA Technical Reports Server (NTRS)

    Roth, D. J.; Tokars, R. P.; Martin, R. E.; Rauser, R. W.; Aldrin, J. C.

    2009-01-01

    Comprehensive and accurate inspections of welded components have become of increasing importance as NASA develops new hardware such as Ares rocket segments for future exploration missions. Simulation and modeling will play an increasing role in the future for nondestructive evaluation in order to better understand the physics of the inspection process, to prove or disprove the feasibility for an inspection method or inspection scenario, for inspection optimization, for better understanding of experimental results, and for assessment of probability of detection. This study presents simulation and experimental results for an ultrasonic phased array inspection of a critical welded structure important for NASA future exploration vehicles. Keywords: nondestructive evaluation, computational simulation, ultrasonics, weld, modeling, phased array

  2. Range sidelobe suppression in wideband phased array radars

    NASA Astrophysics Data System (ADS)

    Belcher, Melvin L., Jr.; Moss, Karen M.

    The authors delineate some considerations in achieving RSL (range sidelobe) suppression in wideband phased arrays. Attention is given to wideband radar characteristics suppression of spurious signals, and sources of wideband RSLs. It is suggested that the parallelism associated with the transmitter and antenna paths should mitigate associated uncorrelated time-varying error modulation. The exciter can be a major RSL contributor unless spurious signal suppression with the SSBM (single sideband modulator) is emphasized in design and calibration procedures.

  3. Optical RF distribution links for MMIC phased array antennas

    NASA Technical Reports Server (NTRS)

    Kunath, Richard R.; Bhasin, Kul B.; Raquet, Charles A.

    1987-01-01

    Conventional methods to distribute RF signals to GaAs Monolithic Microwave Integrated Circuits Phased Array Antennas are inadequate for arrays having large numbers of elements. Optical RF distribution links have been proposed as a lightweight, mechanically flexible, and low volume solution. Three candidate techniques for providing optical RF distribution are discussed along with the electro-optic devices required to configure them. A discussion of the present status of applicable electro-optics devices is also included.

  4. Adaptive multibeam phased array design for a Spacelab experiment

    NASA Technical Reports Server (NTRS)

    Noji, T. T.; Fass, S.; Fuoco, A. M.; Wang, C. D.

    1977-01-01

    The parametric tradeoff analyses and design for an Adaptive Multibeam Phased Array (AMPA) for a Spacelab experiment are described. This AMPA Experiment System was designed with particular emphasis to maximize channel capacity and minimize implementation and cost impacts for future austere maritime and aeronautical users, operating with a low gain hemispherical coverage antenna element, low effective radiated power, and low antenna gain-to-system noise temperature ratio.

  5. Phased-array design for MST and ST radars

    NASA Technical Reports Server (NTRS)

    Ecklund, W. L.

    1986-01-01

    All of the existing radar systems fully dedicated to clear-air radar studies use some type of phased-array antennas. The effects of beam-steering techniques including feed networks and phase shifters; sidelobe control; ground-clutter suppression; low altitude coverage; arrays with integrated radiating elements and feed networks; analysis of coaxial-collinear antennas; use of arrays with multiple beams; and array testing and measure on structural design of the antenna are discussed.

  6. Infinite Phased Array of Microstrip Dipoles in Two Layers

    DTIC Science & Technology

    1989-01-01

    Green’s function appropriate to the two-layer substrate- superstrate structure was used in the formulation of the method of moMents - (continued on back) 20...analysis is presented for an infinite phased array of microstrip dipoles embedded within a two layer substrate structure (sub- strate- superstrate ...characterization of input impedance as a function of phase scan angle. Results for several sub- strate- superstrate structures illustrate the utility of the single

  7. A 32-GHz phased array transmit feed for spacecraft telecommunications

    NASA Technical Reports Server (NTRS)

    Lee, K. A.; Rascoe, D. L.; Crist, R. A.; Huang, J.; Wamhof, P. D.; Lansing, F. S.

    1992-01-01

    A 21-element phased array transmit feed was demonstrated as part of an effort to develop and evaluate state-of-the-art transmitter and receiver components at 32 and 34 GHz for future deep-space missions. Antenna pattern measurements demonstrating electronic beam steering of the two-dimensional array are reported and compared with predictions based on measured performance of MMIC-based phase shifter and amplifier modules and Vivaldi slotline radiating elements.

  8. Optical beam forming techniques for phased array antennas

    NASA Astrophysics Data System (ADS)

    Wu, Te-Kao; Chandler, C.

    Conventional phased array antennas using waveguide or coax for signal distribution are impractical for large scale implementation on satellites or spacecraft because they exhibit prohibitively large system size, heavy weight, high attenuation loss, limited bandwidth, sensitivity to electromagnetic interference (EMI) temperature drifts and phase instability. However, optical beam forming systems are smaller, lighter, and more flexible. Three optical beam forming techniques are identified as applicable to large spaceborne phased array antennas. They are (1) the optical fiber replacement of conventional RF phased array distribution and control components, (2) spatial beam forming, and (3) optical beam splitting with integrated quasi-optical components. The optical fiber replacement and the spatial beam forming approaches were pursued by many organizations. Two new optical beam forming architectures are presented. Both architectures involve monolithic integration of the antenna radiating elements with quasi-optical grid detector arrays. The advantages of the grid detector array in the optical process are the higher power handling capability and the dynamic range. One architecture involves a modified version of the original spatial beam forming approach. The basic difference is the spatial light modulator (SLM) device for controlling the aperture field distribution. The original liquid crystal light valve SLM is replaced by an optical shuffling SLM, which was demonstrated for the 'smart pixel' technology. The advantages are the capability of generating the agile beams of a phased array antenna and to provide simultaneous transmit and receive functions. The second architecture considered is the optical beam splitting approach. This architecture involves an alternative amplitude control for each antenna element with an optical beam power divider comprised of mirrors and beam splitters. It also implements the quasi-optical grid phase shifter for phase control and grid

  9. Optical beam forming techniques for phased array antennas

    NASA Technical Reports Server (NTRS)

    Wu, Te-Kao; Chandler, C.

    1993-01-01

    Conventional phased array antennas using waveguide or coax for signal distribution are impractical for large scale implementation on satellites or spacecraft because they exhibit prohibitively large system size, heavy weight, high attenuation loss, limited bandwidth, sensitivity to electromagnetic interference (EMI) temperature drifts and phase instability. However, optical beam forming systems are smaller, lighter, and more flexible. Three optical beam forming techniques are identified as applicable to large spaceborne phased array antennas. They are (1) the optical fiber replacement of conventional RF phased array distribution and control components, (2) spatial beam forming, and (3) optical beam splitting with integrated quasi-optical components. The optical fiber replacement and the spatial beam forming approaches were pursued by many organizations. Two new optical beam forming architectures are presented. Both architectures involve monolithic integration of the antenna radiating elements with quasi-optical grid detector arrays. The advantages of the grid detector array in the optical process are the higher power handling capability and the dynamic range. One architecture involves a modified version of the original spatial beam forming approach. The basic difference is the spatial light modulator (SLM) device for controlling the aperture field distribution. The original liquid crystal light valve SLM is replaced by an optical shuffling SLM, which was demonstrated for the 'smart pixel' technology. The advantages are the capability of generating the agile beams of a phased array antenna and to provide simultaneous transmit and receive functions. The second architecture considered is the optical beam splitting approach. This architecture involves an alternative amplitude control for each antenna element with an optical beam power divider comprised of mirrors and beam splitters. It also implements the quasi-optical grid phase shifter for phase control and grid

  10. Simulation and data reconstruction for NDT phased array techniques.

    PubMed

    Chatillon, S; de Roumilly, L; Porre, J; Poidevin, C; Calmon, P

    2006-12-22

    Phased array techniques are now widely employed for industrial NDT applications in various contexts. Indeed, phased array present a great adaptability to the inspection configuration and the application of suitable delay laws allows to optimize the detection and characterization performances by taking into account the component geometry, the material characteristics, and the aim of the inspection. In addition, the amount of potential information issued from the inspection is in general greatly enhanced. It is the case when the employed method involve sequences of shots (sectorial scanning, multiple depth focusing etc) or when signals received on the different channels are stored. At last, application of electronic commutation make possible higher acquisition rates. Accompanying these advantages, it is clear that an optimal use of such techniques require the application of simulation-based algorithms at the different stages of the inspection process: When designing the probe by optimizing number and characteristics of element; When conceiving the inspection method by selecting suitable sequences of shots, computing optimized delay laws and evaluating the performances of the control in terms of zone coverage or flaw detection capabilities; When analysing the results by applying simulation-helped visualization and data reconstruction algorithms. For many years the CEA (French Atomic Energy Commission) has been being greatly involved in the development of such phased arrays simulation-based tools. In this paper, we will present recent advances of this activity and show different examples of application carried out on complex situations.

  11. PATL: A RFID Tag Localization based on Phased Array Antenna.

    PubMed

    Qiu, Lanxin; Liang, Xiaoxuan; Huang, Zhangqin

    2017-03-15

    In RFID systems, how to detect the position precisely is an important and challenging research topic. In this paper, we propose a range-free 2D tag localization method based on phased array antenna, called PATL. This method takes advantage of the adjustable radiation angle of the phased array antenna to scan the surveillance region in turns. By using the statistics of the tags' number in different antenna beam directions, a weighting algorithm is used to calculate the position of the tag. This method can be applied to real-time location of multiple targets without usage of any reference tags or additional readers. Additionally, we present an optimized weighting method based on RSSI to increase the locating accuracy. We use a Commercial Off-the-Shelf (COTS) UHF RFID reader which is integrated with a phased array antenna to evaluate our method. The experiment results from an indoor office environment demonstrate the average distance error of PATL is about 21 cm and the optimized approach achieves an accuracy of 13 cm. This novel 2D localization scheme is a simple, yet promising, solution that is especially applicable to the smart shelf visualized management in storage or retail area.

  12. Phased-Array Satcom Antennas Developed for Aeronautical Applications

    NASA Technical Reports Server (NTRS)

    Kerczewski, Robert J.

    2001-01-01

    The Advanced Communications (AC) for Aeronautics research at the NASA Glenn Research Center integrates both aeronautics and space communications technologies to achieve the national objective of upgrading the present National Airspace System infrastructure by responding to the agency's aviation capacity and safety goals. One concept for future air traffic management, free flight, presents a significantly increased demand for communications systems capacity and performance in comparison to current air traffic management practices. Current aeronautical communications systems are incapable of supporting the anticipated demands, and the new digital data communications links that are being developed, or are in the early stages of implementation, are not primarily designed to carry the data-intensive free flight air traffic management (ATM) communications loads. Emerging satellite communications technologies are the best potential long-term solution to provide the capacity and performance necessary to enable a mature free flight concept to be deployed. NASA AC/ATM funded the development of a Boeing-designed Ku-band transmit phased-array antenna, a combined in-house and contract effort. Glenn designed and integrated an Aeronautical Mobile Satellite Communications terminal based on the transmit phased-array antenna and a companion receive phased-array antenna previously developed by Boeing.

  13. Ultrasonic Phased Array Inspection of Seeded Titanium Billet

    NASA Astrophysics Data System (ADS)

    Friedl, J. H.; Gray, T. A.; Khandelwal, P.; Dunhill, T.

    2004-02-01

    As part of efforts by Rolls-Royce to evaluate the use of ultrasonic phased arrays for inspection of titanium billets, a series of ultrasonic phased array inspections were performed at the Center for Nondestructive Evaluation (CNDE). The inspections were performed using a sectorial-annular array designed especially for titanium billets by R/D Tech and supplied to Rolls-Royce. The billet test piece is seeded with thirteen yttria disks, each located at successive depths below the outer diameter surface to just past the billet centerline. The phased array inspections employed both fixed-focus and dynamic-depth-focus (DDF) focal laws in conjunction with several depth gating schemes. Aperture and focal parameters were changed as a function of depth when using fixed-focus focal laws. Results include characterization of transducer performance and delay-time correction of imperfections, signal-to-noise measurements for the yttria disks in the billet test piece, and effects of probe misalignment on flaw sensitivity.

  14. PATL: A RFID Tag Localization based on Phased Array Antenna

    PubMed Central

    Qiu, Lanxin; Liang, Xiaoxuan; Huang, Zhangqin

    2017-01-01

    In RFID systems, how to detect the position precisely is an important and challenging research topic. In this paper, we propose a range-free 2D tag localization method based on phased array antenna, called PATL. This method takes advantage of the adjustable radiation angle of the phased array antenna to scan the surveillance region in turns. By using the statistics of the tags’ number in different antenna beam directions, a weighting algorithm is used to calculate the position of the tag. This method can be applied to real-time location of multiple targets without usage of any reference tags or additional readers. Additionally, we present an optimized weighting method based on RSSI to increase the locating accuracy. We use a Commercial Off-the-Shelf (COTS) UHF RFID reader which is integrated with a phased array antenna to evaluate our method. The experiment results from an indoor office environment demonstrate the average distance error of PATL is about 21 cm and the optimized approach achieves an accuracy of 13 cm. This novel 2D localization scheme is a simple, yet promising, solution that is especially applicable to the smart shelf visualized management in storage or retail area. PMID:28295014

  15. Control of complex components with Smart Flexible Phased Arrays.

    PubMed

    Casula, O; Poidevin, C; Cattiaux, G; Dumas, Ph

    2006-12-22

    The inspection is mainly performed in contact with ultrasonic wedge transducers; However, the shape cannot fit the changing geometries of components (butt weld, nozzle, elbow). The variable thickness of the coupling layer, between the wedge and the local surface, leads to beam distortions and losses of sensitivity. Previous studies have shown that these two phenomena contribute to reduce the inspection performances leading to shadow area, split beam.... Flexible phased arrays have been developed to fit the complex profile and improve such controls. The radiating surface is composed with independent piezoelectric elements mechanically assembled and a profilometer, embedded in the transducer, measures the local distortion. The computed shape is used by an algorithm to compute in real-time the adapted delay laws compensating the distortions of 2D or 3D profiles. Those delay laws are transferred to the real-time UT acquisition system, which applies them to the piezoelectric elements. This self-adaptive process preserves, during the scanning, the features of the focused beam (orientation and focal depth) in the specimen. To validate the concept of the Smart Flexible Phased Array Transducer, prototypes have been integrated to detect flaws machined in mock-ups with realistic irregular 2D and 3D shapes. Inspections have been carried out on samples showing the enhancement performances of the "Smart Flexible Phased Array" and validating the mechanical and acoustical behaviors of these probes.

  16. Phased-array-fed antenna configuration study. Volume 1: Technology assessment

    NASA Technical Reports Server (NTRS)

    Sorbello, R. M.; Zaghloul, A. I.; Lee, B. S.; Siddiqi, S.; Geller, B. D.; Gerson, H. I.; Srinivas, D. N.

    1983-01-01

    The status of the technologies for phased-array-fed dual reflector systems is reviewed. The different aspects of these technologies, including optical performances, phased array systems, problems encountered in phased array design, beamforming networks, MMIC design and its incorporation into waveguide systems, reflector antenna structures, and reflector deployment mechanisms are addressed.

  17. Ultrasonic Phased Arrays for the Inspection of Thick-Section Welds

    DTIC Science & Technology

    2009-09-01

    phased - array ultrasonics in NDE , with specific reference to the inspection of thick- section welds. The...likely that ultrasonic phased arrays will eventually replace conventional ultrasonic methods in many non-destructive evaluation ( NDE ) applications...embraced by the NDE community. The purpose of this report is to present a summary of the advantages and limitations of phased - array ultrasonics

  18. Inspecting Composite Ceramic Armor Using Advanced Signal Processing Together with Phased Array Ultrasound

    DTIC Science & Technology

    2010-01-08

    processing techniques have been developed to help improve phased array ultrasonic inspection and analysis of multi-layered ceramic armor panels. The...INSPECTING COMPOSITE CERAMIC ARMOR USING ADVANCED SIGNAL PROCESSING TOGETHER WITH PHASED ARRAY ULTRASOUND J. S. Steckenrider Illinois College...immersion phased array ultrasound system. Some of these specimens had intentional design defects inserted interior to the specimens. Because of the very

  19. Phased Arrays of Ground and Airborne Mobile Terminals for Satellite Communications

    NASA Technical Reports Server (NTRS)

    Huang, John

    1996-01-01

    Phased array antenna is beginning to play an important in the arena of mobile/satellite communications. Two examples of mobile terminal phased arrays will be shown. Their technical background, challenges, and cost drivers will be discussed. A possible solution to combat some of the deficiencies of the conventional phased array by exploiting the phased reflectarray technology will be briefly presented.

  20. Phased-array vector velocity estimation using transverse oscillations.

    PubMed

    Pihl, Michael J; Marcher, Jonne; Jensen, Jorgen A

    2012-12-01

    A method for estimating the 2-D vector velocity of blood using a phased-array transducer is presented. The approach is based on the transverse oscillation (TO) method. The purposes of this work are to expand the TO method to a phased-array geometry and to broaden the potential clinical applicability of the method. A phased-array transducer has a smaller footprint and a larger field of view than a linear array, and is therefore more suited for, e.g., cardiac imaging. The method relies on suitable TO fields, and a beamforming strategy employing diverging TO beams is proposed. The implementation of the TO method using a phased-array transducer for vector velocity estimation is evaluated through simulation and flow-rig measurements are acquired using an experimental scanner. The vast number of calculations needed to perform flow simulations makes the optimization of the TO fields a cumbersome process. Therefore, three performance metrics are proposed. They are calculated based on the complex TO spectrum of the combined TO fields. It is hypothesized that the performance metrics are related to the performance of the velocity estimates. The simulations show that the squared correlation values range from 0.79 to 0.92, indicating a correlation between the performance metrics of the TO spectrum and the velocity estimates. Because these performance metrics are much more readily computed, the TO fields can be optimized faster for improved velocity estimation of both simulations and measurements. For simulations of a parabolic flow at a depth of 10 cm, a relative (to the peak velocity) bias and standard deviation of 4% and 8%, respectively, are obtained. Overall, the simulations show that the TO method implemented on a phased-array transducer is robust with relative standard deviations around 10% in most cases. The flow-rig measurements show similar results. At a depth of 9.5 cm using 32 emissions per estimate, the relative standard deviation is 9% and the relative bias is -9

  1. Phased Array Ultrasonic Evaluation of Space Shuttle Main Engine (SSME) Nozzle Weld

    NASA Technical Reports Server (NTRS)

    James, Steve; Engel, J.; Kimbrough, D.; Suits, M.; Hopson, George (Technical Monitor)

    2001-01-01

    This viewgraph presentation gives an overview of the phased array ultrasonic evaluation of the Space Shuttle Main Engine (SSME) nozzle weld. Details are given on the nondestructive testing evaluation approach, conventional shear wave and phased array techniques, and an x-ray versus phased array risk analysis. The field set-up was duplicated to the greatest extent possible in the laboratory and the phased array ultrasonic technique was developed and validated prior to weld evaluation. Results are shown for the phased array ultrasonic evaluation and conventional ultrasonic evaluation results.

  2. High frequency power distribution system

    NASA Technical Reports Server (NTRS)

    Patel, Mikund R.

    1986-01-01

    The objective of this project was to provide the technology of high frequency, high power transmission lines to the 100 kW power range at 20 kHz frequency. In addition to the necessary design studies, a 150 m long, 600 V, 60 A transmission line was built, tested and delivered for full vacuum tests. The configuration analysis on five alternative configurations resulted in the final selection of the three parallel Litz straps configuration, which gave a virtually concentric design in the electromagnetic sense. Low inductance, low EMI and flexibility in handling are the key features of this configuration. The final design was made after a parametric study to minimize the losses, weight and inductance. The construction of the cable was completed with no major difficulties. The R,L,C parameters measured on the cable agreed well with the calculated values. The corona tests on insulation samples showed a safety factor of 3.

  3. Ultrasonic Phased Array Inspection Simulations of Welded Components at NASA

    NASA Technical Reports Server (NTRS)

    Roth, D. J.; Tokars, R. P.; Martin, R. E.; Rauser, R. W.; Aldrin, J. C.; Schumacher, E. J.

    2009-01-01

    Comprehensive and accurate inspections of welded components have become of increasing importance as NASA develops new hardware such as Ares rocket segments for future exploration missions. Simulation and modeling will play an increased role in the future for nondestructive evaluation in order to better understand the physics of the inspection process and help explain the experimental results. It will also help to prove or disprove the feasibility for an inspection method or inspection scenario, help optimize inspections, and allow to a first approximation limits of detectability. This study presents simulation and experimental results for an ultrasonic phased array inspection of a critical welded structure important for NASA future exploration vehicles.

  4. SAR processing with stepped chirps and phased array antennas.

    SciTech Connect

    Doerry, Armin Walter

    2006-09-01

    Wideband radar signals are problematic for phased array antennas. Wideband radar signals can be generated from series or groups of narrow-band signals centered at different frequencies. An equivalent wideband LFM chirp can be assembled from lesser-bandwidth chirp segments in the data processing. The chirp segments can be transmitted as separate narrow-band pulses, each with their own steering phase operation. This overcomes the problematic dilemma of steering wideband chirps with phase shifters alone, that is, without true time-delay elements.

  5. Optoelectronic Infrastructure for Radio Frequency and Optical Phased Arrays

    NASA Technical Reports Server (NTRS)

    Cai, Jianhong

    2015-01-01

    Optoelectronic integrated circuits offer radiation-hardened solutions for satellite systems in addition to improved size, weight, power, and bandwidth characteristics. ODIS, Inc., has developed optoelectronic integrated circuit technology for sensing and data transfer in phased arrays. The technology applies integrated components (lasers, amplifiers, modulators, detectors, and optical waveguide switches) to a radio frequency (RF) array with true time delay for beamsteering. Optical beamsteering is achieved by controlling the current in a two-dimensional (2D) array. In this project, ODIS integrated key components to produce common RF-optical aperture operation.

  6. Jet Noise Source Localization Using Linear Phased Array

    NASA Technical Reports Server (NTRS)

    Agboola, Ferni A.; Bridges, James

    2004-01-01

    A study was conducted to further clarify the interpretation and application of linear phased array microphone results, for localizing aeroacoustics sources in aircraft exhaust jet. Two model engine nozzles were tested at varying power cycles with the array setup parallel to the jet axis. The array position was varied as well to determine best location for the array. The results showed that it is possible to resolve jet noise sources with bypass and other components separation. The results also showed that a focused near field image provides more realistic noise source localization at low to mid frequencies.

  7. Photonic implementation of phased array antennas (rf scanning)

    NASA Astrophysics Data System (ADS)

    Nichter, James E.

    1999-07-01

    Phase Array Antennas provided angular scanning (beam steering) from fixed antenna structures. Photonics can accomplish the beam steering with improvements in size and weight along with the remoting benefits utilizing fiber optics. Photonic advantages include True Time Delay beam steering eliminating the beam squint imposed by phase shifted signals produced in an electronic implementation. Another benefit of beam steering is the ability to position nulls in the spacial pattern to reduce the interference signals. Hybrid circuits utilizing both photonic and electronic components take advantages of the best aspects of each technology. Various types of photonic implementations are included.

  8. Reconfigurable Wave Velocity Transmission Lines for Phased Arrays

    NASA Technical Reports Server (NTRS)

    Host, Nicholas Keith; Chen, Chi-Chih; Volakis, John L.

    2012-01-01

    This presentation discussed a novel phased array with an emphasis to simplify the array feed. Specifically, we will demonstrate a simple, low cost feeding approach by mechanically controlling the substrate thickness. The array feed lines are constructed from parallel plate transmission lines whose thickness are adjusted to control their effective dielectric constant (Epsilon_eff). As a result the phase delay/excitation at each array element will be adjusted per desired beam direction. The proposed antenna elements will be overlapping dipoles operating over a 2:1 bandwidth in the Ku-Band spectrum. Preliminary simulation and experimental demonstration of such an array will be presented.

  9. Ultrasonic Phased Array Simulations of Welded Components at NASA

    NASA Astrophysics Data System (ADS)

    Roth, D. J.; Tokars, R. P.; Martin, R. E.; Rauser, R. W.; Aldrin, J. C.

    2009-03-01

    Comprehensive and accurate inspections of welded components have become of increasing importance as NASA develops new hardware such as Ares rocket segments for future exploration missions. Simulation and modeling will play an increasing role in the future for nondestructive evaluation in order to better understand the physics of the inspection process, to prove or disprove the feasibility for an inspection method or inspection scenario, for inspection optimization, for better understanding of experimental results, and for assessment of probability of detection. This study presents simulation and experimental results for an ultrasonic phased array inspection of a critical welded structure important for NASA future exploration vehicles.

  10. An optically controlled Ka-band phased array antenna

    NASA Technical Reports Server (NTRS)

    Kunath, R. R.; Lee, Richard Q.; Martzaklis, K. S.; Shalkhauser, K. A.; Downey, Alan N.; Simons, Rainee N.

    1992-01-01

    The design and development of a small, optically controlled phased array antenna suitable for communication satellite applications are discussed. A vertical integration architecture is used which minimizes the size of the array with its associated beamforming network (BFN). The antenna features a four-element linear microstrip array that uses aperture coupling of the antenna elements to the BFN; a modified Wilkinson power divider BFN; and 32 GHz, four-bit monolithic microwave integrated circuit (MMIC) phase shifters in customized quartz packages with corresponding optoelectronic interface circuits (OEIC's) for control signal reception.

  11. Optical phased array radiating optical vortex with manipulated topological charges.

    PubMed

    Ma, Xiaoliang; Pu, Mingbo; Li, Xiong; Huang, Cheng; Pan, Wenbo; Zhao, Bo; Cui, Jianhua; Luo, Xiangang

    2015-02-23

    Optical antennas are key elements in quantum optics emitting and sensing, and behave wide range applications in optical domain. However, integration of optical antenna radiating orbital angular momentum is still a challenge in nano-scale. We theoretically demonstrate a sub-wavelength phased optical antenna array, which manipulates the distribution of the orbital angular momentum in the near field. Orbital angular momentum with topological charge of 4 can be obtained by controlling the phase distribution of the fundamental mode orbital angular momentum in each antenna element. Our results indicate this phased array may be utilized in high integrated optical communication systems.

  12. A vertically integrated Ka-band phased array antenna

    NASA Technical Reports Server (NTRS)

    Kunath, R. R.; Lee, R. Q.; Martzaklis, K. S.; Shalkhauser, K. A.; Downey, A. N.; Simons, R.

    1992-01-01

    The design, development, and experimental demonstration of a small phased array antenna suitable for applications on communications satellites are discussed. Each of the vertical layers was optimized for performance, and MMICs on custom carriers were characterized prior to insertion. A vertical integration architecture is used which minimizes the size of the array with its associated beamforming network (BFN). The antenna features a four-element linear microstrip array that uses aperture coupling of the antenna elements to the BFN; a modified Wilkinson power divider BFN; and 32 Ghz, 4-bit MMIC phase shifters on customized alumina carriers. Performance data are presented for all components, and far-field antenna radiation patterns are given.

  13. Variable phase sine wave generator for active phased arrays

    NASA Astrophysics Data System (ADS)

    Waters, W. M.

    1992-09-01

    A waveform generator is provided for generating a high frequency waveform. A pulse generator provides a pulse train at a low frequency. A pulse converter converts the pulse train into an alternatingly positive and negative groups of pulses. A bandpass filter passes the alternatingly positive and negative groups of pulses in a frequency band centered at the high frequency to output the generated waveform at the high frequency. When the groups of pulses are a pair of pulses, a sine wave is output from the bandpass filter. A pulse delay circuit can be used to variably delay the pulse train and thereby cause a phase change in the generated waveform.

  14. Ultrasonic phased arrays for nondestructive inspection of forgings

    SciTech Connect

    Wuestenberg, H.; Rotter, B. ); Klanke, H.P. ); Harbecke, D. )

    1993-06-01

    Ultrasonic examinations on large forgings like rotor shafts for turbines or components for nuclear reactors are carried out at various manufacturing stages and during in-service inspections. During the manufacture, most of the inspections are carried out manually. Special in-service conditions, such as those at nuclear pressure vessels, have resulted in the development of mechanized scanning equipment. Ultrasonic probes have improved, and well-adapted sound fields and pulse shapes and based on special imaging procedures for the representation of the reportable reflectors have been applied. Since the geometry of many forgings requires the use of a multitude of angles for the inspections in-service and during manufacture, phased-array probes can be used successfully. The main advantages of the phased-array concept, e.g. the generation of a multitude of angles with the typical increase of redundancy in detection and quantitative evaluation and the possibility to produce pictures of defect situations, will be described in this contribution.

  15. A 220 GHz reflection-type phased array concept study

    NASA Astrophysics Data System (ADS)

    Hedden, Abigail S.; Dietlein, Charles R.; Wikner, David A.

    2011-05-01

    The goal of this project is to enable light-weight, durable, and portable systems capable of performing standoff detection of person-borne improvised explosive devices (PB-IEDs) through the development of millimeter-wave reflection-type phased arrays. Electronic beam steering eliminates the need for complex mechanical scanners that are commonly implemented with millimeter-wave imaging systems and would reduce overall system size and weight. We present a concept study of a 220 GHz reflection-type phased array for the purpose of performing beam scanning of a confocal reflector system. Requirements for effective imaging of the desired target region are established, including spatial resolution, total scan angle, and number of image pixels achievable. We examine the effects of array architecture on beam characteristics as it is scanned off broadside, including Gaussicity and encircled energy. Benchmark requirements are determined and compared with the capabilities of several potential phase shifter technologies, including MEMS-based variable capacitor phase shifters, switches, and varactor diode-based phase shifters.

  16. Application of Phased-array Vibrator System in shallow oil shale exploration

    NASA Astrophysics Data System (ADS)

    Jiang, T.; Lin, J.; Xu, X.

    2011-12-01

    Due to the huge oil and gas demands in China, exploration of unconventional oil shale at shallow depths becomes more critical. 52.83% of the identified reserves in China are from Jilin province and Nong'an is one of the main areas of oil shale in Jilin. The average buried depth of oil shale in Nong'an is between 300m and 800m. Since explosive sources are not allowed to operate in civil area and the inconvenience of vibroseis, Phased-array Vibrator System (PAVS) is applied in the exploration of oil shale in Nong'an. We have developed a series electromagnetic Portable High-frequency Vibrator System (PHVS), including single, combination, and phased-array modes. Single mode is the simplest mode, with output force less than 500N, and thus is only suitable for engineering seismic prospecting. Combination mode is a source array, which uses a controller to synchronize all vibrator units and let them work consistently with each other. Thus, it can increase output force than single case. The field test indicates that it can improve signal-to-noise ratio (SNR) of reflected waves in deep layer significantly. However, it contributes little for signals from shallow layers and sometimes it can even deteriorate shallow reflected signals than single source. This is because for signals reflected from shallow depths, the assumption in combination mode that seismic waves propagate along vertical rays is no longer valid. Therefore, they are not stacked constructively. Phased-array mode belongs to a new source array, whose key part is so-called delay/phase controller. By coordinating the signal of each unit using the controller, the seismic waves can be beamed into any interested direction, based on the underground structure and the depth of interested reflected layer. In this case, SNR of the concerned reflected wave can be improved apparently. PHVS in phased-array mode is called PAVS. We made two field tests to evaluate the performance of PAVS. In the first test, we compare PAVS with

  17. High Frequency Linacs for Hadrontherapy

    NASA Astrophysics Data System (ADS)

    Amaldi, Ugo; Braccini, Saverio; Puggioni, Paolo

    The use of radiofrequency linacs for hadrontherapy was proposed about 20 years ago, but only recently has it been understood that the high repetition rate together with the possibility of very rapid energy variations offers an optimal solution to the present challenge of hadrontherapy: "paint" a moving tumor target in three dimensions with a pencil beam. Moreover, the fact that the energy, and thus the particle range, can be electronically adjusted implies that no absorber-based energy selection system is needed, which, in the case of cyclotron-based centers, is the cause of material activation. On the other side, a linac consumes less power than a synchrotron. The first part of this article describes the main advantages of high frequency linacs in hadrontherapy, the early design studies, and the construction and test of the first high-gradient prototype which accelerated protons. The second part illustrates some technical issues relevant to the design of copper standing wave accelerators, the present developments, and two designs of linac-based proton and carbon ion facilities. Superconductive linacs are not discussed, since nanoampere currents are sufficient for therapy. In the last two sections, a comparison with circular accelerators and an overview of future projects are presented.

  18. High frequency-heated air turbojet

    NASA Technical Reports Server (NTRS)

    Miron, J. H. D.

    1986-01-01

    A description is given of a method to heat air coming from a turbojet compressor to a temperature necessary to produce required expansion without requiring fuel. This is done by high frequency heating, which heats the walls corresponding to the combustion chamber in existing jets, by mounting high frequency coils in them. The current transformer and high frequency generator to be used are discussed.

  19. Large-Aperture Membrane Active Phased-Array Antennas

    NASA Technical Reports Server (NTRS)

    Karasik, Boris; McGrath, William; Leduc, Henry

    2009-01-01

    Large-aperture phased-array microwave antennas supported by membranes are being developed for use in spaceborne interferometric synthetic aperture radar systems. There may also be terrestrial uses for such antennas supported on stationary membranes, large balloons, and blimps. These antennas are expected to have areal mass densities of about 2 kg/sq m, satisfying a need for lightweight alternatives to conventional rigid phased-array antennas, which have typical areal mass densities between 8 and 15 kg/sq m. The differences in areal mass densities translate to substantial differences in total mass in contemplated applications involving aperture areas as large as 400 sq m. A membrane phased-array antenna includes patch antenna elements in a repeating pattern. All previously reported membrane antennas were passive antennas; this is the first active membrane antenna that includes transmitting/receiving (T/R) electronic circuits as integral parts. Other integral parts of the antenna include a network of radio-frequency (RF) feed lines (more specifically, a corporate feed network) and of bias and control lines, all in the form of flexible copper strip conductors on flexible polymeric membranes. Each unit cell of a prototype antenna (see Figure 1) contains a patch antenna element and a compact T/R module that is compatible with flexible membrane circuitry. There are two membrane layers separated by a 12.7-mm air gap. Each membrane layer is made from a commercially available flexible circuit material that, as supplied, comprises a 127-micron-thick polyimide dielectric layer clad on both sides with 17.5-micron-thick copper layers. The copper layers are patterned into RF, bias, and control conductors. The T/R module is located on the back side of the ground plane and is RF-coupled to the patch element via a slot. The T/R module is a hybrid multilayer module assembled and packaged independently and attached to the membrane array. At the time of reporting the information for

  20. Receiver Would Control Phasing of a Phased-Array Antenna

    NASA Technical Reports Server (NTRS)

    Dunn, Charles E.; Young, Lawrence E.

    2006-01-01

    In a proposed digital signal-processing technique, a radio receiver would control the phasing of a phased-array antenna to aim the peaks of the antenna radiation pattern toward desired signal sources while aiming the nulls of the pattern toward interfering signal sources. The technique was conceived for use in a Global Positioning System (GPS) receiver, for which the desired signal sources would be GPS satellites and typical interference sources would be terrestrial objects that cause multipath propagation. The technique could also be used to optimize reception in spread-spectrum cellular-telephone and military communication systems. During reception of radio signals in a conventional phased-array antenna system, received signals at their original carrier frequencies are phase-shifted, then combined by analog circuitry. The combination signal is then subjected to down-conversion and demodulation. In a system according to the proposed technique (see figure), the signal received by each antenna would be subjected to down-conversion, spread-spectrum demodulation, and correlation; this processing would be performed separately from, and simultaneously with, similar processing of signals received by the other antenna elements. Following analog down-conversion to baseband, the signals would be digitized, and all subsequent processing would be digital. In the digital process, residual carriers would be removed and each signal would be correlated with a locally generated model pseudorandum-noise code, all following normal GPS procedure. As part of this procedure, accumulated values would be added in software and the resulting signals would be phase-shifted in software by the amounts necessary to synthesize the desired antenna directional gain pattern of peaks and nulls. The principal advantage of this technique over the conventional radio-frequency-combining technique is that the parallel digital baseband processing of the signals from the various antenna elements would be

  1. Experimental Results for a Photonic Time Reversal Processor for Adaptive Control of an Ultra Wideband Phased Array Antenna

    DTIC Science & Technology

    2008-03-01

    Radar , Boston: Artech House, 1994. 2. H. Zmuda, “ Optical Beamforming for Phased Array Antennas,” Chapter 19, R...Beamforming, Phased Array Antennas, Time Reversal, Ultra Wideband Radar 1 INTRODUCTION 1.1 Photonic Processing for Microwave Phased Array ...Architecture for Broadband Adaptive Nulling with Linear and Conformal Phased Array Antennas”, Fiber and Integrated Optics , vol. 19, no. 2, March 2000, pp.

  2. Phased array ultrasonic processing for enhanced and affordable diagnosis

    NASA Astrophysics Data System (ADS)

    Dominguez, N.; Rougeron, G.; Leberre, S.; Pautel, R.

    2013-01-01

    Phased array ultrasonic reconstruction techniques are often presented as a prospect for better and enhanced diagnosis. However to date few applications of these techniques can be found in the industry, partly because of questions on sizing but also because they often require heavy acquisitions. A way forward is then to propose techniques requiring less intensive data acquisition to make them broadly affordable in practice. Several approaches ranging from full matrix capture to paintbrush acquisitions are presented in this paper in combination with associated reconstruction processing like the Total Focusing Method (TFM) and the Time Domain Topological Energy (TDTE) techniques. Emphasis is given to their relative relevancies and practical applicability on typical configurations of interest for industries. The paper also presents recent efforts made on the acceleration of processing computation times, in particular through the use of GPU architectures.

  3. Complex direct comb spectroscopy with a virtually imaged phased array.

    PubMed

    Scholten, Sarah K; Anstie, James D; Hébert, Nicolas Bourbeau; White, Richard T; Genest, Jérôme; Luiten, Andre N

    2016-03-15

    We demonstrate a simple interferometric technique to directly measure the complex optical transmittance over a large spectral range using a frequency-comb spectrometer based on a virtually imaged phased array. A Michelson interferometer encodes the phase deviations induced by a sample contained in one of its arms into an interferogram image. When combined with an additional image taken from each arm separately, along with a frequency-calibration image, this allows full reconstruction of the sample's optical transfer function. We demonstrate the technique with a vapor cell containing H13C14N, producing transmittance and phase spectra spanning 2.9 THz (∼23  nm) with ∼1 GHz resolution.

  4. Monitoring Growth of Closed Fatigue Crack Using Subharmonic Phased Array

    NASA Astrophysics Data System (ADS)

    Ohara, Y.; Endo, H.; Hashimoto, M.; Shintaku, Y.; Yamanaka, K.

    2010-02-01

    To ensure the safety and reliability of atomic power plants and airplanes, the technique of monitoring closed fatigue cracks is requisite. Here we monitored the distribution of the crack depths and closure behavior in the length direction after 48000 and 87000 fatigue cycles using subharmonic phased array for crack evaluation (SPACE). The crack depths in the subharmonic images were larger than those in the fundamental images. Specifically, the difference was larger at near the side surface than at the center. The percentage of the closed part varied with the crack growth in the specimen. In addition, we fabricated shoe for SPACE to facilitate mechanical scanning. Thus, it was demonstrated that SPACE is useful in monitoring closed fatigue crack growth.

  5. Multiple beam phased array for Space Station Control Zone Communications

    NASA Astrophysics Data System (ADS)

    Halsema, P. B.

    The Space Station Communications Control Zone is a disk shaped region 40 nautical miles in diameter and 10 nautical miles thick centered about the Space Station. It is estimated that 6 simultaneous Multiple Access (MA) channels will be required to satisfy the projected communications needs within this zone. These channels will be used to communicate with MA users located anywhere within the Control Zone. This paper details the tradeoffs and design implementation of a multiple beam integrated phased array to provide antenna coverage of the Control Zone. The array is a compact, modular assembly using Gallium Arsenide circuits, microstrip elements, and advanced packaging techniques. This results in a small, reliable antenna system capable of meeting the projected Space Station requirements and flexible enough to grow and evolve as the Space Station communications needs develop.

  6. Low Noise Performance Perspectives Of Wideband Aperture Phased Arrays

    NASA Astrophysics Data System (ADS)

    Woestenburg, E. E. M.; Kuenen, J. C.

    2004-06-01

    A general analysis of phased array noise properties and measurements, applied to one square meter tiles of the Thousand Element Array (THEA), has resulted in a procedure to define the noise budget for a THEA-tile (Woestenburg and Dijkstra, 2003). The THEA system temperature includes LNA and receiver noise, antenna connecting loss, noise coupling between antenna elements and other possible contributions. This paper discusses the various noise contributions to the THEA system temperature and identifies the areas where improvement can be realized. We will present better understanding of the individual noise contributions using measurements and analysis of single antenna/receiver elements. An improved design for a 1-m2 Low Noise Tile (LNT) will be discussed and optimized low noise performance for the LNT is presented. We will also give future perspectives of the noise performance for such tiles, in relation to the requirements for SKA in the 1 GHz frequency range.

  7. Integrated phased array for wide-angle beam steering.

    PubMed

    Yaacobi, Ami; Sun, Jie; Moresco, Michele; Leake, Gerald; Coolbaugh, Douglas; Watts, Michael R

    2014-08-01

    We demonstrate an on-chip optical phased array fabricated in a CMOS compatible process with continuous, fast (100 kHz), wide-angle (51°) beam-steering suitable for applications such as low-cost LIDAR systems. The device demonstrates the largest (51°) beam-steering and beam-spacing to date while providing the ability to steer continuously over the entire range. Continuous steering is enabled by a cascaded phase shifting architecture utilizing, low power and small footprint, thermo-optic phase shifters. We demonstrate these results in the telecom C-band, but the same design can easily be adjusted for any wavelength between 1.2 and 3.5 μm.

  8. Tunable elastomer-based virtually imaged phased array.

    PubMed

    Metz, Philipp; Block, Hendrik; Behnke, Christopher; Krantz, Matthias; Gerken, Martina; Adam, Jost

    2013-02-11

    Virtually imaged phased arrays (VIPAs) offer a high potential for wafer-level integration and superior optical properties compared to conventional gratings. We introduce an elastomer-based tunable VIPA enabling fine tuning of the dispersion characteristics. It consists of a poly-dimethylsiloxane (PDMS) layer sandwiched between silver bottom and top coatings, which form the VIPA's high reflective and semi-transparent mirror, respectively. The latter also acts as an electrode for Joule heating, such that the optical PDMS resonator cavity tuning is carried out via a combination of thermal expansion and the thermo-optic effect. Analogous to the free spectral range (FSR), based on a VIPA specific dispersion law, we introduce a new characteristic VIPA performance measure, namely the free angular range (FAR). We report a tuning span of one FAR achieved by a 7.2K temperature increase of a 170μm PDMS VIPA. Both resonance quality and tunability are analyzed in numerical simulations and experiments.

  9. Subharmonic phased array for crack evaluation using surface acoustic wave

    NASA Astrophysics Data System (ADS)

    Ouchi, Akihiro; Sugawara, Azusa; Ohara, Yoshikazu; Yamanaka, Kazushi

    2015-07-01

    To accurately measure closed crack length, we proposed an imaging method using a subharmonic phased array for crack evaluation using surface acoustic waves (SAW SPACE) with water immersion. We applied SAW SPACE to the hole specimen in a fundamental array (FA) image. The hole was imaged with high resolution. Subsequently, SAW SPACE was applied to fatigue crack and stress corrosion crack (SCC) specimens. A fatigue crack was imaged in FA and subharmonic array (SA) images, and the length of this particular fatigue crack measured in the images was almost the same as that measured by optical observation. The SCC was imaged and its length was accurately measured in the SA image, whereas it was underestimated in the FA image and by optical observation. Thus, we demonstrated that SAW SPACE with water immersion is useful for the accurate measurement of closed crack length and for imaging the distribution of open and closed parts of cracks with high resolution.

  10. Phased Array Mirror Extendible Large Aperture (PAMELA) Optics Adjustment

    NASA Technical Reports Server (NTRS)

    1995-01-01

    Scientists at Marshall's Adaptive Optics Lab demonstrate the Wave Front Sensor alignment using the Phased Array Mirror Extendible Large Aperture (PAMELA) optics adjustment. The primary objective of the PAMELA project is to develop methods for aligning and controlling adaptive optics segmented mirror systems. These systems can be used to acquire or project light energy. The Next Generation Space Telescope is an example of an energy acquisition system that will employ segmented mirrors. Light projection systems can also be used for power beaming and orbital debris removal. All segmented optical systems must be adjusted to provide maximum performance. PAMELA is an on going project that NASA is utilizing to investigate various methods for maximizing system performance.

  11. Optically controlled phased-array antenna with PSK communications

    NASA Astrophysics Data System (ADS)

    Cooper, Martin J.; Sample, Peter; Lewis, Meirion F.; Wilson, Rebecca A.

    2004-11-01

    An optically controlled RF/microwave/mm-wave phased array antenna has been developed operating at 10 GHz with 30 kHz reconfiguration rate via the use of a micromachined silicon Spatial Light Modulator. A communications function has been demonstrated with a variety of Phase Shift Keying modulation schemes (BPSK, QPSK, MSK) at data rates up to 200 Mbit/s and low BER (<1×10-9). A single channel has been demonstrated at 35 GHz. The properties of photonic components are taken advantage of in several ways: (i) since the carrier frequency is derived from heterodyning of lasers, it is tuneable from almost DC-100 GHz, (ii) the use of optical fiber allows for EMI immune antenna remoting, and (iii) the wide information bandwidth of optical modulators, which in this configuration is carrier frequency independent. The above is achieved in a lightweight and compact format, with considerable scope for further reductions in size and weight.

  12. Photorefractive phased array antenna beam-forming processor

    NASA Astrophysics Data System (ADS)

    Sarto, Anthony W.; Wagner, Kelvin H.; Weverka, Robert T.; Blair, Steven M.; Weaver, Samuel P.

    1996-11-01

    A high bandwidth, large degree-of-freedom photorefractive phased-array antenna beam-forming processor which uses 3D dynamic volume holograms in photorefractive crystals to time integrate the adaptive weights to perform beam steering and jammer-cancellation signal-processing tasks is described. The processor calculates the angle-of-arrival of a desired signal of interest and steers the antenna pattern in the direction of this desired signal by forming a dynamic holographic grating proportional to the correlation between the incoming signal of interest from the antenna array and the temporal waveform of the desired signal. Experimental results of main-beam formation and measured array-functions are presented in holographic index grating and the resulting processor output.

  13. Time-delayed directional beam phased array antenna

    DOEpatents

    Fund, Douglas Eugene; Cable, John William; Cecil, Tony Myron

    2004-10-19

    An antenna comprising a phased array of quadrifilar helix or other multifilar antenna elements and a time-delaying feed network adapted to feed the elements. The feed network can employ a plurality of coaxial cables that physically bridge a microstrip feed circuitry to feed power signals to the elements. The cables provide an incremental time delay which is related to their physical lengths, such that replacing cables having a first set of lengths with cables having a second set of lengths functions to change the time delay and shift or steer the antenna's main beam. Alternatively, the coaxial cables may be replaced with a programmable signal processor unit adapted to introduce the time delay using signal processing techniques applied to the power signals.

  14. Phased-array-fed antenna configuration study, volume 2

    NASA Technical Reports Server (NTRS)

    Sorbello, R. M.; Zaghloul, A. I.; Lee, B. S.; Siddiqi, S.; Geller, B. D.

    1983-01-01

    Increased capacity in future satellite systems can be achieved through antenna systems which provide multiplicity of frequency reuses at K sub a band. A number of antenna configurations which can provide multiple fixed spot beams and multiple independent spot scanning beams at 20 GHz are addressed. Each design incorporates a phased array with distributed MMIC amplifiers and phasesifters feeding a two reflector optical system. The tradeoffs required for the design of these systems and the corresponding performances are presented. Five final designs are studied. In so doing, a type of MMIC/waveguide transition is described, and measured results of the breadboard model are presented. Other hardware components developed are described. This includes a square orthomode transducer, a subarray fed with a beamforming network to measure scanning performance, and another subarray used to study mutual coupling considerations. Discussions of the advantages and disadvantages of the final design are included.

  15. Phased-Array Measurements of Single Flow Hot Jets

    NASA Technical Reports Server (NTRS)

    Bridges, James; Lee, Sang Soo

    2005-01-01

    A 16 microphone phased-array system has been successfully applied to measure jet noise source distributions. In this study, a round convergent nozzle was tested at various hot and cold flow conditions: acoustic Mach numbers are between 0.35 and 1.6 and static temperature ratios are varied from cold to 2.7. The classical beamforming method was applied on narrowband frequencies. From the measured source distributions locations of peak strength were tracked and found to be very consistent between adjacent narrowband frequencies. In low speed heated and unheated jets, the peak source locations vary smoothly from the nozzle exit to downstream as the frequency is decreased. When the static temperature ratio was kept constant, the peak source position moved downstream with increasing acoustic Mach number for the Strouhal numbers smaller than about 1.5. It was also noted that the peak source locations of low frequencies occur farther downstream than the end of potential core.

  16. High Frequency Chandler Wobble Excitation

    NASA Astrophysics Data System (ADS)

    Seitz, F.; Stuck, J.; Thomas, M.

    2003-04-01

    and OMCT forcing fields give no hint for increased excitation power in the Chandler band. Thus it is assumed, that continuous high frequency excitation due to stochastic weather phenomena is responsible for the perpetuation of the Chandler wobble.

  17. Feasibility of using lateral mode coupling method for a large scale ultrasound phased array for noninvasive transcranial therapy.

    PubMed

    Song, Junho; Hynynen, Kullervo

    2010-01-01

    A hemispherical-focused, ultrasound phased array was designed and fabricated using 1372 cylindrical piezoelectric transducers that utilize lateral coupling for noninvasive transcranial therapy. The cylindrical transducers allowed the electrical impedance to be reduced by at least an order of magnitude, such that effective operation could be achieved without electronic matching circuits. In addition, the transducer elements generated the maximum acoustic average surface intensity of 27 W/cm(2). The array, driven at the low (306-kHz) or high frequency (840-kHz), achieved excellent focusing through an ex vivo human skull and an adequate beam steering range for clinical brain treatments. It could electronically steer the ultrasound beam over cylindrical volumes of 100-mm in diameter and 60-mm in height at 306 kHz, and 30-mm in diameter and 30-mm in height at 840 kHz. A scanning laser vibrometer was used to investigate the radial and length mode vibrations of the element. The maximum pressure amplitudes through the skull at the geometric focus were predicted to be 5.5 MPa at 306 kHz and 3.7 MPa at 840 kHz for RF power of 1 W on each element. This is the first study demonstrating the feasibility of using cylindrical transducer elements and lateral coupling in construction of ultrasound phased arrays.

  18. Modeling the radiation of ultrasonic phased-array transducers with Gaussian beams.

    PubMed

    Huang, Ruiju; Schmerr, Lester W; Sedov, Alexander

    2008-12-01

    A new transducer beam model, called a multi-Gaussian array beam model, is developed to simulate the wave fields radiated by ultrasonic phased-array transducers. This new model overcomes the restrictions on using ordinary multi-Gaussian beam models developed for large single-element transducers in phased-array applications. It is demonstrated that this new beam model can effectively model the steered and focused beams of a linear phased-array transducer.

  19. Through Weld Inspection of Wrought Stainless Steel Piping Using Phased Arrays

    SciTech Connect

    Anderson, Michael T.; Cumblidge, Stephen E.; Doctor, Steven R.

    2004-12-31

    Outline: Discuss far-side weld problem and phased array techniques applied. Describe laboratory work on flawed piping specimens using L- and S-wave arrays and provide synopsis of results. Discuss conclusions ofr capability of phased array as applied to austenitic welds. Research Approach: Evaluate phased arrays on unifornly-welded piping specimens. Apply best methods to non-uniform welds. Correlate acoustic responses as function of weld microstructures.

  20. Demonstration Results of the Triband, Multi-Beam Airborne Telemetry Phased Array (AirPA) System

    DTIC Science & Technology

    2015-03-01

    AirPA Phase 3 test event in September 2014, the element level digital beamforming phased array was successfully demonstrated at Edwards Air Force...Phased Array, antenna, digital beam-forming, beamforming, DBF, L-band, S-band, C-band, CTEIP, NAVAIR 16. SECURITY CLASSIFICATION OF...elevation. During the AirPA Phase 3 test event in September 2014, the element level digital beamforming phased array was successfully demonstrated at

  1. Development of ultrasonic phased array systems for applications in tube and pipe inspection

    NASA Astrophysics Data System (ADS)

    Guo, Yanming; Yuan, Qingshan; Sun, Zhigang; Logan, Kevin; Lam, Clive

    2012-05-01

    This paper reports the development of ultrasonic phased array systems used for tubular inspection. First the design of a linear phased array is discussed with considerations of both theoretically and practically important factors. Then systems utilizing the linear phased array are introduced for different applications. To evaluate the system performance, tests were performed on flat bottom holes and artificial notches, including notches in longitudinal, transverse, and oblique orientations made according to API specifications. Test results have been presented.

  2. Affordable Wideband Multifunction Phased Array Antenna Architectures Using Frequency Scaled Radiating Elements

    DTIC Science & Technology

    2014-09-04

    Naval Research Laboratory Washington, DC 20375-5320 NRL/MR/5310--14-9431 Affordable Wideband Multifunction Phased Array Antenna Architectures Using...Wideband Multifunction Phased Array Antenna Architectures Using Frequency Scaled Radiating Elements Rashmi Mital, Dharmesh P. Patel, Jaganmohan B.L. Rao...number of antennas on ships to meet the numerous functional requirements. Recently, wideband phased array antennas are being developed that can

  3. Photonic true-time-delays based on multiplexed substrate-guided wave propagation for phased array antenna applications

    NASA Astrophysics Data System (ADS)

    Chen, Ray T.; Li, Richard L.

    1996-11-01

    A compact and affordable photonic true-time-delay (TTD) beam steering device for phased array antenna applications using multiplexed substrate-guided wave propagation is presented. The TTD design uses holographic input and output couplers to change the direction of beam propagation as well as optical fanout. Optical delays of various delay lines can be adjusted easily through the substrate thickness and the total internal reflection angle inside the substrate material. Broadband microwave signals for feeding the radiating elements are generated through optical heterodyne technique and they are detected by metal-semiconductor-metal detector arrays. The physical aspects of phase-shifters and true-time-delays are first introduced. Then design issues on the photonic TTD architecture and practical constraints on making holographic grating couplers are discussed, especially concerning with recording gratings on DuPont photopolymer materials. Finally, the generation and detection of high frequency microwave signals up to 25 GHz by optical heterodyne techniques are illustrated.

  4. Cantilever RF-MEMS for monolithic integration with phased array antennas on a PCB

    NASA Astrophysics Data System (ADS)

    Aguilar-Armenta, C. J.; Porter, S. J.

    2015-12-01

    This article presents the development and operation of a novel electrostatic metal-to-metal contact cantilever radio-frequency microelectromechanical system (RF-MEMS) switch for monolithic integration with microstrip phased array antennas (PAAs) on a printed circuit board. The switch is fabricated using simple photolithography techniques on a Rogers 4003c substrate, with a footprint of 200 µm × 100 µm, based on a 1 µm-thick copper cantilever. An alternative wet-etching technique for effectively releasing the cantilever is described. Electrostatic and electromagnetic measurements show that the RF-MEMS presents an actuation voltage of 90 V for metal-to-metal contact, an isolation of -8.7 dB, insertion loss of -2.5 dB and a return loss of -15 dB on a 50 Ω microstrip line at 12.5 GHz. For proof-of-concept, a beam-steering 2 × 2 microstrip PAA, based on two 1-bit phase shifters suitable for the monolithic integration of the RF-MEMS, has been designed and measured at 12.5 GHz. Measurements show that the beam-steering system presents effective radiation characteristics with scanning capabilities from broadside towards 29° in the H-plane.

  5. A Study of Microstrip Antennas for Multiple Band and High Frequency Operations.

    DTIC Science & Technology

    1986-03-01

    34 Report No. RADC-TR-81-98. [61 Desoer , Charles A. and Ernest S. Kuh, " Basic Circuit Theory ," 1969 by McGraw-Hill, Inc. 4" 111-12 p. LIST OF FIGURES...improvement in the future. Throughout this report a basic understanding of phased array theory and terminology is assumed. As mentioned above, many excellent...Y. T. Lo, W. F. Richards, P. Simon, and D. D. Harrison, " Theory and Applications for Microstrip Antennas," Proceedings of the Printed Circuit Antenna

  6. Phased Array Antenna Analysis Using Hybrid Finite Element Methods

    DTIC Science & Technology

    1993-06-01

    Waveguide ; (b) Geometry Model for Method of Moments ........................ 4 2. Printed Dipole Radiator: (a) Actual Geometry with Microstrip Balun and...Finite Elem ents . ............................................. 19 11. Equivalence Model for Waveguide /Cavity Problem: (a) Original Problem; (b... Waveguide Array Active Reflection Coefficient - Comparison of Results Uscig Cavity Array (CAVIARR) and General Array (PARANA) Models . 76 45. Rectangular

  7. Thermal dispersion method for an ultrasonic phased-array transducer

    NASA Astrophysics Data System (ADS)

    Choi, Euna; Lee, Wonseok; Roh, Yongrae

    2016-07-01

    When the driving voltage of an ultrasonic transducer is increased to improve the quality of ultrasound images, heat is generated inside the transducer, which can burn the patient’s skin and degrade transducer performance. In this study, the method to disperse the heat inside an ultrasonic phased-array transducer has been examined. The mechanism of temperature rise due to heat generation inside the transducer was investigated by numerical analysis and the effects of the thermal properties of the components of the transducer such as specific heat and thermal conductivity on the temperature rise were analyzed. On the basis of the results, a heat-dispersive structure was devised to reduce the temperature at the surface of the acoustic lens of the transducer. Prototype transducers were fabricated to check the efficacy of the heat-dispersive structure. By experiments, we have confirmed that the new heat-dispersive structure can reduce the internal temperature by as much as 50% in comparison with the conventional structure, which confirms the validity of the thermal dispersion mechanism developed in this work.

  8. Ultrasound cylindrical phased array for transoesophageal thermal therapy: initial studies.

    PubMed

    Melodelima, David; Lafon, Cyril; Prat, Frederic; Birer, Alain; Cathignol, Dominique

    2002-12-07

    This work was undertaken to investigate the feasibility of constructing a cylindrical phased array composed of 64 elements spread around the periphery (OD 10.6 mm) for transoesophageal ultrasound thermotherapy. The underlying operating principle of this applicator is to rotate a plane ultrasound beam electronically. For this purpose, eight adjacent transducers were successively excited with appropriate delay times so as to generate a plane wave. The exposure direction was changed by exciting a different set of eight elements. For these feasibility studies, we used a cylindrical prototype (OD 10.6 mm) composed of 16 elementary transducers distributed over a quarter of the cylinder, all operating at 4.55 MHz. The active part was mechanically reinforced by a rigid damper structure behind the transducers. It was shown that an ultrasound field similar to that emitted by a plane transducer could be generated. Ex vivo experiments on pig's liver demonstrated that the ultrasound beam could be accurately rotated to generate sector-based lesions to a suitable depth (up to 19 mm). Throughout these experiments, exposures lasting 20 s were delivered at an acoustic intensity of 17 W cm(-2). By varying the power from exposure to exposure, the depth of the lesion at different angles could be controlled.

  9. High power compatible internally sensed optical phased array.

    PubMed

    Roberts, Lyle E; Ward, Robert L; Francis, Samuel P; Sibley, Paul G; Fleddermann, Roland; Sutton, Andrew J; Smith, Craig; McClelland, David E; Shaddock, Daniel A

    2016-06-13

    The technical embodiment of the Huygens-Fresnel principle, an optical phased array (OPA) is an arrangement of optical emitters with relative phases controlled to create a desired beam profile after propagation. One important application of an OPA is coherent beam combining (CBC), which can be used to create beams of higher power than is possible with a single laser source, especially for narrow linewidth sources. Here we present an all-fiber architecture that stabilizes the relative output phase by inferring the relative path length differences between lasers using the small fraction of light that is back-reflected into the fiber at the OPA's glass-air interface, without the need for any external sampling optics. This architecture is compatible with high power continuous wave laser sources (e.g., fiber amplifiers) up to 100 W per channel. The high-power compatible internally sensed OPA was implemented experimentally using commercial 15 W fiber amplifiers, demonstrating an output RMS phase stability of λ/194, and the ability to steer the beam at up to 10 kHz.

  10. Phased array ultrasonic approach to turbine blade attachment inspection

    SciTech Connect

    Nottingham, L.D.; Solomon, K.R.; Presson, J.H.

    1994-12-31

    In situations where particular combinations of material susceptibility, stress, steam conditions and steam chemistry come together, certain steam turbine rotors have exhibited stress corrosion cracking (SCC) on the disk side of the blade attachments, where the blades are held to the disk. Cracking has been most prevalent in multiple-hook, fir-tree attachment designs and normally occurs in the corners of the fir-tree hooks. While attempts have been made to perform ultrasonic inspection of the complex fir-tree attachment geometries, results have been mixed. False calls, poor repeatability, a general lack of resolution and lack of a meaningful sizing capability are standing issues. A unique approach to this inspection features a phased array ultrasonic test system that can both focus the ultrasonic beam and steer it to different points within the complex geometry. The focused beam leads directly to significant improvements in detection performance and resolution, as well as the ability to estimate the size of an indication. The ability to steer the beam to different points within the attachment enables comprehensive examination of all critical locations without repeatedly changing and calibrating numerous transducers. Together these features provide more rapid inspections and improved reliability.

  11. Matrix phased array (MPA) imaging technology for resistance spot welds

    SciTech Connect

    Na, Jeong K.; Gleeson, Sean T.

    2014-02-18

    A three-dimensional MPA probe has been incorporated with a high speed phased array electronic board to visualize nugget images of resistance spot welds. The primary application area of this battery operated portable MPA ultrasonic imaging system is in the automotive industry which a conventional destructive testing process is commonly adopted to check the quality of resistance spot welds in auto bodies. Considering an average of five-thousand spot welds in a medium size passenger vehicle, the amount of time and effort given to popping the welds and measuring nugget size are immeasurable in addition to the millions of dollars' worth of scrap metals recycled per plant per year. This wasteful labor intensive destructive testing process has become less reliable as auto body sheet metal has transitioned from thick and heavy mild steels to thin and light high strength steels. Consequently, the necessity of developing a non-destructive inspection methodology has become inevitable. In this paper, the fundamental aspects of the current 3-D probe design, data acquisition algorithms, and weld nugget imaging process are discussed.

  12. PARAS program: Phased array radio astronomy from space

    NASA Technical Reports Server (NTRS)

    Jakubowski, Antoni K.; Haynes, David A.; Nuss, Ken; Hoffmann, Chris; Madden, Michael; Dungan, Michael

    1992-01-01

    An orbiting radio telescope is proposed which, when operated in a Very Long Baseline Interferometry (VLBLI) scheme, would allow higher (than currently available) angular resolution and dynamic range in the maps, and the ability of observing rapidly changing astronomical sources. Using a passive phases array technology, the proposed design consists of 656 hexagonal modules forming a 150 meter diameter dish. Each observatory module is largely autonomous, having its own photovoltaic power supply and low-noise receiver and processor for phase shifting. The signals received by the modules are channeled via fiber optics to the central control computer in the central bus module. After processing and multiplexing, the data is transmitted to telemetry stations on the ground. The truss frame supporting each observatory pane is a hybrid structure consisting of a bottom graphite/epoxy tubular triangle and rigidized inflatable Kevlar tubes connecting the top observatory panel and bottom triangle. Attitude control and stationkeeping functions are performed by a system of momentum wheels in the bus and four propulsion modules located at the compass points on the periphery of the observatory dish. Each propulsion module has four monopropellant thrusters and six hydrazine arcjets, the latter supported by a nuclear reactor. The total mass of the spacecraft is 22,060 kg.

  13. Digital Phased Array Ultrasonic Inspection system with dynamic focusing

    NASA Astrophysics Data System (ADS)

    Hwang, J. S.; Shin, H. J.; Song, S. J.; Song, T. K.

    2000-05-01

    Enhancement of the ultrasonic flaw detection and characterization is expected through the development of a high performance PAULI (Phased Array Ultrasonic Inspection) system which can provide high resolution two-dimensional (sector scan: S-scan) images. The high-resolution S-scan image renders inspection results more readable compared to the conventional A-scan and B-scan results. Therefore, it can improve inspection efficiency and reliability. In this study, the ultrasonic imaging technologies developed in medical applications were adapted to develop a digital PAULI system for nondestructive testing. To provide real-time S-scan images, the PAULI system uses 64 independent transceiver channels controlled by proper delay laws for steering and focusing the ultrasound beams along each scan lines. The PAULI system employs a novel dynamic receive focusing technique in order to optimize the lateral resolution by focusing the ultrasound wave at all imaging points. The dynamic receive focusing is achieved in real-time by digital signal processing methods. The feasibility of PAULI system is demonstrated for the NDE of steel structures.

  14. Evolutionary Design of a Phased Array Antenna Element

    NASA Technical Reports Server (NTRS)

    Globus, Al; Linden, Derek; Lohn, Jason

    2006-01-01

    We present an evolved S-band phased array antenna element design that meets the requirements of NASA's TDRS-C communications satellite scheduled for launch early next decade. The original specification called for two types of elements, one for receive only and one for transmit/receive. We were able to evolve a single element design that meets both specifications thereby simplifying the antenna and reducing testing and integration costs. The highest performance antenna found using a genetic algorithm and stochastic hill-climbing has been fabricated and tested. Laboratory results are largely consistent with simulation. Researchers have been investigating evolutionary antenna design and optimization since the early 1990s, and the field has grown in recent years its computer speed has increased and electromagnetic simulators have improved. Many antenna types have been investigated, including wire antennas, antenna arrays and quadrifilar helical antennas. In particular, our laboratory evolved a wire antenna design for NASA's Space Technology 5 (ST5) spacecraft. This antenna has been fabricated, tested, and is scheduled for launch on the three spacecraft in 2006.

  15. Evolutionary Adaptive Discovery of Phased Array Sensor Signal Identification

    SciTech Connect

    Timothy R. McJunkin; Milos Manic

    2011-05-01

    Tomography, used to create images of the internal properties and features of an object, from phased array ultasonics is improved through many sophisiticated methonds of post processing of data. One approach used to improve tomographic results is to prescribe the collection of more data, from different points of few so that data fusion might have a richer data set to work from. This approach can lead to rapid increase in the data needed to be stored and processed. It also does not necessarily lead to have the needed data. This article describes a novel approach to utilizing the data aquired as a basis for adapting the sensors focusing parameters to locate more precisely the features in the material: specifically, two evolutionary methods of autofocusing on a returned signal are coupled with the derivations of the forumulas for spatially locating the feature are given. Test results of the two novel methods of evolutionary based focusing (EBF) illustrate the improved signal strength and correction of the position of feature using the optimized focal timing parameters, called Focused Delay Identification (FoDI).

  16. Matrix phased array (MPA) imaging technology for resistance spot welds

    NASA Astrophysics Data System (ADS)

    Na, Jeong K.; Gleeson, Sean T.

    2014-02-01

    A three-dimensional MPA probe has been incorporated with a high speed phased array electronic board to visualize nugget images of resistance spot welds. The primary application area of this battery operated portable MPA ultrasonic imaging system is in the automotive industry which a conventional destructive testing process is commonly adopted to check the quality of resistance spot welds in auto bodies. Considering an average of five-thousand spot welds in a medium size passenger vehicle, the amount of time and effort given to popping the welds and measuring nugget size are immeasurable in addition to the millions of dollars' worth of scrap metals recycled per plant per year. This wasteful labor intensive destructive testing process has become less reliable as auto body sheet metal has transitioned from thick and heavy mild steels to thin and light high strength steels. Consequently, the necessity of developing a non-destructive inspection methodology has become inevitable. In this paper, the fundamental aspects of the current 3-D probe design, data acquisition algorithms, and weld nugget imaging process are discussed.

  17. Project PARAS: Phased array radio astronomy from space

    NASA Technical Reports Server (NTRS)

    Nuss, Kenneth; Hoffmann, Christopher; Dungan, Michael; Madden, Michael; Bendakhlia, Monia

    1992-01-01

    An orbiting radio telescope is proposed which, when operated in a very long baseline interferometry (VLBI) scheme, would allow higher than currently available angular resolution and dynamic range in the maps and the ability to observe rapidly changing astronomical sources. Using passive phased array technology, the proposed design consists of 656 hexagonal modules forming a 150-m diameter antenna dish. Each observatory module is largely autonomous, having its own photovoltaic power supply and low-noise receiver and processor for phase shifting. The signals received by the modules are channeled via fiber optics to the central control computer in the central bus module. After processing and multiplexing, the data are transmitted to telemetry stations on the ground. The truss frame supporting each observatory panel is a novel hybrid structure consisting of a bottom graphite/epoxy tubular triangle and rigidized inflatable Kevlar tubes connecting the top observatory panel and the bottom triangle. Attitude control and station keeping functions will be performed by a system of momentum wheels in the bus and four propulsion modules located at the compass points on the periphery of the observatory dish. Each propulsion module has four monopropellant thrusters and four hydrazine arcjets, the latter supported by either a photovoltaic array or a radioisotope thermoelectric generator. The total mass of the spacecraft is about 20,500 kg.

  18. CryoPAF4: a cryogenic phased array feed design

    NASA Astrophysics Data System (ADS)

    Locke, Lisa; Garcia, Dominic; Halman, Mark; Henke, Doug; Hovey, Gary; Jiang, Nianhua; Knee, Lewis; Lacy, Gordon; Loop, David; Rupen, Michael; Veidt, Bruce; Wierzbicki, Ramunas

    2016-07-01

    Phased array feed (PAF) receivers used on radio astronomy telescopes offer the promise of increased fields of view while maintaining the superlative performance attained with traditional single pixel feeds (SPFs). However, the much higher noise temperatures of room temperature PAFs compared to cryogenically-cooled SPFs have prevented their general adoption. Here we describe a conceptual design for a cryogenically cooled 2.8 - 5.18 GHz dual linear polarization PAF with estimated receiver temperature of 11 K. The cryogenic PAF receiver will comprise a 140 element Vivaldi antenna array and low-noise amplifiers housed in a 480 mm diameter cylindrical dewar covered with a RF transparent radome. A broadband two-section coaxial feed is integrated within each metal antenna element to withstand the cryogenic environment and to provide a 50 ohm impedance for connection to the rest of the receiver. The planned digital beamformer performs digitization, frequency band selection, beam forming and array covariance matrix calibration. Coupling to a 15 m offset Gregorian dual-reflector telescope, cryoPAF4 can expect to form 18 overlapping beams increasing the field of view by a factor of 8x compared to a single pixel receiver of equal system temperature.

  19. Matrix phased arrays for the inspection of CFRP-components

    NASA Astrophysics Data System (ADS)

    Kreutzbruck, M.; Brackrock, D.; Brekow, G.; Montag, H.-J.; Boehm, R.; Illerhaus, B.

    2014-02-01

    Lightweight components are increasingly used in different industrial sectors such as transportation, energy generation and automotive. This growing field includes different types of CFRP-structures, hybrid materials and glued components showing - compared to their pure metallic counterparts- a significant more complicated structure in terms of internal interfaces and anisotropy of material parameters. In this work we present the use of matrix phased array to increase the amount of obtained information to enhance the inspection quality. We used different types of carbon materials such as 6 mm thick uni- and bidirectional prepreg specimens containing impact damages. The latter were introduced with different energy levels ranging from 1.3 to 7.2 J. By scanning a 2.25 MHz matrix array with 6 × 10 elements above the prepreg surface and using different angels of incidence a complete 3D-image was generated which allows the detection of defects as small as 1mm in a depth of 4 mm. A comparison with conventional approaches show that the signal-to-noise ratio can be highly increased. This enables us to visualize the region of damage within the impact zone, clearly showing the cone-like damage distribution along increasing material depth. The detection quality allows the estimation of the opening angles of the cone shaped damage, which can be used for further evaluation and quantitation of energy dependent impact damages.

  20. A conformal SHF phased array for aircraft satellite communication

    NASA Astrophysics Data System (ADS)

    Cummings, R.; Kudrna, K.

    1984-03-01

    A receive-only 7.5 GHz microstrip phased array has been developed by Ball Aerospace Systems Division (BASD). This 256 radiating element array provides a gain of 20 dBic over a conical scan region of 120 deg. Two arrays with one on either side of an aircraft would provide near hemispherical coverage. The array consists of four subarrays and can be expanded to achieve higher gain when required. The array is left-hand circularly polarized and has three-bit digital PIN diode phase shifters for steering the beam. A microprocessor-based beam steering controller is used for calculating the phase shifter settings for each beam position. Each subarray includes radiating elements, quadrature hybrids, phase shifters, corporate feed, R.F. chokes in microstrip medium and hybrid PIN diode drivers. The array is approximately 1.5 inches thick and is conformal to the aircraft skin. It is a bolt on assembly only requiring aircraft skin entries for the R.F. output and for control lines. Transmit capability can be provided by merely changing the artwork to go to 8.5 GHz.

  1. Matrix phased arrays for the inspection of CFRP-components

    SciTech Connect

    Kreutzbruck, M.; Brackrock, D.; Brekow, G.; Montag, H.-J.; Boehm, R.; Illerhaus, B.

    2014-02-18

    Lightweight components are increasingly used in different industrial sectors such as transportation, energy generation and automotive. This growing field includes different types of CFRP-structures, hybrid materials and glued components showing - compared to their pure metallic counterparts- a significant more complicated structure in terms of internal interfaces and anisotropy of material parameters. In this work we present the use of matrix phased array to increase the amount of obtained information to enhance the inspection quality. We used different types of carbon materials such as 6 mm thick uni- and bidirectional prepreg specimens containing impact damages. The latter were introduced with different energy levels ranging from 1.3 to 7.2 J. By scanning a 2.25 MHz matrix array with 6 × 10 elements above the prepreg surface and using different angels of incidence a complete 3D-image was generated which allows the detection of defects as small as 1mm in a depth of 4 mm. A comparison with conventional approaches show that the signal-to-noise ratio can be highly increased. This enables us to visualize the region of damage within the impact zone, clearly showing the cone-like damage distribution along increasing material depth. The detection quality allows the estimation of the opening angles of the cone shaped damage, which can be used for further evaluation and quantitation of energy dependent impact damages.

  2. Ku band phased array in a large angular sector

    NASA Astrophysics Data System (ADS)

    Dubost, G.; Gueho, S.; Beguin, D.

    The feasibility of a microstrip, flat, phased, square array performing at high frequency and exhibiting proper technological behavior is demonstrated. A total of 64 three-bit digital PIN diode phase shifters are used to steer the beam. Sum and difference patterns can be formed for every deflected directivity. Data are presented on the efficiency evaluation for different deflection angles, the highest sidelobe levels, the maximum directivity, and the measured average efficiency.

  3. Monolithic optical phased-array transceiver in a standard SOI CMOS process.

    PubMed

    Abediasl, Hooman; Hashemi, Hossein

    2015-03-09

    Monolithic microwave phased arrays are turning mainstream in automotive radars and high-speed wireless communications fulfilling Gordon Moores 1965 prophecy to this effect. Optical phased arrays enable imaging, lidar, display, sensing, and holography. Advancements in fabrication technology has led to monolithic nanophotonic phased arrays, albeit without independent phase and amplitude control ability, integration with electronic circuitry, or including receive and transmit functions. We report the first monolithic optical phased array transceiver with independent control of amplitude and phase for each element using electronic circuitry that is tightly integrated with the nanophotonic components on one substrate using a commercial foundry CMOS SOI process. The 8 × 8 phased array chip includes thermo-optical tunable phase shifters and attenuators, nano-photonic antennas, and dedicated control electronics realized using CMOS transistors. The complex chip includes over 300 distinct optical components and over 74,000 distinct electrical components achieving the highest level of integration for any electronic-photonic system.

  4. Development of portable phased array UT system for real-time flaw imaging

    SciTech Connect

    Goto, M.

    1995-08-01

    Many functions and features of phased array UT technology must be useful for NDE in the industrial field. Some phased array UT systems have been developed for the inspection of nuclear pressure vessel and turbine components. However, phased array UT is still a special NDE technique and it has not been used widely in the past. The reasons of that are system size, cost, operator performance, equipment design and others. TOSHIBA has newly developed PC controlled portable phased array system to solve those problems. The portable phased array UT system is very compact and light but it is able to drive up to 32-channel linear array probe, to display real-time linear/sector B-scan, to display accumulated B-scan with an encoder and to display profile overlaid B-scan. The first applications were turbine component inspections for precise flaw investigation and flaw image data recording.

  5. Phased Array Beamforming and Imaging in Composite Laminates Using Guided Waves

    NASA Technical Reports Server (NTRS)

    Tian, Zhenhua; Leckey, Cara A. C.; Yu, Lingyu

    2016-01-01

    This paper presents the phased array beamforming and imaging using guided waves in anisotropic composite laminates. A generic phased array beamforming formula is presented, based on the classic delay-and-sum principle. The generic formula considers direction-dependent guided wave properties induced by the anisotropic material properties of composites. Moreover, the array beamforming and imaging are performed in frequency domain where the guided wave dispersion effect has been considered. The presented phased array method is implemented with a non-contact scanning laser Doppler vibrometer (SLDV) to detect multiple defects at different locations in an anisotropic composite plate. The array is constructed of scan points in a small area rapidly scanned by the SLDV. Using the phased array method, multiple defects at different locations are successfully detected. Our study shows that the guided wave phased array method is a potential effective method for rapid inspection of large composite structures.

  6. Monolithic Microwave Integrated Circuit (MMIC) Phased Array Demonstrated With ACTS

    NASA Technical Reports Server (NTRS)

    1996-01-01

    Monolithic Microwave Integrated Circuit (MMIC) arrays developed by the NASA Lewis Research Center and the Air Force Rome Laboratory were demonstrated in aeronautical terminals and in mobile or fixed Earth terminals linked with NASA's Advanced Communications Technology Satellite (ACTS). Four K/Ka-band experimental arrays were demonstrated between May 1994 and May 1995. Each array had GaAs MMIC devices at each radiating element for electronic beam steering and distributed power amplification. The 30-GHz transmit array used in uplinks to ACTS was developed by Lewis and Texas Instruments. The three 20-GHz receive arrays used in downlinks from ACTS were developed in cooperation with the Air Force Rome Laboratory, taking advantage of existing Air Force integrated-circuit, active-phased-array development contracts with the Boeing Company and Lockheed Martin Corporation. Four demonstrations, each related to an application of high interest to both commercial and Department of Defense organizations, were conducted. The location, type of link, and the data rate achieved for each of the applications is shown. In one demonstration-- an aeronautical terminal experiment called AERO-X--a duplex voice link between an aeronautical terminal on the Lewis Learjet and ACTS was achieved. Two others demonstrated duplex voice links (and in one case, interactive video links as well) between ACTS and an Army high-mobility, multipurpose wheeled vehicle (HMMWV, or "humvee"). In the fourth demonstration, the array was on a fixed mount and was electronically steered toward ACTS. Lewis served as project manager for all demonstrations and as overall system integrator. Lewis engineers developed the array system including a controller for open-loop tracking of ACTS during flight and HMMWV motion, as well as a laptop data display and recording system used in all demonstrations. The Jet Propulsion Laboratory supported the AERO-X program, providing elements of the ACTS Mobile Terminal. The successful

  7. Airborne ultrasonic phased arrays using ferroelectrets: a new fabrication approach.

    PubMed

    Ealo, Joao L; Camacho, Jorge J; Fritsch, Carlos

    2009-04-01

    In this work, a novel procedure that considerably simplifies the fabrication process of ferroelectret-based multielement array transducers is proposed and evaluated. Also, the potential of ferroelectrets being used as active material for air-coupled ultrasonic transducer design is demonstrated. The new construction method of multi-element transducers introduces 2 distinctive improvements. First, active ferroelectret material is not discretized into elements, and second, the need of structuring upper and/or lower electrodes in advance of the permanent polarization of the film is removed. The aperture discretization and the mechanical connection are achieved in one step using a through-thickness conductive tape. To validate the procedure, 2 linear array prototypes of 32 elements, with a pitch of 3.43 mm and a wide usable frequency range from 30 to 300 kHz, were built and evaluated using a commercial phased-array system. A low crosstalk among elements, below -30 dB, was measured by interferometry. Likewise, a homogeneous response of the array elements, with a maximum deviation of +/-1.8 dB, was obtained. Acoustic beam steering measurements were accomplished at different deflection angles using a calibrated microphone. The ultrasonic beam parameters, namely, lateral resolution, side lobe level, grating lobes, and focus depth, were congruent with theory. Acoustic images of a single reflector were obtained using one of the array elements as the receiver. Resulting images are also in accordance with numerical simulation, demonstrating the feasibility of using these arrays in pulse-echo mode. The proposed procedure simplifies the manufacturing of multidimensional arrays with arbitrary shape elements and not uniformly distributed. Furthermore, this concept can be extended to nonflat arrays as long as the transducer substrate conforms to a developable surface.

  8. Phased-array ultrasonic surface contour mapping system. Technical note

    SciTech Connect

    Fasching, G.E.; Loudin, W.J.; Paton, D.E.; Smith, N.S. Jr.

    1992-11-01

    The development of reliable mechanistic models for prediction of conventional and fluidized-bed combustor and gasifier operation and solids flow behavior in silos or other solids handling and storage components requires knowledge of the contained solids flow characteristics. This knowledge is gained from dynamic experimental measurements of bed top surface contours in addition to measurements of bulk bed properties. The surface contour mapping system (SCMS) provides a means of generating surface contour maps in real time with a unique, automatically focused, density-compensated, digital phased-array scanning, ultrasonic-range measurement system. The system is designed to operate in environments having gas temperatures up to 1,600 {degree}F and pressures to 1,000 psig. Computer simulation of several SCMS candidates and acoustic carrier modulation techniques indicates that a surface measurement resolution of {plus_minus}2 inches over a range of 5 to 20 feet distance between the transmit/receive (T/R) transducers and the bed surface can be expected. The simulation of a particular design, a 9-T/R, 25-pixel bed surface, in which the level of each pixel was randomly set between 5 and 7 feet below the plane of the T/R transducers, then measured using two different modulation techniques, produced excellent results. The simulation of this surface contour mapping system determined the value of the level of each of the 25 pixels to within {plus_minus}1 inch for over 95 percent of more than 100 test cases for one of the modulation techniques, and for over 99 percent of about 100 test cases for a second modulation technique. A hardware implementation of the design simulated but using only a two-T/R, three-pixel SCMS produced results very closely approximating those obtained during the simulation.

  9. High-speed 32×32 MEMS optical phased array

    NASA Astrophysics Data System (ADS)

    Megens, Mischa; Yoo, Byung-Wook; Chan, Trevor; Yang, Weijian; Sun, Tianbo; Chang-Hasnain, Connie J.; Wu, Ming C.; Horsley, David A.

    2014-03-01

    Optical phased arrays (OPAs) with fast response time are of great interest for various applications such as displays, free space optical communications, and lidar. Existing liquid crystal OPAs have millisecond response time and small beam steering angle. Here, we report on a novel 32×32 MEMS OPA with fast response time (<4 microseconds), large field of view (+/-2°), and narrow beam divergence (0.1°). The OPA is composed of high-contrast grating (HCG) mirrors which function as phase shifters. Relative to beam steering systems based on a single rotating MEMS mirror, which are typically limited to bandwidths below 50 kHz, the MEMS OPA described here has the advantage of greatly reduced mass and therefore achieves a bandwidth over 500 kHz. The OPA is fabricated using deep UV lithography to create submicron mechanical springs and electrical interconnects, enabling a high (85%) fill-factor. Each HCG mirror is composed of only a single layer of polysilicon and achieves >99% reflectivity through the use of a subwavelength grating patterned into the mirror's polysilicon surface. Conventional metal-coated MEMS mirrors must be thick (1- 50 μm) to prevent warpage arising from thermal and residual stress. The single material construction used here results in a high degree of flatness even in a thin 400 nm HCG mirror. Beam steering is demonstrated using binary phase patterns and is accomplished with the help of a closed-loop phase control system based on a phase-shifting interferometer that provides in-situ measurement of the phase shift of each mirror in the array.

  10. An introduction to high frequency radioteletype systems

    NASA Astrophysics Data System (ADS)

    Pinnau, Roger R.

    1989-10-01

    A basic introductory guide is provided to modern High Frequency (HF) data communications systems. Described are modern commercial radioteletype systems, data communication protocols, and various secrets of the trade.

  11. Real-time, high frequency QRS electrocardiograph

    NASA Technical Reports Server (NTRS)

    Schlegel, Todd T. (Inventor); DePalma, Jude L. (Inventor); Moradi, Saeed (Inventor)

    2006-01-01

    Real time cardiac electrical data are received from a patient, manipulated to determine various useful aspects of the ECG signal, and displayed in real time in a useful form on a computer screen or monitor. The monitor displays the high frequency data from the QRS complex in units of microvolts, juxtaposed with a display of conventional ECG data in units of millivolts or microvolts. The high frequency data are analyzed for their root mean square (RMS) voltage values and the discrete RMS values and related parameters are displayed in real time. The high frequency data from the QRS complex are analyzed with imbedded algorithms to determine the presence or absence of reduced amplitude zones, referred to herein as RAZs. RAZs are displayed as go, no-go signals on the computer monitor. The RMS and related values of the high frequency components are displayed as time varying signals, and the presence or absence of RAZs may be similarly displayed over time.

  12. High power, high frequency component test facility

    NASA Technical Reports Server (NTRS)

    Roth, Mary Ellen; Krawczonek, Walter

    1990-01-01

    The NASA Lewis Research Center has available a high frequency, high power laboratory facility for testing various components of aerospace and/or terrestrial power systems. This facility is described here. All of its capabilities and potential applications are detailed.

  13. High frequency testing of rubber mounts.

    PubMed

    Vahdati, Nader; Saunders, L Ken Lauderbaugh

    2002-04-01

    Rubber and fluid-filled rubber engine mounts are commonly used in automotive and aerospace applications to provide reduced cabin noise and vibration, and/or motion accommodations. In certain applications, the rubber mount may operate at frequencies as high as 5000 Hz. Therefore, dynamic stiffness of the mount needs to be known in this frequency range. Commercial high frequency test machines are practically nonexistent, and the best high frequency test machine on the market is only capable of frequencies as high as 1000 Hz. In this paper, a high frequency test machine is described that allows test engineers to study the high frequency performance of rubber mounts at frequencies up to 5000 Hz.

  14. Overview of the Advanced High Frequency Branch

    NASA Technical Reports Server (NTRS)

    Miranda, Felix A.

    2015-01-01

    This presentation provides an overview of the competencies, selected areas of research and technology development activities, and current external collaborative efforts of the NASA Glenn Research Center's Advanced High Frequency Branch.

  15. Neural coding of high-frequency tones

    NASA Technical Reports Server (NTRS)

    Howes, W. L.

    1976-01-01

    Available evidence was presented indicating that neural discharges in the auditory nerve display characteristic periodicities in response to any tonal stimulus including high-frequency stimuli, and that this periodicity corresponds to the subjective pitch.

  16. Electronically controlled optical beam-steering by an active phased array of metallic nanoantennas.

    PubMed

    DeRose, C T; Kekatpure, R D; Trotter, D C; Starbuck, A; Wendt, J R; Yaacobi, A; Watts, M R; Chettiar, U; Engheta, N; Davids, P S

    2013-02-25

    An optical phased array of nanoantenna fabricated in a CMOS compatible silicon photonics process is presented. The optical phased array is fed by low loss silicon waveguides with integrated ohmic thermo-optic phase shifters capable of 2π phase shift with ∼ 15 mW of applied electrical power. By controlling the electrical power to the individual integrated phase shifters fixed wavelength steering of the beam emitted normal to the surface of the wafer of 8° is demonstrated for 1 × 8 phased arrays with periods of both 6 and 9 μm.

  17. An optically controlled phased array antenna based on single sideband polarization modulation.

    PubMed

    Zhang, Yamei; Wu, Huan; Zhu, Dan; Pan, Shilong

    2014-02-24

    A novel optically controlled phased array antenna consisting a simple optical beamforming network and an N element linear patch antenna array is proposed and demonstrated. The optical beamforming network is realized by N independent phase shifters using a shared optical single sideband (OSSB) polarization modulator together with N polarization controllers (PCs), N polarization beam splitters (PBSs) and N photodetectors (PDs). An experiment is carried out. A 4-element linear patch antenna array operating at 14 GHz and a 1 × 4 optical beamforming network (OBFN) is employed to realize the phased array antenna. The radiation patterns of the phased array antenna at -30°, 0° and 30° are achieved.

  18. Phased Array Inspection of Titanium Disk Forgings Targeting no. 1/2 FBH Sensitivity

    SciTech Connect

    Roberts, R.A.; Friedl, J.

    2005-04-09

    The phased array implementation of a focused zoned ultrasonic inspection to achieve a >3dB signal-to-noise for no. 1/2 flat bottom holes (FBH) in titanium is reported. Previous work established the ultrasound focusing required to achieve the targeted sensitivity. This work reports on the design of a phased array transducer capable of maintaining the needed focus to the depths required in the forging inspection. The performance of the phased array inspection is verified by examining signal-to-noise of no. 1/2 FBHs contained in coupons cut from actual forgings.

  19. Improved SNR of phased-array PERES coils via simulation study.

    PubMed

    Rodríguez, Alfredo O; Medina, Lucía

    2005-09-21

    A computational comparison of signal-to-noise ratio (SNR) was performed between a conventional phased array of two circular-shaped coils and a petal resonator surface array. The quasi-static model and phased-array optimum SNR were combined to derive an SNR formula for each array. Analysis of mutual inductance between coil petals was carried out to compute the optimal coil separation and optimum number of petal coils. Mutual interaction between coil arrays was not included in the model because this does not drastically affect coil performance. Phased arrays of PERES coils show a 114% improvement in SNR over that of the simplest circular configuration.

  20. Impact: a low cost, reconfigurable, digital beamforming common module building block for next generation phased arrays

    NASA Astrophysics Data System (ADS)

    Paulsen, Lee; Hoffmann, Ted; Fulton, Caleb; Yeary, Mark; Saunders, Austin; Thompson, Dan; Chen, Bill; Guo, Alex; Murmann, Boris

    2015-05-01

    Phased array systems offer numerous advantages to the modern warfighter in multiple application spaces, including Radar, Electronic Warfare, Signals Intelligence, and Communications. However, a lack of commonality in the underlying technology base for DoD Phased Arrays has led to static systems with long development cycles, slow technology refreshes in response to emerging threats, and expensive, application-specific sub-components. The IMPACT module (Integrated Multi-use Phased Array Common Tile) is a multi-channel, reconfigurable, cost-effective beamformer that provides a common building block for multiple, disparate array applications.

  1. Pulse-Echo Phased Array Ultrasonic Inspection of Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS)

    NASA Technical Reports Server (NTRS)

    Johnston, Pat H.

    2010-01-01

    A PRSEUS test article was subjected to controlled impact on the skin face followed by static and cyclic axial compressions. Phased array ultrasonic inspection was conducted before impact, and after each of the test conditions. A linear phased array probe with a manual X-Y scanner was used for interrogation. Ultrasound showed a delamination between the skin and stringer flange adjacent to the impact. As designed, the stitching in the flange arrested the lateral flaw formation. Subsequent ultrasonic data showed no delamination growth due to continued loading. Keywords: Phased Array, Ultrasonics, Composites, Out-of-Autoclave

  2. A parametric study of ultrasonic beam profiles for a linear phased array transducer.

    PubMed

    Lee, J H; Choi, S W

    2000-01-01

    A numerical simulation model is presented to investigate the influences of design parameters of linear phased array transducers on beam focusing and steering performance. The characteristic of ultrasonic beam profiles has been simulated on the basis of the Huygen's superposition principle. For the simulation, a linear phased array is considered as the composition of finite number of elements separated by equidistance. Individual elements are considered as two-dimensional point sources. The waves generated from piezoelectric elements are considered as simplified transient ultrasonic waves that are constructed with the cosine function enveloped with a Hanning window. The characteristic of ultrasonic wave propagation into a medium from the phased array transducer is described. The effects of the number, the interelement spacing, steering angle, the focal length, and frequency bandwidth of the piezoelectric elements on beam directivity and ultrasonic pressure field in a linear phased array transducer are systematically discussed.

  3. Beale Air Force Base, Perimeter Acquisition Vehicle Entry PhasedArray Warning ...

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

    Beale Air Force Base, Perimeter Acquisition Vehicle Entry Phased-Array Warning System, Civil Engineering Storage Building, End of Spencer Paul Road, north of Warren Shingle Road (14th Street), Marysville, Yuba County, CA

  4. Beale Air Force Base, Perimeter Acquisition Vehicle Entry PhasedArray Warning ...

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

    Beale Air Force Base, Perimeter Acquisition Vehicle Entry Phased-Array Warning System, Microwave Equipment Building, End of Spencer Paul Road, north of Warren Shingle Road (14th Street), Marysville, Yuba County, CA

  5. Development of an X-Band Coupled-Oscillator Transmit/Receive Phased Array

    NASA Astrophysics Data System (ADS)

    Venkatesan, J.; Pogorzelski, R.

    2007-08-01

    The development of an 8.4 GHz (X-band) coupled-oscillator phased array employing full-duplex transmit and receive capability is described. Attractive features of phased arrays for deep-space communication include enabling high-data-rate communication and providing low-mass electronic beam steering. The coupled-oscillator phased-array concept seeks to reduce the cost and power consumption incurred in a conventional phased array by simplifying the beam-steering mechanism of the array. In this article, the overall system-level architecture of a full-duplex transmit and receive coupled-oscillator array is described, and the progress made in designing various specific components of a linear 1 x 7 coupled-oscillator array is also detailed.

  6. Measured aperture-array noise temperature of the Mark II phased array feed for ASKAP

    NASA Astrophysics Data System (ADS)

    Chippendale, A. P.; Brown, A. J.; Beresford, R. J.; Hampson, G. A.; Shaw, R. D.; Hayman, D. B.; Macleod, A.; Forsyth, A. R.; Hay, S. G.; Leach, M.; Cantrall, C.; Brothers, M. L.; Hotan, A. W.

    2015-11-01

    We have measured the aperture-array noise temperature of the first Mk. II phased array feed that CSIRO has built for the Australian Square Kilometre Array Pathfinder telescope. As an aperture array, the Mk. II phased array feed achieves a beam equivalent noise temperature less than 40 K from 0.78 GHz to 1.7 GHz and less than 50 K from 0.7 GHz to 1.8 GHz for a boresight beam directed at the zenith. We believe these are the lowest reported noise temperatures over these frequency ranges for ambient-temperature phased arrays. The measured noise temperature includes receiver electronics noise, ohmic losses in the array, and stray radiation from sidelobes illuminating the sky and ground away from the desired field of view. This phased array feed was designed for the Australian Square Kilometre Array Pathfinder to demonstrate fast astronomical surveys with a wide field of view for the Square Kilometre Array.

  7. Development of components for an S-band phased array antenna subsystem

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The system requirements, module test data, and S-band phased array subsystem test data are discussed. Of the two approaches to achieving antenna gain (mechanically steered reflector or electronically steered phased array), the phased array approach offers the greatest simplicity and lowest cost (size, weight, power, and dollars) for this medium gain. A competitive system design is described as well as hardware evaluation which will lead to timely availability of this technology for implementing such a system. The objectives of the study were: to fabricate and test six engineering model transmit/receive microelectronics modules; to design, fabricate, and test one dc and logic multilayer manifold; and to integrate and test an S-band phased array antenna subsystem composed of antenna elements, seven T/R modules, RF manifolds and dc manifold.

  8. New customizable phased array UT instrument opens door for furthering research and better industrial implementation

    SciTech Connect

    Dao, Gavin; Ginzel, Robert

    2014-02-18

    Phased array UT as an inspection technique in itself continues to gain wide acceptance. However, there is much room for improvement in terms of implementation of Phased Array (PA) technology for every unique NDT application across several industries (e.g. oil and petroleum, nuclear and power generation, steel manufacturing, etc.). Having full control of the phased array instrument and customizing a software solution is necessary for more seamless and efficient inspections, from setting the PA parameters, collecting data and reporting, to the final analysis. NDT researchers and academics also need a flexible and open platform to be able to control various aspects of the phased array process. A high performance instrument with advanced PA features, faster data rates, a smaller form factor, and capability to adapt to specific applications, will be discussed.

  9. Manipulation of Liquids Using Phased Array Generation of Acoustic Radiation Pressure

    NASA Technical Reports Server (NTRS)

    Oeftering, Richard C. (Inventor)

    2000-01-01

    A phased array of piezoelectric transducers is used to control and manipulate contained as well as uncontained fluids in space and earth applications. The transducers in the phased array are individually activated while being commonly controlled to produce acoustic radiation pressure and acoustic streaming. The phased array is activated to produce a single pulse, a pulse burst or a continuous pulse to agitate, segregate or manipulate liquids and gases. The phased array generated acoustic radiation pressure is also useful in manipulating a drop, a bubble or other object immersed in a liquid. The transducers can be arranged in any number of layouts including linear single or multi- dimensional, space curved and annular arrays. The individual transducers in the array are activated by a controller, preferably driven by a computer.

  10. Beale Air Force Base, Perimeter Acquisition Vehicle Entry PhasedArray Warning ...

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

    Beale Air Force Base, Perimeter Acquisition Vehicle Entry Phased-Array Warning System, Satellite Communications Terminal, End of Spencer Paul Road, north of Warren Shingle Road (14th Street), Marysville, Yuba County, CA

  11. Phased Array Ultrasonic Sound Field Mapping in Cast Austenitic Stainless Steel

    SciTech Connect

    Crawford, Susan L.; Prowant, Matthew S.; Cinson, Anthony D.; Larche, Michael R.; Diaz, Aaron A.; Anderson, Michael T.

    2014-05-31

    This study maps the phased array-generated acoustic sound fields through three types of CASS microstructure in four specimens to quantitatively assess the beam formation effectiveness in these materials.

  12. Two-dimensional beam steering using a thermo-optic silicon photonic optical phased array

    NASA Astrophysics Data System (ADS)

    Rabinovich, William S.; Goetz, Peter G.; Pruessner, Marcel W.; Mahon, Rita; Ferraro, Mike S.; Park, Doe; Fleet, Erin; DePrenger, Michael J.

    2016-11-01

    Many components for free-space optical (FSO) communication systems have shrunken in size over the last decade. However, the steering systems have remained large and power hungry. Nonmechanical beam steering offers a path to reducing the size of these systems. Optical phased arrays can allow integrated beam steering elements. One of the most important aspects of an optical phased array technology is its scalability to a large number of elements. Silicon photonics can potentially offer this scalability using CMOS foundry techniques. A phased array that can steer in two dimensions using the thermo-optic effect is demonstrated. No wavelength tuning of the input laser is needed and the design allows a simple control system with only two inputs. A benchtop FSO link with the phased array in both transmit and receive mode is demonstrated.

  13. 20-GHz phased-array-fed antennas utilizing distributed MMIC modules

    NASA Technical Reports Server (NTRS)

    Sorbello, R. M.; Zaghloul, A. I.; Siddiqi, S.; Geller, B. D.; Lee, B. S.

    1986-01-01

    The feasibility of phased-array-fed dual-reflector systems with distributed power and phase control, and utilizing monolithic microwave integrated circuit modules, is demonstrated. Secondary radiation patterns for various antenna configurations, calculated using a method in which the phased array for each scanning direction is simulated by a fictitious point source, are computed to determine the achievable EIRP levels, sidelobe isolation, and cross-polarization isolation. The focal-region-fed Cassegrain reflector was found to be best suited for fixed multiple beam applications, while the phased-array-fed dual-reflector configuration was selected for multiple scanning beams. Key elements of the phased-array design including a radiating square horn and a square orthomode transducer were fabricated and tested.

  14. Monolithic optical integrated control circuitry for GaAs MMIC-based phased arrays

    NASA Technical Reports Server (NTRS)

    Bhasin, K. B.; Ponchak, G. E.; Kascak, T. J.

    1985-01-01

    Gallium arsenide (GaAs) monolithic microwave integrated circuits (MMIC's) show promise in phased-array antenna applications for future space communications systems. Their efficient usage will depend on the control of amplitude and phase signals for each MMIC element in the phased array and in the low-loss radiofrequency feed. For a phased array contining several MMIC elements a complex system is required to control and feed each element. The characteristics of GaAs MMIC's for 20/30-GHz phased-array systems are discussed. The optical/MMIC interface and the desired characteristics of optical integrated circuits (OIC's) for such an interface are described. Anticipated fabrication considerations for eventual full monolithic integration of optical integrated circuits with MMIC's on a GaAs substrate are presented.

  15. Beale Air Force Base, Perimeter Acquisition Vehicle Entry PhasedArray Warning ...

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

    Beale Air Force Base, Perimeter Acquisition Vehicle Entry Phased-Array Warning System, Techinical Equipment Building, End of Spencer Paul Road, north of Warren Shingle Road (14th Street), Marysville, Yuba County, CA

  16. Beale Air Force Base, Perimeter Acquisition Vehicle Entry PhasedArray ...

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

    - Beale Air Force Base, Perimeter Acquisition Vehicle Entry Phased-Array Warning System, Techinical Equipment Building, End of Spencer Paul Road, north of Warren Shingle Road (14th Street), Marysville, Yuba County, CA

  17. Beale Air Force Base, Perimeter Acquisition Vehicle Entry PhasedArray Warning ...

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

    Beale Air Force Base, Perimeter Acquisition Vehicle Entry Phased-Array Warning System, Emergency Generator Enclosure, End of Spencer Paul Road, north of Warren Shingle Road (14th Street), Marysville, Yuba County, CA

  18. Beale Air Force Base, Perimeter Acquisition Vehicle Entry PhasedArray Warning ...

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

    Beale Air Force Base, Perimeter Acquisition Vehicle Entry Phased-Array Warning System, Clean Lubrication Oil Storage Tank & Enclosure, End of Spencer Paul Road, north of Warren Shingle Road (14th Street), Marysville, Yuba County, CA

  19. Beale Air Force Base, Perimeter Acquisition Vehicle Entry PhasedArray Warning ...

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

    Beale Air Force Base, Perimeter Acquisition Vehicle Entry Phased-Array Warning System, Supply Warehouse, End of Spencer Paul Road, north of Warren Shingle Road (14th Street), Marysville, Yuba County, CA

  20. Beale Air Force Base, Perimeter Acquisition Vehicle Entry PhasedArray Warning ...

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

    Beale Air Force Base, Perimeter Acquisition Vehicle Entry Phased-Array Warning System, Electric Substation, End of Spencer Paul Road, north of Warren Shingle Road (14th Street), Marysville, Yuba County, CA

  1. An Update on Phased Array Results Obtained on the GE Counter-Rotating Open Rotor Model

    NASA Technical Reports Server (NTRS)

    Podboy, Gary; Horvath, Csaba; Envia, Edmane

    2013-01-01

    Beamform maps have been generated from 1) simulated data generated by the LINPROP code and 2) actual experimental phased array data obtained on the GE Counter-rotating open rotor model. The beamform maps show that many of the tones in the experimental data come from their corresponding Mach radius. If the phased array points to the Mach radius associated with a tone then it is likely that the tone is a result of the loading and thickness noise on the blades. In this case, the phased array correctly points to where the noise is coming from and indicates the axial location of the loudest source in the image but not necessarily the correct vertical location. If the phased array does not point to the Mach radius associated with a tone then some mechanism other than loading and thickness noise may control the amplitude of the tone. In this case, the phased array may or may not point to the actual source. If the source is not rotating it is likely that the phased array points to the source. If the source is rotating it is likely that the phased array indicates the axial location of the loudest source but not necessarily the correct vertical location. These results indicate that you have to be careful in how you interpret phased array data obtained on an open rotor since they may show the tones coming from a location other than the source location. With a subsonic tip speed open rotor the tones can come form locations outboard of the blade tips. This has implications regarding noise shielding.

  2. Control, Filtering and Prediction for Phased Arrays in Directed Energy Systems

    DTIC Science & Technology

    2016-04-30

    AFRL-RD-PS- AFRL-RD-PS- TR-2016-0029 TR-2016-0029 CONTROL, FILTERING AND PREDICTION FOR PHASED ARRAYS IN DIRECTED ENERGY SYSTEMS Steve Gibson...UNLIMITED. AIR FORCE RESEARCH LABORATORY Directed Energy Directorate 3550 Aberdeen Ave SE AIR FORCE MATERIEL COMMAND KIRTLAND AIR FORCE BASE, NM...Filtering and Prediction for Phased Arrays in Directed Energy Systems 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER

  3. Phased Array Ultrasonic Examination of Space Shuttle Main Engine Nozzle Weld

    NASA Technical Reports Server (NTRS)

    James, S.; Engel, J.; Kimbrough, D.; Suits, M.; McCool, Alex (Technical Monitor)

    2001-01-01

    This paper describes a Phased Array Ultrasonic Examination that was developed for the examination of a limited access circumferential Inconel 718 fusion weld of a Space Shuttle Main Engine Nozzle - Cone. The paper discusses the selection and formation criteria used for the phased array focal laws, the reference standard that simulated hardware conditions, the examination concept, and results. Several unique constraints present during this examination included limited probe movement to a single axis and one-sided access to the weld.

  4. Optical phased array using single crystalline silicon high-contrast-gratings for beamsteering

    NASA Astrophysics Data System (ADS)

    Yoo, Byung-Wook; Chan, Trevor; Megens, Mischa; Sun, Tianbo; Yang, Weijian; Rao, Yi; Horsley, David A.; Chang-Hasnain, Connie J.; Wu, Ming C.

    2013-03-01

    We present a single crystalline silicon optical phased array using high-contrast-gratings (HCG) for fast two dimensional beamforming and beamsteering at 0.5 MHz. Since there are various applications for beamforming and beamsteering such as 3D imaging, optical communications, and light detection and ranging (LIDAR), it is great interest to develop ultrafast optical phased arrays. However, the beamsteering speed of optical phased arrays using liquid crystal and electro-wetting are typically limited to tens of milliseconds. Optical phased arrays using micro-electro-mechanical systems (MEMS) technologies can operate in the submegahertz range, but generally require metal coatings. The metal coating unfortunately cause bending of mirrors due to thermally induced stress. The novel MEMS-based optical phased array presented here consists of electrostatically driven 8 × 8 HCG pixels fabricated on a silicon-on-insulator (SOI) wafer. The HCG mirror is designed to have 99.9% reflectivity at 1550 nm wavelength without any reflective coating. The size of the HCG mirror is 20 × 20 μm2 and the mass is only 140 pg, much lighter than traditional MEMS mirrors. Our 8 × 8 optical phased array has a total field of view of +/-10° × 10° and a beam width of 2°. The maximum phase shift regarding the actuation gap defined by a 2 μm buried oxide layer of a SOI wafer is 1.7π at 20 V.

  5. A study program on large aperture electronic scanning phased array antennas for the shuttle imaging microwave system

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Fundamental phased array theory and performance parameters are discussed in terms of their application to microwave radiometry, and four scanning phased arrays representing current examples of state-of-the-art phased array technology are evaluated for potential use as components of the multispectral antenna system for the space shuttle imaging microwave system (SIMS). A discussion of problem areas, both in performance and fabrication is included, with extrapolations of performance characteristics for phased array antennas of increased sizes up to 20 m by 20 m. The possibility of interlacing two or more phased arrays to achieve a multifrequency aperture is considered, and, finally, a specific antenna system is recommended for use with SIMS.

  6. A high frequency silicon pressure sensor

    NASA Technical Reports Server (NTRS)

    Kahng, S. K.; Gross, C.

    1980-01-01

    Theoretical and design considerations as well as fabrication and experimental work involved in the development of high-frequency silicon pressure sensors with an ultra-small diaphragm are discussed. A sensor is presented with a rectangular diaphragm of 0.0127 cm x 0.0254 cm x 1.06 micron; the sensor has a natural frequency of 625 kHz and a sensitivity of 0.82 mv/v-psi. High-frequency results from shock tube testing and low-frequency (less than 50 kHz) comparison with microphones are given.

  7. Metrology For High-Frequency Nanoelectronics

    SciTech Connect

    Wallis, T. Mitch; Imtiaz, Atif; Nembach, Hans T.; Rice, Paul; Kabos, Pavel

    2007-09-26

    Two metrological tools for high-frequency measurements of nanoscale systems are described: (i) two/N-port analysis of nanoscale devices as well as (ii) near-field scanning microwave microscopy (NSMM) for materials characterization. Calibrated two/N-port measurements were made on multiwalled carbon nanotubes (MWNT) welded to a coplanar waveguide. Significant changes in the extracted high-frequency electrical response of the welded MWNT were measured when the contacts to the MWNT were modified. Additionally, NSMM was used to characterize films of nanotube soot deposited on copper and sapphire substrates. The material properties of the films showed a strong dependence on the substrate material.

  8. Low-Cost Phased Array Antenna for Sounding Rockets, Missiles, and Expendable Launch Vehicles

    NASA Technical Reports Server (NTRS)

    Mullinix, Daniel; Hall, Kenneth; Smith, Bruce; Corbin, Brian

    2012-01-01

    A low-cost beamformer phased array antenna has been developed for expendable launch vehicles, rockets, and missiles. It utilizes a conformal array antenna of ring or individual radiators (design varies depending on application) that is designed to be fed by the recently developed hybrid electrical/mechanical (vendor-supplied) phased array beamformer. The combination of these new array antennas and the hybrid beamformer results in a conformal phased array antenna that has significantly higher gain than traditional omni antennas, and costs an order of magnitude or more less than traditional phased array designs. Existing omnidirectional antennas for sounding rockets, missiles, and expendable launch vehicles (ELVs) do not have sufficient gain to support the required communication data rates via the space network. Missiles and smaller ELVs are often stabilized in flight by a fast (i.e. 4 Hz) roll rate. This fast roll rate, combined with vehicle attitude changes, greatly increases the complexity of the high-gain antenna beam-tracking problem. Phased arrays for larger ELVs with roll control are prohibitively expensive. Prior techniques involved a traditional fully electronic phased array solution, combined with highly complex and very fast inertial measurement unit phased array beamformers. The functional operation of this phased array is substantially different from traditional phased arrays in that it uses a hybrid electrical/mechanical beamformer that creates the relative time delays for steering the antenna beam via a small physical movement of variable delay lines. This movement is controlled via an innovative antenna control unit that accesses an internal measurement unit for vehicle attitude information, computes a beam-pointing angle to the target, then points the beam via a stepper motor controller. The stepper motor on the beamformer controls the beamformer variable delay lines that apply the appropriate time delays to the individual array elements to properly

  9. Piezoelectric phased array acousto-ultrasonic interrogation of damage in thin plates

    NASA Astrophysics Data System (ADS)

    Purekar, Ashish S.

    Structural Health Monitoring (SHM) and Condition Based Maintenance (CBM) systems can provide substantial benefits for aging aerospace systems as well as newer systems still in the design process. In aging aerospace systems, a retrofitted SHM system would alert users of incipient damage preventing catastrophic failure. For newer systems, incorporating a SHM approach and using CBM techniques can reduce life-cycle costs. Central to such SHM and CBM systems is the ability to detect damage in a structure. Traditional approaches to damage detection in structures involve one of two methods. In the modal dynamics approach, the natural frequencies and modeshapes of a structure shift when damage occurs. The location, type, and amount of damage is determined by the shifts in the modal properties due to damage. Alternately, in an Ultrasonics approach, the structure is scanned with a specialized transducer which induces high frequency vibrations in the structure. Damage in the structure is inferred when these vibrations are altered. In the same vein as Ultrasonics, Acoustic Emission based methods listen for energy release in the structure upon defect growth. All of these techniques have limitations which hinder their usage in a practical system. This thesis attempts to develop a methodology with the benefits of the modal approach as well as the Ultrasonics/Acoustic Emission approach. The methodology is commonly referred to as an Acousto-Ultrasonic technique for damage detection. The structural dynamics of plate structures is described as wavelike in nature where the plate is a medium for wave propagation. For thin plates, bulk wave propagation is described using Lamb wave modes. The two fundamental modes of wave propagation are the in-plane acoustic mode and the transverse bending mode. The interaction of these waves with a discontinuity or damaged region changes the way the waves propagate. Part of the incident wavefront is reflected back while the rest is transmitted through

  10. Advanced Extremely High Frequency Satellite (AEHF)

    DTIC Science & Technology

    2015-12-01

    Selected Acquisition Report (SAR) RCS: DD-A&T(Q&A)823-261 Advanced Extremely High Frequency Satellite (AEHF) As of FY 2017 President’s Budget...Office Estimate RDT&E - Research, Development, Test, and Evaluation SAR - Selected Acquisition Report SCP - Service Cost Position TBD - To Be

  11. Psychophysical tuning curves at very high frequencies

    NASA Astrophysics Data System (ADS)

    Yasin, Ifat; Plack, Christopher J.

    2005-10-01

    For most normal-hearing listeners, absolute thresholds increase rapidly above about 16 kHz. One hypothesis is that the high-frequency limit of the hearing-threshold curve is imposed by the transmission characteristics of the middle ear, which attenuates the sound input [Masterton et al., J. Acoust. Soc. Am. 45, 966-985 (1969)]. An alternative hypothesis is that the high-frequency limit of hearing is imposed by the tonotopicity of the cochlea [Ruggero and Temchin, Proc. Nat. Acad. Sci. U.S.A. 99, 13206-13210 (2002)]. The aim of this study was to test these hypotheses. Forward-masked psychophysical tuning curves (PTCs) were derived for signal frequencies of 12-17.5 kHz. For the highest signal frequencies, the high-frequency slopes of some PTCs were steeper than the slope of the hearing-threshold curve. The results also show that the human auditory system displays frequency selectivity for characteristic frequencies (CFs) as high as 17 kHz, above the frequency at which absolute thresholds begin to increase rapidly. The findings suggest that, for CFs up to 17 kHz, the high-frequency limitation in humans is imposed in part by the middle-ear attenuation, and not by the tonotopicity of the cochlea.

  12. Landau damping with high frequency impedance

    SciTech Connect

    Blaskiewicz,M.

    2009-05-04

    Coupled bunch longitudinal stability in the presence of high frequency impedances is considered. A frequency domain technique is developed and compared with simulations. The frequency domain technique allows for absolute stability tests and is applied to the problem of longitudinal stability in RHIC with the new 56 MHz RF system.

  13. Process controlling of a high-frequency cauter during tissue treatment

    NASA Astrophysics Data System (ADS)

    Wurzer, Helmut; Maeckel, Rainer; Lademann, Juergen; Liess, Hans-Dieter

    1995-01-01

    We present the process controlling of a high-frequency surgery generator during tissue treatment. Hereby, the temporal behavior of the voltage and the current are measured and then the finger print of the generated light arc in the electrical characteristic is analyzed by the control unit. This unit forces the high-frequency generator to supply an appropriate electrical power for different kinds of tissue. The functional ability is verified by cuts with different set points of the controlled variable, therefore, different degrees of slough, and cuts through tissue heterojunctions.

  14. Design and experiment of 256-element ultrasound phased array for noninvasive focused ultrasound surgery.

    PubMed

    Lu, Mingzhu; Wan, Mingxi; Xu, Feng; Wang, Xiaodong; Chang, Xiaozhen

    2006-12-22

    A 256-element phased array high intensity focused ultrasound system has been designed and constructed in our laboratory. The 256-element spherical-section ultrasound phased array made from piezocomposite material operates at 1.1 MHz with 11-cm radius of curvature, 14-cm outer diameter, and 3.4-cm diameter central hole for mounting diagnostic ultrasound imaging probe. First, the explicit sound field calculation approach for the spherical-section phased array and the genetic optimal algorithm are briefly introduced as the optimal focus pattern control methods. Then, the design guidelines of 256-element spherical-section focused ultrasound phased array and 256-channel driver system are given. The results of single on and off axial focus, multiple on and off axial foci, half sub-array focus pattern provide further evidence for the 3D focus steering and sub-array mode for avoiding obstacles in focused ultrasound surgery. The multi-foci pattern can enlarge the treatment volume to 22 times larger than that of a single focus in one sonication. Finally, in vitro and transparent tissue-mimicking phantom experiment results confirm the ability of 256-element spherical-section phased array system to induce thermal lesions for noninvasive ultrasound surgery.

  15. High-Resolution Ultrasonic Imaging of Dento-Periodontal Tissues Using a Multi-Element Phased Array System.

    PubMed

    Nguyen, Kim-Cuong T; Le, Lawrence H; Kaipatur, Neelambar R; Zheng, Rui; Lou, Edmond H; Major, Paul W

    2016-10-01

    Intraoral ultrasonography uses high-frequency mechanical waves to study dento-periodontium. Besides the advantages of portability and cost-effectiveness, ultrasound technique has no ionizing radiation. Previous studies employed a single transducer or an array of transducer elements, and focused on enamel thickness and distance measurement. This study used a phased array system with a 128-element array transducer to image dento-periodontal tissues. We studied two porcine lower incisors from a 6-month-old piglet using 20-MHz ultrasound. The high-resolution ultrasonographs clearly showed the cross-sectional morphological images of the hard and soft tissues. The investigation used an integration of waveform analysis, travel-time calculation, and wavefield simulation to reveal the nature of the ultrasound data, which makes the study novel. With the assistance of time-distance radio-frequency records, we robustly justified the enamel-dentin interface, dentin-pulp interface, and the cemento-enamel junction. The alveolar crest level, the location of cemento-enamel junction, and the thickness of alveolar crest were measured from the images and compared favorably with those from the cone beam computed tomography with less than 10% difference. This preliminary and fundamental study has reinforced the conclusions from previous studies, that ultrasonography has great potential to become a non-invasive diagnostic imaging tool for quantitative assessment of periodontal structures and better delivery of oral care.

  16. Turbulence in unsteady flow at high frequencies

    NASA Technical Reports Server (NTRS)

    Kuhn, Gary D.

    1990-01-01

    Turbulent flows subjected to oscillations of the mean flow were simulated using a large-eddy simulation computer code for flow in a channel. The objective of the simulations was to provide better understanding of the effects of time-dependent disturbances on the turbulence of a boundary layer and of the underlying physical phenomena regarding the basic interaction between the turbulence and external disturbances. The results confirmed that turbulence is sensitive to certain ranges of frequencies of disturbances. However, no direct connection was found between the frequency of imposed disturbances and the characteristic 'burst' frequency of turbulence. New insight into the nature of turbulence at high frequencies was found. Viscous phenomena near solid walls were found to be the dominant influence for high-frequency perturbations.

  17. High-current, high-frequency capacitors

    NASA Astrophysics Data System (ADS)

    Renz, D. D.

    1983-06-01

    The NASA Lewis high-current, high-frequency capacitor development program was conducted under a contract with Maxwell Laboratories, Inc., San Diego, California. The program was started to develop power components for space power systems. One of the components lacking was a high-power, high-frequency capacitor. Some of the technology developed in this program may be directly usable in an all-electric airplane. The materials used in the capacitor included the following: the film is polypropylene, the impregnant is monoisopropyl biphenyl, the conductive epoxy is Emerson and Cuming Stycast 2850 KT, the foil is aluminum, the case is stainless steel (304), and the electrode is a modified copper-ceramic.

  18. High-current, high-frequency capacitors

    NASA Technical Reports Server (NTRS)

    Renz, D. D.

    1983-01-01

    The NASA Lewis high-current, high-frequency capacitor development program was conducted under a contract with Maxwell Laboratories, Inc., San Diego, California. The program was started to develop power components for space power systems. One of the components lacking was a high-power, high-frequency capacitor. Some of the technology developed in this program may be directly usable in an all-electric airplane. The materials used in the capacitor included the following: the film is polypropylene, the impregnant is monoisopropyl biphenyl, the conductive epoxy is Emerson and Cuming Stycast 2850 KT, the foil is aluminum, the case is stainless steel (304), and the electrode is a modified copper-ceramic.

  19. High Frequency Guided Wave Virtual Array SAFT

    NASA Astrophysics Data System (ADS)

    Roberts, R.; Pardini, A.; Diaz, A.

    2003-03-01

    The principles of the synthetic aperture focusing technique (SAFT) are generalized for application to high frequency plate wave signals. It is shown that a flaw signal received in long-range plate wave propagation can be analyzed as if the signals were measured by an infinite array of transducers in an unbounded medium. It is shown that SAFT-based flaw sizing can be performed with as few as three or less actual measurement positions.

  20. Apparatus for measuring high frequency currents

    NASA Technical Reports Server (NTRS)

    Hagmann, Mark J. (Inventor); Sutton, John F. (Inventor)

    2003-01-01

    An apparatus for measuring high frequency currents includes a non-ferrous core current probe that is coupled to a wide-band transimpedance amplifier. The current probe has a secondary winding with a winding resistance that is substantially smaller than the reactance of the winding. The sensitivity of the current probe is substantially flat over a wide band of frequencies. The apparatus is particularly useful for measuring exposure of humans to radio frequency currents.

  1. [High-frequency oscillatory ventilation in neonates].

    PubMed

    2002-09-01

    High-frequency oscillatory ventilation (HFOV) may be considered as an alternative in the management of severe neonatal respiratory failure requiring mechanical ventilation. In patients with diffuse pulmonary disease, HFOV can applied as a rescue therapy with a high lung volume strategy to obtain adequate alveolar recruitment. We review the mechanisms of gas exchange, as well as the indications, monitoring and special features of the use HVOF in the neonatal period.

  2. Ionospheric modifications in high frequency heating experiments

    SciTech Connect

    Kuo, Spencer P.

    2015-01-15

    Featured observations in high-frequency (HF) heating experiments conducted at Arecibo, EISCAT, and high frequency active auroral research program are discussed. These phenomena appearing in the F region of the ionosphere include high-frequency heater enhanced plasma lines, airglow enhancement, energetic electron flux, artificial ionization layers, artificial spread-F, ionization enhancement, artificial cusp, wideband absorption, short-scale (meters) density irregularities, and stimulated electromagnetic emissions, which were observed when the O-mode HF heater waves with frequencies below foF2 were applied. The implication and associated physical mechanism of each observation are discussed and explained. It is shown that these phenomena caused by the HF heating are all ascribed directly or indirectly to the excitation of parametric instabilities which instigate anomalous heating. Formulation and analysis of parametric instabilities are presented. The results show that oscillating two stream instability and parametric decay instability can be excited by the O-mode HF heater waves, transmitted from all three heating facilities, in the regions near the HF reflection height and near the upper hybrid resonance layer. The excited Langmuir waves, upper hybrid waves, ion acoustic waves, lower hybrid waves, and field-aligned density irregularities set off subsequent wave-wave and wave-electron interactions, giving rise to the observed phenomena.

  3. Nonparaxial multi-Gaussian beam models and measurement models for phased array transducers.

    PubMed

    Zhao, Xinyu; Gang, Tie

    2009-01-01

    A nonparaxial multi-Gaussian beam model is proposed in order to overcome the limitation that paraxial Gaussian beam models lose accuracy in simulating the beam steering behavior of phased array transducers. Using this nonparaxial multi-Gaussian beam model, the focusing and steering sound fields generated by an ultrasonic linear phased array transducer are calculated and compared with the corresponding results obtained by paraxial multi-Gaussian beam model and more exact Rayleigh-Sommerfeld integral model. In addition, with help of this novel nonparaxial method, an ultrasonic measurement model is provided to investigate the sensitivity of linear phased array transducers versus steering angles. Also the comparisons of model predictions with experimental results are presented to certify the accuracy of this provided measurement model.

  4. Adhesive defect detection in composite adhesive joints using phased array transducers

    NASA Astrophysics Data System (ADS)

    Ren, Baiyang; Lissenden, Cliff J.

    2015-03-01

    Composite materials are widely used in aircraft structures due to their high specific stiffness and strength. The laminated nature of composite structures makes them subject to disbond and delamination. These types of defects will compromise the integrity of the structure and therefore need to be monitored. To monitor aircraft structures, light weight transducers capable of large area coverage are beneficial. Ultrasonic guided waves are able to travel long distance and are sensitive to localized defects. The multi-modal characteristic of propagating guided waves requires optimal mode selection and excitation. Phased array transducers provide good versatility for optimal mode excitation since they can excite different guided wave modes preferentially. Phased array transducers designed for structural health monitoring (SHM) applications are employed in this work to study the interaction between adhesive defects and guided wave modes. Amplitude ratios and wave packet composition are utilized as defect indicators that are uniquely available due to the phased array transducers.

  5. [Regularized inhomogeneity correction method for phased array image in magnetic resonance imaging].

    PubMed

    Guo, Hongyu; Pei, Xiaomin; Luo, Weitao; Dai, Jianpin

    2011-10-01

    Phased array coils (multiple receiver coil systems) have been extensively used for acquisition of MR images owing to their ability of increasing SNR, extending field-of-view (FOV), and reducing acquisition time. But the SOS algorithm,which is main method for phased array image reconstruction,will cause inhomogeneity in reconstructed image. A regularized least square method for phased array image combination is proposed in this paper. In the method, an additional reference scan is performed in advance. By using the reference scan, coil sensitivity map can be acquired, and image reconstructed from reference scan can be used as reference data in the regulation term. Experiments showed that the image uniformity was greatly improved by this method with scanning phantom and volunteer.

  6. The relationships between dispersion loss and sidelobe levels in wideband phased-array radars

    NASA Astrophysics Data System (ADS)

    Howard, Robert L., III; Belcher, Melvin L.; Corey, Larry E.

    Wideband phased-array radar systems experience significant problems created by frequency dispersion in the phased-array antenna. This phenomena has previously been studied for systems employing linear frequency modulation (LFM). LFM's vulnerability to deceptive electronic countermeasures (ECM) and signal-to-noise loss due to the amplitude weighting required to sufficiently suppress range sidelobes limit its usefulness. Pseudo-random noise (PRN) coded waveforms are capable of solving both these problems. This paper examines how the phased-array antenna affects the radar's performance when PRN coded waveforms are used. Issues of dispersion loss, grating lobe rejection, and compressed pulse shapes are considered. Where appropriate, results are compared to results from LFM systems. Sets of normalized curves are presented that quantify these effects in terms of signal bandwidth, subarray size, and antenna scan angle.

  7. Phased array feed design technology for Large Aperture Microwave Radiometer (LAMR) Earth observations

    NASA Technical Reports Server (NTRS)

    Schuman, H. K.

    1992-01-01

    An assessment of the potential and limitations of phased array antennas in space-based geophysical precision radiometry is described. Mathematical models exhibiting the dependence of system and scene temperatures and system sensitivity on phased array antenna parameters and components such as phase shifters and low noise amplifiers (LNA) are developed. Emphasis is given to minimum noise temperature designs wherein the LNA's are located at the array level, one per element or subarray. Two types of combiners are considered: array lenses (space feeds) and corporate networks. The result of a survey of suitable components and devices is described. The data obtained from that survey are used in conjunction with the mathematical models to yield an assessment of effective array antenna noise temperature for representative geostationary and low Earth orbit systems. Practical methods of calibrating a space-based, phased array radiometer are briefly addressed as well.

  8. Free space optical communication link using a silicon photonic optical phased array

    NASA Astrophysics Data System (ADS)

    Rabinovich, William S.; Goetz, Peter G.; Pruessner, Marcel; Mahon, Rita; Ferraro, Mike S.; Park, Doe; Fleet, Erin; DePrenger, Michael J.

    2015-03-01

    Many components for free space optical communication systems have shrunken in size over the last decade. However, the steering systems have remained large and power hungry. Non-mechanical beam steering offers a path to reducing the size of these systems. Optical phased arrays can allow integrated beam steering elements. One of the most important aspects of an optical phased array technology is its scalability to a large number of elements. Silicon photonics can potentially offer this scalability using CMOS foundry techniques. In this paper a small-scale silicon photonic optical phased array is demonstrated for both the transmitter and receiver functions in a free space optical link. The device using an array of thermo-optically controlled waveguide phase shifters and demonstrates one-dimensional steering with a single control electrode. Transmission of a digitized video data stream over the link is shown.

  9. Phased array compaction cell for measurement of the transversely isotropic elastic properties of compacting sediments

    SciTech Connect

    Nihei, K.T.; Nakagawa, S.; Reverdy, F.; Meyer, L.R.; Duranti, L.; Ball, G.

    2010-12-15

    Sediments undergoing compaction typically exhibit transversely isotropic (TI) elastic properties. We present a new experimental apparatus, the phased array compaction cell, for measuring the TI elastic properties of clay-rich sediments during compaction. This apparatus uses matched sets of P- and S-wave ultrasonic transducers located along the sides of the sample and an ultrasonic P-wave phased array source, together with a miniature P-wave receiver on the top and bottom ends of the sample. The phased array measurements are used to form plane P-waves that provide estimates of the phase velocities over a range of angles. From these measurements, the five TI elastic constants can be recovered as the sediment is compacted, without the need for sample unloading, recoring, or reorienting. This paper provides descriptions of the apparatus, the data processing, and an application demonstrating recovery of the evolving TI properties of a compacting marine sediment sample.

  10. Identifying equivalent sound sources from aeroacoustic simulations using a numerical phased array

    NASA Astrophysics Data System (ADS)

    Pignier, Nicolas J.; O'Reilly, Ciarán J.; Boij, Susann

    2017-04-01

    An application of phased array methods to numerical data is presented, aimed at identifying equivalent flow sound sources from aeroacoustic simulations. Based on phased array data extracted from compressible flow simulations, sound source strengths are computed on a set of points in the source region using phased array techniques assuming monopole propagation. Two phased array techniques are used to compute the source strengths: an approach using a Moore-Penrose pseudo-inverse and a beamforming approach using dual linear programming (dual-LP) deconvolution. The first approach gives a model of correlated sources for the acoustic field generated from the flow expressed in a matrix of cross- and auto-power spectral values, whereas the second approach results in a model of uncorrelated sources expressed in a vector of auto-power spectral values. The accuracy of the equivalent source model is estimated by computing the acoustic spectrum at a far-field observer. The approach is tested first on an analytical case with known point sources. It is then applied to the example of the flow around a submerged air inlet. The far-field spectra obtained from the source models for two different flow conditions are in good agreement with the spectra obtained with a Ffowcs Williams-Hawkings integral, showing the accuracy of the source model from the observer's standpoint. Various configurations for the phased array and for the sources are used. The dual-LP beamforming approach shows better robustness to changes in the number of probes and sources than the pseudo-inverse approach. The good results obtained with this simulation case demonstrate the potential of the phased array approach as a modelling tool for aeroacoustic simulations.

  11. EHF monolithic phased arrays - A stepping-stone to the future

    NASA Astrophysics Data System (ADS)

    McIlvenna, John F.; Schindler, John K.

    Current EHF monolithic phased-array technology is assessed; near-term technology needs are evaluated; and future developments in this field are projected. It is noted that such arrays are thought to be able to satisfy cost, real-estate, aerodynamic and radar-cross-section constraints. Test results on multielement monolithic subarrays operating at 20 and 44 GHz are examined. Finally, the connection between current state-of-the-art subarray technology and Smart Skins, the projected omnipotent phased array of the future, is discussed.

  12. Detection of wheel rim by immersion scan of phased array ultrasonic flaw testing

    NASA Astrophysics Data System (ADS)

    Cai, Yi-He; Guo, Jian-qiang; Wang, Ze-yong; Gao, Xiao-rong; Jiang, Xiang-dong; Li, Xi

    2015-02-01

    In order to achieve the in-service detection to high speed train wheel rims, this article analyzed the effects of the number of array elements to image focusing and image quality using water immersion ultrasonic phased array technology. Also, the effects of the depth of water to detecting technique had been researched. According to the results of the experiments, the number of optimal array elements, the corresponding thickness of immersion layer, and the optimal range of water's depth had been obtained. Thus, appropriate references had been provided to water immersion ultrasonic phased array testing.

  13. Ultrasonic Phased Array Inspection of Flaws on Weld Fusion Faces Using Full Matrix Capture

    NASA Astrophysics Data System (ADS)

    Long, R.; Russell, J.; Cawley, P.; Habgood, N.

    2009-03-01

    Work is being conducted to develop phased array inspection of stainless steel welded pipes. Ideally this uses waves reflected and mode converted at the inner surface of the pipe, but most commercial phased array controllers do not currently provide for this. Our solution was to use Full Matrix Capture (FMC) and process the data ourselves. This paper explains the FMC principle, describes the signal processing algorithms along with introducing the Almost Total Focusing Method (ATFM) and illustrates how the processed data was presented. The inspections were also modeled using the CEA CIVA software and compared to experimental results.

  14. Multiple-access phased array antenna simulator for a digital beam forming system investigation

    NASA Technical Reports Server (NTRS)

    Kerczewski, Robert J.; Yu, John; Walton, Joanne C.; Perl, Thomas D.; Andro, Monty; Alexovich, Robert E.

    1992-01-01

    Future versions of data relay satellite systems are currently being planned by NASA. Being given consideration for implementation are on-board digital beamforming techniques which will allow multiple users to simultaneously access a single S-band phased array antenna system. To investigate the potential performance of such a system, a laboratory simulator has been developed at NASA's Lewis Research Center. This paper describes the system simulator, and in particular, the requirements, design, and performance of a key subsystem, the phased array antenna simulator, which provides realistic inputs to the digital processor including multiple signals, noise, and nonlinearities.

  15. High speed optical phased array using high contrast grating all-pass filters.

    PubMed

    Yang, Weijian; Sun, Tianbo; Rao, Yi; Megens, Mischa; Chan, Trevor; Yoo, Byung-Wook; Horsley, David A; Wu, Ming C; Chang-Hasnain, Connie J

    2014-08-25

    We report a high speed 8x8 optical phased array using tunable 1550 nm all-pass filters with ultrathin high contrast gratings (HCGs) as the microelectromechanical-actuated top reflectors. The all-pass filter design enables a highly efficient phase tuning (1.7 π) with a small actuation voltage (10 V) and actuation displacement of the HCG (50 nm). The microelectromechanical HCG structure facilitates a high phase tuning speed >0.5 MHz. Beam steering is experimentally demonstrated with the optical phased array.

  16. Pulse-echo phased array ultrasonic inspection of pultruded rod stitched efficient unitized structure (PRSEUS)

    SciTech Connect

    Johnston, P. H.

    2011-06-23

    A PRSEUS test article was subjected to controlled impact on the skin face followed by static and cyclic axial compressions. Phased array ultrasonic inspection was conducted before impact, and after each of the test conditions. A linear phased array probe with a manual X-Y scanner was used for interrogation. Ultrasound showed a delamination between the skin and stringer flange adjacent to the impact. As designed, the stitching in the flange arrested the lateral flaw formation. Subsequent ultrasonic data showed no delamination growth due to continued loading.

  17. Inspection of Spot Welds Using a Portable Ultrasonic Phased-Array System

    SciTech Connect

    Reverdy, F.; Hopkins, D.

    2005-04-09

    Results were presented last year to demonstrate the feasibility of using an ultrasonic phased array to inspect spot welds. Analysis of the signals in the Fourier domain allows identification of satisfactory, undersized and defective welds. Signal- and image-processing techniques have been implemented with the goal of extracting the dimensions of the weld nugget. The results presented here were obtained using a portable phased-array controller. Toward developing a fully portable system, a housing for the probe is under development with an integrated mechanical scanning system.

  18. A design concept for an MMIC (Monolithic Microwave Integrated Circuit) microstrip phased array

    NASA Technical Reports Server (NTRS)

    Lee, Richard Q.; Smetana, Jerry; Acosta, Roberto

    1987-01-01

    A conceptual design for a microstrip phased array with monolithic microwave integrated circuit (MMIC) amplitude and phase controls is described. The MMIC devices used are 20 GHz variable power amplifiers and variable phase shifters recently developed by NASA contractors for applications in future Ka proposed design, which concept is for a general NxN element array of rectangular lattice geometry. Subarray excitation is incorporated in the MMIC phased array design to reduce the complexity of the beam forming network and the number of MMIC components required.

  19. Pulse-Echo Phased Array Ultrasonic Inspection of Pultruded Rod Stitched Efficient Unitized Structure (prseus)

    NASA Astrophysics Data System (ADS)

    Johnston, P. H.

    2011-06-01

    A PRSEUS test article was subjected to controlled impact on the skin face followed by static and cyclic axial compressions. Phased array ultrasonic inspection was conducted before impact, and after each of the test conditions. A linear phased array probe with a manual X-Y scanner was used for interrogation. Ultrasound showed a delamination between the skin and stringer flange adjacent to the impact. As designed, the stitching in the flange arrested the lateral flaw formation. Subsequent ultrasonic data showed no delamination growth due to continued loading.

  20. Liquid sodium testing of in-house phased array EMAT transducer for L-wave applications

    SciTech Connect

    Le Bourdais, F.; Le Polles, T.; Baque, F.

    2015-07-01

    This paper describes the development of an in-house phased array EMAT transducer for longitudinal wave inspection in liquid sodium. The work presented herein is part of an undergoing project aimed at improving in-service inspection techniques for the ASTRID reactor project. The design process of the phased array EMAT probe is briefly explained and followed by a review of experimental test results. We first present test results obtained in the laboratory while the last part of the paper describes the liquid sodium testing and the produced ultrasound images. (authors)

  1. Multiple-access phased array antenna simulator for a digital beam-forming system investigation

    NASA Technical Reports Server (NTRS)

    Kerczewski, Robert J.; Yu, John; Walton, Joanne C.; Perl, Thomas D.; Andro, Monty; Alexovich, Robert E.

    1992-01-01

    Future versions of data relay satellite systems are currently being planned by NASA. Being given consideration for implementation are on-board digital beamforming techniques which will allow multiple users to simultaneously access a single S-band phased array antenna system. To investigate the potential performance of such a system, a laboratory simulator has been developed at NASA's Lewis Research Center. This paper describes the system simulator, and in particular, the requirements, design and performance of a key subsystem, the phased array antenna simulator, which provides realistic inputs to the digital processor including multiple signals, noise, and nonlinearities.

  2. Ultrasonic Phased Array Inspection for an Isogrid Structural Element with Cracks

    NASA Technical Reports Server (NTRS)

    Roth, D. J.; Tokars, R. P.; Martin, R. E.; Rauser, R. W.; Aldrin, J. C.; Schumacher, E. J.

    2010-01-01

    In this investigation, a T-shaped aluminum alloy isogrid stiffener element used in aerospace applications was inspected with ultrasonic phased array methods. The isogrid stiffener element had various crack configurations emanating from bolt holes. Computational simulation methods were used to mimic the experiments in order to help understand experimental results. The results of this study indicate that it is at least partly feasible to interrogate this type of geometry with the given flaw configurations using phased array ultrasonics. The simulation methods were critical in helping explain the experimental results and, with some limitation, can be used to predict inspection results.

  3. Visualization of phased-array sound fields and flaw interaction using the photoelastic effect

    NASA Astrophysics Data System (ADS)

    Schmitte, T.; Orth, T.; Kersting, T.

    2012-05-01

    In order to visualize ultrasound in steel the photoelastic imager is a complementary technique to simulations, with the advantage that real transducers are used. In this contribution we show the linear behavior of the derived photoelastic signal and compare the results to FEM calculations. We use the result for quantitative analysis of sound-fields of immersion and phased array transducers. Interesting results are derived by analysis of the influence of missing elements on the shape and intensity of phased array (PA) ultrasonic pulses. Furthermore the formation of grating lobes from PA excitation is demonstrated and the plurality of waves generated from a small notch is displayed exemplarily.

  4. Printed-Circuit Cross-Slot Antenna

    NASA Technical Reports Server (NTRS)

    Foy, Wong; Chung, Hsien-Hsien; Peng, Sheng Y.

    1990-01-01

    Coupling between perpendicular slots suppressed. Balanced feed configuration minimizes coupling between slots of printed-circuit cross-slot antenna unit. Unit and array have conventional cavity-backed-printed-circuit, crossed-slot antenna design. Strip-line feeders behind planar conductive antenna element deliver power to horizontal slot in opposite phase. As result, little or no power propagates into vertical slot. Similar considerations apply to strip lines that feed vertical slot. Units of this type elements of phased-array antennas for radar, mobile/satellite communications, and other applications requiring flush mounting and/or rapid steering of beams with circular polarization.

  5. High-frequency Rayleigh-wave method

    USGS Publications Warehouse

    Xia, J.; Miller, R.D.; Xu, Y.; Luo, Y.; Chen, C.; Liu, J.; Ivanov, J.; Zeng, C.

    2009-01-01

    High-frequency (???2 Hz) Rayleigh-wave data acquired with a multichannel recording system have been utilized to determine shear (S)-wave velocities in near-surface geophysics since the early 1980s. This overview article discusses the main research results of high-frequency surface-wave techniques achieved by research groups at the Kansas Geological Survey and China University of Geosciences in the last 15 years. The multichannel analysis of surface wave (MASW) method is a non-invasive acoustic approach to estimate near-surface S-wave velocity. The differences between MASW results and direct borehole measurements are approximately 15% or less and random. Studies show that simultaneous inversion with higher modes and the fundamental mode can increase model resolution and an investigation depth. The other important seismic property, quality factor (Q), can also be estimated with the MASW method by inverting attenuation coefficients of Rayleigh waves. An inverted model (S-wave velocity or Q) obtained using a damped least-squares method can be assessed by an optimal damping vector in a vicinity of the inverted model determined by an objective function, which is the trace of a weighted sum of model-resolution and model-covariance matrices. Current developments include modeling high-frequency Rayleigh-waves in near-surface media, which builds a foundation for shallow seismic or Rayleigh-wave inversion in the time-offset domain; imaging dispersive energy with high resolution in the frequency-velocity domain and possibly with data in an arbitrary acquisition geometry, which opens a door for 3D surface-wave techniques; and successfully separating surface-wave modes, which provides a valuable tool to perform S-wave velocity profiling with high-horizontal resolution. ?? China University of Geosciences (Wuhan) and Springer-Verlag GmbH 2009.

  6. Leaf Printing.

    ERIC Educational Resources Information Center

    Mitchell, Charles W.

    1985-01-01

    Using many different media, students can turn leaves into images which can be used for study, bulletin boards, collections, and identification. The simple techniques described include pastel printing, smoke prints, ink or tempura printing, bleach printing on t-shirts, ditto machine printing using carbon paper, and making cutouts. (DH)

  7. The LASI high-frequency ellipticity system

    SciTech Connect

    Sternberg, B.K.; Poulton, M.M.

    1995-10-01

    A high-frequency, high-resolution, electromagnetic (EM) imaging system has been developed for environmental geophysics surveys. Some key features of this system include: (1) rapid surveying to allow dense spatial sampling over a large area, (2) high-accuracy measurements which are used to produce a high-resolution image of the subsurface, (3) measurements which have excellent signal-to-noise ratio over a wide bandwidth (31 kHz to 32 MHz), (4) large-scale physical modeling to produce accurate theoretical responses over targets of interest in environmental geophysics surveys, (5) rapid neural network interpretation at the field site, and (6) visualization of complex structures during the survey.

  8. Inverter design for high frequency power distribution

    NASA Technical Reports Server (NTRS)

    King, R. J.

    1985-01-01

    A class of simple resonantly commutated inverters are investigated for use in a high power (100 KW - 1000 KW) high frequency (10 KHz - 20 KHz) AC power distribution system. The Mapham inverter is found to provide a unique combination of large thyristor turn-off angle and good utilization factor, much better than an alternate 'current-fed' inverter. The effects of loading the Mapham inverter entirely with rectifier loads are investigated by simulation and with an experimental 3 KW 20 KHz inverter. This inverter is found to be well suited to a power system with heavy rectifier loading.

  9. The LASI high-frequency ellipticity system

    SciTech Connect

    Sternberg, B.K.; Poulton, M.M.

    1995-12-31

    A high-frequency, high-resolution, electromagnetic (EM) imaging system has been developed for environmental geophysics surveys. Some key features of this system include: (1) rapid surveying to allow dense spatial sampling over a large area, (2) high-accuracy measurements which are used to produce a high-resolution image of the subsurface, (3) measurements which have excellent signal-to-noise ratio over a wide bandwidth (31 kHz to 32 MHz), (4) large-scale physical modeling to produce accurate theoretical responses over targets of interest in environmental geophysics surveys, (5) rapid neural network interpretation at the field site, and (6) visualization of complex structures during the survey.

  10. High frequency dynamic pressure calibration technique

    NASA Technical Reports Server (NTRS)

    Davis, P. A.; Zasimowich, R. F.

    1985-01-01

    A high frequency dynamic calibration technique for pressure transducers has been developed using a siren pressure generator (SPG). The SPG is an inlet-area-modulated device generating oscillating waveforms with dynamic pressure amplitudes up to 58.6 kPa (8.5 psi) in a frequency range of 1 to 10 kHz. A description of the generator, its operating characteristics and instrumentation used for pressure amplitude and frequency measurements is given. Waveform oscillographs and spectral analysis of the pressure transducers' output signals are presented.

  11. High frequency dynamic pressure calibration technique

    NASA Astrophysics Data System (ADS)

    Davis, P. A.; Zasimowich, R. F.

    A high frequency dynamic calibration technique for pressure transducers has been developed using a siren pressure generator (SPG). The SPG is an inlet-area-modulated device generating oscillating waveforms with dynamic pressure amplitudes up to 58.6 kPa (8.5 psi) in a frequency range of 1 to 10 kHz. A description of the generator, its operating characteristics and instrumentation used for pressure amplitude and frequency measurements is given. Waveform oscillographs and spectral analysis of the pressure transducers' output signals are presented.

  12. RF Breakdown in High Frequency Accelerators

    SciTech Connect

    Doebert, S

    2004-05-27

    RF breakdown in high-frequency accelerators appears to limit the maximum achievable gradient as well as the reliability of such devices. Experimental results from high power tests, obtained mostly in the framework of the NLC/GLC project at 11 GHz and from the CLIC study at 30 GHz, will be used to illustrate the important issues. The dependence of the breakdown phenomena on rf pulse length, operating frequency and fabrication material will be described. Since reliability is extremely important for large scale accelerators such as a linear collider, the measurements of breakdown rate as a function of the operating gradient will be highlighted.

  13. Noise temperature in graphene at high frequencies

    NASA Astrophysics Data System (ADS)

    Rengel, Raúl; Iglesias, José M.; Pascual, Elena; Martín, María J.

    2016-07-01

    A numerical method for obtaining the frequency-dependent noise temperature in monolayer graphene is presented. From the mobility and diffusion coefficient values provided by Monte Carlo simulation, the noise temperature in graphene is studied up to the THz range, considering also the influence of different substrate types. The influence of the applied electric field is investigated: the noise temperature is found to increase with the applied field, dropping down at high frequencies (in the sub-THz range). The results show that the low-frequency value of the noise temperature in graphene on a substrate tends to be reduced as compared to the case of suspended graphene due to the important effect of remote polar phonon interactions, thus indicating a reduced emitted noise power; however, at very high frequencies the influence of the substrate tends to be significantly reduced, and the differences between the suspended and on-substrate cases tend to be minimized. The values obtained are comparable to those observed in GaAs and semiconductor nitrides.

  14. High frequency inductive lamp and power oscillator

    DOEpatents

    MacLennan, Donald A.; Dymond, Jr., Lauren E.; Gitsevich, Aleksandr; Grimm, William G.; Kipling, Kent; Kirkpatrick, Douglas A.; Ola, Samuel A.; Simpson, James E.; Trimble, William C.; Tsai, Peter; Turner, Brian P.

    2001-01-01

    A high frequency inductively coupled electrodeless lamp includes an excitation coil with an effective electrical length which is less than one half wavelength of a driving frequency applied thereto, preferably much less. The driving frequency may be greater than 100 MHz and is preferably as high as 915 MHz. Preferably, the excitation coil is configured as a non-helical, semi-cylindrical conductive surface having less than one turn, in the general shape of a wedding ring. At high frequencies, the current in the coil forms two loops which are spaced apart and parallel to each other. Configured appropriately, the coil approximates a Helmholtz configuration. The lamp preferably utilizes an bulb encased in a reflective ceramic cup with a pre-formed aperture defined therethrough. The ceramic cup may include structural features to aid in alignment and I or a flanged face to aid in thermal management. The lamp head is preferably an integrated lamp head comprising a metal matrix composite surrounding an insulating ceramic with the excitation integrally formed on the ceramic. A novel solid-state oscillator preferably provides RF power to the lamp. The oscillator is a single active element device capable of providing over 70 watts of power at over 70% efficiency. Various control circuits may be employed to adjust the driving frequency of the oscillator.

  15. High Frequency Plasma Generators for Ion Thrusters

    NASA Technical Reports Server (NTRS)

    Divergilio, W. F.; Goede, H.; Fosnight, V. V.

    1981-01-01

    The results of a one year program to experimentally adapt two new types of high frequency plasma generators to Argon ion thrusters and to analytically study a third high frequency source concept are presented. Conventional 30 cm two grid ion extraction was utilized or proposed for all three sources. The two plasma generating methods selected for experimental study were a radio frequency induction (RFI) source, operating at about 1 MHz, and an electron cyclotron heated (ECH) plasma source operating at about 5 GHz. Both sources utilize multi-linecusp permanent magnet configurations for plasma confinement. The plasma characteristics, plasma loading of the rf antenna, and the rf frequency dependence of source efficiency and antenna circuit efficiency are described for the RFI Multi-cusp source. In a series of tests of this source at Lewis Research Center, minimum discharge losses of 220+/-10 eV/ion were obtained with propellant utilization of .45 at a beam current of 3 amperes. Possible improvement modifications are discussed.

  16. High frequency inductive lamp and power oscillator

    DOEpatents

    MacLennan, Donald A.; Turner, Brian P.; Dolan, James T.; Kirkpatrick, Douglas A.; Leng, Yongzhang

    2000-01-01

    A high frequency inductively coupled electrodeless lamp includes an excitation coil with an effective electrical length which is less than one half wavelength of a driving frequency applied thereto, preferably much less. The driving frequency may be greater than 100 MHz and is preferably as high as 915 MHz. Preferably, the excitation coil is configured as a non-helical, semi-cylindrical conductive surface having less than one turn, in the general shape of a wedding ring. At high frequencies, the current in the coil forms two loops which are spaced apart and parallel to each other. Configured appropriately, the coil approximates a Helmholtz configuration. The lamp preferably utilizes an bulb encased in a reflective ceramic cup with a pre-formed aperture defined therethrough. The ceramic cup may include structural features to aid in alignment and/or a flanged face to aid in thermal management. The lamp head is preferably an integrated lamp head comprising a metal matrix composite surrounding an insulating ceramic with the excitation integrally formed on the ceramic. A novel solid-state oscillator preferably provides RF power to the lamp. The oscillator is a single active element device capable of providing over 70 watts of power at over 70% efficiency. Various control circuits may be employed to match the driving frequency of the oscillator to a plurality of tuning states of the lamp.

  17. High-Frequency Fluctuations During Magnetic Reconnection

    NASA Astrophysics Data System (ADS)

    Jara-Almonte, J.; Ji, H.; Daughton, W. S.; Roytershteyn, V.; Yamada, M.; Yoo, J.; Fox, W. R., II

    2014-12-01

    During collisionless reconnection, the decoupling of the field from the plasma is known to occur only within the localized ion and electron diffusion regions, however predictions from fully kinetic simulations do not agree with experimental observations on the size of the electron diffusion region, implying differing reconnection mechanisms. Previous experiments, along with 2D and 3D simulations, have conclusively shown that this discrepancy cannot be explained by either classical collisions or Lower-Hybrid Drift Instability (Roytershtyn 2010, 2013). Due to computational limitations, however, previous simulations were constrained to have minimal scale separation between the electron skin depth and the Debye length (de/λD ~ 10), much smaller than in experiments (de/λD ~ 300). This lack of scale-separation can drastically modify the electrostatic microphysics within the diffusion layer. Using 3D, fully explicit kinetic simulations with a realistic and unprecedentedly large separation between the Debye length and the electron skin depth, de/λD = 64, we show that high frequency electrostatic waves (ω >> ωLH) can exist within the electron diffusion region. These waves generate small-scale turbulence within the electron diffusion region which acts to broaden the layer. Anomalous resistivity is also generated by the turbulence and significantly modifies the force balance. In addition to simulation results, initial experimental measurements of high frequency fluctuations (electrostatic and electromagnetic, f ≤ 1 GHz) in the Magnetic Reconnection Experiment (MRX) will be presented.

  18. Through Weld Inspection of Wrought Stainless Steel Piping Using Phased-Array Ultrasonic Probes.

    SciTech Connect

    Anderson, Michael T.; Cumblidge, Stephen E.; Doctor, Steven R.

    2004-08-05

    A study was conducted to assess the ability of phased-array ultrasonic techniques to detect and accurately determine the size of flaws from the far-side of wrought austenitic piping welds. Far-side inspections of these welds are currently performed on a “best effort” basis and do not conform to ASME Code Section XI Appendix VIII performance demonstration requirements. For this study, four circumferential welds in 610mm diameter, 36mm thick ASTM A-358, Grade 304 vintage austenitic stainless steel pipe were examined. The welds were fabricated with varied welding parameters; both horizontal and vertical pipe orientations were used, with air and water backing, to simulate field welding conditions. A series of saw cuts, electro-discharge machined (EDM) notches, and implanted fatigue cracks were placed into the heat affected zones of the welds. The saw cuts and notches range in depth from 7.5% to 28.4% through-wall. The implanted cracks ranged in depth from 5% through wall to 64% through wall. The welds were examined with two phased-array probes, a 2.0 MHz transmit-receive longitudinal wave array and a 2.0 MHz transmit-receive shear wave array. These examinations showed that both phased-array transducers were able to detect and accurately length-size, but not depth size, all of the notches and flaws through the welds. The phased-array results were not strongly affected by the different welding techniques used in each weld.

  19. Progress and prospects of silicon-based design for optical phased array

    NASA Astrophysics Data System (ADS)

    Hu, Weiwei; Peng, Chao; Chang-Hasnain, Connie

    2016-03-01

    The high-speed, high-efficient, compact phase modulator array is indispensable in the Optical-phased array (OPA) which has been considered as a promising technology for realizing flexible and efficient beam steering. In our research, two methods are presented to utilize high-contrast grating (HCG) as high-efficient phase modulator. One is that HCG possesses high-Q resonances that origins from the cancellation of leaky waves. As a result, sharp resonance peaks appear on the reflection spectrum thus HCGs can be utilized as efficient phase shifters. Another is that low-Q mode HCG is utilized as ultra-lightweight mirror. With MEMS technology, small HCG displacement (~50 nm) leads to large phase change (~1.7π). Effective beam steering is achieved in Connie Chang-Hasnian's group. On the other hand, we theoretically and experimentally investigate the system design for silicon-based optical phased array, including the star coupler, phased array, emission elements and far-field patterns. Further, the non-uniform optical phased array is presented.

  20. Real-time B-scan ultrasonic imaging using a digital phased array system for NDE

    NASA Astrophysics Data System (ADS)

    Dunki-Jacobs, Robert; Thomas, Lewis

    A demonstration is presented of the ability to produce real-time images of metals on the basis of a phased-array ultrasound system. Attention is given to the critical role played by a beam-former. It is established that the present imaging system's resolution approaches the theoretical capabilities of the given aperture size and wavelength.

  1. Two dimensional thermo-optic beam steering using a silicon photonic optical phased array

    NASA Astrophysics Data System (ADS)

    Mahon, Rita; Preussner, Marcel W.; Rabinovich, William S.; Goetz, Peter G.; Kozak, Dmitry A.; Ferraro, Mike S.; Murphy, James L.

    2016-03-01

    Components for free space optical communication terminals such as lasers, amplifiers, and receivers have all seen substantial reduction in both size and power consumption over the past several decades. However, pointing systems, such as fast steering mirrors and gimbals, have remained large, slow and power-hungry. Optical phased arrays provide a possible solution for non-mechanical beam steering devices that can be compact and lower in power. Silicon photonics is a promising technology for phased arrays because it has the potential to scale to many elements and may be compatible with CMOS technology thereby enabling batch fabrication. For most free space optical communication applications, two-dimensional beam steering is needed. To date, silicon photonic phased arrays have achieved two-dimensional steering by combining thermo-optic steering, in-plane, with wavelength tuning by means of an output grating to give angular tuning, out-of-plane. While this architecture might work for certain static communication links, it would be difficult to implement for moving platforms. Other approaches have required N2 controls for an NxN element phased array, which leads to complexity. Hence, in this work we demonstrate steering using the thermo-optic effect for both dimensions with a simplified steering mechanism requiring only two control signals, one for each steering dimension.

  2. An RF phased array applicator designed for hyperthermia breast cancer treatments.

    PubMed

    Wu, Liyong; McGough, Robert J; Arabe, Omar Ali; Samulski, Thaddeus V

    2006-01-07

    An RF phased array applicator has been constructed for hyperthermia treatments in the intact breast. This RF phased array consists of four antennas mounted on a Lexan water tank, and geometric focusing is employed so that each antenna points in the direction of the intended target. The operating frequency for this phased array is 140 MHz. The RF array has been characterized both by electric field measurements in a water tank and by electric field simulations using the finite-element method. The finite-element simulations are performed with HFSS software, where the mesh defined for finite-element calculations includes the geometry of the tank enclosure and four end-loaded dipole antennas. The material properties of the water tank enclosure and the antennas are also included in each simulation. The results of the finite-element simulations are compared to the measured values for this configuration, and the results, which include the effects of amplitude shading and phase shifting, show that the electric field predicted by finite-element simulations is similar to the measured field. Simulations also show that the contributions from standing waves are significant, which is consistent with measurement results. Simulated electric field and bio-heat transfer results are also computed within a simple 3D breast model. Temperature simulations show that, although peak temperatures are generated outside the simulated tumour target, this RF phased array applicator is an effective device for regional hyperthermia in the intact breast.

  3. A prototype high-speed optically-steered X-band phased array antenna.

    PubMed

    Wu, Pengfei; Tang, Suning; Raible, Daniel E

    2013-12-30

    We develop a prototype of optically-steered X-band phased array antenna with capabilities of multi-band and multi-beam operations. It exploits high-speed wavelength tunable lasers for optical true-time delays over a dispersive optical fiber link, enabling agile, broadband and vibration-free RF beam steering with large angle.

  4. Prostate cancer: comparison of local staging accuracy of pelvic phased-array coil alone versus integrated endorectal-pelvic phased-array coils. Local staging accuracy of prostate cancer using endorectal coil MR imaging.

    PubMed

    Fütterer, Jurgen J; Engelbrecht, Marc R; Jager, Gerrit J; Hartman, Robert P; King, Bernard F; Hulsbergen-Van de Kaa, Christina A; Witjes, J Alfred; Barentsz, Jelle O

    2007-04-01

    To compare the visibility of anatomical details and prostate cancer local staging performance of pelvic phased-array coil and integrated endorectal-pelvic phased-array coil MR imaging, with histologic analysis serving as the reference standard. MR imaging was performed in 81 consecutive patients with biopsy-proved prostate cancer, prior to radical prostatectomy, on a 1.5T scanner. T2-weighted fast spin echo images of the prostate were obtained using phased-array coil and endorectal-pelvic phased-array coils. Prospectively, one radiologist, retrospectively, two radiologists and two less experienced radiologists working in consensus, evaluated and scored all endorectal-pelvic phased-array imaging, with regard to visibility of anatomical details and local staging. Receiver operator characteristics (ROC) analysis was performed. Anatomical details of the overall prostate were significantly better evaluated using the endorectal-pelvic phased-array coil setup (P<0.05). The overall local staging accuracy, sensitivity and specificity for the pelvic phased-array coil was 59% (48/81), 56% (20/36) and 62% (28/45), and for the endorectal-pelvic phased-array coils 83% (67/81), 64% (23/36) and 98% (44/45) respectively, for the prospective reader. Accuracy and specificity were significantly better with endorectal-pelvic phased-array coils (P<0.05). The overall staging accuracy, sensitivity and specificity for the retrospective readers were 78-79% (P<0.05), 56-58% and 96%, for the endorectal-pelvic phased-array coils. Area under the ROC curve (Az) was significantly higher for endorectal-pelvic phased-array coils (Az=0.74) compared to pelvic phased-array coil (Az=0.57), for the prospective reader. The use of endorectal-pelvic phased array coils resulted in significant improvement of anatomic details, extracapsular extension accuracy and specificity. Overstaging is reduced significantly with equal sensitivity when an endorectal-pelvic phased-array coil is used.

  5. Software for Displaying High-Frequency Test Data

    NASA Technical Reports Server (NTRS)

    Elmore, Jason L.

    2003-01-01

    An easy-to-use, intuitive computer program was written to satisfy a need of test operators and data requestors to quickly view and manipulate high-frequency test data recorded at the East and West Test Areas at Marshall Space Flight Center. By enabling rapid analysis, this program makes it possible to reduce times between test runs, thereby potentially reducing the overall cost of test operations. The program can be used to perform quick frequency analysis, using multiple fast- Fourier-transform windowing and amplitude options. The program can generate amplitude-versus-time plots with full zoom capabilities, frequency-component plots at specified time intervals, and waterfall plots (plots of spectral intensity versus frequency at successive small time intervals, showing the changing frequency components over time). There are options for printing of the plots and saving plot data as text files that can be imported into other application programs. The program can perform all of the aforementioned plotting and plot-data-handling functions on a relatively inexpensive computer; other software that performs the same functions requires computers with large amounts of power and memory.

  6. High-Frequency Mechanostimulation of Cell Adhesion.

    PubMed

    Kadem, Laith F; Suana, K Grace; Holz, Michelle; Wang, Wei; Westerhaus, Hannes; Herges, Rainer; Selhuber-Unkel, Christine

    2017-01-02

    Cell adhesion is regulated by molecularly defined protein interactions and by mechanical forces, which can activate a dynamic restructuring of adhesion sites. Previous attempts to explore the response of cell adhesion to forces have been limited to applying mechanical stimuli that involve the cytoskeleton. In contrast, we here apply a new, oscillatory type of stimulus through push-pull azobenzenes. Push-pull azobenzenes perform a high-frequency, molecular oscillation upon irradiation with visible light that has frequently been applied in polymer surface relief grating. We here use these oscillations to address single adhesion receptors. The effect of molecular oscillatory forces on cell adhesion has been analyzed using single-cell force spectroscopy and gene expression studies. Our experiments demonstrate a reinforcement of cell adhesion as well as upregulated expression levels of adhesion-associated genes as a result of the nanoscale "tickling" of integrins. This novel type of mechanical stimulus provides a previously unprecedented molecular control of cellular mechanosensing.

  7. Computer modeling of tactical high frequency antennas

    NASA Astrophysics Data System (ADS)

    Gregory, Bobby G., Jr.

    1992-06-01

    The purpose of this thesis was to compare the performance of three tactical high frequency antennas to be used as possible replacement for the Tactical Data Communications Central (TDCC) antennas. The antennas were modeled using the Numerical Electromagnetics Code, Version 3 (NEC3), and the Eyring Low Profile and Buried Antenna Modeling Program (PAT7) for several different frequencies and ground conditions. The performance was evaluated by comparing gain at the desired takeoff angles, the voltage standing wave ratio of each antenna, and its omni-directional capability. The buried antenna models, the ELPA-302 and horizontal dipole, were most effective when employed over poor ground conditions. The best performance under all conditions tested was demonstrated by the HT-20T. Each of these antennas have tactical advantages and disadvantages and can optimize communications under certain conditions. The selection of the best antenna is situation dependent. An experimental test of these models is recommended to verify the modeling results.

  8. Parametric nanomechanical amplification at very high frequency.

    PubMed

    Karabalin, R B; Feng, X L; Roukes, M L

    2009-09-01

    Parametric resonance and amplification are important in both fundamental physics and technological applications. Here we report very high frequency (VHF) parametric resonators and mechanical-domain amplifiers based on nanoelectromechanical systems (NEMS). Compound mechanical nanostructures patterned by multilayer, top-down nanofabrication are read out by a novel scheme that parametrically modulates longitudinal stress in doubly clamped beam NEMS resonators. Parametric pumping and signal amplification are demonstrated for VHF resonators up to approximately 130 MHz and provide useful enhancement of both resonance signal amplitude and quality factor. We find that Joule heating and reduced thermal conductance in these nanostructures ultimately impose an upper limit to device performance. We develop a theoretical model to account for both the parametric response and nonequilibrium thermal transport in these composite nanostructures. The results closely conform to our experimental observations, elucidate the frequency and threshold-voltage scaling in parametric VHF NEMS resonators and sensors, and establish the ultimate sensitivity limits of this approach.

  9. Degradation of PAHs by high frequency ultrasound.

    PubMed

    Manariotis, Ioannis D; Karapanagioti, Hrissi K; Chrysikopoulos, Constantinos V

    2011-04-01

    Polycyclic aromatic hydrocarbons (PAHs) are persistent organic compounds, which have been reported in the literature to efficiently degrade at low (e.g. 20 kHz) and moderate (e.g. 506 kHz) ultrasound frequencies. The present study focuses on degradation of naphthalene, phenanthrene, and pyrene by ultrasound at three different relatively high frequencies (i.e. 582, 862, and 1142 kHz). The experimental results indicate that for all three frequencies and power inputs ≥ 133 W phenanthrene degrades to concentrations lower than our experimental detection limit (<1 μg/L). Phenanthrene degrades significantly faster at 582 kHz than at 862 and 1142 kHz. For all three frequencies, the degradation rates per unit mass are similar for naphthalene and phenanthrene and lower for pyrene. Furthermore, naphthalene degradation requires less energy than phenanthrene, which requires less energy than pyrene under the same conditions. No hexane-extractable metabolites were identified in the solutions.

  10. Fundamentals of bipolar high-frequency surgery.

    PubMed

    Reidenbach, H D

    1993-04-01

    In endoscopic surgery a very precise surgical dissection technique and an efficient hemostasis are of decisive importance. The bipolar technique may be regarded as a method which satisfies both requirements, especially regarding a high safety standard in application. In this context the biophysical and technical fundamentals of this method, which have been known in principle for a long time, are described with regard to the special demands of a newly developed field of modern surgery. After classification of this method into a general and a quasi-bipolar mode, various technological solutions of specific bipolar probes, in a strict and in a generalized sense, are characterized in terms of indication. Experimental results obtained with different bipolar instruments and probes are given. The application of modern microprocessor-controlled high-frequency surgery equipment and, wherever necessary, the integration of additional ancillary technology into the specialized bipolar instruments may result in most useful and efficient tools of a key technology in endoscopic surgery.

  11. High-frequency ultrasonic wire bonding systems

    PubMed

    Tsujino; Yoshihara; Sano; Ihara

    2000-03-01

    The vibration characteristics of longitudinal-complex transverse vibration systems with multiple resonance frequencies of 350-980 kHz for ultrasonic wire bonding of IC, LSI or electronic devices were studied. The complex vibration systems can be applied for direct welding of semiconductor tips (face-down bonding, flip-chip bonding) and packaging of electronic devices. A longitudinal-complex transverse vibration bonding system consists of a complex transverse vibration rod, two driving longitudinal transducers 7.0 mm in diameter and a transverse vibration welding tip. The vibration distributions along ceramic and stainless-steel welding tips were measured at up to 980 kHz. A high-frequency vibration system with a height of 20.7 mm and a weight of less than 15 g was obtained.

  12. Using Silver Nano-Particle Ink in Electrode Fabrication of High Frequency Copolymer Ultrasonic Transducers: Modeling and Experimental Investigation

    PubMed Central

    Decharat, Adit; Wagle, Sanat; Jacobsen, Svein; Melandsø, Frank

    2015-01-01

    High frequency polymer-based ultrasonic transducers are produced with electrodes thicknesses typical for printed electrodes obtained from silver (Ag) nano-particle inks. An analytical three-port network is used to study the acoustic effects imposed by a thick electrode in a typical layered transducer configuration. Results from the network model are compared to experimental findings for the implemented transducer configuration, to obtain a better understanding of acoustical effects caused by the additional printed mass loading. The proposed investigation might be supportive of identification of suitable electrode-depositing methods. It is also believed to be useful as a feasibility study for printed Ag-based electrodes in high frequency transducers, which may reduce both the cost and production complexity of these devices. PMID:25903552

  13. High frequency, high power capacitor development

    NASA Astrophysics Data System (ADS)

    White, C. W.; Hoffman, P. S.

    1983-03-01

    A program to develop a special high energy density, high power transfer capacitor to operate at frequency of 40 kHz, 600 V rms at 125 A rms plus 600 V dc bias for space operation. The program included material evaluation and selection, a capacitor design was prepared, a thermal analysis performed on the design. Fifty capacitors were manufactured for testing at 10 kHz and 40 kHz for 50 hours at Industrial Electric Heating Co. of Columbus, Ohio. The vacuum endurance test used on environmental chamber and temperature plate furnished by Maxwell. The capacitors were energized with a special power conditioning apparatus developed by Industrial Electric Heating Co. Temperature conditions of the capacitors were monitored by IEHCo test equipment. Successful completion of the vacuum endurance test series confirmed achievement of the main goal of producing a capacitor or reliable operation at high frequency in an environment normally not hospitable to electrical and electronic components. The capacitor developed compared to a typical commercial capacitor at the 40 kHz level represents a decrease in size and weight by a factor of seven.

  14. Aerodynamics of high frequency flapping wings

    NASA Astrophysics Data System (ADS)

    Hu, Zheng; Roll, Jesse; Cheng, Bo; Deng, Xinyan

    2010-11-01

    We investigated the aerodynamic performance of high frequency flapping wings using a 2.5 gram robotic insect mechanism developed in our lab. The mechanism flaps up to 65Hz with a pair of man-made wing mounted with 10cm wingtip-to-wingtip span. The mean aerodynamic lift force was measured by a lever platform, and the flow velocity and vorticity were measured using a stereo DPIV system in the frontal, parasagittal, and horizontal planes. Both near field (leading edge vortex) and far field flow (induced flow) were measured with instantaneous and phase-averaged results. Systematic experiments were performed on the man-made wings, cicada and hawk moth wings due to their similar size, frequency and Reynolds number. For insect wings, we used both dry and freshly-cut wings. The aerodynamic force increase with flapping frequency and the man-made wing generates more than 4 grams of lift at 35Hz with 3 volt input. Here we present the experimental results and the major differences in their aerodynamic performances.

  15. High-Frequency Observations of Blazars

    NASA Technical Reports Server (NTRS)

    Marscher, A. P.; Marchenko-Jorstad, S. G.; Mattox, J. R.; Wehrle, A. E.; Aller, M. F.

    2000-01-01

    We report on the results of high-frequency VLBA observations of 42 gamma-ray bright blazars monitored at 22 and 43 GHz between 1993.9 and 1997.6. In 1997 the observations included polarization-sensitive imaging. The cores of gamma-ray blazars are only weakly polarized, with EVPAs (electric-vector position angles) usually within 40 deg of the local direction of the jet. The EVPAs of the jet components are usually within 20 deg of the local jet direction. The apparent speeds of the gamma-ray bright blazars are considerably faster than in the general population of bright compact radio sources. Two X-ray flares (observed with RXTE) of the quasar PKS 1510-089 appear to be related to radio flares, but with the radio leading the X-ray variations by about 2 weeks. This can be explained either by synchrotron self-Compton emission in a component whose variations are limited by light travel time or by the Mirror Compton model.

  16. High-Frequency Observations of Blazars

    NASA Technical Reports Server (NTRS)

    Marscher, A. P.; Marchenko-Jorstad, S. G.; Mattox, J. R.; Wehrle, A. E.; Aller, M. F.

    2000-01-01

    We report on the results of high-frequency VLBA observations of 42 gamma ray bright blazars monitored at 22 and 43 GHz between 1993.9 and 1997-6. In 1997 the observations included polarization-sensitive imaging. The cores of gamma ray blazars are only weakly polarized, with EVPAs (electric-vector position angles) usually within 40 degrees of the local direction of the jet. The EVPAs of the jet components are usually within 20 degrees of the local jet direction. The apparent speeds of the gamma ray bright blazars are considerably faster than in the general population of bright compact radio sources. Two X-ray flares (observed with RXTE) of the quasar PKS 1510-089 appear to be related to radio flares, but with the radio leading the X-ray variations by about 2 weeks. This can be explained either by synchrotron self-Compton emission in a component whose variations are limited by light travel time or by the Mirror Compton model.

  17. A high frequency electromagnetic impedance imaging system

    SciTech Connect

    Tseng, Hung-Wen; Lee, Ki Ha; Becker, Alex

    2003-01-15

    Non-invasive, high resolution geophysical mapping of the shallow subsurface is necessary for delineation of buried hazardous wastes, detecting unexploded ordinance, verifying and monitoring of containment or moisture contents, and other environmental applications. Electromagnetic (EM) techniques can be used for this purpose since electrical conductivity and dielectric permittivity are representative of the subsurface media. Measurements in the EM frequency band between 1 and 100 MHz are very important for such applications, because the induction number of many targets is small and the ability to determine the subsurface distribution of both electrical properties is required. Earlier workers were successful in developing systems for detecting anomalous areas, but quantitative interpretation of the data was difficult. Accurate measurements are necessary, but difficult to achieve for high-resolution imaging of the subsurface. We are developing a broadband non-invasive method for accurately mapping the electrical conductivity and dielectric permittivity of the shallow subsurface using an EM impedance approach similar to the MT exploration technique. Electric and magnetic sensors were tested to ensure that stray EM scattering is minimized and the quality of the data collected with the high-frequency impedance (HFI) system is good enough to allow high-resolution, multi-dimensional imaging of hidden targets. Additional efforts are being made to modify and further develop existing sensors and transmitters to improve the imaging capability and data acquisition efficiency.

  18. High-frequency plasma-heating apparatus

    DOEpatents

    Brambilla, Marco; Lallia, Pascal

    1978-01-01

    An array of adjacent wave guides feed high-frequency energy into a vacuum chamber in which a toroidal plasma is confined by a magnetic field, the wave guide array being located between two toroidal current windings. Waves are excited in the wave guide at a frequency substantially equal to the lower frequency hybrid wave of the plasma and a substantially equal phase shift is provided from one guide to the next between the waves therein. For plasmas of low peripheral density gradient, the guides are excited in the TE.sub.01 mode and the output electric field is parallel to the direction of the toroidal magnetic field. For exciting waves in plasmas of high peripheral density gradient, the guides are excited in the TM.sub.01 mode and the magnetic field at the wave guide outlets is parallel to the direction of the toroidal magnetic field. The wave excited at the outlet of the wave guide array is a progressive wave propagating in the direction opposite to that of the toroidal current and is, therefore, not absorbed by so-called "runaway" electrons.

  19. A High Frequency Model of Cascade Noise

    NASA Technical Reports Server (NTRS)

    Envia, Edmane

    1998-01-01

    Closed form asymptotic expressions for computing high frequency noise generated by an annular cascade in an infinite duct containing a uniform flow are presented. There are two new elements in this work. First, the annular duct mode representation does not rely on the often-used Bessel function expansion resulting in simpler expressions for both the radial eigenvalues and eigenfunctions of the duct. In particular, the new representation provides an explicit approximate formula for the radial eigenvalues obviating the need for solutions of the transcendental annular duct eigenvalue equation. Also, the radial eigenfunctions are represented in terms of exponentials eliminating the numerical problems associated with generating the Bessel functions on a computer. The second new element is the construction of an unsteady response model for an annular cascade. The new construction satisfies the boundary conditions on both the cascade and duct walls simultaneously adding a new level of realism to the noise calculations. Preliminary results which demonstrate the effectiveness of the new elements are presented. A discussion of the utility of the asymptotic formulas for calculating cascade discrete tone as well as broadband noise is also included.

  20. Plant Responses to High Frequency Electromagnetic Fields

    PubMed Central

    Vian, Alain; Davies, Eric; Gendraud, Michel; Bonnet, Pierre

    2016-01-01

    High frequency nonionizing electromagnetic fields (HF-EMF) that are increasingly present in the environment constitute a genuine environmental stimulus able to evoke specific responses in plants that share many similarities with those observed after a stressful treatment. Plants constitute an outstanding model to study such interactions since their architecture (high surface area to volume ratio) optimizes their interaction with the environment. In the present review, after identifying the main exposure devices (transverse and gigahertz electromagnetic cells, wave guide, and mode stirred reverberating chamber) and general physics laws that govern EMF interactions with plants, we illustrate some of the observed responses after exposure to HF-EMF at the cellular, molecular, and whole plant scale. Indeed, numerous metabolic activities (reactive oxygen species metabolism, α- and β-amylase, Krebs cycle, pentose phosphate pathway, chlorophyll content, terpene emission, etc.) are modified, gene expression altered (calmodulin, calcium-dependent protein kinase, and proteinase inhibitor), and growth reduced (stem elongation and dry weight) after low power (i.e., nonthermal) HF-EMF exposure. These changes occur not only in the tissues directly exposed but also systemically in distant tissues. While the long-term impact of these metabolic changes remains largely unknown, we propose to consider nonionizing HF-EMF radiation as a noninjurious, genuine environmental factor that readily evokes changes in plant metabolism. PMID:26981524

  1. High frequency, high power capacitor development

    NASA Technical Reports Server (NTRS)

    White, C. W.; Hoffman, P. S.

    1983-01-01

    A program to develop a special high energy density, high power transfer capacitor to operate at frequency of 40 kHz, 600 V rms at 125 A rms plus 600 V dc bias for space operation. The program included material evaluation and selection, a capacitor design was prepared, a thermal analysis performed on the design. Fifty capacitors were manufactured for testing at 10 kHz and 40 kHz for 50 hours at Industrial Electric Heating Co. of Columbus, Ohio. The vacuum endurance test used on environmental chamber and temperature plate furnished by Maxwell. The capacitors were energized with a special power conditioning apparatus developed by Industrial Electric Heating Co. Temperature conditions of the capacitors were monitored by IEHCo test equipment. Successful completion of the vacuum endurance test series confirmed achievement of the main goal of producing a capacitor or reliable operation at high frequency in an environment normally not hospitable to electrical and electronic components. The capacitor developed compared to a typical commercial capacitor at the 40 kHz level represents a decrease in size and weight by a factor of seven.

  2. Two-dimensional analytic modeling of acoustic diffraction for ultrasonic beam steering by phased array transducers.

    PubMed

    Wang, Tiansi; Zhang, Chong; Aleksov, Aleksandar; Salama, Islam; Kar, Aravinda

    2017-04-01

    Phased array ultrasonic transducers enable modulating the focal position of the acoustic waves, and this capability is utilized in many applications, such as medical imaging and non-destructive testing. This type of transducers also provides a mechanism to generate tilted wavefronts in acousto-optic deflectors to deflect laser beams for high precision advanced laser material processing. In this paper, a theoretical model is presented for the diffraction of ultrasonic waves emitted by several phased array transducers into an acousto-optic medium such as TeO2 crystal. A simple analytic expression is obtained for the distribution of the ultrasonic displacement field in the crystal. The model prediction is found to be in good agreement with the results of a numerical model that is based on a non-paraxial multi-Gaussian beam (NMGB) model.

  3. Nonlinear ultrasonic phased array imaging of closed cracks using global preheating and local cooling

    NASA Astrophysics Data System (ADS)

    Ohara, Yoshikazu; Takahashi, Koji; Ino, Yoshihiro; Yamanaka, Kazushi

    2015-10-01

    Closed cracks are the main cause of underestimation in ultrasonic inspection, because the ultrasound transmits through the crack. Specifically, the measurement of closed-crack depth in coarse-grained materials, which are highly attenuative due to linear scatterings at the grains, is the most difficult issue. To solve this problem, we have developed a temporary crack opening method, global preheating and local cooling (GPLC), using tensile thermal stress, and a high-selectivity imaging method, load difference phased array (LDPA), based on the subtraction of phased array images between different stresses. To demonstrate our developed method, we formed a closed fatigue crack in coarse-grained stainless steel (SUS316L) specimen. As a result of applying it to the specimen, the high-selectivity imaging performance was successfully demonstrated. This will be useful in improving the measurement accuracy of closed-crack depths in coarse-grained material.

  4. Experimental characterization of ultrasonic phased arrays for the nondestructive evaluation of concrete structures

    SciTech Connect

    Azar, L.; Wooh, S.C.

    1999-02-01

    Novel ultrasonic phased arrays were developed and their feasibility was tested for assessing the condition of concrete structures. These sensors are based on low frequency ultrasound technology, which, to date, has been the preferred method for concrete testing. By combining multiple transducer elements in a linear configuration, dynamic phase focusing and steering of the ultrasound beam is possible. An automated testing assembly was used to assess the steering and focusing performance of the array in a cementitious medium. Experimental results demonstrate excellent steerability and accuracy when compared to the numerical simulation presented. The effective steering and focusing behavior in concrete signifies that phased arrays can be used as the primary imaging and scanning device for large scale concrete structures.

  5. DC electric field induced phase array self-assembly of Au nanoparticles

    NASA Astrophysics Data System (ADS)

    Yadavali, S.; Sachan, R.; Dyck, O.; Kalyanaraman, R.

    2014-11-01

    In this work we report the discovery of phase array self-assembly, a new way to spontaneously make periodic arrangements of metal nanoparticles. An initially random arrangement of gold (Au) or silver (Ag) nanoparticles on SiO2/Si substrates was irradiated with linearly polarized (P) laser light in the presence of a dc electric (E) field applied to the insulating substrate. For E fields parallel to the laser polarization (E \\parallel P), the resulting periodic ordering was single-crystal like with extremely low defect density and covered large macroscopic areas. The E field appears to be modifying the phase between radiation scattered by the individual nanoparticles thus leading to enhanced interference effects. While phase array behavior is widely known in antenna technology, this is the first evidence that it can also aid in nanoscale self-assembly. These results provide a simple way to produce periodic metal nanoparticles over large areas.

  6. Application of Ultrasonic Phased Array Technology to the Detection of Defect in Composite Stiffened-structures

    NASA Astrophysics Data System (ADS)

    Zhou, Yuan-Qi; Zhan, Li-Hua

    2016-05-01

    Composite stiffened-structure consists of the skin and stringer has been widely used in aircraft fuselage and wings. The main purpose of the article is to detect the composite material reinforced structure accurately and explore the relationship between defect formation and structural elements or curing process. Based on ultrasonic phased array inspection technology, the regularity of defects in the manufacture of composite materials are obtained, the correlation model between actual defects and nondestructive testing are established. The article find that the forming quality of deltoid area in T-stiffened structure is obviously improved by pre-curing, the defects of hat-stiffened structure are affected by the mandrel. The results show that the ultrasonic phased array inspection technology can be an effectively way for the detection of composite stiffened-structures, which become an important means to control the defects of composite and improve the quality of the product.

  7. Grating lobes analysis based on blazed grating theory for liquid crystal optical-phased array

    NASA Astrophysics Data System (ADS)

    Chen, Jian; Cui, Guolong; Kong, Lingjiang; Xiao, Feng; Liu, Xin; Zhang, Xiaoguang

    2013-09-01

    The grating lobes of the liquid crystal optical-phased array (LCOPA) based on blazed grating theory is studied. Using the Fraunhofer propagation principle, the analytical expressions of the far-field intensity distribution are derived. Subsequently, we can obtain both the locations and the intensities of the grating lobes. The derived analytical functions that provide an insight into single-slit diffraction and multislit interference effect on the grating lobes are discussed. Utilizing the conventional microwave-phased array technique, the intensities of the grating lobes and the main lobe are almost the same. Different from this, the derived analytical functions demonstrate that the intensities of the grating lobes are less than that of the main lobe. The computer simulations and experiments show that the proposed method can correctly estimate the locations and the intensities of the grating lobes for a LCOPA simultaneously.

  8. Modeling and simulation of ultrasound fields generated by 2D phased array transducers for medical applications.

    PubMed

    Matrone, G; Quaglia, F; Magenes, G

    2010-01-01

    Modern ultrasound imaging instrumentation for clinical applications allows real-time volumetric scanning of the patients' body. 4D imaging has been made possible thanks to the development of new echographic probes which consist in 2D phased arrays of piezoelectric transducers. In these new devices it is the system electronics which properly drives the matrix elements and focuses the beam in order to obtain a sequence of volumetric images. This paper introduces an ultrasound field simulator based on the Spatial Impulse Response method which is being properly developed to analyze the characteristics of the ultrasound field generated by a 2D phased array of transducers. Thanks to its high configurability by the user, it will represent a very useful tool for electronics designers in developing 4D ultrasound imaging systems components.

  9. Feasibility of a multipurpose transceiver module for phased array radar and EW applications using RFIC technology

    NASA Astrophysics Data System (ADS)

    Al-Sarawi, Said; Hansen, Hedley; Zhu, Yingbo

    2007-12-01

    Phased array antennas have a large number of civilian and military applications. In this paper we briefly review common approaches to an integrated implementation of radar and electronic warfare digital phase array module and highlight features that are common to both of these applications. Then we discuss how the promising features of the radio frequency integrated circuit (RFIC)-based technology can be utilized in building a transceiver module that meets the requirements of both radar and electronic warfare applications with minimum number of external components. This is achieved by researching the pros and cons of the different receiver architectures and their performance from the targeted applications point of view. Then, we survey current RFIC technologies and highlight the pros and cons of these technologies and how they impact the performance of the discussed receiver architectures.

  10. Performance of a mmWave beamformed phased array system for indoor LOS communication

    NASA Astrophysics Data System (ADS)

    Amjad, Kinnan; Xu, Huaping

    2016-11-01

    Millimeter waves (mmWaves) spectrum ranging from 30GHz to 300GHz is emerging as a potential solution to the bandwidth problem faced by the wireless communication now a days. The advancements in the antenna technology has enabled the fabrication of antenna arrays or phased array systems which when used with techniques like spatial multiplexing and beamforming has enabled the use of mmWaves for both indoor and outdoor communication systems by providing gain and selectivity. This has also opened the doors for its potential use in long range and cellular communications. The 60GHz band also know as the oxygen absorption band due to its higher attenuation and unlicensed operation is a good candidate for use in secure and confined communications. In this paper we have investigated the performance of a beamformed phased array system in the mmWave spectrum. The performance is measured for varying the source and noise location and compared for a Linear and Rectangular array.

  11. Optical techniques to feed and control GaAs MMIC modules for phased array antenna applications

    NASA Technical Reports Server (NTRS)

    Bhasin, K. B.; Anzic, G.; Kunath, R. R.; Connolly, D. J.

    1986-01-01

    A complex signal distribution system is required to feed and control GaAs monolithic microwave integrated circuits (MMICs) for phased array antenna applications above 20 GHz. Each MMIC module will require one or more RF lines, one or more bias voltage lines, and digital lines to provide a minimum of 10 bits of combined phase and gain control information. In a closely spaced array, the routing of these multiple lines presents difficult topology problems as well as a high probability of signal interference. To overcome GaAs MMIC phased array signal distribution problems optical fibers interconnected to monolithically integrated optical components with GaAs MMIC array elements are proposed as a solution. System architecture considerations using optical fibers are described. The analog and digital optical links to respectively feed and control MMIC elements are analyzed. It is concluded that a fiber optic network will reduce weight and complexity, and increase reliability and performance, but higher power will be required.

  12. Design and Validation of Rugged Microwave Photonic Network for Phased-Array Radar

    NASA Astrophysics Data System (ADS)

    Mathur, Manisha; Rai, J. K.; Sridhar, N.

    2015-11-01

    Military radar has the requirement of 24 × 7 operation in harsh environments with a high level of safety and integrity built in for equipment and personnel working with it. This article presents an application of a microwave photonic network for phased-array military radar. The design challenge is to realize faithful reproduction of the input microwave signals over extreme temperature and frequency ranges. Environmental testing has been carried out to validate the performance of the proposed microwave photonic network over 2-4 GHz and a temperature range of -20°C to +55°C. The result shows that the photonic network can be successfully utilized for phased-array radar.

  13. Frequency-domain photoacoustic phased array probe for biomedical imaging applications.

    PubMed

    Telenkov, Sergey; Alwi, Rudolf; Mandelis, Andreas; Worthington, Arthur

    2011-12-01

    We report the development of a frequency-domain biomedical photoacoustic imaging system that utilizes a continuous-wave laser source with a custom intensity modulation pattern, ultrasonic phased array for signal detection, and processing coupled with a beam-forming algorithm for reconstruction of photoacoustic correlation images. Sensitivity to optical contrast was demonstrated using tissue-mimicking phantoms and in-vivo tissue samples.

  14. Development of the Phase Synchronization Circuit for Wirelessly Distributed Digital Phased Array

    DTIC Science & Technology

    2009-09-01

    retrieved on August 2, 2009. [14] C. H. Tong, “System study and design of broad-band U-slot microstrip patch antennas for aperstuctures and...a wireless channel. Compared to conventional phased array systems, its advantages are adaptability, survivability and flexibility . Phase...more flexible and robust than the current circuit and thus more desirable for future applications of the WDDPA. 15. NUMBER OF PAGES 130 14

  15. Measured Sensitivity of the First Mark II Phased Array Feed on an ASKAP Antenna

    NASA Astrophysics Data System (ADS)

    Chippendale, A. P.; Brown, A. J.; Beresford, R. J.; Hampson, G. A.; Macleod, A.; Shaw, R. D.; Brothers, M. L.; Cantrall, C.; Forsyth, A. R.; Hay, S. G.; Leach, M.

    2015-09-01

    This paper presents the measured sensitivity of CSIRO's first Mk. II phased array feed (PAF) on an ASKAP antenna. The Mk. II achieves a minimum system-temperature-over-efficiency T_{sys}/η of 78 K at 1.23 GHz and is 95 K or better from 835 MHz to 1.8 GHz. This PAF was designed for the Australian SKA Pathfinder telescope to demonstrate fast astronomical surveys with a wide field of view for the Square Kilometre Array (SKA).

  16. Experimental research on beam steering characteristics of liquid crystal optical phased array

    NASA Astrophysics Data System (ADS)

    Li, Man; Cai, Jun; Xu, Hong; Wang, Xiangru; Wu, Liang

    2016-01-01

    Beam steering characteristics of transmission liquid crystal optical phased array(LC-OPA) were measured using ultra precision electronic autocollimator. A continuous beam steering with a constant angular resolution in the order of 20 μrad is obtained experimentally from 0° to 6° based on the method of variable period grating (VPG).Meanwhile, the angular repeatability of less than 4 μrad (RMS) has been achieved.

  17. The Application of Phased Array Ultrasonic Techniques for Inspection of Railway Axles from Their End Face

    NASA Astrophysics Data System (ADS)

    Liaptsis, D.; Cooper, I.; Boyle, K.; Nicholson, P. I.

    2011-06-01

    As part of the development of a non destructive testing (NDT) system combining complementary inspection techniques, an inspection system based on phased array ultrasonic testing (PAUT) for detection of transverse cracking in solid railway axles is being developed. This paper presents the initial study, which includes the PAUT experimental setup and the initial results obtained after testing the system on railway axle blocks. The inspection of solid axles from their axle end face is investigated.

  18. Initial High-Power-CW-Laser Testing of Liquid-Crystal Optical Phased Arrays

    DTIC Science & Technology

    2010-02-01

    AFRL-RY-WP-TR-2010-1043 INITIAL HIGH-POWER-CW-LASER TESTING OF LIQUID-CRYSTAL OPTICAL PHASED ARRAYS Bert Whitaker OptiMetrics, Inc...Bert Whitaker (OptiMetrics, Inc.) Scott Harris (Flatiron Research, LLC) 5d. PROJECT NUMBER 2003 5e. TASK NUMBER 11 5f. WORK UNIT NUMBER...to a Carl Zeiss petrographic microscope. The crossed polarizers in this microscope highlighted the presence of LC material due to its birefringence

  19. Phased Array Ultrasound: Initial Development of PAUT Inspection of Self-Reacting Friction Stir Welds

    NASA Technical Reports Server (NTRS)

    Rairigh, Ryan

    2008-01-01

    This slide presentation reviews the development of Phased Array Ultrasound (PAUT) as a non-destructive examination method for Self Reacting Friction Stir Welds (SR-FSW). PAUT is the only NDE method which has been shown to detect detrimental levels of Residual Oxide Defect (ROD), which can result in significant decrease in weld strength. The presentation reviews the PAUT process, and shows the results in comparison with x-ray radiography.

  20. Holographic optical elements (HOEs) for true-time delays aimed at phased-array antenna applications

    NASA Astrophysics Data System (ADS)

    Chen, Ray T.; Li, Richard L.

    1996-05-01

    True time-delay beam steering in optical domain for phased-array antenna application using multiplexed substrate guided wave propagation is introduced. Limitations of practical true- time-delays are discussed. Aspects on making holographic grating couplers are considered. Finally, experimental results on the generation of 25 GHz broadband microwave signals by optical heterodyne technique and 1-to-30 massive substrate guided wave optical fanout with an uniform fanout intensity distribution are presented.

  1. Comparison of steering angle and bandwidth for various phased array antenna concepts

    NASA Astrophysics Data System (ADS)

    Bonjour, Romain; Singleton, Matthew; Leuchtmann, Pascal; Leuthold, Juerg

    2016-08-01

    In this paper we compare different integratable ultra-fast tunable true-time delay concepts with respect to their performances in a phased array system. The performances of the schemes are assessed with respect to the supported range, i.e. the range within which beam steering for a given fractional bandwidth can be achieved with a gain flatness better than 3 dB. We also compare the array gain as of function of steering angle and fractional bandwidth.

  2. Equivalent flaw time-of-flight diffraction sizing with ultrasonic phased arrays

    NASA Astrophysics Data System (ADS)

    Engle, Brady J.; Schmerr, Lester W., Jr.; Sedov, Alexander

    2013-01-01

    Ultrasonic phased array transducers can be used to extend traditional time-of-flight diffraction (TOFD) crack sizing, resulting in more quantitative information about the crack being obtained. Traditional TOFD yields a single length parameter, while the equivalent flaw time-of-flight diffraction crack sizing method (EFTOFD) described here uses data from multiple look-angles to fit an equivalent degenerate ellipsoid to the crack. The size and orientation of the equivalent flaw can be used to estimate the actual crack size.

  3. Development of a twin crystal membrane coupled conformable phased array for the inspection of austenitic welds

    SciTech Connect

    Russell, J.; Long, R.; Cawley, P.

    2011-06-23

    The inspection of welded austenitic stainless steel components can be challenging. Austenitic welds contain an anisotropic, inhomogeneous grain structure which causes attenuation, scattering and beam bending. The inspection of components where the weld cap has not been removed is even more difficult due to the irregularity of the surface geometry. A twin crystal membrane coupled device has now been produced containing two linear phased arrays positioned adjacent to one another within the same housing. The arrays are angled relative to one another so that the transducer provides a pseudo-focusing effect at a depth corresponding to the beam crossing point. This type of design is used to improve the signal to noise ratio of the defect response in comparison to simple linear phased array transducer designs and to remove an internal noise signal found in linear phased array devices. Experimental results obtained from the through weld inspection of an austenitic stainless steel component with an undressed weld cap using the twin crystal membrane device are presented. These results demonstrate that small lack of side wall fusion defects can be reliably detected in large complex structures.

  4. System-Level Integrated Circuit (SLIC) Technology Development for Phased Array Antenna Applications

    NASA Technical Reports Server (NTRS)

    Windyka, John A.; Zablocki, Ed G.

    1997-01-01

    This report documents the efforts and progress in developing a 'system-level' integrated circuit, or SLIC, for application in advanced phased array antenna systems. The SLIC combines radio-frequency (RF) microelectronics, digital and analog support circuitry, and photonic interfaces into a single micro-hybrid assembly. Together, these technologies provide not only the amplitude and phase control necessary for electronic beam steering in the phased array, but also add thermally-compensated automatic gain control, health and status feedback, bias regulation, and reduced interconnect complexity. All circuitry is integrated into a compact, multilayer structure configured for use as a two-by-four element phased array module, operating at 20 Gigahertz, using a Microwave High-Density Interconnect (MHDI) process. The resultant hardware is constructed without conventional wirebonds, maintains tight inter-element spacing, and leads toward low-cost mass production. The measured performances and development issues associated with both the two-by-four element module and the constituent elements are presented. Additionally, a section of the report describes alternative architectures and applications supported by the SLIC electronics. Test results show excellent yield and performance of RF circuitry and full automatic gain control for multiple, independent channels. Digital control function, while suffering from lower manufacturing yield, also proved successful.

  5. Image-guided ultrasound phased arrays are a disruptive technology for non-invasive therapy

    NASA Astrophysics Data System (ADS)

    Hynynen, Kullervo; Jones, Ryan M.

    2016-09-01

    Focused ultrasound offers a non-invasive way of depositing acoustic energy deep into the body, which can be harnessed for a broad spectrum of therapeutic purposes, including tissue ablation, the targeting of therapeutic agents, and stem cell delivery. Phased array transducers enable electronic control over the beam geometry and direction, and can be tailored to provide optimal energy deposition patterns for a given therapeutic application. Their use in combination with modern medical imaging for therapy guidance allows precise targeting, online monitoring, and post-treatment evaluation of the ultrasound-mediated bioeffects. In the past there have been some technical obstacles hindering the construction of large aperture, high-power, densely-populated phased arrays and, as a result, they have not been fully exploited for therapy delivery to date. However, recent research has made the construction of such arrays feasible, and it is expected that their continued development will both greatly improve the safety and efficacy of existing ultrasound therapies as well as enable treatments that are not currently possible with existing technology. This review will summarize the basic principles, current statures, and future potential of image-guided ultrasound phased arrays for therapy.

  6. Design of an optically controlled Ka-band GaAs MMIC phased-array antenna

    NASA Technical Reports Server (NTRS)

    Kunath, Richard R.; Claspy, Paul C.; Richard, Mark A.; Bhasin, Kul B.

    1990-01-01

    Phased array antennas long were investigated to support the agile, multibeam radiating apertures with rapid reconfigurability needs of radar and communications. With the development of the Monolithic Microwave Integrated Circuit (MMIC), phased array antennas having the stated characteristics are becoming realizable. However, at K-band frequencies (20 to 40 GHz) and higher, the problem of controlling the MMICs using conventional techniques either severely limits the array size or becomes insurmountable due to the close spacing of the radiating elements necessary to achieve the desired antenna performance. Investigations were made that indicate using fiber optics as a transmission line for control information for the MMICs provides a potential solution. By adding an optical interface circuit to pre-existing MMIC designs, it is possible to take advantage of the small size, lightweight, mechanical flexibility and RFI/EMI resistant characteristics of fiber optics to distribute MMIC control signals. The architecture, circuit development, testing and integration of optically controlled K-band MMIC phased array antennas are described.

  7. Design of an optically controlled Ka-band GaAs MMIC phased-array antenna

    NASA Astrophysics Data System (ADS)

    Kunath, Richard R.; Claspy, Paul C.; Richard, Mark A.; Bhasin, Kul B.

    Phased array antennas long were investigated to support the agile, multibeam radiating apertures with rapid reconfigurability needs of radar and communications. With the development of the Monolithic Microwave Integrated Circuit (MMIC), phased array antennas having the stated characteristics are becoming realizable. However, at K-band frequencies (20 to 40 GHz) and higher, the problem of controlling the MMICs using conventional techniques either severely limits the array size or becomes insurmountable due to the close spacing of the radiating elements necessary to achieve the desired antenna performance. Investigations were made that indicate using fiber optics as a transmission line for control information for the MMICs provides a potential solution. By adding an optical interface circuit to pre-existing MMIC designs, it is possible to take advantage of the small size, lightweight, mechanical flexibility and RFI/EMI resistant characteristics of fiber optics to distribute MMIC control signals. The architecture, circuit development, testing and integration of optically controlled K-band MMIC phased array antennas are described.

  8. Design of an optically controlled Ka-band GaAs MMIC phased-array antenna

    NASA Astrophysics Data System (ADS)

    Kunath, Richard R.; Bhasin, Kul B.; Claspy, Paul C.; Richard, Mark A.

    1990-06-01

    Phased array antennas long were investigated to support the agile, multibeam radiating apertures with rapid reconfigurability needs of radar and communications. With the development of the Monolithic Microwave Integrated Circuit (MMIC), phased array antennas having the stated characteristics are becoming realizable. However, at K-band frequencies (20 to 40 GHz) and higher, the problem of controlling the MMICs using conventional techniques either severely limits the array size or becomes insurmountable due to the close spacing of the radiating elements necessary to achieve the desired antenna performance. Investigations were made that indicate using fiber optics as a transmission line for control information for the MMICs provides a potential solution. By adding an optical interface circuit to pre-existing MMIC designs, it is possible to take advantage of the small size, lightweight, mechanical flexibility and RFI/EMI resistant characteristics of fiber optics to distribute MMIC control signals. The architecture, circuit development, testing and integration of optically controlled K-band MMIC phased array antennas are described.

  9. K-Band Phased Array Developed for Low- Earth-Orbit Satellite Communications

    NASA Technical Reports Server (NTRS)

    Anzic, Godfrey

    1999-01-01

    Future rapid deployment of low- and medium-Earth-orbit satellite constellations that will offer various narrow- to wide-band wireless communications services will require phased-array antennas that feature wide-angle and superagile electronic steering of one or more antenna beams. Antennas, which employ monolithic microwave integrated circuits (MMIC), are perfectly suited for this application. Under a cooperative agreement, an MMIC-based, K-band phased-array antenna is being developed with 50/50 cost sharing by the NASA Lewis Research Center and Raytheon Systems Company. The transmitting array, which will operate at 19 gigahertz (GHz), is a state-of-the-art design that features dual, independent, electronically steerable beam operation ( 42 ), a stand-alone thermal management, and a high-density tile architecture. This array can transmit 622 megabits per second (Mbps) in each beam from Earth orbit to small Earth terminals. The weight of the total array package is expected to be less than 8 lb. The tile integration technology (flip chip MMIC tile) chosen for this project represents a major advancement in phased-array engineering and holds much promise for reducing manufacturing costs.

  10. The OSU self-phased array for propagation measurements using the 11.7 GHz CTS beacon

    NASA Technical Reports Server (NTRS)

    Theobold, D. M.; Hodge, D. B.

    1976-01-01

    A self phased array was developed for propagation measurements on an earth-space path. The 11.7 GHz CTS beacon was used as the signal source. The self phased array was used to measure angle of arrival as well as attenuation and scintillation statistics. The performance of the array is described, and sample data are presented. The tracking capability of the self phased array was also studied. This technique permits fully electronic, nonmechanical satellite tracking, thus simplifying unmanned operation and eliminating severe weather tracking constraints.

  11. High Frequency QRS ECG Accurately Detects Cardiomyopathy

    NASA Technical Reports Server (NTRS)

    Schlegel, Todd T.; Arenare, Brian; Poulin, Gregory; Moser, Daniel R.; Delgado, Reynolds

    2005-01-01

    High frequency (HF, 150-250 Hz) analysis over the entire QRS interval of the ECG is more sensitive than conventional ECG for detecting myocardial ischemia. However, the accuracy of HF QRS ECG for detecting cardiomyopathy is unknown. We obtained simultaneous resting conventional and HF QRS 12-lead ECGs in 66 patients with cardiomyopathy (EF = 23.2 plus or minus 6.l%, mean plus or minus SD) and in 66 age- and gender-matched healthy controls using PC-based ECG software recently developed at NASA. The single most accurate ECG parameter for detecting cardiomyopathy was an HF QRS morphological score that takes into consideration the total number and severity of reduced amplitude zones (RAZs) present plus the clustering of RAZs together in contiguous leads. This RAZ score had an area under the receiver operator curve (ROC) of 0.91, and was 88% sensitive, 82% specific and 85% accurate for identifying cardiomyopathy at optimum score cut-off of 140 points. Although conventional ECG parameters such as the QRS and QTc intervals were also significantly longer in patients than controls (P less than 0.001, BBBs excluded), these conventional parameters were less accurate (area under the ROC = 0.77 and 0.77, respectively) than HF QRS morphological parameters for identifying underlying cardiomyopathy. The total amplitude of the HF QRS complexes, as measured by summed root mean square voltages (RMSVs), also differed between patients and controls (33.8 plus or minus 11.5 vs. 41.5 plus or minus 13.6 mV, respectively, P less than 0.003), but this parameter was even less accurate in distinguishing the two groups (area under ROC = 0.67) than the HF QRS morphologic and conventional ECG parameters. Diagnostic accuracy was optimal (86%) when the RAZ score from the HF QRS ECG and the QTc interval from the conventional ECG were used simultaneously with cut-offs of greater than or equal to 40 points and greater than or equal to 445 ms, respectively. In conclusion 12-lead HF QRS ECG employing

  12. [Genetic algorithm application to multi-focus patterns of 256-element phased array for focused ultrasound surgery].

    PubMed

    Xu, Feng; Wan, Mingxi; Lu, Mingzhu

    2008-10-01

    The genetic optimal algorithm and sound field calculation approach for the spherical-section phased array are presented in this paper. The in-house manufactured 256-element phased array focused ultrasound surgery system is briefly described. The on-axis single focus and off-axis single focus are simulated along with the axis-symmetric six-focus patter and the axis-asymmetric four-focus pattern using a 256-element phased array and the genetic optimal algorithm and sound field calculation approach. The experimental results of the described 256-element phased array focused ultrasound surgery system acting on organic glass and phantom are also analyzed. The results of the simulations and experiments confirm the applicability of the genetic algorithm and field calculation approaches in accurately steering three dimensional foci and focus.

  13. Development of phased array techniques to improve characterization of defect located in a component of complex geometry.

    PubMed

    Mahaut, Steve; Roy, Olivier; Beroni, Claude; Rotter, Bernhard

    2002-05-01

    Ultrasonic inspection of complex geometry components has to cope with different problems: limited access of the area assumed to be insonified, beam misorientation and distortions, loss of sensitivity. Those harmful effects can lead to inspection performance degradations, especially in terms of defect detection and characterization. Phased array techniques may be used to overcome such difficulties, as they can provide an optimal mastering of the ultrasonic beam radiated through the inspected component. This paper presents some applications of phased array inspections carried out by the French Atomic Energy Commission (CEA) and the French Company of Electricity (EDF) in the framework of R&D studies. Inspections of components with varying profile (of planar and cylindrical parts, misalignment and local depression), and containing artificial reflectors have been carried out with pulse echo immersion techniques, using standard and phased arrays transducers. Optimal delay laws have been applied to preserve the beam characteristics in spite of the varying profile geometry encountered as the phased array transducer was moved over the component. Those delay laws allow to efficiently compensate the beam distortions generated by the profile geometry. They were computed using a specific model and compared to experimental delays obtained using through transmission tests. Experimental and simulation results showed that the defect detection and characterization performances were greatly enhanced using phased array techniques. In the presented examples, with standard transducers, defects located below the irregular parts of the specimen were partially detected, in accurately located or even missed, whereas phased array inspections enabled to detect and locate all of these defects.

  14. Development of a pseudo phased array technique using EMATs for DM weld testing

    NASA Astrophysics Data System (ADS)

    Cobb, Adam C.; Fisher, Jay L.; Shiokawa, Nobuyuki; Hamano, Toshiaki; Horikoshi, Ryoichi; Ido, Nobukazu

    2015-03-01

    Ultrasonic inspection of dissimilar metal (DM) welds in piping with cast austenitic stainless steel (CASS) has been an area ongoing research for many years given its prevalence in the petrochemical and nuclear industries. A typical inspection strategy for pipe welds is to use an ultrasonic phased array system to scan the weld from a sensor located on the outer surface of the pipe. These inspection systems generally refract either longitudinal or shear vertical (SV) waves at varying angles to inspect the weld radially. In DM welds, however, the welding process can produce a columnar grain structure in the CASS material in a specific orientation. This columnar grain structure can skew ultrasonic waves away from their intended path, especially for SV and longitudinal wave modes. Studies have shown that inspection using the shear horizontal (SH) wave mode significantly reduces the effect of skewing. Electromagnetic acoustic transducers (EMATs) are known to be effective for producing SH waves in field settings. This paper presents an inspection strategy that seeks to reproduce the scanning and imaging capabilities of a commercial phase array system using EMATs. A custom-built EMAT was used to collect data at multiple propagation angles, and a processing strategy known as the synthetic aperture focusing technique (SAFT) was used to combine the data to produce an image. Results are shown using this pseudo phased array technique to inspect samples with a DM weld and artificial defects, demonstrating the potential of this approach in a laboratory setting. Recommendations for future work to transition the technique to the field are also provided.

  15. Jet-Surface Interaction Test: Phased Array Noise Source Localization Results

    NASA Technical Reports Server (NTRS)

    Podboy, Gary G.

    2012-01-01

    An experiment was conducted to investigate the effect that a planar surface located near a jet flow has on the noise radiated to the far-field. Two different configurations were tested: 1) a shielding configuration in which the surface was located between the jet and the far-field microphones, and 2) a reflecting configuration in which the surface was mounted on the opposite side of the jet, and thus the jet noise was free to reflect off the surface toward the microphones. Both conventional far-field microphone and phased array noise source localization measurements were obtained. This paper discusses phased array results, while a companion paper discusses far-field results. The phased array data show that the axial distribution of noise sources in a jet can vary greatly depending on the jet operating condition and suggests that it would first be necessary to know or be able to predict this distribution in order to be able to predict the amount of noise reduction to expect from a given shielding configuration. The data obtained on both subsonic and supersonic jets show that the noise sources associated with a given frequency of noise tend to move downstream, and therefore, would become more difficult to shield, as jet Mach number increases. The noise source localization data obtained on cold, shock-containing jets suggests that the constructive interference of sound waves that produces noise at a given frequency within a broadband shock noise hump comes primarily from a small number of shocks, rather than from all the shocks at the same time. The reflecting configuration data illustrates that the law of reflection must be satisfied in order for jet noise to reflect off of a surface to an observer, and depending on the relative locations of the jet, the surface, and the observer, only some of the jet noise sources may satisfy this requirement.

  16. Phased-array cancellation of nonlinear FWM in coherent OFDM dispersive multi-span links.

    PubMed

    Nazarathy, Moshe; Khurgin, Jacob; Weidenfeld, Rakefet; Meiman, Yehuda; Cho, Pak; Noe, Reinhold; Shpantzer, Isaac; Karagodsky, Vadim

    2008-09-29

    We develop an analytic model of Coherent Optical Orthogonal Frequency Division Multiplexing (OFDM) propagation and detection over multi-span long-haul fiber links, comprehensively and rigorously analyzing the impairments due the combined effects of FWM, Dispersion and ASE noise. Consistent with prior work of Innoe and Schadt in the WDM context, our new closed-form expressions for the total FWM received power fluctuations in the wake of dispersive phase mismatch in OFDM transmission, indicate that the FWM contributions of the multitude of spans build-up on a phased-array basis. For particular ultra-long haul link designs, the effectiveness of dispersion in reducing FWM is far greater than previously assumed in OFDM system analysis. The key is having the dominant FWM intermodulation products due to the multiple spans, destructively interfere, mutually cancelling their FWM intermodulation products, analogous to operating at the null of a phased-array antenna system. By applying the new analysis tools, this mode of effectively mitigating the FWM impairment, is shown under specific dispersion and spectral management conditions, to substantially suppress the FWM power fluctuations. Accounting for the phased-array concept and applying the compact OFDM design formulas developed here, we analyzed system performance of a 40 Gbps coherent OFDM system, over standard G.652 fiber, with cyclic prefix based electronic dispersion compensation but no optical compensation along the link. The transmission range for 10-3 target BER is almost tripled from 2560 km to 6960 km, relative to a reference system performing optical dispersion compensation in every span (ideally accounting for FWM and ASE noise and the cyclic prefix overhead, but excluding additional impairments).

  17. Development of a pseudo phased array technique using EMATs for DM weld testing

    SciTech Connect

    Cobb, Adam C. Fisher, Jay L.; Shiokawa, Nobuyuki; Hamano, Toshiaki; Horikoshi, Ryoichi; Ido, Nobukazu

    2015-03-31

    Ultrasonic inspection of dissimilar metal (DM) welds in piping with cast austenitic stainless steel (CASS) has been an area ongoing research for many years given its prevalence in the petrochemical and nuclear industries. A typical inspection strategy for pipe welds is to use an ultrasonic phased array system to scan the weld from a sensor located on the outer surface of the pipe. These inspection systems generally refract either longitudinal or shear vertical (SV) waves at varying angles to inspect the weld radially. In DM welds, however, the welding process can produce a columnar grain structure in the CASS material in a specific orientation. This columnar grain structure can skew ultrasonic waves away from their intended path, especially for SV and longitudinal wave modes. Studies have shown that inspection using the shear horizontal (SH) wave mode significantly reduces the effect of skewing. Electromagnetic acoustic transducers (EMATs) are known to be effective for producing SH waves in field settings. This paper presents an inspection strategy that seeks to reproduce the scanning and imaging capabilities of a commercial phase array system using EMATs. A custom-built EMAT was used to collect data at multiple propagation angles, and a processing strategy known as the synthetic aperture focusing technique (SAFT) was used to combine the data to produce an image. Results are shown using this pseudo phased array technique to inspect samples with a DM weld and artificial defects, demonstrating the potential of this approach in a laboratory setting. Recommendations for future work to transition the technique to the field are also provided.

  18. The effect of electronically steering a phased array ultrasound transducer on near-field tissue heating

    PubMed Central

    Payne, Allison; Vyas, Urvi; Todd, Nick; Bever, Joshua de; Christensen, Douglas A.; Parker, Dennis L.

    2011-01-01

    Purpose: This study presents the results obtained from both simulation and experimental techniques that show the effect of mechanically or electronically steering a phased array transducer on proximal tissue heating. Methods: The thermal response of a nine-position raster and a 16-mm diameter circle scanning trajectory executed through both electronic and mechanical scanning was evaluated in computer simulations and experimentally in a homogeneous tissue-mimicking phantom. Simulations were performed using power deposition maps obtained from the hybrid angular spectrum (HAS) method and applying a finite-difference approximation of the Pennes’ bioheat transfer equation for the experimentally used transducer and also for a fully sampled transducer to demonstrate the effect of acoustic window, ultrasound beam overlap and grating lobe clutter on near-field heating. Results: Both simulation and experimental results show that electronically steering the ultrasound beam for the two trajectories using the 256-element phased array significantly increases the thermal dose deposited in the near-field tissues when compared with the same treatment executed through mechanical steering only. In addition, the individual contributions of both beam overlap and grating lobe clutter to the near-field thermal effects were determined through comparing the simulated ultrasound beam patterns and resulting temperature fields from mechanically and electronically steered trajectories using the 256-randomized element phased array transducer to an electronically steered trajectory using a fully sampled transducer with 40 401 phase-adjusted sample points. Conclusions: Three distinctly different three distinctly different transducers were simulated to analyze the tradeoffs of selected transducer design parameters on near-field heating. Careful consideration of design tradeoffs and accurate patient treatment planning combined with thorough monitoring of the near-field tissue temperature will

  19. Fundamental study of molten pool depth measurement method using an ultrasonic phased array system

    NASA Astrophysics Data System (ADS)

    Mizota, Hirohisa; Nagashima, Yoshiaki; Obana, Takeshi

    2015-07-01

    The molten pool depth measurement method using an ultrasonic phased array system has been developed. The molten pool depth distribution is evaluated by comparing the times taken by the ultrasonic wave to propagate through a molten pool and a solid-phase and through only the solid-phase near the molten pool. Maximum molten pool depths on a flat type-304 stainless-steel plate, formed with a gas tungsten arc welding machine for different welding currents from 70 to 150 A, were derived within an error of ±0.5 mm.

  20. Surface estimation methods with phased-arrays for adaptive ultrasonic imaging in complex components

    NASA Astrophysics Data System (ADS)

    Robert, S.; Calmon, P.; Calvo, M.; Le Jeune, L.; Iakovleva, E.

    2015-03-01

    Immersion ultrasonic testing of structures with complex geometries may be significantly improved by using phased-arrays and specific adaptive algorithms that allow to image flaws under a complex and unknown interface. In this context, this paper presents a comparative study of different Surface Estimation Methods (SEM) available in the CIVA software and used for adaptive imaging. These methods are based either on time-of-flight measurements or on image processing. We also introduce a generalized adaptive method where flaws may be fully imaged with half-skip modes. In this method, both the surface and the back-wall of a complex structure are estimated before imaging flaws.

  1. Laser induced ultrasonic phased array using full matrix capture data acquisition and total focusing method.

    PubMed

    Stratoudaki, Theodosia; Clark, Matt; Wilcox, Paul D

    2016-09-19

    Laser ultrasonics is a technique where lasers are employed to generate and detect ultrasound. A data collection method (full matrix capture) and a post processing imaging algorithm, the total focusing method, both developed for ultrasonic arrays, are modified and used in order to enhance the capabilities of laser ultrasonics for nondestructive testing by improving defect detectability and increasing spatial resolution. In this way, a laser induced ultrasonic phased array is synthesized. A model is developed and compared with experimental results from aluminum samples with side drilled holes and slots at depths of 5 - 20 mm from the surface.

  2. An Evaluation of Signal Processing Tools for Improving Phased Array Ultrasonic Weld Inspection

    SciTech Connect

    Ramuhalli, Pradeep; Cinson, Anthony D.; Crawford, Susan L.; Harris, Robert V.; Diaz, Aaron A.; Anderson, Michael T.

    2011-03-24

    Cast austenitic stainless steel (CASS) commonly used in U.S. nuclear power plants is a coarse-grained, elastically anisotropic material. The coarse-grained nature of CASS makes ultrasonic inspection of in-service components difficult. Recently, low-frequency phased array ultrasound has emerged as a candidate for the CASS piping weld inspection. However, issues such as low signal-to-noise ratio and difficulty in discriminating between flaw and non-flaw signals remain. This paper discusses the evaluation of a number of signal processing algorithms for improving flaw detection in CASS materials. The full paper provides details of the algorithms being evaluated, along with preliminary results.

  3. Modulation error in active-aperture phased-array radar systems

    NASA Astrophysics Data System (ADS)

    Belcher, M. L.; Howard, R. L.; Mitchell, M. A.

    Range sidelobe (RSL) suppression is presently treated in the context of active arrays that are defined by a phased-array antenna, which is driven by either distributed solid-state element-level modules or tube-driven subarray-level transmitters and receivers. An account is given of the basic methodology for achievement of low-RSL performance in active arrays, using modulation-error compensation. Attention is given to the performance limits imposed by modulation-error decorrelation and noise-limited error characterization.

  4. Hemispheric Imaging of Galactic Neutral Hydrogen with a Phased Array Antenna System

    NASA Astrophysics Data System (ADS)

    Wijnholds, Stefan J.; De Bruyn, A. Ger; Bregman, Jaap D.; Bij De Vaate, Jan Geralt

    2004-06-01

    The thousand element array (THEA) system is a phased array system consisting of 1 m2 tiles having 64 Vivaldi elements each, arranged on a regular 8-by-8 grid, which has been developed as a demonstrator of technology and applicability for SKA. In this paper we present imaging results of Galactic neutral hydrogen with THEA. Measurements have been taken using a dense 2-by-2 array of four tiles as a four tile adder. The results are compared with results from the Leiden-Dwingeloo Survey, showing qualitative agreement, but also indicating that further studies are needed on the instrumental characteristics.

  5. Continuous Beam Steering From A Segmented Liquid Crystal Optical Phased Array

    NASA Technical Reports Server (NTRS)

    Pouch, John; Nguyen, Hung; Miranda, Felix; Titus, Charles M.; Bos, Philip J.

    2002-01-01

    Optical communications to and from deep space probes will require beams possessing divergence on the order of a microradian, and must be steered with sub-microradian precision. Segmented liquid crystal spatial phase modulators, a type of optical phased array, are considered for this ultra-high resolution beam steering. It is shown here that in an ideal device of this type, there are ultimately no restrictions on the angular resolution. Computer simulations are used to obtain that result, and to analyze the influence of beam truncation and substrate flatness on the performance of this type of device.

  6. Novel Phased Array Scanning Employing A Single Feed Without Using Individual Phase Shifters

    NASA Technical Reports Server (NTRS)

    Host, Nicholas K.; Chen, Chi-Chih; Volakis, John L.; Miranda, Felix A.

    2012-01-01

    Phased arrays afford many advantages over mechanically steered systems. However, they are also more complex, heavy, and most of all costly. The high cost mainly originates from the complex feeding structure. This paper proposes a novel feeding scheme to eliminate all phase shifters and achieve scanning via one-dimensional motion. Beam scanning is achieved via a series fed array incorporating feeding transmission lines whose wave velocity can be mechanically adjusted. Along with the line design, ideal element impedances to be used in conjunction with the line are derived. Practical designs are shown which achieve scanning to +/-30deg from boresight. Finally, a prototype is fabricated and measured, demonstrating the concept.

  7. Characterization of an optical phased array for use in free space optical communication antennas

    NASA Astrophysics Data System (ADS)

    Anisimov, Igor; Harris, Scott R.; Stadler, Brian K.

    2008-08-01

    Liquid Crystal Optical Phased Arrays (LCOPA) capable of steering optical beams over large angles require very large number of individually addressable electrodes that can be reduced by grouping the electrodes into periodic pattern to modulate phase profiles with consequent stepwise phase corrections made by an additional LCOPA. Such phase ramp-corrector configuration allows for reductions in the total number of the addressed electrodes and results in lower costs of development and manufacturing of LCOPA devices. Characterization of the device made by Teledyne Scientific for an experimental RF/EO antenna has been accomplished. Issues concerning optical beam steering efficiency, incident angle dependency and transparent electrodes alignment were investigated.

  8. Extending the scanning angle of a phased array antenna by using a null-space medium

    PubMed Central

    Sun, Fei; He, Sailing

    2014-01-01

    By introducing a columnar null-space region as the reference space, we design a radome that can extend the scanning angle of a phased array antenna (PAA) by a predetermined relationship (e.g. a linear relationship between the incident angle and steered output angle can be achieved). After some approximation, we only need two homogeneous materials to construct the proposed radome layer by layer. This kind of medium is called a null-space medium, which has been studied and fabricated for realizing hyper-lenses and some other devices. Numerical simulations verify the performance of our radome. PMID:25355198

  9. Continuous Beam Steering From a Segmented Liquid Crystal Optical Phased Array

    NASA Technical Reports Server (NTRS)

    Titus, Charles M.; Pouch, John; Nguyen, Hung; Miranda, Felix; Bos, Philip J.

    2002-01-01

    Optical communications to and from deep space probes will require beams possessing divergence on the order of a microradian, and must be steered with sub-microradian precision. Segmented liquid crystal spatial phase modulators, a type of optical phased array, are considered for this ultra-high resolution beam steering. It is shown here that in an ideal device of this type, there are ultimately no restrictions on the angular resolution. Computer simulations are used to obtain that result, and to analyze the influence of beam truncation and substrate flatness on the performance of this type of device.

  10. Assessment of weld quality of aerospace grade metals by using ultrasonic matrix phased array technology

    NASA Astrophysics Data System (ADS)

    Na, Jeong K.; Gleeson, Sean T.

    2014-03-01

    Advantages of two dimensional electronic ultrasonic beam focusing, steering and scanning with the matrix phased array (MPA) technology has been used to visualize the conditions of resistance spot welds in auto vehicle grade advanced high strength steel carbon steels nondestructively. Two of the commonly used joining techniques, resistance spot welding and resistance seam welding, for thin aerospace grade plates made of aluminum, titanium, and stainless steels have also been inspected with the same MPA NDE system. In this study, a detailed discussions of the current MPA based ultrasonic real time imaging methodology has been made followed by some of the NDT results obtained with various welded test coupons.

  11. Bit error rate testing of fiber optic data links for MMIC-based phased array antennas

    NASA Astrophysics Data System (ADS)

    Shalkhauser, K. A.; Kunath, R. R.; Daryoush, A. S.

    1990-06-01

    The measured bit-error-rate (BER) performance of a fiber optic data link to be used in satellite communications systems is presented and discussed. In the testing, the link was measured for its ability to carry high burst rate, serial-minimum shift keyed (SMSK) digital data similar to those used in actual space communications systems. The fiber optic data link, as part of a dual-segment injection-locked RF fiber optic link system, offers a means to distribute these signals to the many radiating elements of a phased array antenna. Test procedures, experimental arrangements, and test results are presented.

  12. Bit error rate testing of fiber optic data links for MMIC-based phased array antennas

    NASA Technical Reports Server (NTRS)

    Shalkhauser, K. A.; Kunath, R. R.; Daryoush, A. S.

    1990-01-01

    The measured bit-error-rate (BER) performance of a fiber optic data link to be used in satellite communications systems is presented and discussed. In the testing, the link was measured for its ability to carry high burst rate, serial-minimum shift keyed (SMSK) digital data similar to those used in actual space communications systems. The fiber optic data link, as part of a dual-segment injection-locked RF fiber optic link system, offers a means to distribute these signals to the many radiating elements of a phased array antenna. Test procedures, experimental arrangements, and test results are presented.

  13. Image reconstruction from phased-array data based on multichannel blind deconvolution.

    PubMed

    She, Huajun; Chen, Rong-Rong; Liang, Dong; Chang, Yuchou; Ying, Leslie

    2015-11-01

    In this paper we consider image reconstruction from fully sampled multichannel phased array MRI data without knowledge of the coil sensitivities. To overcome the non-uniformity of the conventional sum-of-square reconstruction, a new framework based on multichannel blind deconvolution (MBD) is developed for joint estimation of the image function and the sensitivity functions in image domain. The proposed approach addresses the non-uniqueness of the MBD problem by exploiting the smoothness of both functions in the image domain through regularization. Results using simulation, phantom and in vivo experiments demonstrate that the reconstructions by the proposed algorithm are more uniform than those by the existing methods.

  14. Beam-steering and jammer-nulling photorefractive phased-array radar processor

    NASA Astrophysics Data System (ADS)

    Sarto, Anthony W.; Weverka, Robert T.; Wagner, Kelvin H.

    1994-06-01

    We are developing a class of optical phased-array-radar processors which use the large number of degrees-of-freedom available in 3D photorefractive volume holograms to time integrate the adaptive weights to perform beam-steering and jammer-cancellation signal-processing tasks for very large phased-array antennas. We have experimentally demonstrated independently the two primary subsystems of the beam-steering and jammer-nulling phased-array radar processor, the beam-forming subsystem and the jammer-nulling subsystem, as well as simultaneous main beam formation and jammer suppression in the combined processor. The beam-steering subsystem calculates the angle of arrival of a desired signal of interest and steers the antenna pattern in the direction of this desired signal by forming a dynamic holographic grating proportional to the correlation between the incoming signal of interest from the antenna array and the temporal waveform of the desired signal. This grating is formed by repetitively applying the temporal waveform of the desired signal to a single acousto-optic Bragg cell and allowing the diffracted component from the Bragg cell to interfere with an optical mapping of the received phased-array antenna signal at a photorefractive crystal. The diffracted component from this grating is the antenna output modified by an array function pointed towards the desired signal of interest. This beam-steering task is performed with the only a priori information being that of the knowledge of a temporal waveform that correlates well with the desired signal and that the delay of the desired signal remains within the time aperture of the Bragg cell. The jammer-nulling subsystem computes the angles-of- arrival of multiple interfering narrowband radar jammers and adaptively steers nulls in the antenna pattern in order to extinguish the jammers by implementing a modified LMS algorithm in the optical domain. This task is performed in a second photorefractive crystal where

  15. Simulation research on beam steering technology based on optical phased array

    NASA Astrophysics Data System (ADS)

    Tian, Junlin; Pan, Xudong

    2015-02-01

    The principle of beam steering technology based on optical phased array (OPA), which is composed of individual phase-modulating units, is introduced. By use of Fraunhofer diffraction and Fourier transformation, the OPA models are established. The influence of main parameters of OPA on beam steering efficiency, including duty ratio (ratio of effective unit size to total unit size), total unit size, unit number, and steering angle, is simulated and analyzed. It shows that beam steering efficiency of OPA is improved with larger duty ratio, smaller total unit size, and smaller steering angle, while the number of units has a very small impact on beam steering efficiency.

  16. Assessment of Microphone Phased Array for Measuring Launch Vehicle Lift-off Acoustics

    NASA Technical Reports Server (NTRS)

    Garcia, Roberto

    2012-01-01

    The specific purpose of the present work was to demonstrate the suitability of a microphone phased array for launch acoustics applications via participation in selected firings of the Ares I Scale Model Acoustics Test. The Ares I Scale Model Acoustics Test is a part of the discontinued Constellation Program Ares I Project, but the basic understanding gained from this test is expected to help development of the Space Launch System vehicles. Correct identification of sources not only improves the predictive ability, but provides guidance for a quieter design of the launch pad and optimization of the water suppression system. This document contains the results of the NASA Engineering and Safety Center assessment.

  17. On-clip high frequency reliability and failure test structures

    DOEpatents

    Snyder, Eric S.; Campbell, David V.

    1997-01-01

    Self-stressing test structures for realistic high frequency reliability characterizations. An on-chip high frequency oscillator, controlled by DC signals from off-chip, provides a range of high frequency pulses to test structures. The test structures provide information with regard to a variety of reliability failure mechanisms, including hot-carriers, electromigration, and oxide breakdown. The system is normally integrated at the wafer level to predict the failure mechanisms of the production integrated circuits on the same wafer.

  18. On-clip high frequency reliability and failure test structures

    DOEpatents

    Snyder, E.S.; Campbell, D.V.

    1997-04-29

    Self-stressing test structures for realistic high frequency reliability characterizations. An on-chip high frequency oscillator, controlled by DC signals from off-chip, provides a range of high frequency pulses to test structures. The test structures provide information with regard to a variety of reliability failure mechanisms, including hot-carriers, electromigration, and oxide breakdown. The system is normally integrated at the wafer level to predict the failure mechanisms of the production integrated circuits on the same wafer. 22 figs.

  19. High Frequency Acoustic Propagation using Level Set Methods

    DTIC Science & Technology

    2007-01-01

    solution of the high frequency approximation to the wave equation. Traditional solutions to the Eikonal equation in high frequency acoustics are...curvature can be extracted at any point of the front from the level set function (provided the normal and curvature are well-defined at that point ), and... points per wavelength to resolve the wave). Ray tracing is therefore the current standard for high frequency propagation modeling. LSM may provide

  20. High-frequency Probing Diagnostic for Hall Current Plasma Thrusters

    SciTech Connect

    A.A. Litvak; Y. Raitses; N.J. Fisch

    2001-10-25

    High-frequency oscillations (1-100 MHz) in Hall thrusters have apparently eluded significant experimental scrutiny. A diagnostic setup, consisting of a single Langmuir probe, a special shielded probe connector-positioner, and an electronic impedance-matching circuit, was successfully built and calibrated. Through simultaneous high-frequency probing of the Hall thruster plasma at multiple locations, high-frequency plasma waves have been identified and characterized for various thruster operating conditions.

  1. Optimization of a phased-array transducer for multiple harmonic imaging in medical applications: frequency and topology.

    PubMed

    Matte, Guillaume M; Van Neer, Paul L M J; Danilouchkine, Mike G; Huijssen, Jacob; Verweij, Martin D; de Jong, Nico

    2011-03-01

    Second-harmonic imaging is currently one of the standards in commercial echographic systems for diagnosis, because of its high spatial resolution and low sensitivity to clutter and near-field artifacts. The use of nonlinear phenomena mirrors is a great set of solutions to improve echographic image resolution. To further enhance the resolution and image quality, the combination of the 3rd to 5th harmonics--dubbed the superharmonics--could be used. However, this requires a bandwidth exceeding that of conventional transducers. A promising solution features a phased-array design with interleaved low- and high-frequency elements for transmission and reception, respectively. Because the amplitude of the backscattered higher harmonics at the transducer surface is relatively low, it is highly desirable to increase the sensitivity in reception. Therefore, we investigated the optimization of the number of elements in the receiving aperture as well as their arrangement (topology). A variety of configurations was considered, including one transmit element for each receive element (1/2) up to one transmit for 7 receive elements (1/8). The topologies are assessed based on the ratio of the harmonic peak pressures in the main and grating lobes. Further, the higher harmonic level is maximized by optimization of the center frequency of the transmitted pulse. The achievable SNR for a specific application is a compromise between the frequency-dependent attenuation and nonlinearity at a required penetration depth. To calculate the SNR of the complete imaging chain, we use an approach analogous to the sonar equation used in underwater acoustics. The generated harmonic pressure fields caused by nonlinear wave propagation were modeled with the iterative nonlinear contrast source (INCS) method, the KZK, or the Burger's equation. The optimal topology for superharmonic imaging was an interleaved design with 1 transmit element per 6 receive elements. It improves the SNR by ~5 dB compared with

  2. A random phased array device for delivery of high intensity focused ultrasound.

    PubMed

    Hand, J W; Shaw, A; Sadhoo, N; Rajagopal, S; Dickinson, R J; Gavrilov, L R

    2009-10-07

    Randomized phased arrays can offer electronic steering of a single focus and simultaneous multiple foci concomitant with low levels of secondary maxima and are potentially useful as sources of high intensity focused ultrasound (HIFU). This work describes laboratory testing of a 1 MHz random phased array consisting of 254 elements on a spherical shell of radius of curvature 130 mm and diameter 170 mm. Acoustic output power and efficiency are measured for a range of input electrical powers, and field distributions for various single- and multiple-focus conditions are evaluated by a novel technique using an infrared camera to provide rapid imaging of temperature changes on the surface of an absorbing target. Experimental results show that the array can steer a single focus laterally to at least +/-15 mm off axis and axially to more than +/-15 mm from the centre of curvature of the array and patterns of four and five simultaneous foci +/-10 mm laterally and axially whilst maintaining low intensity levels in secondary maxima away from the targeted area in good agreement with linear theoretical predictions. Experiments in which pork meat was thermally ablated indicate that contiguous lesions several cm(3) in volume can be produced using the patterns of multiple foci.

  3. Ultrasonic non-destructive testing of pieces of complex geometry with a flexible phased array transducer

    PubMed

    Chatillon; Cattiaux; Serre; Roy

    2000-03-01

    Ultrasonic non-destructive testing of components of complex geometry in the nuclear industry faces several difficulties: sensitivity variations due to unmatched contact, inaccurate localization of defects due to variations of transducer orientation, and uncovered area of the component. To improve the performances of such testing and defect characterization, we propose a new concept of ultrasonic contact phased array transducer. The phased array transducer has a flexible radiating surface able to fit the actual surface of the piece to optimize the contact and thus the sensitivity of the test. To control the transmitted field, and therefore to improve the defect characterization, a delay law optimizing algorithm is developed. To assess the capability of such a transducer, the Champ-Sons model, developed at the French Atomic Energy Commission for predicting field radiated by arbitrary transducers into pieces, has to be extended to sources directly in contact with pieces of complex geometry. The good behavior of this new type of probe predicted by computations is experimentally validated with a jointed transducer positioned on pieces of various profiles.

  4. Circumferential phased array of shear-horizontal wave magnetostrictive patch transducers for pipe inspection.

    PubMed

    Kim, Hoe Woong; Lee, Joo Kyung; Kim, Yoon Young

    2013-02-01

    Several investigations report effective uses of magnetostrictive patch transducers to generate and measure longitudinal and torsional guided waves in a pipe. They can be used to form a phased array for the circumferential inspection of pipes. Although there are circumferential phased arrays employing piezoelectric transducers or EMAT's, no magnetostrictive patch transducer based array system has been attempted. In this investigation, we aim to develop a circumferential phased magnetostrictive patch transducer (PMPT) array that can focus shear-horizontal waves at any target point on a cylindrical surface of a pipe. For the development, a specific configuration of a PMPT array employing six magnetostrictive patch transducers is proposed. A wave simulation model is also developed to determine time delays and amplitudes of signals generated by the transducers of the array. This model should be able to predict accurately the angular profiles of shear-horizontal waves generated by the transducers. For wave focusing, the time reversal idea will be utilized. The wave focusing ability of the developed PMPT array is tested with multiple-crack detection experiments. Imaging of localized surface inspection regions is also attempted by using wave signals measured by the developed PMPT array system.

  5. Two-dimensional refractive index modulation by phased array transducers in acousto-optic deflectors.

    PubMed

    Wang, Tiansi; Zhang, Chong; Aleksov, Aleksandar; Salama, Islam; Kar, Aravinda

    2017-01-20

    Acousto-optic deflectors are photonic devices that are used for scanning high-power laser beams in advanced microprocessing applications such as marking and direct writing. The operation of conventional deflectors mostly relies on one-dimensional sinusoidal variation of the refractive index in an acousto-optic medium. Sometimes static phased array transducers, such as step configuration or planar configuration transducer architecture, are used to tilt the index modulation planes for achieving higher performance and higher resolution than a single transducer AO device. However, the index can be modulated in two dimensions, and the modulation plane can be tilted arbitrarily by creating dynamic phase gratings in the medium using phased array transducers. This type of dynamic two-dimensional acousto-optic deflector can provide better performance using, for example, a large deflection angle and high diffraction efficiency. This paper utilizes an ultrasonic beam steering approach to study the two-dimensional strain-induced index modulation due to the photoelastic effect. The modulation is numerically simulated, and the effects of various parameters, such as the operating radiofrequency of the transducers, the ultrasonic beam steering angle, and different combinations of pressure on each element of the transducer array, are demonstrated.

  6. Phased Array Noise Source Localization Measurements Made on a Williams International FJ44 Engine

    NASA Technical Reports Server (NTRS)

    Podboy, Gary G.; Horvath, Csaba

    2010-01-01

    A 48-microphone planar phased array system was used to acquire noise source localization data on a full-scale Williams International FJ44 turbofan engine. Data were acquired with the array at three different locations relative to the engine, two on the side and one in front of the engine. At the two side locations the planar microphone array was parallel to the engine centerline; at the front location the array was perpendicular to the engine centerline. At each of the three locations, data were acquired at eleven different engine operating conditions ranging from engine idle to maximum (take off) speed. Data obtained with the array off to the side of the engine were spatially filtered to separate the inlet and nozzle noise. Tones occurring in the inlet and nozzle spectra were traced to the low and high speed spools within the engine. The phased array data indicate that the Inflow Control Device (ICD) used during this test was not acoustically transparent; instead, some of the noise emanating from the inlet reflected off of the inlet lip of the ICD. This reflection is a source of error for far field noise measurements made during the test. The data also indicate that a total temperature rake in the inlet of the engine is a source of fan noise.

  7. Capabilities of Ultrasonic Phased Arrays for Far-Side Examinations of Austenitic Stainless Steel Piping Welds

    SciTech Connect

    Anderson, Michael T.; Cumblidge, Stephen E.; Doctor, Steven R.

    2006-10-01

    A study was conducted to assess the ability of advanced ultrasonic techniques to detect and accurately determine the size of flaws from the far-side of wrought austenitic piping welds. Far-side inspections of nuclear system austenitic piping welds are currently performed on a “best effort” basis and do not conform to ASME Code Section XI Appendix VIII performance demonstration requirements for near side inspection. For this study, four circumferential welds in 610mm (24inch) diameter, 36mm (1.42inch) thick ASTM A-358, Grade 304 vintage austenitic stainless steel pipe were examined. The welds were fabricated with varied welding parameters; both horizontal and vertical pipe orientations were used, with air and water backing, to simulate field welding conditions. A series of saw cuts, electro-discharge machined (EDM) notches, and implanted fatigue cracks were placed into the heat affected zones of the welds. The saw cuts and notches ranged in depth from 7.5% to 28.4% through-wall. The implanted cracks ranged in depth from 5% through-wall to 64% through-wall. The welds were examined with phased array technology at 2.0 MHz, and compared to conventional ultrasonic techniques as a baseline. The examinations showed that phased-array methods were able to detect and accurately length-size, but not depth size, the notches and flaws through the welds. The ultrasonic results were insensitive to the different welding techniques used in each weld.

  8. Low Frequency Phased Array Application for Crack Detection in Cast Austenitic Piping

    SciTech Connect

    Anderson, Michael T.; Cumblidge, Stephen E.; Doctor, Steven R.

    2006-10-01

    As part of a multi-year program funded by the United States Nuclear Regulatory Commission (US NRC) to address nondestructive examination (NDE) reliability of inservice inspection (ISI) programs, studies conducted at the Pacific N¬orthwest National Laboratory (PNNL) in Richland, Washington, have focused on assessing novel NDE approaches for the inspection of coarse-grained, cast stainless steel reactor components. The primary objective of this work is to provide information to the US NRC on the utility, effec¬tiveness and reliability of ultrasonic testing (UT) as related to the ISI of primary piping components in US commercial nuclear power plants. This paper describes progress, recent developments and results from an assessment of a portion of the work relating to the ultrasonic low frequency phased array inspection technique. Westinghouse Owner’s Group (WOG) cast stainless steel pipe segments with thermal and mechanical fatigue cracks, PNNL samples containing thermal fatigue cracks and several blank vintage specimens having very coarse grains that are representative of early centrifugally cast piping installed in PWRs, were used for assessing the inspection method. The phased array approach was implemented using an R/D Tech Tomoscan III system operating at 1.0 MHz and 500 kHz, providing composite volumetric images of the samples. Several dual, transmit-receive, custom designed low-frequency arrays were employed in laboratory trials. Results from laboratory studies for assessing detection, localization and length sizing effectiveness are discussed.

  9. Low Frequency Phased Array Techniques for Crack Detection in Cast Austenitic Piping Welds: A Feasibility Study

    SciTech Connect

    Anderson, Michael T.; Cumblidge, Stephen E.; Doctor, Steven R.

    2007-01-01

    Studies conducted at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington have focused on developing and evaluating the reliability of nondestructive testing (NDT) approaches for coarse-grained stainless steel reactor components. The objective of this work is to provide information to the United States Nuclear Regulatory Commission (NRC) on the utility, effectiveness and limitation of NDT techniques as related to inservice testing of primary system piping components in pressurized water reactors. We examined cast stainless steel pipe specimens containing thermal and mechanical fatigue cracks located close to the weld roots and having inner and outer diameter surface geometrical conditions that simulate several water reactor primary piping configurations. In addition, segments of vintage centrifugally cast piping were examined to characterize the inherent acoustic noise and scattering caused by grain structures and to determine the consistency of ultrasonic responses when propagating through differing microstructures. Advanced ultrasonic phased array techniques were applied from the outside surface of these specimens using automated scanning devices and water coupling. The phased array approach was implemented with a modified instrument operating at low frequencies, and composite volumetric images of the specimens were generated. Results from laboratory studies for assessing crack detection effectiveness in cast stainless steel as a function of frequency are discussed in this paper.

  10. LOW-FREQUENCY PHASED-ARRAY METHODS FOR CRACK DETECTION IN CAST AUSTENITIC PIPING COMPONENTS

    SciTech Connect

    Anderson, Michael T.; Crawford, Susan L.; Cumblidge, Stephen E.; Diaz, Aaron A.; Doctor, Steven R.

    2008-01-01

    Studies at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington, are being conducted to evaluate nondestructive examination (NDE) approaches for inspecting coarse-grained, austenitic stainless steel reactor components. The work provides information to the United States Nuclear Regulatory Commission (NRC) on the utility, effectiveness, limitations, and reliability of advanced inspection techniques for application on safety-related components in commercial nuclear power plants. This paper describes results from recent assessments using a low-frequency phased-array methodology for detecting cracks in cast austenitic piping welds. Piping specimens that contain thermal and mechanical fatigue cracks located adjacent to welds were examined. The specimens have surface geometrical conditions and weld features that simulate portions of primary piping systems in many U.S. pressurized water reactors (PWRs). In addition, segments of vintage centrifugally cast piping were examined to assess inherent acoustic noise and scattering due to grain structures and determine consistency of ultrasonic (UT) responses from varied circumferential locations. The phased-array UT methods were applied from the outside surface of the specimens using automated scanning devices and water coupling, and employed a modified instrument operating between 500 kHz and 1.0 MHz. Composite volumetric images of the specimens were generated. Results from laboratory studies for assessing crack detection and sizing effectiveness are discussed, including acoustic parameters observed in centrifugally cast piping base materials.

  11. Jet-Surface Interaction Test: Phased Array Noise Source Localization Results

    NASA Technical Reports Server (NTRS)

    Podboy, Gary

    2012-01-01

    Subsonic jets are relatively simple. The peak noise source location gradually moves upstream toward the nozzle as frequency increases. 2) Supersonic jets are more complicated. The peak noise source location moves downstream as frequency increases through a BBSN hump. 3) In both subsonic and supersonic jets the peak noise source location corresponding to a given frequency of noise moves downstream as jet Mach number increases. 4) The noise generated at a given frequency in a BBSN hump is generated by a small number of shocks, not from all the shocks at the same time. 5) Single microphone spectrum levels decrease when the noise source locations measured with the phased array are blocked by a shielding surface. This consistency validates the phased array data and the stationary monopole source model used to process it. 6) Reflecting surface data illustrate that the law of reflection must be satisfied for noise to reflect off a surface toward an observer. Depending on the relative locations of the jet, the surface and the observer only some of the jet noise sources may satisfy this requirement. 7) The low frequency noise created when a jet flow impinges on a surface comes primarily from the trailing edge regardless of the axial extent impacted by the flow.

  12. Three-Dimensional Mid-Air Acoustic Manipulation by Ultrasonic Phased Arrays

    PubMed Central

    Ochiai, Yoichi; Hoshi, Takayuki; Rekimoto, Jun

    2014-01-01

    The essence of levitation technology is the countervailing of gravity. It is known that an ultrasound standing wave is capable of suspending small particles at its sound pressure nodes. The acoustic axis of the ultrasound beam in conventional studies was parallel to the gravitational force, and the levitated objects were manipulated along the fixed axis (i.e. one-dimensionally) by controlling the phases or frequencies of bolted Langevin-type transducers. In the present study, we considered extended acoustic manipulation whereby millimetre-sized particles were levitated and moved three-dimensionally by localised ultrasonic standing waves, which were generated by ultrasonic phased arrays. Our manipulation system has two original features. One is the direction of the ultrasound beam, which is arbitrary because the force acting toward its centre is also utilised. The other is the manipulation principle by which a localised standing wave is generated at an arbitrary position and moved three-dimensionally by opposed and ultrasonic phased arrays. We experimentally confirmed that expanded-polystyrene particles of 0.6 mm, 1 mm, and 2 mm in diameter could be manipulated by our proposed method. PMID:24849371

  13. Measuring Noise Temperatures of Phased-Array Antennas for Astronomy at CSIRO

    NASA Astrophysics Data System (ADS)

    Chippendale, A. P.; Hayman, D. B.; Hay, S. G.

    We describe the development of a noise-temperature testing capability for phased-array antennas operating in receive mode from 0.7 GHz to 1.8 GHz. Sampled voltages from each array port were recorded digitally as the zenith-pointing array under test was presented with three scenes: (1) a large microwave absorber at ambient temperature, (2) the unobstructed radio sky, and (3) broadband noise transmitted from a reference antenna centred over and pointed at the array under test. The recorded voltages were processed in software to calculate the beam equivalent noise temperature for a maximum signal-to-noise ratio beam steered at the zenith. We introduced the reference-antenna measurement to make noise measurements with reproducible, well-defined beams directed at the zenith and thereby at the centre of the absorber target. We applied a detailed model of cosmic and atmospheric contributions to the radio sky emission that we used as a noise-temperature reference. We also present a comprehensive analysis of measurement uncertainty including random and systematic effects. The key systematic effect was due to uncertainty in the beamformed antenna pattern and how efficiently it illuminates the absorber load. We achieved a combined uncertainty as low as 4 K for a 40 K measurement of beam equivalent noise temperature. The measurement and analysis techniques described in this paper were pursued to support noise-performance verification of prototype phased-array feeds for the Australian Square Kilometre Array Pathfinder telescope.

  14. Phased Array-Based Saft for Defect Sizing on Power Plant Components

    NASA Astrophysics Data System (ADS)

    Brekow, G.; Brackrock, D.; Boehm, R.; Kreutzbruck, M.

    2009-03-01

    Quantitative NDE methods play a key role when it comes to inspect components, which requires high operational safety. UT-SAFT is one of the well-known reconstruction tools, which provides information about the defect size. In this work we studied the use of phased array technique in combination with the SAFT algorithm to inspect power plant components. As a first example we inspected a real-sized mock-up model representing a part of a reactor pressure vessel with a 180 mm-thick ferritic base material followed by a 6 mm-thick austenitic cladding layer. The phased array probe was coupled at the outer ferritic surface. We detected and sized fatigue cracks within the cladding with a depth ranging from 4 mm to 10 mm. Secondly, we investigated a mock-up model resembling a nozzle including a thermo sleeve inlet and a maximum wall thickness of about 37 mm. Artificially inserted notches with a depth of 3 mm could be detected and sized, where the thermo sleeve is welded at the inside of the nozzle.

  15. Limitations of Phased Array Beamforming in Open Rotor Noise Source Imaging

    NASA Technical Reports Server (NTRS)

    Horvath, Csaba; Envia, Edmane; Podboy, Gary G.

    2013-01-01

    Phased array beamforming results of the F31/A31 historical baseline counter-rotating open rotor blade set were investigated for measurement data taken on the NASA Counter-Rotating Open Rotor Propulsion Rig in the 9- by 15-Foot Low-Speed Wind Tunnel of NASA Glenn Research Center as well as data produced using the LINPROP open rotor tone noise code. The planar microphone array was positioned broadside and parallel to the axis of the open rotor, roughly 2.3 rotor diameters away. The results provide insight as to why the apparent noise sources of the blade passing frequency tones and interaction tones appear at their nominal Mach radii instead of at the actual noise sources, even if those locations are not on the blades. Contour maps corresponding to the sound fields produced by the radiating sound waves, taken from the simulations, are used to illustrate how the interaction patterns of circumferential spinning modes of rotating coherent noise sources interact with the phased array, often giving misleading results, as the apparent sources do not always show where the actual noise sources are located. This suggests that a more sophisticated source model would be required to accurately locate the sources of each tone. The results of this study also have implications with regard to the shielding of open rotor sources by airframe empennages.

  16. Three-dimensional mid-air acoustic manipulation by ultrasonic phased arrays.

    PubMed

    Ochiai, Yoichi; Hoshi, Takayuki; Rekimoto, Jun

    2014-01-01

    The essence of levitation technology is the countervailing of gravity. It is known that an ultrasound standing wave is capable of suspending small particles at its sound pressure nodes. The acoustic axis of the ultrasound beam in conventional studies was parallel to the gravitational force, and the levitated objects were manipulated along the fixed axis (i.e. one-dimensionally) by controlling the phases or frequencies of bolted Langevin-type transducers. In the present study, we considered extended acoustic manipulation whereby millimetre-sized particles were levitated and moved three-dimensionally by localised ultrasonic standing waves, which were generated by ultrasonic phased arrays. Our manipulation system has two original features. One is the direction of the ultrasound beam, which is arbitrary because the force acting toward its centre is also utilised. The other is the manipulation principle by which a localised standing wave is generated at an arbitrary position and moved three-dimensionally by opposed and ultrasonic phased arrays. We experimentally confirmed that expanded-polystyrene particles of 0.6 mm, 1 mm, and 2 mm in diameter could be manipulated by our proposed method.

  17. Recent Enhancements of the Phased Array Mirror Extendible Large Aperture (PAMELA) Telescope Testbed at MSFC

    NASA Technical Reports Server (NTRS)

    Rakoczy, John; Montgomery, Edward E.; Lindner, Jeff

    2000-01-01

    Recent incremental upgrades to the Phased Array Mirror Extendible Large Aperture (PAMELA) telescope testbed have enabled the demonstration of phasing (with a monochromatic source) of clusters of primary mirror segments down to the diffraction limit. PAMELA upgrades include an improved Shack-Hartmann wavefront sensor, passive viscoelastic damping treatments for the voice-coil actuators, mechanical improvement of mirror surface figures, and optical bench baffling. This report summarizes the recent PAMELA upgrades, discusses the lessons learned, and presents a status of this unique testbed for wavefront sensing and control. The Marshall Space Flight Center acquired the Phased Array Mirror Extendible Large Aperture (PAMELA) telescope in 1993 after Kaman Aerospace was unable to complete integration and testing under the limited SDIO and DARPA funding. The PAMELA is a 36-segment, half-meter aperture, adaptive telescope which utilizes a Shack-Hartmann wavefront sensor, inductive coil edge sensors, voice coil actuators, imaging CCD cameras and interferometry for figure alignment, wavefront sensing and control. MSFC originally obtained the PAMELA to supplement its research in the interactions of control systems with flexible structures. In August 1994, complete tip, tilt and piston control was successfully demonstrated using the Shack-Hartmann wavefront sensor and the inductive edge sensors.

  18. Recent Enhancements of the Phased Array Mirror Extendible Large Aperture (PAMELA) Telescope Testbed at MSFC

    NASA Technical Reports Server (NTRS)

    Rakoczy, John; Burdine, Robert (Technical Monitor)

    2001-01-01

    Recent incremental upgrades to the Phased Array Mirror Extendible Large Aperture (PAMELA) telescope testbed have enabled the demonstration of phasing (with a monochromatic source) of clusters of primary mirror segments down to the diffraction limit. PAMELA upgrades include in improved Shack-Hartmann wavefront sensor, passive viscoelastic damping treatments for the voice-coil actuators, mechanical improvement of mirror surface figures, and optical bench baffling. This report summarizes the recent PAMELA upgrades, discusses the lessons learned, and presents a status of this unique testbed for wavefront sensing and control. The Marshall Space Flight Center acquired the Phased Array Mirror Extendible Large Aperture (PAMELA) telescope in 1993 after Kaman Aerospace was unable to complete integration and testing under the limited SDIO and DARPA funding. The PAMELA is a 36-segment, half-meter aperture, adaptive telescope which utilizes a Shack-Hartmann wavefront sensor, inductive coil edge sensors, voice coil actuators, imaging CCD cameras and interferometry for figure alignment, wavefront sensing and control. MSFC originally obtained the PAMELA to supplement its research in the interactions of control systems with flexible structures. In August 1994, complete tip, tilt and piston control was successfully demonstrated using the Shack-Hartmann wavefront sensor and the inductive edge sensors.

  19. Wavenumber-frequency deconvolution of aeroacoustic microphone phased array data of arbitrary coherence

    NASA Astrophysics Data System (ADS)

    Bahr, Christopher J.; Cattafesta, Louis N.

    2016-11-01

    Deconvolution of aeroacoustic data acquired with microphone phased arrays is a computationally challenging task for distributed sources with arbitrary coherence. A new technique for performing such deconvolution is proposed. This technique relies on analysis of the array data in the wavenumber-frequency domain, allowing for fast convolution and reduced storage requirements when compared to traditional coherent deconvolution. A positive semidefinite constraint for the iterative deconvolution procedure is implemented and shows improved behavior in terms of quantifiable convergence metrics when compared to a standalone covariance inequality constraint. A series of simulations validates the method's ability to resolve coherence and phase angle relationships between partially coherent sources, as well as determines convergence criteria for deconvolution analysis. Simulations for point sources near the microphone phased array show potential for handling such data in the wavenumber-frequency domain. In particular, a physics-based integration boundary calculation is described, and can successfully isolate sources and track the appropriate integration bounds with and without the presence of flow. Magnitude and phase relationships between multiple sources are successfully extracted. Limitations of the deconvolution technique are determined from the simulations, particularly in the context of a simulated acoustic field in a closed test section wind tunnel with strong boundary layer contamination. A final application to a trailing edge noise experiment conducted in an open-jet wind tunnel matches best estimates of acoustic levels from traditional calculation methods and qualitatively assesses the coherence characteristics of the trailing edge noise source.

  20. Ultrasonic Phased Array Evaluation of Control Rod Drive Mechanism (CRDM) Nozzle Interference Fit and Weld Region

    SciTech Connect

    Cinson, Anthony D.; Crawford, Susan L.; MacFarlan, Paul J.; Mathews, Royce; Hanson, Brady D.; Diaz, Aaron A.

    2011-07-31

    Ultrasonic phased array data were collected on a removed-from-service CRDM nozzle specimen to assess a previously reported leak path. First a mock-up CRDM specimen was evaluated that contained two 0.076-mm (3.0-mil) interference fit regions formed from an actual Inconel CRDM tube and two 152.4-mm (6.0-in.) thick carbon steel blocks. One interference fit region has a series of precision crafted electric discharge machining (EDM) notches at various lengths, widths, depths, and spatial separations for establishing probe sensitivity, resolution and calibration. The other interference fit has zones of boric acid (crystal form) spaced periodically between the tube and block to represent an actively leaking CRDM nozzle assembly in the field. Ultrasonic phased-array evaluations were conducted using an immersion 8-element annular 5.0-MHz probe from the tube inner diameter (ID). A variety of focal laws were employed to evaluate the interference fit regions and J grove weld, where applicable. Responses from the mock-up specimen were evaluated to determine detection limits and characterization ability as well as contrast the ultrasonic response differences with the presence of boric acid in the fit region. Nozzle 63, from the North Anna Unit-2 nuclear power plant, was evaluated to assess leakage path(s) and was destructively dismantled to allow a visual verification of the leak path(s).

  1. Considerations for Using Phased Array Ultrasonics in a Fully Automated Inspection System

    NASA Astrophysics Data System (ADS)

    Kramb, V. A.; Olding, R. B.; Sebastian, J. R.; Hoppe, W. C.; Petricola, D. L.; Hoeffel, J. D.; Gasper, D. A.; Stubbs, D. A.

    2004-02-01

    The University of Dayton Research Institute (UDRI) under contract by the US Air Force has designed and constructed a fully automated ultrasonic inspection system for the detection of embedded defects in rotating gas turbine engine components. The system performs automated inspections using the "scan plan" concept developed for the Air Force sponsored "Retirement For Cause" (RFC) automated eddy current system. Execution of the scan plan results in a fully automated inspection process producing engine component accept/reject decisions based on probability of detection (POD) information. Use of the phased-array ultrasonic instrument and probes allows for optimization of both the sensitivity and resolution for each inspection through electronic beamforming, scanning, and focusing processes. However, issues such as alignment of the array probe, calibration of individual elements and overall beam response prior to the inspection have not been addressed for an automated system. This paper will discuss current progress in the development of an automated alignment and calibration procedure for various phased array apertures and specimen geometries.

  2. Modeling and Simulation of Phased Array Antennas to Support Next-Generation Satellite Design

    NASA Technical Reports Server (NTRS)

    Tchorowski, Nicole; Murawski, Robert; Manning, Robert; Fuentes, Michael

    2016-01-01

    Developing enhanced simulation capabilities has become a significant priority for the Space Communications and Navigation (SCaN) project at NASA as new space communications technologies are proposed to replace aging NASA communications assets, such as the Tracking and Data Relay Satellite System (TDRSS). When developing the architecture for these new space communications assets, it is important to develop updated modeling and simulation methodologies, such that competing architectures can be weighed against one another and the optimal path forward can be determined. There have been many simulation tools developed here at NASA for the simulation of single RF link budgets, or for the modeling and simulation of an entire network of spacecraft and their supporting SCaN network elements. However, the modeling capabilities are never fully complete and as new technologies are proposed, gaps are identified. One such gap is the ability to rapidly develop high fidelity simulation models of electronically steerable phased array systems. As future relay satellite architectures are proposed that include optical communications links, electronically steerable antennas will become more desirable due to the reduction in platform vibration introduced by mechanically steerable devices. In this research, we investigate how modeling of these antennas can be introduced into out overall simulation and modeling structure. The ultimate goal of this research is two-fold. First, to enable NASA engineers to model various proposed simulation architectures and determine which proposed architecture meets the given architectural requirements. Second, given a set of communications link requirements for a proposed satellite architecture, determine the optimal configuration for a phased array antenna. There is a variety of tools available that can be used to model phased array antennas. To meet our stated goals, the first objective of this research is to compare the subset of tools available to us

  3. Monitoring method and apparatus using high-frequency carrier

    DOEpatents

    Haynes, H.D.

    1996-04-30

    A method and apparatus for monitoring an electrical-motor-driven device by injecting a high frequency carrier signal onto the power line current. The method is accomplished by injecting a high frequency carrier signal onto an AC power line current. The AC power line current supplies the electrical-motor-driven device with electrical energy. As a result, electrical and mechanical characteristics of the electrical-motor-driven device modulate the high frequency carrier signal and the AC power line current. The high frequency carrier signal is then monitored, conditioned and demodulated. Finally, the modulated high frequency carrier signal is analyzed to ascertain the operating condition of the electrical-motor-driven device. 6 figs.

  4. Monitoring method and apparatus using high-frequency carrier

    DOEpatents

    Haynes, Howard D.

    1996-01-01

    A method and apparatus for monitoring an electrical-motor-driven device by injecting a high frequency carrier signal onto the power line current. The method is accomplished by injecting a high frequency carrier signal onto an AC power line current. The AC power line current supplies the electrical-motor-driven device with electrical energy. As a result, electrical and mechanical characteristics of the electrical-motor-driven device modulate the high frequency carrier signal and the AC power line current. The high frequency carrier signal is then monitored, conditioned and demodulated. Finally, the modulated high frequency carrier signal is analyzed to ascertain the operating condition of the electrical-motor-driven device.

  5. A 4-channel 3 Tesla phased array receive coil for awake rhesus monkey fMRI and diffusion MRI experiments.

    PubMed

    Khachaturian, Mark Haig

    2010-01-01

    Awake monkey fMRI and diffusion MRI combined with conventional neuroscience techniques has the potential to study the structural and functional neural network. The majority of monkey fMRI and diffusion MRI experiments are performed with single coils which suffer from severe EPI distortions which limit resolution. By constructing phased array coils for monkey MRI studies, gains in SNR and anatomical accuracy (i.e., reduction of EPI distortions) can be achieved using parallel imaging. The major challenges associated with constructing phased array coils for monkeys are the variation in head size and space constraints. Here, we apply phased array technology to a 4-channel phased array coil capable of improving the resolution and image quality of full brain awake monkey fMRI and diffusion MRI experiments. The phased array coil is that can adapt to different rhesus monkey head sizes (ages 4-8) and fits in the limited space provided by monkey stereotactic equipment and provides SNR gains in primary visual cortex and anatomical accuracy in conjunction with parallel imaging and improves resolution in fMRI experiments by a factor of 2 (1.25 mm to 1.0 mm isotropic) and diffusion MRI experiments by a factor of 4 (1.5 mm to 0.9 mm isotropic).

  6. Simulation and experiment for the inspection of stainless steel bolts in servicing using an ultrasonic phased array

    NASA Astrophysics Data System (ADS)

    Chen, Jinzhong; He, Renyang; Kang, Xiaowei; Yang, Xuyun

    2015-10-01

    The non-destructive testing of small-sized (M12-M20) stainless steel bolts in servicing is always a technical problem. This article focuses on the simulation and experimental research of stainless steel bolts with an artificial defect reflector using ultrasonic phased array inspection. Based on the observation of the sound field distribution of stainless steel bolts in ultrasonic phased array as well as simulation modelling and analysis of the phased array probes' detection effects with various defect sizes, different artificial defect reflectors of M16 stainless steel bolts are machined in reference to the simulation results. Next, those bolts are tested using a 10-wafer phased array probe with 5 MHz. The test results finally prove that ultrasonic phased array can detect 1-mm cracks in diameter with different depths of M16 stainless steel bolts and a metal loss of Φ1 mm of through-hole bolts, which provides technical support for future non-destructive testing of stainless steel bolts in servicing.

  7. Non-destructive visualization of linear explosive-induced Pyroshock using phase arrayed laser-induced shock in a space launcher composite

    NASA Astrophysics Data System (ADS)

    kyeong Jang, Jae; Ryul Lee, Jung

    2015-07-01

    Separation mechanism of Space launch vehicles are used in various separation systems and pyrotechnic devices. The operation of these pyrotechnic devices generates Pyroshock that can cause failures in electronic components. The prediction of high frequency structural response, especially the shock response spectrum (SRS), is important. This paper presents a non-destructive visualization and simulation of linear explosive-induced Pyroshock using phase arrayed Laser-induced shock. The proposed method includes a laser shock test based on laser beam and filtering zone conditioning to predict the SRS of Pyroshock. A ballistic test based on linear explosive and non-contact Laser Doppler Vibrometers and a nondestructive Laser shock measurement using laser excitation and several PZT sensors, are performed using a carbon composite sandwich panel. The similarity of the SRS of the conditioned laser shock to that of the real explosive Pyroshock is evaluated with the Mean Acceleration Difference. The average of MADs over the two training points was 33.64%. And, MAD at verification point was improved to 31.99%. After that, experimentally found optimal conditions are applied to any arbitrary points in laser scanning area. Finally, it is shown that linear explosive-induced real Pyroshock wave propagation can be visualized with high similarity based on the proposed laser technology.

  8. Interference mitigation for simultaneous transmit and receive applications on digital phased array systems

    NASA Astrophysics Data System (ADS)

    Snow, Trevor M.

    As analog-to-digital (ADC) and digital-to-analog conversion (DAC) technologies become cheaper and digital processing capabilities improve, phased array systems with digital transceivers at every element will become more commonplace. These architectures offer greater capability over traditional analog systems and enable advanced applications such as multiple-input, multiple-output (MIMO) communications, adaptive beamforming, space-time adaptive processing (STAP), and MIMO for radar. Capabilities for such systems are still limited by the need for isolating self-interference from transmitters at co-located receivers. The typical approach of time-sharing the antenna aperture between transmitters and receivers works but leaves the receivers blind for a period of time. For full-duplex operation, some systems use separate frequency bands for transmission and reception, but these require fixed filtering which reduces the system's ability to adapt to its environment and is also an inefficient use of spectral resources. To that end, tunable, high quality-factor filters are used for sub-band isolation and protect receivers while allowing open reception at other frequencies. For more flexibility, another emergent area of related research has focused on co-located spatial isolation using multiple antennas and direct injection of interference cancellation signals into receivers, which enables same-frequency full-duplex operation. With all these methods, self-interference must be reduced by an amount that prevents saturation of the ADC. Intermodulation products generated in the receiver in this process can potentially be problematic, as certain intermodulation products may appear to come from a particular angle and cohere in the beamformer. This work explores various digital phased array architectures and the how the flexibility afforded by an all-digital beamforming architecture, layered with other methods of isolation, can be used to reduce self-interference within the system

  9. Jet-Surface Interaction Test: Phased Array Noise Source Localization Results

    NASA Technical Reports Server (NTRS)

    Podboy, Gary G.

    2013-01-01

    An experiment was conducted to investigate the effect that a planar surface located near a jet flow has on the noise radiated to the far-field. Two different configurations were tested: 1) a shielding configuration in which the surface was located between the jet and the far-field microphones, and 2) a reflecting configuration in which the surface was mounted on the opposite side of the jet, and thus the jet noise was free to reflect off the surface toward the microphones. Both conventional far-field microphone and phased array noise source localization measurements were obtained. This paper discusses phased array results, while a companion paper (Brown, C.A., "Jet-Surface Interaction Test: Far-Field Noise Results," ASME paper GT2012-69639, June 2012.) discusses far-field results. The phased array data show that the axial distribution of noise sources in a jet can vary greatly depending on the jet operating condition and suggests that it would first be necessary to know or be able to predict this distribution in order to be able to predict the amount of noise reduction to expect from a given shielding configuration. The data obtained on both subsonic and supersonic jets show that the noise sources associated with a given frequency of noise tend to move downstream, and therefore, would become more difficult to shield, as jet Mach number increases. The noise source localization data obtained on cold, shock-containing jets suggests that the constructive interference of sound waves that produces noise at a given frequency within a broadband shock noise hump comes primarily from a small number of shocks, rather than from all the shocks at the same time. The reflecting configuration data illustrates that the law of reflection must be satisfied in order for jet noise to reflect off of a surface to an observer, and depending on the relative locations of the jet, the surface, and the observer, only some of the jet noise sources may satisfy this requirement.

  10. Development of a Microphone Phased Array Capability for the Langley 14- by 22-Foot Subsonic Tunnel

    NASA Technical Reports Server (NTRS)

    Humphreys, William M.; Brooks, Thomas F.; Bahr, Christopher J.; Spalt, Taylor B.; Bartram, Scott M.; Culliton, William G.; Becker, Lawrence E.

    2014-01-01

    A new aeroacoustic measurement capability has been developed for use in open-jet testing in the NASA Langley 14- by 22-Foot Subsonic Tunnel (14x22 tunnel). A suite of instruments has been developed to characterize noise source strengths, locations, and directivity for both semi-span and full-span test articles in the facility. The primary instrument of the suite is a fully traversable microphone phased array for identification of noise source locations and strengths on models. The array can be mounted in the ceiling or on either side of the facility test section to accommodate various test article configurations. Complementing the phased array is an ensemble of streamwise traversing microphones that can be placed around the test section at defined locations to conduct noise source directivity studies along both flyover and sideline axes. A customized data acquisition system has been developed for the instrumentation suite that allows for command and control of all aspects of the array and microphone hardware, and is coupled with a comprehensive data reduction system to generate information in near real time. This information includes such items as time histories and spectral data for individual microphones and groups of microphones, contour presentations of noise source locations and strengths, and hemispherical directivity data. The data acquisition system integrates with the 14x22 tunnel data system to allow real time capture of facility parameters during acquisition of microphone data. The design of the phased array system has been vetted via a theoretical performance analysis based on conventional monopole beamforming and DAMAS deconvolution. The performance analysis provides the ability to compute figures of merit for the array as well as characterize factors such as beamwidths, sidelobe levels, and source discrimination for the types of noise sources anticipated in the 14x22 tunnel. The full paper will summarize in detail the design of the instrumentation

  11. [Experiences in high frequency audiometry and possible applications (author's transl)].

    PubMed

    Dieroff, H G

    1976-09-01

    Observations on the ultrasonic perception of noise-impaired persons gave rise to use the high frequency audiometry described by Fletcher for the early recognition of noise-induced damages. Using commercial equipment we found that the earpiece was not adapted to high frequency conditions. The adaptation problem and ways of modification are described in detail. After having improved the coupling features reproducible hearing curves were obtained. Examinations were carried out on workers, whose noise exposure exceeded the critical intensity by only a few dB. The following 3 categories of impairment were found: 1. Normal hearing between 125 and 8,000 Hz as well as in the high frequency region. 2. Unsignificant noise-induced impairments between 125 and 8,000 Hz; no high frequency hearing. 3. Acoustic hearing; no high frequency hearing. The results are discussed. It is supposed that high frequency hearing losses due to noise and chemical noxious exposure (streptomycin) are valuable in diagnostics and prognostics. Accordingly persons are to be assessed as noise sensitive, when there is no more high frequency hearing before practising noise work.

  12. High-frequency energy in singing and speech

    NASA Astrophysics Data System (ADS)

    Monson, Brian Bruce

    While human speech and the human voice generate acoustical energy up to (and beyond) 20 kHz, the energy above approximately 5 kHz has been largely neglected. Evidence is accruing that this high-frequency energy contains perceptual information relevant to speech and voice, including percepts of quality, localization, and intelligibility. The present research was an initial step in the long-range goal of characterizing high-frequency energy in singing voice and speech, with particular regard for its perceptual role and its potential for modification during voice and speech production. In this study, a database of high-fidelity recordings of talkers was created and used for a broad acoustical analysis and general characterization of high-frequency energy, as well as specific characterization of phoneme category, voice and speech intensity level, and mode of production (speech versus singing) by high-frequency energy content. Directionality of radiation of high-frequency energy from the mouth was also examined. The recordings were used for perceptual experiments wherein listeners were asked to discriminate between speech and voice samples that differed only in high-frequency energy content. Listeners were also subjected to gender discrimination tasks, mode-of-production discrimination tasks, and transcription tasks with samples of speech and singing that contained only high-frequency content. The combination of these experiments has revealed that (1) human listeners are able to detect very subtle level changes in high-frequency energy, and (2) human listeners are able to extract significant perceptual information from high-frequency energy.

  13. Phased array ultrasonic testing of dissimilar metal welds using geometric based referencing delay law technique

    NASA Astrophysics Data System (ADS)

    Han, Taeyoung; Schubert, Frank; Hillmann, Susanne; Meyendorf, Norbert

    2015-03-01

    Phased array ultrasonic testing (PAUT) techniques are widely used for the non-destructive testing (NDT) of austenitic welds to find defects like cracks. However, the propagation of ultrasound waves through the austenitic material is intricate due to its inhomogeneous and anisotropic nature. Such a characteristic leads beam path distorted which causes the signal to be misinterpreted. By employing a reference block which is cutout from the mockup of which the structure is a dissimilar metal weld (DMW), a new method of PAUT named as Referencing Delay Law Technique (RDLT) is introduced. With the RDLT, full matrix capture (FMC) was used for data acquisition. To reconstruct the images, total focusing method (TFM) was used. After the focal laws were calculated, PAUT was then performed. As a result, the flaws are more precisely positioned with significantly increased signal-to-noise ratio (SNR).

  14. Experimental validation of an 8 element EMAT phased array probe for longitudinal wave generation

    NASA Astrophysics Data System (ADS)

    Le Bourdais, Florian; Marchand, Benoit

    2015-03-01

    Sodium cooled Fast Reactors (SFR) use liquid sodium as a coolant. Liquid sodium being opaque, optical techniques cannot be applied to reactor vessel inspection. This makes it necessary to develop alternative ways of assessing the state of the structures immersed in the medium. Ultrasonic pressure waves are well suited for inspection tasks in this environment, especially using pulsed electromagnetic acoustic transducers (EMAT) that generate the ultrasound directly in the liquid sodium. The work carried out at CEA LIST is aimed at developing phased array EMAT probes conditioned for reactor use. The present work focuses on the experimental validation of a newly manufactured 8 element probe which was designed for beam forming imaging in a liquid sodium environment. A parametric study is carried out to determine the optimal setup of the magnetic assembly used in this probe. First laboratory tests on an aluminium block show that the probe has the required beam steering capabilities.

  15. Characterization of the system functions of ultrasonic linear phased array inspection systems.

    PubMed

    Huang, Ruiju; Schmerr, Lester W

    2009-02-01

    This work characterizes the electrical and electromechanical aspects of an ultrasonic linear phased array inspection system, using a matrix of system functions that are obtained from the measured response of individual array elements in a simple reference experiment. It is shown that for the arrays tested all these system functions are essentially identical, allowing one to use a single system function to characterize the entire array, as done for an ordinary single element transducer. The variation of this single system function with the number of elements firing in the array or with changes of the delay law used is examined. It is also demonstrated that once such a single system function is obtained for an array, it can be used in a complete ultrasonic measurement model to accurately predict the array response measured from a reference reflector in an immersion setup.

  16. A novel method to design sparse linear arrays for ultrasonic phased array.

    PubMed

    Yang, Ping; Chen, Bin; Shi, Ke-Ren

    2006-12-22

    In ultrasonic phased array testing, a sparse array can increase the resolution by enlarging the aperture without adding system complexity. Designing a sparse array involves choosing the best or a better configuration from a large number of candidate arrays. We firstly designed sparse arrays by using a genetic algorithm, but found that the arrays have poor performance and poor consistency. So, a method based on the Minimum Redundancy Linear Array was then adopted. Some elements are determined by the minimum-redundancy array firstly in order to ensure spatial resolution and then a genetic algorithm is used to optimize the remaining elements. Sparse arrays designed by this method have much better performance and consistency compared to the arrays designed only by a genetic algorithm. Both simulation and experiment confirm the effectiveness.

  17. Simulating ultrasound fields for 2D phased-array probes design optimization.

    PubMed

    Matrone, Giulia; Quaglia, Fabio; Magenes, Giovanni

    2011-01-01

    Nowadays, ultrasound diagnostic imaging is one of the non-invasive techniques mostly used in the clinical practice. Recent advances in this field have brought to the development of small and portable systems. New bidimensional probes consisting of 2D phased arrays, allow to obtain real-time 3D representations of moving organs and blood vessels anatomy. Being the complexity of such 4D ultrasound imaging systems significantly increased, new challenges concerning electronics integration arise for designers. In this paper a software simulator is described, which has been developed in order to model ultrasound wave generation, pressure field distribution and echoes reception, with the aim to become a useful tool for optimizing the probe design. The paper mainly focuses on linear ultrasound field modeling; preliminary results on non-linear interactions with contrast agents are also here introduced.

  18. Electron Cyclotron / Bernstein Wave Heating and Current Drive Experiments using Phased-array Antenna in QUEST

    SciTech Connect

    Idei, H.; Zushi, H.; Hanada, K.; Nakamura, K.; Fujisawa, A.; Hasegawa, M.; Yoshida, N.; Watanebe, H.; Tokunaga, K.; Nagashima, Y.; Kawasaki, S.; Nakashima, H.; Higashijima, A.; Sakamoto, M.; Ejiri, A.; Takase, Y.; Sakaguchi, M.; Kalinnikova, E.; Ishiguro, M.; Tashima, S.

    2011-12-23

    The phased-array antenna system for Electron Cyclotron/Bernstein Wave Heating and Current Drive experiments has been developed in the QUEST. The antenna was designed to excite a pure O-mode wave in the oblique injection for the O-X-B mode conversion experiments, and its good performances were confirmed at a low power level. The plasma current (<{approx}15 kA) with an aspect ratio of 1.5 was started up and sustained by only RF injection in the low-density operations. The long pulse discharge of 10 kA was also attained for 37 s. The new density window to sustain the plasma current was observed in the high-density plasmas. The single-null divertor configuration with the high plasma current (<{approx}25 kA) was attained in the 17 s plasma sustainment.

  19. Using Phased Array Ultrasonic Testing in Lieu of Radiography for Acceptance of Carbon Steel Piping Welds

    SciTech Connect

    Moran, Traci L.; Anderson, Michael T.; Cinson, Anthony D.; Crawford, Susan L.; Nove, Carol A.

    2014-08-01

    The Pacific Northwest National Laboratory (PNNL) is conducting studies for the U.S. Nuclear Regulatory Commission (NRC) to assess the capability, effectiveness, and reliability of ultrasonic testing (UT) as a replacement method for radiographic testing (RT) for volumetric examination of nuclear power plant (NPP) components. This particular study focused on evaluating the use of UT on carbon steel plate welds. Welding fabrication flaws included a combination of planar and volumetric types, e.g., incomplete fusion, lack of penetration, cracks, porosity, and slag inclusions. The examinations were conducted using phased-array (PA) UT techniques applied primarily for detection and flaw type characterization. This paper will discuss the results of using UT in lieu of RT for detection and classification of fabrication flaws in carbon steel plate welds.

  20. Rigorous investigation of the array-tilt aberration for hexagonal, optical phased arrays.

    PubMed

    Hyde, Milo W; Wyman, Jason E; Tyler, Glenn A

    2014-04-10

    An investigation of the array-tilt aberration for hexagonal, optical phased arrays is presented. The investigation begins with theoretical derivations of the far-zone radiated field, the array factor, and the far-field radiated power for the seven-element hexagonal array with array tilt present. Physical insights gained from this analysis are discussed. An analytical treatment of correlation-based array-tilt estimators is also undertaken. Two novel array-tilt estimation techniques are developed from the analysis. The new techniques are shown to be significantly more efficient computationally than the traditional estimation approach. Simulation and experimental results are presented to validate the new array-tilt estimation methods.

  1. Ultra-sharp plasmonic resonances from monopole optical nanoantenna phased arrays

    SciTech Connect

    Li, Shi-Qiang; Bruce Buchholz, D.; Zhou, Wei; Ketterson, John B.; Ocola, Leonidas E.; Sakoda, Kazuaki; Chang, Robert P. H.

    2014-06-09

    Diffractively coupled plasmonic resonances possess both ultra-sharp linewidths and giant electric field enhancement around plasmonic nanostructures. They can be applied to create a new generation of sensors, detectors, and nano-optical devices. However, all current designs require stringent index-matching at the resonance condition that limits their applicability. Here, we propose and demonstrate that it is possible to relieve the index-matching requirement and to induce ultra-sharp plasmon resonances in an ordered vertically aligned optical nano-antenna phased array by transforming a dipole resonance to a monopole resonance with a mirror plane. Due to the mirror image effect, the monopole resonance not only retained the dipole features but also enhanced them. The engineered resonances strongly suppressed the radiative decay channel, resulting in a four-order of magnitude enhancement in local electric field and a Q-factor greater than 200.

  2. LONG-TERM CALIBRATION STABILITY OF A RADIO ASTRONOMICAL PHASED ARRAY FEED

    SciTech Connect

    Elmer, Michael; Jeffs, Brian D.; Warnick, Karl F.

    2013-01-01

    There are many challenges associated with the implementation of a phased array feed for radio astronomy applications. Among these is the need to have an adequate set of calibration measurements so that reliable beamformers can be computed. Changes in the operating environment and temporal gain drift in the electronics contribute to calibration drift, which affects the beamformer performance. We will show that calibration measurements are relatively stable over a 5 day period and may remain so for up to 70 days or longer. We have incorporated the use of a calibration update system that has the potential to refresh a set of old calibrators, specifically correcting for electronic gain drift. However, the long-term variations that are present with fresh, current calibrators are greater than the degradation due to using an old calibration set, suggesting that, at this time, there is not a need for sophisticated calibration update systems or algorithms.

  3. High-extinction virtually imaged phased array-based Brillouin spectroscopy of turbid biological media.

    PubMed

    Fiore, Antonio; Zhang, Jitao; Shao, Peng; Yun, Seok Hyun; Scarcelli, Giuliano

    2016-05-16

    Brillouin microscopy has recently emerged as a powerful technique to characterize the mechanical properties of biological tissue, cell, and biomaterials. However, the potential of Brillouin microscopy is currently limited to transparent samples, because Brillouin spectrometers do not have sufficient spectral extinction to reject the predominant non-Brillouin scattered light of turbid media. To overcome this issue, we combined a multi-pass Fabry-Perot interferometer with a two-stage virtually imaged phased array spectrometer. The Fabry-Perot etalon acts as an ultra-narrow band-pass filter for Brillouin light with high spectral extinction and low loss. We report background-free Brillouin spectra from Intralipid solutions and up to 100 μm deep within chicken muscle tissue.

  4. AN ULTRASONIC PHASED ARRAY EVALUATION OF CAST AUSTENITIC STAINLESS STEEL PRESSURIZER SURGE LINE PIPING WELDS

    SciTech Connect

    Diaz, Aaron A.; Cinson, Anthony D.; Crawford, Susan L.; Moran, Traci L.; Anderson, Michael T.

    2010-07-22

    A set of circumferentially oriented thermal fatigue cracks (TFCs) were implanted into three cast austenitic stainless steel (CASS) pressurizer (PZR) surge-line specimens (pipe-to-elbow welds) that were fabricated using vintage CASS materials formed in the 1970s, and flaw responses from these cracks were used to evaluate detection and sizing performance of the phased-array (PA) ultrasonic testing (UT) methods applied. Four different custom-made PA probes were employed in this study, operating nominally at 800 kHz, 1.0 MHz, 1.5 MHz, and 2.0 MHz center frequencies. The CASS PZR surge-line specimens were polished and chemically etched to bring out the microstructures of both pipe and elbow segments. Additional studies were conducted and documented to address baseline CASS material noise and observe possible ultrasonic beam redirection phenomena.

  5. Ultrasonic Phased Array Implementation of the Inside Diameter Creeping Wave Sizing Method

    SciTech Connect

    Timothy R. McJunkin; J. Mark Davis; Dennis C. Kunerth; Arthur D. Watkins

    2006-05-01

    This paper describes a technique for implementing the ultrasonic inside diameter (ID) creeping wave technique for detection and sizing ID connected defects using a phased array ultrasonic system. The technique uses multiple focal laws to produce the examination modes. The first focal law is designed to create a shear wave nominally at the critical angle for mode conversion to a longitudinal wave at the ID of a part, thus creating a creeping wave. This focal law is focused at the ID to improve sensitivity. The rest of the laws are designed to create tandem sound paths that progress up a vertical surface directly above the focal point of the creeping wave generation point. When a defect on the inner surface is detected with the creeping wave, the height of the defect can be measured from the response of a set of tandem laws without readjusting the position of the probe. Results from standard one-inch long notches of varying depths are presented.

  6. Characterization of Service Induced Flaws on the Far Side of Austenitic Welds Using Phased Array Technology

    SciTech Connect

    Anderson, Michael T.; Cumblidge, Stephen E.

    2004-01-01

    Conventional ultrasonic testing methods continue to exhibit problems for applications involving coarse-grained structures. Pacific Northwest National Laboratory is evaluating the capabilities and limitations of phased array (PA) technology to detect service-type flaws in these coarse-grained materials. The work is being sponsored by the U.S. Nuclear Regulatory Commission, Office of Research. Work to determine detection capabilities through welds with varied grain structures is being explored to provide a better understanding of the acoustic properties of these welded structures. Piping specimens with welds fabricated in vertical and horizontal positions to simulate field conditions have been studied. The insights gained from the austenitic piping will be applied to dissimilar metal weld configurations, corrosion resistant clad piping and cast stainless steels. This paper presents results for using PA ultrasonic technology to determine the effectiveness of detecting and accurately characterizing flaws on the far-side of austenitic piping welds.

  7. System-Level Integrated Circuit (SLIC) development for phased array antenna applications

    NASA Technical Reports Server (NTRS)

    Shalkhauser, K. A.; Raquet, C. A.

    1991-01-01

    A microwave/millimeter wave system-level integrated circuit (SLIC) being developed for use in phased array antenna applications is described. The program goal is to design, fabricate, test, and deliver an advanced integrated circuit that merges radio frequency (RF) monolithic microwave integrated circuit (MMIC) technologies with digital, photonic, and analog circuitry that provide control, support, and interface functions. As a whole, the SLIC will offer improvements in RF device performance, uniformity, and stability while enabling accurate, rapid, repeatable control of the RF signal. Furthermore, the SLIC program addresses issues relating to insertion of solid state devices into antenna systems, such as the reduction in number of bias, control, and signal lines. Program goals, approach, and status are discussed.

  8. System-level integrated circuit (SLIC) development for phased array antenna applications

    NASA Technical Reports Server (NTRS)

    Shalkhauser, K. A.; Raquet, C. A.

    1991-01-01

    A microwave/millimeter wave system-level integrated circuit (SLIC) being developed for use in phased array antenna applications is described. The program goal is to design, fabricate, test, and deliver an advanced integrated circuit that merges radio frequency (RF) monolithic microwave integrated circuit (MMIC) technologies with digital, photonic, and analog circuitry that provide control, support, and interface functions. As a whole, the SLIC will offer improvements in RF device performance, uniformity, and stability while enabling accurate, rapid, repeatable control of the RF signal. Furthermore, the SLIC program addresses issues relating to insertion of solid state devices into antenna systems, such as the reduction in number of bias, control, and signal lines. Program goals, approach, and status are discussed.

  9. The application of taylor weighting, digital phase shifters, and digital attenuators to phased-array antennas.

    SciTech Connect

    Brock, Billy C.

    2008-03-01

    Application of Taylor weighting (taper) to an antenna aperture can achieve low peak sidelobes, but combining the Taylor weighting with quantized attenuators and phase shifters at each radiating element will impact the performance of a phased-array antenna. An examination of array performance is undertaken from the simple point of view of the characteristics of the array factor. Design rules and guidelines for determining the Taylor-weighting parameters, the number of bits required for the digital phase shifter, and the dynamic range and number of bits required for the digital attenuator are developed. For a radar application, when each element is fed directly from a transmit/receive module, the total power radiated by the array will be reduced as a result of the taper. Consequently, the issue of whether to apply the taper on both transmit and receive configurations, or only on the receive configuration is examined with respect to two-way sidelobe performance.

  10. Two-dimensional optical phased array antenna on silicon-on-insulator.

    PubMed

    Van Acoleyen, Karel; Rogier, Hendrik; Baets, Roel

    2010-06-21

    Optical wireless links can offer a very large bandwidth and can act as a complementary technology to radiofrequency links. Optical components nowadays are however rather bulky. Therefore, we have investigated the potential of silicon photonics to fabricated integrated components for wireless optical communication. This paper presents a two-dimensional phased array antenna consisting of grating couplers that couple light off-chip. Wavelength steering of $0.24 degrees /nm is presented reducing the need of active phase modulators. The needed steering range is $1.5 degrees . The 3dB angular coverage range of these antennas is about $0.007pi sr with a directivity of more than 38dBi and antenna losses smaller than 3dB.

  11. Developing an integrated photonic system with a simple beamforming architecture for phased-array antennas.

    PubMed

    Zhou, Weimin; Stead, Michael; Weiss, Steven; Okusaga, Olukayode; Jiang, Lingjun; Anderson, Stephen; Rena Huang, Z

    2017-01-20

    We have designed a simplified true-time-delay beamforming architecture using integrated photonics for phased-array antennas. This architecture can independently control multiple RF beams simultaneously with only a single tuning parameter to steer the beam in each direction for each beam. We have made a proof-of-the-principle demonstration of an X-band, 30×4-elements, fiber-optics-based beamformer for one-dimensional steering in transmission mode. The goal is to develop a semiconductor-based integrated photonic circuit so that a 2D beamforming array for both transmit and receive operations can be made on a single chip. For that, we have designed a Si-based integrated waveguide circuit using two types of "slow-light" waveguide for tunable time delays for two-dimensional steering.

  12. Thermal imaging of plasma with a phased array antenna in QUEST

    SciTech Connect

    Mishra, Kishore Nagata, K.; Akimoto, R.; Banerjee, S.; Idei, H.; Zushi, H.; Hanada, K.; Hasegawa, M.; Nakamura, K.; Fujisawa, A.; Nagashima, Y.; Onchi, T.; Kuzmin, A.; Yamamoto, M. K.

    2014-11-15

    A thermal imaging system to measure plasma Electron Bernstein Emission (EBE) emanating from the mode conversion region in overdense plasma is discussed. Unlike conventional ECE/EBE imaging, this diagnostics does not employ any active mechanical scanning mirrors or focusing optics to scan for the emission cones in plasma. Instead, a standard 3 × 3 waveguide array antenna is used as a passive receiver to collect emission from plasma and imaging reconstruction is done by accurate measurements of phase and intensity of these signals by heterodyne detection technique. A broadband noise source simulating the EBE, is installed near the expected mode conversion region and its position is successfully reconstructed using phase array technique which is done in post processing.

  13. RF MEMS Phase Shifters and their Application in Phase Array Antennas

    NASA Technical Reports Server (NTRS)

    Scardelletti, Maximilian; Ponchak, George E.; Zaman, Afroz J.; Lee, Richard Q.

    2005-01-01

    Electronically scanned arrays are required for space based radars that are capable of tracking multiple robots, rovers, or other assets simultaneously and for beam-hopping communication systems between the various assets. ^Traditionally, these phased array antennas used GaAs Monolithic Microwave Integrated Circuit (MMIC) phase shifters, power amplifiers, and low noise amplifiers to amplify and steer the beam, but the development of RF MEMS switches over the past ten years has enabled system designers to consider replacing the GaAs MMIC phase shifters with RF Micro-Electro Mechanical System (MEMS) phase shifters. In this paper, the implication of replacing the relatively high loss GaAs MMICs with low loss MEMS phase shifters is investigated.

  14. High-extinction virtually imaged phased array-based Brillouin spectroscopy of turbid biological media

    NASA Astrophysics Data System (ADS)

    Fiore, Antonio; Zhang, Jitao; Shao, Peng; Yun, Seok Hyun; Scarcelli, Giuliano

    2016-05-01

    Brillouin microscopy has recently emerged as a powerful technique to characterize the mechanical properties of biological tissue, cell, and biomaterials. However, the potential of Brillouin microscopy is currently limited to transparent samples, because Brillouin spectrometers do not have sufficient spectral extinction to reject the predominant non-Brillouin scattered light of turbid media. To overcome this issue, we combined a multi-pass Fabry-Perot interferometer with a two-stage virtually imaged phased array spectrometer. The Fabry-Perot etalon acts as an ultra-narrow band-pass filter for Brillouin light with high spectral extinction and low loss. We report background-free Brillouin spectra from Intralipid solutions and up to 100 μm deep within chicken muscle tissue.

  15. Phased arrays: A strategy to lower the energy threshold for neutrinos

    NASA Astrophysics Data System (ADS)

    Wissel, Stephanie; Avva, Jessica; Bechtol, Keith; Chesebro, Tyler; Cremonesi, Linda; Gupta, Anusha; Ludwig, Andrew; Messino, Wesley; Miki, Christian; Nichol, Ryan; Oberla, Eric; Romero-Wolf, Andrew; Saltzberg, David; Schlupf, Chandler; Shipp, Nora; Varner, Gary; Vieregg, Abigail

    2017-03-01

    In-ice radio arrays are optimized for detecting the highest energy, cosmogenic neutrinos expected to be produced though cosmic ray interactions with background photons. However, there are two expected populations of high energy neutrinos: the astrophysical flux observed by IceCube ( 1 PeV) and the cosmogenic flux ( 1017 eV or 100 PeV). Typical radio arrays employ a noise-riding trigger, which limits their minimum energy threshold based on the background noise temperature of the ice. Phased radio arrays could lower the energy threshold by combining the signals from several channels before triggering, thereby improving the signal-to-noise at the trigger level. Reducing the energy threshold would allow radio experiments to more efficiently overlap with optical Cherenkov neutrino telescopes as well as for more efficient searches for cosmogenic neutrinos. We discuss the proposed technique and prototypical phased arrays deployed in an anechoic chamber and at Greenland's Summit Station.

  16. Plasmonic phased array feeder enabling ultra-fast beam steering at millimeter waves.

    PubMed

    Bonjour, R; Burla, M; Abrecht, F C; Welschen, S; Hoessbacher, C; Heni, W; Gebrewold, S A; Baeuerle, B; Josten, A; Salamin, Y; Haffner, C; Johnston, P V; Elder, D L; Leuchtmann, P; Hillerkuss, D; Fedoryshyn, Y; Dalton, L R; Hafner, C; Leuthold, J

    2016-10-31

    In this paper, we demonstrate an integrated microwave phoneeded for beamtonics phased array antenna feeder at 60 GHz with a record-low footprint. Our design is based on ultra-compact plasmonic phase modulators (active area <2.5µm2) that not only provide small size but also ultra-fast tuning speed. In our design, the integrated circuit footprint is in fact only limited by the contact pads of the electrodes and by the optical feeding waveguides. Using the high speed of the plasmonic modulators, we demonstrate beam steering with less than 1 ns reconfiguration time, i.e. the beam direction is reconfigured in-between 1 GBd transmitted symbols.

  17. Experimental analysis of beam pointing system based on liquid crystal optical phase array

    NASA Astrophysics Data System (ADS)

    Shi, Yubin; Zhang, Jianmin; Zhang, Zhen

    2016-12-01

    In this paper, we propose and demonstrate an elementary non-mechanical beam aiming and steering system with a single liquid crystal optical phase array (LC-OPA) and charge-coupled device (CCD). With the conventional method of beam steering control, the LC-OPA device can realize one dimensional beam steering continuously. An improved beam steering strategy is applied to realize two dimensional beam steering with a single LC-OPA. The whole beam aiming and steering system, including an LC-OPA and a retroreflective target, is controlled by the monitor. We test the feasibility of beam steering strategy both in one dimension and in two dimension at first, then the whole system is build up based on the improved strategy. The experimental results show that the max experimental pointing error is 56 μrad, and the average pointing error of the system is 19 μrad.

  18. Experimental validation of an 8 element EMAT phased array probe for longitudinal wave generation

    SciTech Connect

    Le Bourdais, Florian Marchand, Benoit

    2015-03-31

    Sodium cooled Fast Reactors (SFR) use liquid sodium as a coolant. Liquid sodium being opaque, optical techniques cannot be applied to reactor vessel inspection. This makes it necessary to develop alternative ways of assessing the state of the structures immersed in the medium. Ultrasonic pressure waves are well suited for inspection tasks in this environment, especially using pulsed electromagnetic acoustic transducers (EMAT) that generate the ultrasound directly in the liquid sodium. The work carried out at CEA LIST is aimed at developing phased array EMAT probes conditioned for reactor use. The present work focuses on the experimental validation of a newly manufactured 8 element probe which was designed for beam forming imaging in a liquid sodium environment. A parametric study is carried out to determine the optimal setup of the magnetic assembly used in this probe. First laboratory tests on an aluminium block show that the probe has the required beam steering capabilities.

  19. Testing a modified ASKAP Mark II phased array feed on the 64 m Parkes radio telescope

    NASA Astrophysics Data System (ADS)

    Chippendale, A. P.; Beresford, R. J.; Deng, X.; Leach, M.; Reynolds, J. E.; Kramer, M.; Tzioumis, T.

    2016-09-01

    We present the first installation and characterization of a phased array feed (PAF) on the 64 m Parkes radio telescope. The combined system operates best between 0.8 GHz and 1.74 GHz where the beamformed noise temperature is between 45 K and 60 K, the aperture efficiency ranges from 70% to 80%, and the effective field of view is 1.4 deg^2 at 1310 MHz. After a 6-month trial observing program at Parkes, the PAF will be installed on the 100 m antenna at Effelsberg. This is the first time a PAF has been installed on a large single-antenna radio telescope and made available to astronomers.

  20. The Implications of Encoder/Modulator/ Phased Array Designs for Future Broadband LEO Communications

    NASA Technical Reports Server (NTRS)

    Vanderaar, Mark; Jensen, Chris A.; Terry, John D.

    1997-01-01

    In this paper we summarize the effects of modulation and channel coding on the design of wide angle scan, broadband, phased army antennas. In the paper we perform several trade studies. First, we investigate the amplifier back-off requirement as a function of variability of modulation envelope. Specifically, we contrast constant and non-constant envelope modulations, as well as single and multiple carrier schemes. Additionally, we address the issues an(f concerns of using pulse shaping filters with the above modulation types. Second, we quantify the effects of beam steering on the quality of data, recovery using selected modulation techniques. In particular, we show that the frequency response of the array introduces intersymbol interference for broadband signals and that the mode of operation for the beam steering controller may introduce additional burst or random errors. Finally, we show that the encoder/modulator design must be performed in conjunction with the phased array antenna design.

  1. Design and fabrication of a 5 MHz ultrasonic phased array probe with curved transducer

    NASA Astrophysics Data System (ADS)

    Fischer, Julia; Herzog, Thomas; Walter, Susan; Heuer, Henning

    2013-05-01

    A 5 MHz, 16-element phased array concave ultrasonic probe for non-destructive testing has been designed, fabricated and tested. To improve the probes performance its curvature, as opposed to present solutions, was not obtained by adding a corresponding delay wedge, but rather by manufacturing the functional elements (i.e. active material, matching layer) with a curvature. The piezoelectric material used here was a 1-3 composite material made of PZT. The finished probe was tested on a steel half circle with the corresponding radius (100 mm) and on the Olympus PAUT test piece. Good results could be obtained. Three transverse holes with a diameter of 1 mm and a distance of 5 mm to one another could be detected and resolved.

  2. Full-matrix capture and USB3.0 for open platform phased array instruments

    NASA Astrophysics Data System (ADS)

    Dao, Gavin; Lallement, Rémi; Carcreff, Ewen; Braconnier, Dominique

    2016-02-01

    Nondestructive evaluation (NDE) using ultrasonic waves is an efficient technique to assess industrial component integrity. The use of array probes enables inspection flexibility and advanced imaging techniques such as the total focusing method (TFM). In particular, the TFM imaging approach tremendously increases the quantity of data compared to conventional ultrasonic testing. Data transfer rates from the ultrasonic equipment to the computer are therefore continuously increasing due to large quantities of data and high speed inspections. In this work, we propose to use a USB 3.0 communication protocol for high speed throughput in a phased array device. To our knowledge, such protocol has not be proposed before for such an equipment. In this paper, we show that this protocol offers high transfer rates and is suitably adapted to ultrasonic inspection with array probes.

  3. Acousto-optic liquid-crystal analog beam former for phased-array antennas.

    PubMed

    Riza, N A

    1994-06-10

    A compact phased-array antenna acousto-optic beam former with element-level analog phase (0-2π) and amplitude control using nematic-liquid-crystal display-type technology is experimentally demonstrated. Measurements indicate > 6-bit phase control and 52.6 dB of amplitude-attenuation control. High-quality error calibration and antenna sidelobe-level control is possible with this low-control-power analog beam former. Optical system options using rf Bragg cells or wideband Bragg cells are discussed, with the rf design being the current preferred approach. Transmit-receive beam forming based on frequency upconversion-downconversion by electronic mixing is introduced for the rf Bragg-cell beam former, and comparisons with digital beam forming are highlighted. A millimeter-wave signal generation and control optical architecture is described.

  4. V-band pseudomorphic HEMT MMIC phased array components for space communications

    NASA Astrophysics Data System (ADS)

    Lan, G. L.; Pao, C. K.; Wu, C. S.; Hu, M.; Downey, Alan N.

    1992-08-01

    Recent advances in pseudomorphic high-electron-mobility transistor (PMHEMT) monolithic microwave integrated circuit (MMIC) technology have made it the preferred candidate for high performance millimeter-wave components for phased array applications. The development of V-band PMHEMT/MMIC components including power amplifiers and phase shifters is described. For the single-stage MMIC power amplifier employing a 200 micron PMHEMT, we achieved 151.4 mW output power (757.0 mW/mm) with 1.8 dB associated gain and 26.4 percent power-added efficiency at 60 GHz. A two-stage MMIC amplifier utilizing the same devices demonstrated small-signal gain as high as 15 dB at 58 GHz. And, for the phase shifter, a four-bit phase shifter with less than 8 dB insertion loss from 61 to 63 GHz was measured.

  5. Phased array ultrasonic inspection method for homogeneous tube inspection over a wide oblique angle range

    NASA Astrophysics Data System (ADS)

    Lepage, Benoit; Painchaud-April, Guillaume

    2017-02-01

    As seamless tube manufacturers push quality requirements for their products, automated phased array Rotating Tube Inspection Systems (RTIS) are now required to provide continuous NDE detection performances over a wide angular range of oblique flaws. One major impact of this new reality is a paradigm shift for the calibration method use. This change is driven by the requirement to meet homogeneous detection over broad oblique flaw angle intervals, whereas standard practice only requires calibration at specific discrete angles. This paper presents an innovative method specifically designed to obtain high productivity and homogeneous inspection measurements over an oblique flaw range extending from -45 to 45 degrees. Experimental results from the application of the method on various tubes presenting multiple artificial flaws support the quantitative performance evaluation.

  6. On-chip silicon optical phased array for two-dimensional beam steering.

    PubMed

    Kwong, David; Hosseini, Amir; Covey, John; Zhang, Yang; Xu, Xiaochuan; Subbaraman, Harish; Chen, Ray T

    2014-02-15

    A 16-element optical phased array integrated on chip is presented for achieving two-dimensional (2D) optical beam steering. The device is fabricated on the silicon-on-insulator platform with a 250 nm silicon device layer. Steering is achieved via a combination of wavelength tuning and thermo-optic phase shifting with a switching power of P(π)=20  mW per channel. Using a silicon waveguide grating with a polycrystalline silicon overlay enables narrow far field beam widths while mitigating the precise etching needed for conventional shallow etch gratings. Using this system, 2D steering across a 20°×15° field of view is achieved with a sidelobe level better than 10 dB and with beam widths of 1.2°×0.5°.

  7. Phased Array Ghost Elimination (PAGE) for Segmented SSFP Imaging With Interrupted Steady-State

    PubMed Central

    Kellman, Peter; Guttman, Michael A.; Herzka, Daniel A.; McVeigh, Elliot R.

    2007-01-01

    Steady-state free precession (SSFP) has recently proven to be valuable for cardiac imaging due to its high signal-to-noise ratio and blood-myocardium contrast. Data acquired using ECG-triggered, segmented sequences during the approach to steady-state, or return to steady-state after interruption, may have ghost artifacts due to periodic k-space distortion. Schemes involving several preparatory RF pulses have been proposed to restore steady-state, but these consume imaging time during early systole. Alternatively, the phased-array ghost elimination (PAGE) method may be used to remove ghost artifacts from the first several frames. PAGE was demonstrated for cardiac cine SSFP imaging with interrupted steady-state using a simple alpha/2 magnetization preparation and storage scheme and a spatial tagging preparation. PMID:12465121

  8. Ultrasonic Phased Array Evaluation of Control Rod Drive Mechanism (CRDM) Nozzle Interference Fit and Weld Region

    SciTech Connect

    Cinson, Anthony D.; Crawford, Susan L.; MacFarlan, Paul J.; Mathews, Royce; Hanson, Brady D.; Diaz, Aaron A.

    2011-10-01

    In this investigation, non-destructive and destructive testing were used to evaluate potential boric acid leakage paths around an Alloy 600 CRDM penetration (Nozzle 63) from the North Anna Unit 2 reactor pressure vessel head that was removed from service in 2003. For this investigation, Nozzle 63 was examined using phased array ultrasonic testing. Prior to examining Nozzle 63, a CRDM penetration mockup with known notches and boric acid deposits was used to assess probe sensitivity, resolution and calibration. Following the non-destructive testing of Nozzle 63, the nozzle was destructively examined to visually assess the leak paths. These destructive and nondestructive results are compared and results are presented. The results of this investigation may be used by NRC to evaluate licensees’ volumetric leak path assessment methodologies and to support regulatory inspection requirements.

  9. Beam-Switch Transient Effects in the RF Path of the ICAPA Receive Phased Array Antenna

    NASA Technical Reports Server (NTRS)

    Sands, O. Scott

    2003-01-01

    When the beam of a Phased Array Antenna (PAA) is switched from one pointing direction to another, transient effects in the RF path of the antenna are observed. Testing described in the report has revealed implementation-specific transient effects in the RF channel that are associated with digital clocking pulses that occur with transfer of data from the Beam Steering Controller (BSC) to the digital electronics of the PAA under test. The testing described here provides an initial assessment of the beam-switch phenomena by digitally acquiring time series of the RF communications channel, under CW excitation, during the period of time that the beam switch transient occurs. Effects are analyzed using time-frequency distributions and instantaneous frequency estimation techniques. The results of tests conducted with CW excitation supports further Bit-Error-Rate (BER) testing of the PAA communication channel.

  10. Precision SAW filters for a large phased-array radar system

    NASA Astrophysics Data System (ADS)

    Haydl, W. H.; Sander, W.; Wirth, W.-D.

    1981-05-01

    The electronically steerable radar (ELRA) at the Forschungsinstitut fuer Funk und Mathematik is an experimental S-band phased-array radar system consisting of separate transmitting and receiving arrays employing several coherent and incoherent signal-processing and data-handling techniques, incorporating multiple beam and multifunction operation for target search and tracking, adaptive interference suppression, and target resolution. This paper deals with the development and application of two types of SAW filters for the IF amplifier channel of the receiving array. Compared to conventional filters with lumped elements, these filters have some important merits. By making use of a special tuning technique, the center frequencies of all filters were adjusted, resulting in an rms deviation of less than 1 kHz. One type of the SAW filters represents an almost ideal approach of realizing a matched filter for rectangular shaped pulses. The conformity of the frequency responses of several hundred filters improved the noise suppression capability of the system.

  11. A hybrid computational model for ultrasound phased-array heating in presence of strongly scattering obstacles.

    PubMed

    Botros, Y Y; Volakis, J L; VanBaren, P; Ebbini, E S

    1997-11-01

    A computationally efficient hybrid ray-physical optics (HRPO) model is presented for the analysis and synthesis of multiple-focus ultrasound heating patterns through the human rib cage. In particular, a ray method is used to propagate the ultrasound fields from the source to the frontal plane of the rib cage. The physical-optics integration method is then employed to obtain the intensity pattern inside the rib cage. The solution of the matrix system is carried out by using the pseudo inverse technique to synthesize the desired heating pattern. The proposed technique guides the fields through the intercostal spacings between the solid ribs and, thus, minimal intensity levels are observed over the solid ribs. This simulation model allows for the design and optimization of large-aperture phased-array applicator systems for noninvasive ablative thermal surgery in the heart and liver through the rib cage.

  12. Hierarchical Phased Array Antenna Focal Plane for Cosmic Microwave Background Polarization and Sub-mm Observations

    NASA Astrophysics Data System (ADS)

    Lee, Adrian

    We propose to develop planar-antenna-coupled superconducting bolometer arrays for observations at sub-millimeter to millimeter wavelengths. Our pixel architecture features a dual-polarization, log-periodic antenna with a 5:1 bandwidth ratio, followed by a filter bank that divides the total bandwidth into several broad photometric bands. We propose to develop an hierarchical phased array of our basic pixel type that gives optimal mapping speed (sensitivity) over a much broader range of frequencies. The advantage of this combination of an intrinsically broadband pixel with hierarchical phase arraying include a combination of greatly reduced focal-plane mass, higher array sensitivity, and a larger number of spectral bands compared to focal-plane designs using conventional single-color pixels. These advantages have the potential to greatly reduce cost and/or increase performance of NASA missions in the sub-millimeter to millimeter bands. For CMB polarization, a wide frequency range of about 30 to 400 GHz is required to subtract galactic foregrounds. As an example, the multichroic architecture we propose could reduce the focal plane mass of the EPIC-IM CMB polarization mission study concept by a factor of 4, with great savings in required cryocooler performance and therefore cost. We have demonstrated the lens-coupled antenna concept in the POLARBEAR groundbased CMB polarization experiment which is now operating in Chile. That experiment uses a single-band planar antenna that gives excellent beam properties and optical efficiency. POLARBEAR recently succeeded in detecting gravitational lensing B-modes in the CMB polarization. In the laboratory, we have measured two octaves of total bandwidth in the log-periodic sinuous antenna. We have built filter banks of 2, 3, and 7 bands with 4, 6, and 14 bolometers per pixel for two linear polarizations. Pixels of this type are slated to be deployed on the ground in POLARBEAR and SPT-3G and proposed to be used on a balloon by EBEX

  13. Experimental instrumentation system for the Phased Array Mirror Extendible Large Aperture (PAMELA) test program

    NASA Technical Reports Server (NTRS)

    Boykin, William H., Jr.

    1993-01-01

    Adaptive optics are used in telescopes for both viewing objects with minimum distortion and for transmitting laser beams with minimum beam divergence and dance. In order to test concepts on a smaller scale, NASA MSFC is in the process of setting up an adaptive optics test facility with precision (fraction of wavelengths) measurement equipment. The initial system under test is the adaptive optical telescope called PAMELA (Phased Array Mirror Extendible Large Aperture). Goals of this test are: assessment of test hardware specifications for PAMELA application and the determination of the sensitivities of instruments for measuring PAMELA (and other adaptive optical telescopes) imperfections; evaluation of the PAMELA system integration effort and test progress and recommended actions to enhance these activities; and development of concepts and prototypes of experimental apparatuses for PAMELA.

  14. On adaptive phased-array tracking in the presence of main-lobe jammer suppression

    NASA Astrophysics Data System (ADS)

    Blanding, Wayne R.; Koch, Wolfgang; Nickel, Ulrich

    2006-05-01

    Advances in characterizing the angle measurement covariance for phased array monopulse radar systems that use adaptive beamforming to null out a jammer source allow for the use of improved sensor models in tracking algorithms. Using a detection probability likelihood function consisting of a Gaussian sum that incorporates negative contact measurement information, three tracking systems are compared when used to track a maneuvering target passing into and through standoff jammer interference. Each tracker differs in how closely it replicates sensor performance in terms of accuracy of measurement covariance and the use of negative information. Only the tracker that uses both the negative contact information and corrected angle measurement covariance is able to consistently reacquire the target when it exits the jammer interference.

  15. MRI-compatible ultrasound heating system with ring-shaped phased arrays for breast tumor thermal therapy.

    PubMed

    Chen, Hung-Nien; Chen, Guan-Ming; Lin, Bo-Sian; Lien, Pi-Hsien; Chen, Yung-Yaw; Chen, Gin-Shin; Lin, Win-Li

    2013-01-01

    Therapeutic ultrasound transducers can carry out precise and efficient power deposition for tumor thermal therapy under the guidance of magnetic resonance imaging. For a better heating, organ-specific ultrasound transducers with precision location control system should be developed for tumors located at various organs. It is feasible to perform a better heating for breast tumor thermal therapy with a ring-shaped ultrasound phased-array transducer. In this study, we developed ring-shaped phased-array ultrasound transducers with 1.0 and 2.5 MHz and a precision location control system to drive the transducers to the desired location to sonicate the designated region. Both thermo-sensitive hydrogel phantom and ex vivo fresh pork were used to evaluate the heating performance of the transducers. The results showed that the ring-shaped phased array ultrasound transducers were very promising for breast tumor heating with the variation of heating patterns and without overheating the ribs.

  16. SAFT-assisted sound beam focusing using phased arrays (PA-SAFT) for non-destructive evaluation

    NASA Astrophysics Data System (ADS)

    Nanekar, Paritosh; Kumar, Anish; Jayakumar, T.

    2015-04-01

    Focusing of sound has always been a subject of interest in ultrasonic non-destructive evaluation. An integrated approach to sound beam focusing using phased array and synthetic aperture focusing technique (PA-SAFT) has been developed in the authors' laboratory. The approach involves SAFT processing on ultrasonic B-scan image collected by a linear array transducer using a divergent sound beam. The objective is to achieve sound beam focusing using fewer elements than the ones required using conventional phased array. The effectiveness of the approach is demonstrated on aluminium blocks with artificial flaws and steel plate samples with embedded volumetric weld flaws, such as slag and clustered porosities. The results obtained by the PA-SAFT approach are found to be comparable to those obtained by conventional phased array and full matrix capture - total focusing method approaches.

  17. Simulation of 3-D radiation beam patterns propagated through a planar interface from ultrasonic phased array transducers.

    PubMed

    Song, Sung-Jin; Kim, Chang-Hwan

    2002-05-01

    Phased array transducers are quite often mounted on solid wedges with specific angles in many practical ultrasonic inspections of thin plates <10 mm in their thickness or welded joints with convex crowns. For the reliable application of phased array techniques with testing set-up, it is essential to have thorough understanding on the characteristics of radiation beam pattern produced in the interrogated medium. To address such a need, this paper proposes a systematic way to calculate full 3-D radiation beam patterns produced in the interrogated solid medium by phased array transducers mounted on a solid wedge. In order to investigate the characteristics of radiation beam patterns in steel, simulation is carried out for 7.5 MHz array transducers mounted on an acrylic wedge with the angle of 15.45 degrees with various of steering angles and/or focal planes.

  18. An ultrasound cylindrical phased array for deep heating in the breast: theoretical design using heterogeneous models.

    PubMed

    Bakker, J F; Paulides, M M; Obdeijn, I M; van Rhoon, G C; van Dongen, K W A

    2009-05-21

    The objective of this theoretical study is to design an ultrasound (US) cylindrical phased array that can be used for hyperthermia (40-44 degrees C) treatment of tumours in the intact breast. Simultaneously, we characterize the influence of acoustic and thermal heterogeneities on the specific absorption rate (SAR) and temperature patterns to determine the necessity of using heterogeneous models for a US applicator design and treatment planning. Cylindrical configurations of monopole transducers are studied on their ability to generate interference patterns that can be steered electronically to the location of the target region. Hereto, design parameters such as frequency, number of transducers per ring, ring distance and number of rings are optimized to obtain a small primary focus, while suppressing secondary foci. The models account for local heterogeneities in both acoustic (wave velocity and absorption) and thermal (blood perfusion rate, heat capacity and conductivity) tissue properties. We used breast models with a central tumour (30x20x38 mm3) and an artificial thorax tumour (sphere with a radius of 25 mm) to test the design. Simulations predict that a US cylindrical phased array, consisting of six rings with 32 transducers per ring, a radius of 75 mm and 66 mm distance between the first and sixth transducer ring, operating at a frequency of 100 kHz, can be used to obtain 44 degrees C in the centre of tumours located anywhere in the intact breast. The dimensions of the volumes enclosed by the 41 degrees C iso-temperature are 19x19x21 mm3 and 21x21x32 mm3 for the central and the thorax tumours, respectively. It is demonstrated that acoustic and thermal heterogeneities do not disturb the SAR and temperature patterns.

  19. An Automated Dosing Method for a HIFU Device Containing Multiple Phased Arrays

    NASA Astrophysics Data System (ADS)

    Zeng, Xiaozheng Jenny; Barnes, Steve; Sekins, K. Michael

    2010-03-01

    A device containing multiple 2D therapeutic and imaging ultrasound phased arrays is proposed for acoustic hemostasis applications. An automated dosing algorithm selects the optimal combination of therapeutic phased arrays and calculates the acoustic power required of each array. Simulations demonstrate that therapeutic temperatures (70° C

  20. Fundamental performance assessment of 2-D myocardial elastography in a phased-array configuration.

    PubMed

    Luo, Jianwen; Lee, Wei-Ning; Konofagou, Elisa E

    2009-10-01

    Two-dimensional myocardial elastography, an RF-based, speckle-tracking technique, uses 1-D cross-correlation and recorrelation methods in a 2-D search, and can estimate and image the 2-D transmural motion and deformation of the myocardium so as to characterize the cardiac function. Based on a 3-D finite-element (FE) canine left-ventricular model, a theoretical framework was previously developed by our group to evaluate the estimation quality of 2-D myocardial elastography using a linear array. In this paper, an ultrasound simulation program, Field II, was used to generate the RF signals of a model of the heart in a phased-array configuration and under 3-D motion conditions; thus simulating a standard echocardiography exam. The estimation method of 2-D myocardial elastography was adapted for use with such a configuration. All elastographic displacements and strains were found to be in good agreement with the FE solutions, as indicated by the mean absolute error (MAE) between the two. The classified first and second principal strains approximated the radial and circumferential strains, respectively, in the phased-array configuration. The results at different sonographic signal-to-noise ratios (SNR(s)) showed that the MAEs of the axial, lateral, radial, and circumferential strains remained relatively constant when the SNR(s) was equal to or higher than 20 dB. The MAEs of the strain estimation were not significantly affected when the acoustic attenuation was included in the simulations. A significantly reduced number of scatterers could be used to speed up the simulation, without sacrificing the estimation quality.The proposed framework can further be used to assess the estimation quality, explore the theoretical limitation and investigate the effects of various parameters in 2-D myocardial elastography under more realistic conditions.

  1. Using Low-Frequency Phased Arrays to Detect Cracks in Cast Austenitic Piping Components

    SciTech Connect

    Anderson, Michael T.; Cumblidge, Stephen E.; Doctor, Steven R.

    2005-12-30

    As part of a multi-year program funded by the United States Nuclear Regulatory Commission (US NRC) to address NDE reliability of inservice inspection (ISI) programs, recent studies conducted at the Pacific N¬orthwest National Laboratory (PNNL) in Richland, Washington, have focused on assessing novel NDE approaches for the inspection of coarse-grained, cast stainless steel reactor components. The primary objective of this work is to provide information to the US NRC on the utility, effec¬tiveness and reliability of ultrasonic testing (UT) and eddy current testing (ET) inspection techniques as related to the ISI of primary piping components in pressurized water reactors (PWRs). This paper describes progress, recent developments and early results from an assessment of a portion of this work relating to the ultrasonic low frequency phased array inspection technique. Westinghouse Owner’s Group (WOG) cast stainless steel pipe segments with thermal and mechanical fatigue cracks, PNNL samples containing thermal fatigue cracks and several blank vintage specimens having very coarse grains that are representative of early centrifugally cast piping installed in PWRs, are being used for assessing the inspection method. The phased array approach was implemented using an R/D Tech Tomoscan III system operating at 1.0 MHz and 500 kHz, providing composite volumetric images of the samples. Several dual, transmit-receive, custom designed low-frequency arrays are employed in laboratory trials. Results from laboratory studies for assessing detection of thermal and mechanical fatigue cracks in cast stainless steel piping welds are discussed. This work was sponsored by the U.S. Nuclear Regulatory Commission under Contract DE-AC06-76RLO 1830; NRC JCN Y6604; Mr. Wallace Norris, Program Monitor.

  2. Acoustic investigation of wall jet over a backward-facing step using a microphone phased array

    NASA Astrophysics Data System (ADS)

    Perschke, Raimund F.; Ramachandran, Rakesh C.; Raman, Ganesh

    2015-02-01

    The acoustic properties of a wall jet over a hard-walled backward-facing step of aspect ratios 6, 3, 2, and 1.5 are studied using a 24-channel microphone phased array at Mach numbers up to M=0.6. The Reynolds number based on inflow velocity and step height assumes values from Reh = 3.0 ×104 to 7.2 ×105. Flow without and with side walls is considered. The experimental setup is open in the wall-normal direction and the expansion ratio is effectively 1. In case of flow through a duct, symmetry of the flow in the spanwise direction is lost downstream of separation at all but the largest aspect ratio as revealed by oil paint flow visualization. Hydrodynamic scattering of turbulence from the trailing edge of the step contributes significantly to the radiated sound. Reflection of acoustic waves from the bottom plate results in a modulation of power spectral densities. Acoustic source localization has been conducted using a 24-channel microphone phased array. Convective mean-flow effects on the apparent source origin have been assessed by placing a loudspeaker underneath a perforated flat plate and evaluating the displacement of the beamforming peak with inflow Mach number. Two source mechanisms are found near the step. One is due to interaction of the turbulent wall jet with the convex edge of the step. Free-stream turbulence sound is found to be peaked downstream of the step. Presence of the side walls increases free-stream sound. Results of the flow visualization are correlated with acoustic source maps. Trailing-edge sound and free-stream turbulence sound can be discriminated using source localization.

  3. Passive monitoring using a combination of focused and phased array radiometry: a simulation study.

    PubMed

    Farantatos, Panagiotis; Karanasiou, Irene S; Uzunoglu, Nikolaos

    2011-01-01

    Aim of this simulation study is to use the focusing properties of a conductive ellipsoidal reflector in conjunction with directive phased microwave antenna configurations in order to achieve brain passive monitoring with microwave radiometry. One of the main modules of the proposed setup which ensures the necessary beamforming and focusing on the body and brain areas of interest is a symmetrical axis ellipsoidal conductive wall cavity. The proposed system operates in an entirely non-invasive contactless manner providing temperature and/or conductivity variations monitoring and is designed to also provide hyperthermia treatment. In the present paper, the effect of the use of patch antennas as receiving antennas on the system's focusing properties and specifically the use of phased array setups to achieve scanning of the areas under measurement is investigated. Extensive simulations to compute the electric field distributions inside the whole ellipsoidal reflector and inside two types of human head models were carried out using single and two element microstrip patch antennas. The results show that clear focusing (creation of "hot spots") inside the head models is achieved at 1.53GHz. In the case of the two element antennas, the "hot spot" performs a linear scan around the brain area of interest while the phase difference of the two microstrip patch antennas significantly affects the way the scanning inside the head model is achieved. In the near future, phased array antennas with multiband and more elements will be used in order to enhance the system scanning properties toward the acquisition of tomography images without the need of subject movement.

  4. The Architecture of an LWA Station - A New Phased-array Radio Telescope

    NASA Astrophysics Data System (ADS)

    Craig, Joseph; Rickard, L.; Ellingson, S.; Taylor, G.; Pihlstrom, Y.; Kassim, N.; Ray, P.; Clarke, T.; D'Addario, L.; Navarro, R.; Cohen, A.; Crane, P.; Hicks, B.; Polisensky, E.; Schmitt, H.; Cox, L.

    2009-05-01

    The Long Wavelength Array (LWA) is part of a new class of large low-frequency interferometric telescopes. The complete LWA will consist of more than 50 phased array "stations" distributed over a roughly 400 km diameter region in New Mexico. Each station will consist of 256 pairs of dipole-type antennas whose signals are formed into beams, with outputs transported to a central location for high-resolution aperture synthesis imaging. The resulting image sensitivity is estimated to be a few mJy with a resolution of 8" to 2" (20 to 80 MHz). Phase I of the LWA is nearly complete, with completion of PDR, construction of the first full station (LWA-1) in 2009-10, and operation as a stand-alone instrument in 2010. Utilizing modern FPGA computing, LWA-1 will form four independent (in both frequency and pointing) beams on the sky, and provide instantaneous bandwidths of 8 MHz per beam, spectral resolutions down to 100 Hz, and temporal resolutions down to 0.1 ms in the range of 10 to 88 MHz. Signals from 512 dipole antennas will be digitized without frequency conversion (a homodyne receiver architecture), allowing direct beam-formation of the entire LWA bandwidth. As the station will operate as a fully electronic phased array, very little repointing time is required. This will allow the beams to be cycled rapidly among many calibration sources on millisecond timescales. This scheme could provide real-time calibration of the turbulent ionospheric conditions, which limit both resolution and sensitivity at low-frequencies. The LWA Project is funded through a contract from the Office of Naval Research to the University of New Mexico. Partnering with UNM are the Naval Research Laboratory, Virginia Tech, the Jet Propulsion Laboratory, Los Alamos National Laboratory, and the University of Iowa. Basic research in radio astronomy at the Naval Research Laboratory is supported by 6.1 base funding.

  5. Phased Array-Fed Reflector (PAFR) Antenna Architectures for Space-Based Sensors

    NASA Technical Reports Server (NTRS)

    Cooley, Michael E.

    2014-01-01

    Communication link and target ranges for satellite communications (SATCOM) and space-based sensors (e.g. radars) vary from approximately 1000 km (for LEO satellites) to 35,800 km (for GEO satellites). At these long ranges, large antenna gains are required and legacy payloads have usually employed large reflectors with single beams that are either fixed or mechanically steered. For many applications, there are inherent limitations that are associated with the use of these legacy antennas/payloads. Hybrid antenna designs using Phased Array Fed Reflectors (PAFRs) provide a compromise between reflectors and Direct Radiating phased Arrays (DRAs). PAFRs provide many of the performance benefits of DRAs while utilizing much smaller, lower cost (feed) arrays. The primary limitation associated with hybrid PAFR architectures is electronic scan range; approximately +/-5 to +/- 10 degrees is typical, but this range depends on many factors. For LEO applications, the earth FOV is approximately +/-55 degrees which is well beyond the range of electronic scanning for PAFRs. However, for some LEO missions, limited scanning is sufficient or the CONOPS and space vehicle designs can be developed to incorporate a combination mechanical slewing and electronic scanning. In this paper, we review, compare and contrast various PAFR architectures with a focus on their general applicability to space missions. We compare the RF performance of various PAFR architectures and describe key hardware design and implementation trades. Space-based PAFR designs are highly multi-disciplinary and we briefly address key hardware engineering design areas. Finally, we briefly describe two PAFR antenna architectures that have been developed at Northrop Grumman.

  6. Printed Electronics

    NASA Technical Reports Server (NTRS)

    Crain, John M. (Inventor); Lettow, John S. (Inventor); Aksay, Ilhan A. (Inventor); Korkut, Sibel (Inventor); Chiang, Katherine S. (Inventor); Chen, Chuan-Hua (Inventor); Prud'Homme, Robert K. (Inventor)

    2015-01-01

    Printed electronic device comprising a substrate onto at least one surface of which has been applied a layer of an electrically conductive ink comprising functionalized graphene sheets and at least one binder. A method of preparing printed electronic devices is further disclosed.

  7. Printed Electronics

    NASA Technical Reports Server (NTRS)

    Crain, John M. (Inventor); Lettow, John S. (Inventor); Aksay, Ilhan A. (Inventor); Korkut, Sibel A. (Inventor); Chiang, Katherine S. (Inventor); Chen, Chuan-Hua (Inventor); Prud'Homme, Robert K. (Inventor)

    2014-01-01

    Printed electronic device comprising a substrate onto at least one surface of which has been applied a layer of an electrically conductive ink comprising functionalized graphene sheets and at least one binder. A method of preparing printed electronic devices is further disclosed.

  8. Printed electronics

    NASA Technical Reports Server (NTRS)

    Crain, John M. (Inventor); Lettow, John S. (Inventor); Aksay, Ilhan A. (Inventor); Korkut, Sibel A. (Inventor); Chiang, Katherine S. (Inventor); Chen, Chuan-hua (Inventor); Prud'Homme, Robert K. (Inventor)

    2012-01-01

    Printed electronic device comprising a substrate onto at least one surface of which has been applied a layer of an electrically conductive ink comprising functionalized graphene sheets and at least one binder. A method of preparing printed electronic devices is further disclosed.

  9. Printed Electronics

    NASA Technical Reports Server (NTRS)

    Crain, John M. (Inventor); Lettow, John S. (Inventor); Aksay, Ilhan A. (Inventor); Korkut, Sibel (Inventor); Chiang, Katherine S. (Inventor); Chen, Chuan-Hua (Inventor); Prud'Homme, Robert K. (Inventor)

    2016-01-01

    Printed electronic device comprising a substrate onto at least one surface of which has been applied a layer of an electrically conductive ink comprising functionalized graphene sheets and at least one binder. A method of preparing printed electronic devices is further disclosed.

  10. Face Prints.

    ERIC Educational Resources Information Center

    Hadash, Dre Ann

    1984-01-01

    Eighth graders made prints of their own faces, using photographic papers and chemicals. Describes the supplies needed and the printing process involved. Because junior high school students are so concerned with self, this was a very meaningful activity for them. (CS)

  11. Digital printing

    NASA Astrophysics Data System (ADS)

    Sobotka, Werner K.

    1997-02-01

    Digital printing is described as a tool to replace conventional printing machines completely. Still this goal was not reached until now with any of the digital printing technologies to be described in the paper. Productivity and costs are still the main parameters and are not really solved until now. Quality in digital printing is no problem anymore. Definition of digital printing is to transfer digital datas directly on the paper surface. This step can be carried out directly or with the use of an intermediate image carrier. Keywords in digital printing are: computer- to-press; erasable image carrier; image carrier with memory. Digital printing is also the logical development of the new digital area as it is pointed out in Nicholas Negropotes book 'Being Digital' and also the answer to networking and Internet technologies. Creating images text and color in one country and publishing the datas in another country or continent is the main advantage. Printing on demand another big advantage and last but not least personalization the last big advantage. Costs and being able to coop with this new world of prepress technology is the biggest disadvantage. Therefore the very optimistic growth rates for the next few years are really nonexistent. The development of complete new markets is too slow and the replacing of old markets is too small.

  12. Thermal therapy for breast tumors by using a cylindrical ultrasound phased array with multifocus pattern scanning: a preliminary numerical study.

    PubMed

    Ho, Cheng-Shiao; Ju, Kuen-Cheng; Cheng, Tze-Yuan; Chen, Yung-Yaw; Lin, Win-Li

    2007-08-07

    The purpose of this study is to investigate the feasibility of using a 1 MHz cylindrical ultrasound phased array with multifocus pattern scanning to produce uniform heating for breast tumor thermal therapy. The breast was submerged in water and surrounded by the cylindrical ultrasound phased array. A multifocus pattern was generated and electrically scanned by the phased array to enlarge the treatment lesion in single heating. To prevent overheating normal tissues, a large planning target volume (PTV) would be divided into several planes with several subunits on each plane and sequentially treated with a cooling phase between two successive heatings of the subunit. Heating results for different target temperatures (T(tgt)), blood perfusion rates and sizes of the PTV have been studied. Furthermore, a superficial breast tumor with different water temperatures was also studied. Results indicated that a higher target temperature would produce a slightly larger thermal lesion, and a higher blood perfusion rate would not affect the heating lesion size but increase the heating time significantly. The acoustic power deposition and temperature elevations in ribs can be minimized by orienting the acoustic beam from the ultrasound phased array approximately parallel to the ribs. In addition, a large acoustic window on the convex-shaped breast surface for the proposed ultrasound phased array and the cooling effect of water would prevent the skin overheating for the production of a lesion at any desired location. This study demonstrated that the proposed cylindrical ultrasound phased array can provide effective heating for breast tumor thermal therapy without overheating the skin and ribs within a reasonable treatment time.

  13. Phased-array ultrasound technology enhances accuracy of dual frequency ultrasound measurements - towards improved ultrasound bone diagnostics.

    PubMed

    Linder, Hans; Malo, Markus K H; Liukkonen, Jukka; Jurvelin, Jukka S; Töyräs, Juha

    2016-08-01

    Overlying soft tissues attenuate ultrasound backscattered from bone, complicating diagnostics of osteoporosis at the most important fracture sites. Dual-frequency ultrasound technique (DFUS) has been proposed to solve this problem through determination of thickness and composition of overlying soft tissue. This study applies DFUS technique for the first time with a phased-array transducer to investigate if the thickness of two interfering layers (oil and water) can be accurately determined in a variety of configurations. Results indicate that DFUS may be used with phased-array ultrasound systems, making them a suitable combination to consider in future development of clinical in vivo ultrasound methodologies.

  14. Concept design of an 80-dual polarization element cryogenic phased array camera for the Arecibo Radio Telescope

    NASA Astrophysics Data System (ADS)

    Cortes-Medellin, German; Parshley, Stephen; Campbell, Donald B.; Warnick, Karl F.; Jeffs, Brian D.; Ganesh, Rajagopalan

    2016-08-01

    This paper presents the current concept design for ALPACA (Advanced L-Band Phased Array Camera for Arecibo) an L-Band cryo-phased array instrument proposed for the 305 m radio telescope of Arecibo. It includes the cryogenically cooled front-end with 160 low noise amplifiers, a RF-over-fiber signal transport and a digital beam former with an instantaneous bandwidth of 312.5 MHz per channel. The camera will digitally form 40 simultaneous beams inside the available field of view of the Arecibo telescope optics, with an expected system temperature goal of 30 K.

  15. High-frequency matrix converter with square wave input

    DOEpatents

    Carr, Joseph Alexander; Balda, Juan Carlos

    2015-03-31

    A device for producing an alternating current output voltage from a high-frequency, square-wave input voltage comprising, high-frequency, square-wave input a matrix converter and a control system. The matrix converter comprises a plurality of electrical switches. The high-frequency input and the matrix converter are electrically connected to each other. The control system is connected to each switch of the matrix converter. The control system is electrically connected to the input of the matrix converter. The control system is configured to operate each electrical switch of the matrix converter converting a high-frequency, square-wave input voltage across the first input port of the matrix converter and the second input port of the matrix converter to an alternating current output voltage at the output of the matrix converter.

  16. High frequency ultrasound with color Doppler in dermatology*

    PubMed Central

    Barcaui, Elisa de Oliveira; Carvalho, Antonio Carlos Pires; Lopes, Flavia Paiva Proença Lobo; Piñeiro-Maceira, Juan; Barcaui, Carlos Baptista

    2016-01-01

    Ultrasonography is a method of imaging that classically is used in dermatology to study changes in the hypoderma, as nodules and infectious and inflammatory processes. The introduction of high frequency and resolution equipments enabled the observation of superficial structures, allowing differentiation between skin layers and providing details for the analysis of the skin and its appendages. This paper aims to review the basic principles of high frequency ultrasound and its applications in different areas of dermatology. PMID:27438191

  17. High frequency, small signal MH loops of ferromagnetic thin films

    NASA Technical Reports Server (NTRS)

    Grimes, C. A.; Ong, K. G.

    2000-01-01

    A method is presented for transforming the high frequency bias susceptibility measurements of ferromagnetic thin films into the form of a MH loop with, depending upon the measurement geometry, the y-axis zero crossing giving a measure of the coercive force or anisotropy field. The loops provide a measure of the quantitative and qualitative high frequency switching properties of ferromagnetic thin films. c2000 American Institute of Physics.

  18. Characterizing Earthquake Rupture Properties Using Peak High-Frequency Offset

    NASA Astrophysics Data System (ADS)

    Wen, L.; Meng, L.

    2014-12-01

    Teleseismic array back-projection (BP) of high frequency (~1Hz) seismic waves has been recently applied to image the aftershock sequence of the Tohoku-Oki earthquake. The BP method proves to be effective in capturing early aftershocks that are difficult to be detected due to the contamination of the mainshock coda wave. Furthermore, since the event detection is based on the identification of the local peaks in time series of the BP power, the resulting event location corresponds to the peak high-frequency energy rather than the hypocenter. In this work, we show that the comparison between the BP-determined catalog and conventional phase-picking catalog provides estimates of the spatial and temporal offset between the hypocenter and the peak high-frequency radiation. We propose to measure this peak high-frequency shift of global earthquakes between M4.0 to M7.0. We average the BP locations calibrated by multiple reference events to minimize the uncertainty due to the variation of 3D path effects. In our initial effort focusing on the foreshock and aftershock sequence of the 2014 Iquique earthquake, we find systematic shifts of the peak high-frequency energy towards the down-dip direction. We find that the amount of the shift is a good indication of rupture length, which scales with the earthquake magnitude. Further investigations of the peak high frequency offset may provide constraints on earthquake source properties such as rupture directivity, rupture duration, rupture speed, and stress drop.

  19. 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

  20. SweepSAR: Beam-forming on Receive Using a Reflector-Phased Array Feed Combination for Spaceborne SAR

    NASA Technical Reports Server (NTRS)

    Freeman, A.; Krieger, G.; Rosen, P.; Younis, M.; Johnson, W. T. K.; Huber, S.; Jordan, R.; Moreira, A.

    2012-01-01

    In this paper, an alternative approach is described that is suited for longer wavelength SARs in particular, employing a large, deployable reflector antenna and a much simpler phased array feed. To illuminate a wide swath, a substantial fraction of the phased array feed is excited on transmit to sub-illuminate the reflector. Shorter transmit pulses are required than for conventional SAR. On receive, a much smaller portion of the phased array feed is used to collect the return echo, so that a greater portion of the reflector antenna area is used. The locus of the portion of the phased array used on receive is adjusted using an analog beam steering network, to 'sweep' the receive beam(s) across the illuminated swath, tracking the return echo. This is similar in some respects to the whiskbroom approach to optical sensors, hence the name: SweepSAR.SweepSAR has advantages over conventional SAR in that it requires less transmit power, and if the receive beam is narrow enough, it is relatively immune to range ambiguities. Compared to direct radiating arrays with digital beam- forming, it is much simpler to implement, uses currently available technologies, is better suited for longer wavelength systems, and does not require extremely high data rates or onboard processing.