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Sample records for antenna array synthesis

  1. Synthesis of Taylor and Bayliss patterns for linear antenna arrays

    NASA Astrophysics Data System (ADS)

    Shelton, J. P.

    1981-08-01

    The history of synthesis techniques for designing linear antenna arrays with low sidelobe patterns is reviewed briefly, and the limitations that are encountered with very low sidelobes and/or small arrays are pointed out. Taylor's continuous aperture synthesis procedure is outlined, and a technique for transforming it for application to a discrete array is described. Discrete-array design equation for Taylor and Bayliss synthesis procedures are given. A set of programs for use on a programmable calculator are presented.

  2. Synthesis of Volumetric Ring Antenna Array for Terrestrial Coverage Pattern

    PubMed Central

    Reyna, Alberto; Panduro, Marco A.; Del Rio Bocio, Carlos

    2014-01-01

    This paper presents a synthesis of a volumetric ring antenna array for a terrestrial coverage pattern. This synthesis regards the spacing among the rings on the planes X-Y, the positions of the rings on the plane X-Z, and uniform and concentric excitations. The optimization is carried out by implementing the particle swarm optimization. The synthesis is compared with previous designs by resulting with proper performance of this geometry to provide an accurate coverage to be applied in satellite applications with a maximum reduction of the antenna hardware as well as the side lobe level reduction. PMID:24701150

  3. Feasibility study of a synthesis procedure for array feeds to improve radiation performance of large distorted reflector antennas

    NASA Technical Reports Server (NTRS)

    Stutzman, W. L.; Takamizawa, K.; Werntz, P.; Lapean, J.; Barts, R.; Shen, B.

    1992-01-01

    Virginia Tech has several articles which support the NASA Langley effort in the area of large aperture radiometric antenna systems. This semi-annual report reports on the following activities: a feasibility study of a synthesis procedure for array feeds to improve radiation performance of large distorted reflector antennas and the design of array feeds for large reflector antennas.

  4. Feasibility study of a synthesis procedure for array feeds to improve radiation performance of large distorted reflector antennas

    NASA Technical Reports Server (NTRS)

    Stutzman, W. L.; Takamizawa, K.; Werntz, P.; Lapean, J.; Barts, R.

    1991-01-01

    The following subject areas are covered: General Reflector Antenna Systems Program version 7(GRASP7); Multiple Reflector Analysis Program for Cylindrical Antennas (MRAPCA); Tri-Reflector 2D Synthesis Code (TRTDS); a geometrical optics and a physical optics synthesis techniques; beam scanning reflector, the type 2 and 6 reflectors, spherical reflector, and multiple reflector imaging systems; and radiometric array design.

  5. Design and synthesis of flexible switching 1 × 2 antenna array on Kapton substrate

    NASA Astrophysics Data System (ADS)

    Georges Rabobason, Yvon; Rigas, Grigorios; Swaisaenyakorn, Srijittar; Mirkhaydarov, Bobur; Ravelo, Blaise; Shkunov, Maxim; Young, Paul; Benjelloun, Nabil

    2016-06-01

    Flexible front- and back-end RF/analogue system antennas were recently emerged. However, little flexible antenna system design is available so far, in planar hybrid technology with surface mounted components. This paper describes the design feasibility of flexible switching 1 × 2 antenna array system. It acts as a switching antenna implemented in hexapole configuration. The system is comprised of a key element RF switch terminated by two identical patch antennas associated to half-wave elementary transmission lines (TLs). A detailed theory illustrating the global S-parameter model determination in function of the given RF-switch return and insertion losses is established. In difference to the conventional microwave circuit theory, the proposed equivalent S-parameter model is originally built with the non-standard optimized antenna load. Thus, the synthesis method of the terminal antenna input impedance and the output access line characteristic impedance is formulated in function of the specified return and optimal transmission losses. The design method and theoretical approach feasibility is verified with the demonstrator of flexible switching 1 × 2 antenna array printed on Kapton substrate. The circuit prototype is implemented in hybrid planar technology integrating patch antenna operating at about 6 GHz and a packaged GaAs RF switch associated to the RF/DC signal decoupling accessory mounted surface components. Simulations of the designed circuit transmission and isolation losses from 5.5 GHz to 7 GHz were carried out by using the commercial RF switch S-parameter touchstone model provided by the manufacturer. The simulated and measured return losses are compared and discussed. Then, the measured radiation patterns confirm the proposed switched antenna concept feasibility.

  6. A pattern synthesis technique for array feeds to improve radiation performance of large distorted reflector antennas

    NASA Technical Reports Server (NTRS)

    Smith, William T.; Stutzman, Warren L.

    1992-01-01

    Technologies exist for construction of antennas with adaptive surfaces that can compensate for many of the larger distortions caused by thermal and gravitational forces. However, as the frequency and size of the reflectors increase, the subtle surface errors become significant and degrade the overall electromagnetic performance. Electronic compensation through an adaptive feed array offers a means for mitigation of surface distortion effects. A pattern synthesis approach for electromagnetic compensation of surface error is presented. The pattern synthesis approach uses a localized algorithm in which pattern corrections are directed toward specific portions of the pattern requiring improvement. The pattern synthesis technique uses radiation pattern data to perform the compensation.

  7. Adaptive multibeam antenna array

    NASA Astrophysics Data System (ADS)

    Novikov, V. I.

    1984-01-01

    An adaptive multibeam antenna array is considered which will enhance the advantages of a plain one. By providing simultaneous reception of signals from different directions and their sequential processing. The optimization of the array control for maximum interference suppression in the radiation pattern is emphasized. The optimum control is sought with respect to the signal-to-interference power ratio as a genaralized criterion. Sampled useful signals and transmission coefficients are found to be complex-conjugate quantities, assuming compatible formation of beams, so that synphasal equiamplitude addition of signals from all array element is attainable by unique settings of the weight factors. Calculations are simplified by letting the useful signal power in the 1-th beam be approximately equal to the k-th weight factor, before optimizing the weight vector for maximum signal-to-interference ratio. A narrowband interference described by power P and vector V of signal distribution over the array is considered as an example, to demonstrate the algorithm of synthesis. The algorithm, using the Butler matrix, was executed experimentally on a computer for a linear equidistant antenna array of 32 elements with compatible formation of beams.

  8. Feasibility study of a synthesis procedure for array feeds to improve radiation performance of large distorted reflector antennas

    NASA Technical Reports Server (NTRS)

    Stutzman, W. L.; Takamizawa, K.; Werntz, P.; Lapean, J.; Barts, R.; Shen, B.

    1991-01-01

    Virginia Tech is involved in a number of activities with NASA Langley related to large aperture radiometric antenna systems. These efforts are summarized and the focus of this report is on the feasibility study of a synthesis procedure for array feeds to improve radiation performance of large distorted reflector antennas; however, some results for all activities are reported.

  9. Conformal array antenna subsystem

    NASA Astrophysics Data System (ADS)

    1985-04-01

    An antenna subsystem to communicate between Ariane 4 and a data relay satellite was studied, concluding that the original ideas on ring antennas should be corrected due to the wide margin of coverage required in elevation for such antennas, which implies the need of splitting the coverage. Nevertheless, the study of cylindrical and conical conformal arrays was continued in view of their intrinsic interest. Needed coverages with specified gain can be obtained with a set of microstrip circular patch antennas. For the lower stage, a single patch is enough. For geostationary missions, one horizontal array is used, and for heliosynchronous missions two horizontal arrays and a vertical one. The numerical study carried out on omniazimuthal ring antennas shows that a tendency to omnidirectional pattern exists in spite of the directivity of the elementary radiators. A small pointing improvement of the meridian pattern can be obtained by means of conical arrays instead of the cylindrical ones.

  10. Subsurface Deployable Antenna Array

    DTIC Science & Technology

    2009-09-25

    States Patent No. 6,710,746, issued March 23, 2004, to Anderson et al., discloses an antenna having a reconfigurable length, and a method of...an antenna linear extension and retraction apparatus and method of use for a submersible device. The apparatus includes a body having a cavity... microwave communications while at cruising speed and depth. [0027] It is a still further object of the present invention to provide an antenna array

  11. Directivity of Antenna Arrays

    NASA Astrophysics Data System (ADS)

    Bulgakova, A. A.; Gorobets, N. N.; Katrich, V. A.; Lyashchenko, V. A.

    2016-12-01

    Purpose: Theoretical investigation of directive gains of linear and planar antenna arrays depending on the distance between radiators and wavelength. Design/methodology/approach: Computing methods in applied mathematics in MathCad were used to calculate the twofold integrals of the radiation pattern over power throughout the whole space observed, defining the directivity in the most general terms. Patterns of radiators, i. e. elements of antenna arrays, are specified by mathematical models. The calculation accounts for the subintegral fast oscillating function. Findings: Calculations and analysis of a directive gain according to the number of radiators and distances between them in fractions of wavelength are made. It is shown that at the ratio of distance between radiators to wave-length being d/λ =0.5 the directivity of array of isotropic radiators is 1.5N², N – number of radiators. When increasing the d/λ to 0.65÷0.97 the directivity increases according to the law close to the linear one up to the maximum possible value for the specified number of radiators. With the increase of d/λ to the values greater than one, the directivity is significantly reduced (the “blinding” effect of non-phased antenna arrays) and its dependence with the growth of d/λ is decaying and oscillating in character. By that, the transfer function of antenna arrays has some vital difference from the transfer function of continuous antennas. Conclusions: Antenna arrays distort the waveform and spectrum of radiated and received signals as a result of irregular changes of their directivity depending on wavelength. The detected “blinding” effect of non-phased antenna arrays of large electrical dimensions must be taken into account in wideband and superwideband radio-electronics systems, especially in radio astronomy, telecommunications systems and superwideband radar.

  12. Imaging antenna arrays

    NASA Technical Reports Server (NTRS)

    Rutledge, D. B.; Muha, M. S.

    1982-01-01

    Many millimeter and far-infrared imaging systems are limited in sensitivity and speed because they depend on a single scanned element. Because of recent advances in planar detectors such as Schottky diodes, superconducting tunnel junctions, and microbolometers, an attractive approach to this problem is a planar antenna array with integrated detectors. A planar line antenna array and optical system for imaging has been developed. The significant advances are a 'reverse-microscope' optical configuration and a modified bow-tie antenna design. In the 'reverse-microscope' configuration, a lens is attached to the bottom of the substrate containing the antennas. Imaging is done through the substrate. This configuration eliminates the troublesome effects of substrate surface waves. The substrate lens has only a single refracting surface, making possible a virtually aplanatic system, with little spherical aberration or coma. The array is characterized by an optical transfer function that is easily measured. An array with 19 dB crosstalk levels between adjacent antennas has been tested and it was found that the array captured 50 percent of the available power. This imaging system was diffraction limited.

  13. Conformal Antenna Array Design Handbook

    DTIC Science & Technology

    1981-09-01

    PLANAR ARRAY PHASE C LbP=IowITH CORRECT CONFORMAL ARRAY PHASE C NbPt NOe OF PhS&. SH-IFT UITSPII- NoP*.GT*1O CONRCLT PHASES ARE USED C TAP19PATTLRN...of Antenna Arrays, Radio Science , Vol. 3, May 1968, pp. 401-522. M. T. Ma, "Theory and Application of Antenna Arrays", Wiley, New York, 1974, Chapter

  14. Electronic switching spherical array antenna

    NASA Technical Reports Server (NTRS)

    Stockton, R.

    1978-01-01

    This work was conducted to demonstrate the performance levels attainable with an ESSA (Electronic Switching Spherical Array) antenna by designing and testing an engineering model. The antenna was designed to satisfy general spacecraft environmental requirements and built to provide electronically commandable beam pointing capability throughout a hemisphere. Constant gain and beam shape throughout large volumetric coverage regions are the principle characteristics. The model is intended to be a prototype of a standard communications and data handling antenna for user scientific spacecraft with the Tracking and Data Relay Satellite System (TDRSS). Some additional testing was conducted to determine the feasibility of an integrated TDRSS and GPS (Global Positioning System) antenna system.

  15. JPL Large Advanced Antenna Station Array Study

    NASA Technical Reports Server (NTRS)

    1978-01-01

    In accordance with study requirements, two antennas are described: a 30 meter standard antenna and a 34 meter modified antenna, along with a candidate array configuration for each. Modified antenna trade analyses are summarized, risks analyzed, costs presented, and a final antenna array configuration recommendation made.

  16. The collinear coaxial array antenna

    NASA Astrophysics Data System (ADS)

    Brammer, D. J.; Williams, D.

    1981-03-01

    A design of a coaxial vertical antenna proposed in the ARRL antenna handbook is analyzed. A numerical analysis was carried out using the moment method. A variety of antenna configurations in the 160 MHz design frequency are analyzed and current distribution, gain, polar diagrams and impedances are calculated. The analysis is carried out for simple configurations and extended to a case with 16 repeated center sections. The effects of using lossy cable in the construction is also investigated. A defect in the original ARRL design is rectified. An array of an overall length 5.33 wavelengths is shown to have a gain of 10.69 dB.

  17. Feasibility study of a synthesis procedure for array feeds to improve radiation performance of large distorted reflector antennas

    NASA Technical Reports Server (NTRS)

    Stutzman, W. L.; Takamizawa, K.; Werntz, P.; Lapean, J.; Shen, B.

    1993-01-01

    The manpower on this effort was reduced during this reporting period. Activity in the past six months is summarized. The Type 1 antenna is complete and documentation is in final phases. The Type 2 antenna design is complete and a journal article was prepared and was accepted for publication in EEE Transactions on Antennas and Propagation. The spherical antenna configurations are complete and a journal article will appear in the June 1993 issue of EEE Transactions on Antennas and Propagation. In addition, a patent for the spherical antenna is being pursued. The final current activity is that of optimization techniques and they are approaching completion as well. The Tri-Reflector synthesis code (TSAP) was put into user friendly format. A user's guide (Report 93-13) was written and distributed to LaRC. Work continues on EASY7. EASY7 is a user friendly code used to create an input file to GRASP7.

  18. 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.

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

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

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

  20. Analysis and Synthesis of Microstrip Antennas Including Mutual Coupling

    DTIC Science & Technology

    1988-09-01

    E N 11. TITLE (/b*I* Secwfty OuodlCaUOn~) Analysis and Synthesis of Microstrip Antennas Including Mutual Coupling 12. PERSONAL AUTHOR(S) K~oichiro...GROUP SUB-GROUP Array Antennas, Microstrip Antennas, Array Analysis, Array Synthesis, Array Theory, Microwave Network Analysi! 19. ABSTRACT (Continue...VIRGI-J~NIA TECH ANALYSIS AND SYNTHESIS OF [. MICROSTRIP ANTENNAS INCLUDING MUTUAL COUPLING o0000 0 0 a o 0 0 0 0 0 o 0 00 0 00 o00000 0o000 0 0 0 a 0 0 0o

  1. Intense terahertz antenna array with interdigital electrodes

    NASA Astrophysics Data System (ADS)

    Hou, Lei; Shi, Wei; Xu, Ming; Chen, Yong

    2008-12-01

    In this work a powerful terahertz antenna array with interdigital electrodes is fabricated, and the performance of one antenna unit is compared with a conventional resonant dipole antenna. The antenna unit has a better capacity of generating THz wave compared with a conventional resonant dipole antenna at the same bias electrical field and the same laser energy. However only 23 % of THz wave transmitted through the ceramic substrate of antenna array, if there is a hole drilled through ceramic substrate to release the THz wave, the THz amplitude of entire interdigital antenna array with 8 antenna units can be more than 10 times larger than that of resonant dipole antenna. To get this result, the pump beam is focused into a linear beam by a cylindrical lens to trigger the antenna array, and the linear THz wave is focused by a polyethylene lens before it reaches ZnTe crystal.

  2. 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.

  3. Feasibility study of a synthesis procedure for array feeds to improve radiation performance of large distorted reflector antennas

    NASA Technical Reports Server (NTRS)

    Stutzman, W. L.; Smith, W. T.

    1990-01-01

    Surface errors on parabolic reflector antennas degrade the overall performance of the antenna. Space antenna structures are difficult to build, deploy and control. They must maintain a nearly perfect parabolic shape in a harsh environment and must be lightweight. Electromagnetic compensation for surface errors in large space reflector antennas can be used to supplement mechanical compensation. Electromagnetic compensation for surface errors in large space reflector antennas has been the topic of several research studies. Most of these studies try to correct the focal plane fields of the reflector near the focal point and, hence, compensate for the distortions over the whole radiation pattern. An alternative approach to electromagnetic compensation is presented. The proposed technique uses pattern synthesis to compensate for the surface errors. The pattern synthesis approach uses a localized algorithm in which pattern corrections are directed specifically towards portions of the pattern requiring improvement. The pattern synthesis technique does not require knowledge of the reflector surface. It uses radiation pattern data to perform the compensation.

  4. Feasibility study of a synthesis procedure for array feeds to improve radiation performance of large distorted reflector antennas

    NASA Technical Reports Server (NTRS)

    Stutzman, W. L.; Takamizawa, K.; Werntz, P.; Lapean, J.; Barts, R.; Shen, B.; Dunn, D.

    1992-01-01

    The topics covered include the following: (1) performance analysis of the Gregorian tri-reflector; (2) design and performance of the type 6 reflector antenna; (3) a new spherical main reflector system design; (4) optimization of reflector configurations using physical optics; (5) radiometric array design; and (7) beam efficiency studies.

  5. Synthesis of multiple shaped beam antenna patterns

    NASA Technical Reports Server (NTRS)

    Stutzman, W. L.; Coffey, E. L.

    1973-01-01

    Results are presented of research into the problem of finding an excitation of a given antenna such that the desired radiation pattern is approximated to within acceptable limits. This is to be done in such a fashion that boundary conditions involving hardware limitations may be inserted into the problem. The intended application is synthesis of multiple shaped beam antennas. Since this is perhaps the most difficult synthesis problem an antenna engineer is likely to encounter, the approach taken was to include as a by-product capability for synthesizing simpler patterns. The synthesis technique has been almost totally computerized. The class of antennas which may be synthesized with the computer program are those which may be represented as planar (continuous or discrete) current distributions. The technique is not limited in this sense and could indeed by extended to include, for example, the synthesis of conformal arrays or current distributions on the surface of reflectors. The antenna types which the program is set up to synthesize are: line source, rectangular aperture, circular aperture, linear array, rectangular array, and arbitrary planar array.

  6. 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.

  7. Hybrid antenna synthesis for reconfigurable contoured beams

    NASA Astrophysics Data System (ADS)

    Searle, A. D.; Westcott, B. S.

    1993-08-01

    A reflector illuminated by a small phased array is an attractive antenna configuration for systems requiring reconfigurable contoured beams. The use of a shaped reflector can provide control of the feed power distribution and antenna geometry. A systematic reflector synthesis technique based on geometric optics is formulated, using complex coordinate notation and illustrated by application to a simple design requirement. Results demonstrate that geometric shaping can be successfully applied to systems with distributed sources, and that significant beam reconfiguration can be achieved by phase-only control of the feed array.

  8. Resonance spectra of diabolo optical antenna arrays

    NASA Astrophysics Data System (ADS)

    Guo, Hong; Simpkins, Blake; Caldwell, Joshua D.; Guo, Junpeng

    2015-10-01

    A complete set of diabolo optical antenna arrays with different waist widths and periods was fabricated on a sapphire substrate by using a standard e-beam lithography and lift-off process. Fabricated diabolo optical antenna arrays were characterized by measuring the transmittance and reflectance with a microscope-coupled FTIR spectrometer. It was found experimentally that reducing the waist width significantly shifts the resonance to longer wavelength and narrowing the waist of the antennas is more effective than increasing the period of the array for tuning the resonance wavelength. Also it is found that the magnetic field enhancement near the antenna waist is correlated to the shift of the resonance wavelength.

  9. Resonance spectra of diabolo optical antenna arrays

    SciTech Connect

    Guo, Hong; Guo, Junpeng; Simpkins, Blake; Caldwell, Joshua D.

    2015-10-15

    A complete set of diabolo optical antenna arrays with different waist widths and periods was fabricated on a sapphire substrate by using a standard e-beam lithography and lift-off process. Fabricated diabolo optical antenna arrays were characterized by measuring the transmittance and reflectance with a microscope-coupled FTIR spectrometer. It was found experimentally that reducing the waist width significantly shifts the resonance to longer wavelength and narrowing the waist of the antennas is more effective than increasing the period of the array for tuning the resonance wavelength. Also it is found that the magnetic field enhancement near the antenna waist is correlated to the shift of the resonance wavelength.

  10. Phased array antenna for space shuttle orbiter

    NASA Technical Reports Server (NTRS)

    Davidson, Shayla E.

    1987-01-01

    The National Aeronautics and Space Administration is developing a distributed phased array antenna at the Lyndon B. Johnson Space Center as a possible upgrade for the Space Shuttle Orbiter S-band phase modulation communications system. The antenna consists of an eight-element transmit section, eight-element receive section, and a single L-band receive element. The antenna design is constrained by the existing Orbiter system and space environment. The solution to the interface design problems led to an antenna system which provides improved link margins and yet supports previous operational configurations. This paper describes the system development, antenna hardware, and the interface consideration which led to the final design.

  11. Wideband Microstrip Antenna-Feeding Array

    NASA Technical Reports Server (NTRS)

    Huang, John

    1990-01-01

    Special impedance-matching probes help reduce feed complexity. Lightweight array of microstrip antenna elements designed to transmit and illuminate reflector antenna with circularly polarized radiation at 1,545 to 1,550 MHz and to receive circularly polarized radiation at 1,646 to 1,660 MHz. Microstrip array is cluster of 7 subarrays containing total of 28 microstrip patches. Produces cicularly polarized beam with suitable edge taper to illuminate reflector antenna. Teardrop-shaped feed probe provides gradual change of field from coaxial transmission line into microstrip substrate. Intended to be part of larger overlapping-cluster array generating multiple contiguous beams.

  12. Adaptive antenna arrays for weak interfering signals

    NASA Technical Reports Server (NTRS)

    Gupta, I. J.

    1985-01-01

    The interference protection provided by adaptive antenna arrays to an Earth station or satellite receive antenna system is studied. The case where the interference is caused by the transmission from adjacent satellites or Earth stations whose signals inadverently enter the receiving system and interfere with the communication link is considered. Thus, the interfering signals are very weak. To increase the interference suppression, one can either decrease the thermal noise in the feedback loops or increase the gain of the auxiliary antennas in the interfering signal direction. Both methods are examined. It is shown that one may have to reduce the noise correlation to impractically low values and if directive auxiliary antennas are used, the auxiliary antenna size may have to be too large. One can, however, combine the two methods to achieve the specified interference suppression with reasonable requirements of noise decorrelation and auxiliary antenna size. Effects of the errors in the steering vector on the adaptive array performance are studied.

  13. Juno Microwave Radiometer Patch Array Antennas

    NASA Technical Reports Server (NTRS)

    Chamberlain, N.; Chen, J.; Focardi, P.; Hodges, R.; Hughes, R.; Jakoboski, J.; Venkatesan, J.; Zawadzki, M.

    2009-01-01

    Juno is a mission in the NASA New Frontiers Program with the goal of significantly improving our understanding of the formation and structure of Jupiter. This paper discusses the modeling and measurement of the two patch array antennas. An overview of the antenna architecture, design and development at JPL is provided, along with estimates of performance and the results of measurements.

  14. Phased-Antenna-Array Conical Scanning

    NASA Technical Reports Server (NTRS)

    Lesh, J. R.

    1984-01-01

    Antenna pointing faster than mechanical scanning. Three antenna phased array connected to receiving signal-processing system through two phase-shifting networks. Two networks simultaneously steer phased array in two slightly-different beam directions; one for scanning, one for tracking. Technique has many uses in military and civilian radar, principally in tracking aircraft, balloonborne weather instruments, and other moving signal sources or reflectors.

  15. Fundamental Limitations of Phased Array Antenna Elements

    DTIC Science & Technology

    2015-12-15

    Radiation Q of InfinitePlanar Dipole Phased Arrays, IEEE Transactions on Antennas and Propagation, (01 2014): 153. doi: Yong Heui Cho, Do-Hoon Kwon...element bandwidth bounds were found in terms of the strengths of the induced electric and magnetic dipole moments, taking into account of the coupling...Distribution Unlimited UU UU UU UU 15-12-2015 1-Oct-2012 30-Sep-2015 Final Report: Fundamental Limitations of Phased Array Antenna Elements The views

  16. Microstrip antennas and arrays on chiral substrates

    NASA Astrophysics Data System (ADS)

    Pozar, David M.

    1992-10-01

    Results are presented for isolated microstrip antennas and infinite arrays of microstrip antennas printed on chiral substrates, computed from full-wave spectral domain moment method solutions. Data for resonant length, impedance, directivity, efficiency, cross-polarization level, and scan performance are given, and compared to results obtained for a dielectric substrate of the same thickness and permittivity. It is concluded that, from the point of view of antenna characteristics, there does not seem to be any advantage to using chiral antenna substrates, while there are disadvantages in terms of increased cross-pol levels and losses due to surface wave excitation.

  17. Graphene array antenna for 5G applications

    NASA Astrophysics Data System (ADS)

    Sa'don, Siti Nor Hafizah; Kamarudin, Muhammad Ramlee; Ahmad, Fauzan; Jusoh, Muzammil; Majid, Huda A.

    2017-02-01

    Fifth generation (5G) needs to provide better coverage than the previous generation. However, high frequency and millimeter wave experience penetration loss, propagation loss and even more loss in energy for long distance. Hence, a graphene array antenna is proposed for high gain to cover a long distance communications since array antenna enables in providing more directive beams. The investigation is conducted on three types of substrates with gain achieved is more than 7 dBi. The gain obtained is good since it is comparable with other studies. In addition, these antennas consume small numbers of elements to achieve high gain.

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

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

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

  19. Monitoring techniques for phased-array antennas

    NASA Astrophysics Data System (ADS)

    Ronen, J.; Clarke, R. H.

    1985-12-01

    The problem of monitoring phased-array antennas in general and microwave landing system (MLS) in particular is considered. Various methods of monitoring phased-array antennas are suggested. One is based on changes in the far field radiation pattern arising from defects in the array. Another method uses the near-field to far-field transformation, based on the concept of the plane-wave spectrum, for the detection of defects in the antenna. A third method is based on near-field measurements and uses the properties of the Fresnel integral. The methods were simulated on the computer and, where possible, were tested by experiment. A comparative assessment of the methods is given, and an operational monitoring system is suggested for the MLS phased array.

  20. Planar microstrip YAGI antenna array

    NASA Astrophysics Data System (ADS)

    Huang, John

    1993-06-01

    A directional microstrip antenna includes a driven patch surrounded by an isolated reflector and one or more coplanar directors, all separated from a ground plane on the order of 0.1 wavelength or less to provide end fire beam directivity without requiring power dividers or phase shifters. The antenna may be driven at a feed point a distance from the center of the driven patch in accordance with conventional microstrip antenna design practices for H-plane coupled or horizontally polarized signals. The feed point for E-plane coupled or vertically polarized signals is at a greater distance from the center than the first distance. This feed point is also used for one of the feed signals for circularly polarized signals. The phase shift between signals applied to feed points for circularly polarized signals must be greater than the conventionally required 90 degrees and depends upon the antenna configuration.

  1. Planar microstrip YAGI antenna array

    NASA Technical Reports Server (NTRS)

    Huang, John (Inventor)

    1993-01-01

    A directional microstrip antenna includes a driven patch surrounded by an isolated reflector and one or more coplanar directors, all separated from a ground plane on the order of 0.1 wavelength or less to provide end fire beam directivity without requiring power dividers or phase shifters. The antenna may be driven at a feed point a distance from the center of the driven patch in accordance with conventional microstrip antenna design practices for H-plane coupled or horizontally polarized signals. The feed point for E-plane coupled or vertically polarized signals is at a greater distance from the center than the first distance. This feed point is also used for one of the feed signals for circularly polarized signals. The phase shift between signals applied to feed points for circularly polarized signals must be greater than the conventionally required 90 degrees and depends upon the antenna configuration.

  2. Trends in Array Antenna Research,

    DTIC Science & Technology

    1977-06-01

    is written: 81. Ruze, J. (1952) Physical Limitations on Antennas. MIT Research Lab . Electronics Tech. Rept. 248. 82. Miller, C. J. (19G4...MIT Radiation Lab ., Cambridge, MA, Hep 479. Ruze, J. (19f>5) Lateral feed displacement in a paraboloid, IEEE Trans. Antennas Propagation...field effects such U the use of a filter near small diffrating obstacles, and in the presence of fields with pseudo- random phase variations. The

  3. The development of inflatable array antennas

    NASA Technical Reports Server (NTRS)

    Huang, J.

    2001-01-01

    Inflatable array antennas are being developed to significantly reduce the mass, the launch vehicle's stowage volume, and the cost of future spacecraft systems. Three inflatable array antennas, recently developed for spacecraft applications, are a 3.3 m x 1.0 m L-band synthetic-aperture radar (SAR) array, a 1.0 m-diameter X-band telecom reflectarray, and a 3 m-diameter Ka-band telecom reflectarray. All three antennas are similar in construction, and each consists of an inflatable tubular frame that supports and tensions a multi-layer thin-membrane RF radiating surface with printed microstrip patches. The L-band SAR array achieved a bandwidth of 80 MHz, an aperture efficiency of 74%, and a total mass of 15 kg. The X-band reflectarray achieved an aperture efficiency of 37%, good radiation patterns, and a total mass of 1.2 kg (excluding the inflation system). The 3 m Ka-band reflectarray achieved a surface flatness of 0.1 mm RMS, good radiation patterns, and a total mass of 12.8 kg (excluding the inflation system). These antennas demonstrated that inflatable arrays are feasible across the microwave and millimeter-wave spectrums. Further developments of these antennas are deemed necessary, in particular, in the area of qualifying the inflatable structures for space-environment usage.

  4. Magnetic antenna excitation of whistler modes. II. Antenna arrays

    NASA Astrophysics Data System (ADS)

    Stenzel, R. L.; Urrutia, J. M.

    2014-12-01

    The excitation of whistler modes from magnetic loop antennas has been investigated experimentally. The field topology of the excited wave driven by a single loop antenna has been measured for different loop orientations with respect to the uniform background field. The fields from two or more antennas at different locations are then created by superposition of the single-loop data. It is shown that an antenna array can produce nearly plane waves which cannot be achieved with single antennas. By applying a phase shift along the array, oblique wave propagation is obtained. This allows a meaningful comparison with plane wave theory. The Gendrin mode and oblique cyclotron resonance are demonstrated. Wave helicity and polarization in space and time are demonstrated and distinguished from the magnetic helicity of the wave field. The superposition of two oblique plane whistler modes produces in a "whistler waveguide" mode whose polarization and helicity properties are explained. The results show that single point measurements cannot properly establish the wave character of wave packets. The laboratory observations are relevant for excitation and detection of whistler modes in space plasmas.

  5. Magnetic antenna excitation of whistler modes. II. Antenna arrays

    SciTech Connect

    Stenzel, R. L.; Urrutia, J. M.

    2014-12-15

    The excitation of whistler modes from magnetic loop antennas has been investigated experimentally. The field topology of the excited wave driven by a single loop antenna has been measured for different loop orientations with respect to the uniform background field. The fields from two or more antennas at different locations are then created by superposition of the single-loop data. It is shown that an antenna array can produce nearly plane waves which cannot be achieved with single antennas. By applying a phase shift along the array, oblique wave propagation is obtained. This allows a meaningful comparison with plane wave theory. The Gendrin mode and oblique cyclotron resonance are demonstrated. Wave helicity and polarization in space and time are demonstrated and distinguished from the magnetic helicity of the wave field. The superposition of two oblique plane whistler modes produces in a “whistler waveguide” mode whose polarization and helicity properties are explained. The results show that single point measurements cannot properly establish the wave character of wave packets. The laboratory observations are relevant for excitation and detection of whistler modes in space plasmas.

  6. Signal space models for antenna arrays

    NASA Astrophysics Data System (ADS)

    Sandler, S. S.

    1985-04-01

    Some concepts in retinal vision are related here to the area of antennas and antenna arrays. In particular, the principles of insect motion detection based on visual cues have been applied to time-domain radar analysis. Using an example in which simple specular scattering applies, relative velocities are shown to be directly calculable in the case of short temporal pulse radar from phase-independent information for either a moving radar or a moving target.

  7. Antenna-Coupled Bolometer Arrays for Astrophysics

    NASA Astrophysics Data System (ADS)

    Bock, James

    Bolometers offer the best sensitivity in the far-infrared to millimeter-wave region of the electromagnetic spectrum. We are developing arrays of feedhorn-coupled bolometers for the ESA/NASA Planck Surveyor and Herschel Space Observatory. Advances in the format and sensitivity of bolometric focal plane array enables future astrophysics mission opportunities, such as CMB polarimetry and far-infrared/submillimeter spectral line surveys. Compared to bolometers with extended area radiation absorbers, antenna-coupled bolometers offer active volumes that are orders of magnitude smaller. Coupled to lithographed micro-strip filters and antennas, antenna-coupled bolometer arrays allow flexible focal plane architectures specialized for imaging, polarimetry, and spectroscopy. These architectures greatly reduce the mass of sub-Kelvin bolometer focal planes that drive the design of bolometric instrumentation.

  8. Breadboard Signal Processor for Arraying DSN Antennas

    NASA Technical Reports Server (NTRS)

    Jongeling, Andre; Sigman, Elliott; Chandra, Kumar; Trinh, Joseph; Soriano, Melissa; Navarro, Robert; Rogstad, Stephen; Goodhart, Charles; Proctor, Robert; Jourdan, Michael; Rayhrer, Benno

    2008-01-01

    A recently developed breadboard version of an advanced signal processor for arraying many antennas in NASA s Deep Space Network (DSN) can accept inputs in a 500-MHz-wide frequency band from six antennas. The next breadboard version is expected to accept inputs from 16 antennas, and a following developed version is expected to be designed according to an architecture that will be scalable to accept inputs from as many as 400 antennas. These and similar signal processors could also be used for combining multiple wide-band signals in non-DSN applications, including very-long-baseline interferometry and telecommunications. This signal processor performs functions of a wide-band FX correlator and a beam-forming signal combiner. [The term "FX" signifies that the digital samples of two given signals are fast Fourier transformed (F), then the fast Fourier transforms of the two signals are multiplied (X) prior to accumulation.] In this processor, the signals from the various antennas are broken up into channels in the frequency domain (see figure). In each frequency channel, the data from each antenna are correlated against the data from each other antenna; this is done for all antenna baselines (that is, for all antenna pairs). The results of the correlations are used to obtain calibration data to align the antenna signals in both phase and delay. Data from the various antenna frequency channels are also combined and calibration corrections are applied. The frequency-domain data thus combined are then synthesized back to the time domain for passing on to a telemetry receiver

  9. An LTCC 94 GHz Antenna Array

    SciTech Connect

    Aguirre, J; Pao, H; Lin, H; Garland, P; O'Neill, D; Horton, K

    2007-12-21

    An antenna array is designed in low-temperature cofired ceramic (LTCC) Ferro A6M{trademark} for a mm-wave application. The antenna is designed to operate at 94 GHz with a few percent bandwidth. A key manufacturing technology is the use of 3 mil diameter vias on a 6 mil pitch to construct the laminated waveguides that form the beamforming network and radiating elements. Measurements for loss in the laminated waveguide are presented. The slot-fed cavity-radiating element is designed to account for extremely tight mutual coupling between elements. The array incorporates a slot-fed multi-layer beamforming network.

  10. Deployable Wide-Aperture Array Antennas

    NASA Technical Reports Server (NTRS)

    Fink, Patrick W.; Dobbins, Justin A.; Lin, Greg Y.; Chu, Andrew; Scully, Robert C.

    2005-01-01

    Inexpensive, lightweight array antennas on flexible substrates are under development to satisfy a need for large-aperture antennas that can be stored compactly during transport and deployed to full size in the field. Conceived for use aboard spacecraft, antennas of this type also have potential terrestrial uses . most likely, as means to extend the ranges of cellular telephones in rural settings. Several simple deployment mechanisms are envisioned. One example is shown in the figure, where the deployment mechanism, a springlike material contained in a sleeve around the perimeter of a flexible membrane, is based on a common automobile window shade. The array can be formed of antenna elements that are printed on small sections of semi-flexible laminates, or preferably, elements that are constructed of conducting fabric. Likewise, a distribution network connecting the elements can be created from conventional technologies such as lightweight, flexible coaxial cable and a surface mount power divider, or preferably, from elements formed from conductive fabrics. Conventional technologies may be stitched onto a supporting flexible membrane or contained within pockets that are stitched onto a flexible membrane. Components created from conductive fabrics may be attached by stitching conductive strips to a nonconductive membrane, embroidering conductive threads into a nonconductive membrane, or weaving predetermined patterns directly into the membrane. The deployable antenna may comprise multiple types of antenna elements. For example, thin profile antenna elements above a ground plane, both attached to the supporting flexible membrane, can be used to create a unidirectional boresight radiation pattern. Or, antenna elements without a ground plane, such as bow-tie dipoles, can be attached to the membrane to create a bidirectional array such as that shown in the figure. For either type of antenna element, the dual configuration, i.e., elements formed of slots in a conductive

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  18. A thirty-six element array antenna system

    NASA Technical Reports Server (NTRS)

    Graf, E. R.

    1969-01-01

    Thirty-six element square array, with mutual coupling between crossed slots for array elements, is used as an electronically scanned tracking antenna. The system does not require the movement of the antenna or the presence of an operator.

  19. Feasibility study of a synthesis procedure for array feeds to improve radiation performance of large distorted reflector antennas

    NASA Technical Reports Server (NTRS)

    Stutzman, Warren L.; Takamizawa, K.; Werntz, P.; Lapean, J.; Shen, B.

    1993-01-01

    Virginia Tech has several activities which support the NASA Langley effort in the area of large aperture radiometric antenna systems. This semi-annual report discusses the major areas of research and progress made.

  20. 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.

  1. Biologically-inspired, electrically small antenna arrays

    NASA Astrophysics Data System (ADS)

    Masoumi, Amir Reza

    First, the motivation behind adding a passive external coupling network after antenna arrays is discussed, the concept of biomimetic antenna arrays (BMAAs) introduced and some of the previous work done in this area have been reviewed. Next, a BMAA which achieves an angular resolution of roughly 15 times its regular counterpart is introduced and fully characterized. The introduced BMAA employs transformers which considerably degrade its performance, namely its output power. To cicumvent this shortcoming a new architecture of a BMAA that does not employ transformers and therefore yields a higher output power for the same angular resolution has been subsequently presented. Moreover, a detailed noise analysis of this BMAA is carried out and the output noise of the new architecture is compared with the output noise of the original design. The modified twoelement BMAA architecture is then extended to multiple elements. A novel nonlinear optimization process is introduced that maximizes the total power captured by the BMAA for a given angular resolution and the concept illustrated for a three-element antenna array. Next an optimum two-element BMAA which achieves the maximum possible angular resolution while obtaining the same output power level of a regular antenna array with the same elements and spacing is introduced. A novel two-element superdirective array based on this optimum BMAA has been also discussed. The passive BMAAs discussed in this thesis have a relatively narrow bandwidth. To extend the bandwidth of BMAAs, non- Foster networks have been employed in their external coupling networks and it has been demonstrated that they can increase their bandwidth by a factor of roughly 33. Finally, the BMAA concept has been extended to nano-antenna arrays and a concept for designing sub-wavelength angle-sensing detectors at optical wavelengths has been introduced.

  2. Phased Antenna Array for Global Navigation Satellite System Signals

    NASA Technical Reports Server (NTRS)

    Turbiner, Dmitry (Inventor)

    2015-01-01

    Systems and methods for phased array antennas are described. Supports for phased array antennas can be constructed by 3D printing. The array elements and combiner network can be constructed by conducting wire. Different parameters of the antenna, like the gain and directivity, can be controlled by selection of the appropriate design, and by electrical steering. Phased array antennas may be used for radio occultation measurements.

  3. Terahertz Array Receivers with Integrated Antennas

    NASA Technical Reports Server (NTRS)

    Chattopadhyay, Goutam; Llombart, Nuria; Lee, Choonsup; Jung, Cecile; Lin, Robert; Cooper, Ken B.; Reck, Theodore; Siles, Jose; Schlecht, Erich; Peralta, Alessandro; hide

    2011-01-01

    Highly sensitive terahertz heterodyne receivers have been mostly single-pixel. However, now there is a real need of multi-pixel array receivers at these frequencies driven by the science and instrument requirements. In this paper we explore various receiver font-end and antenna architectures for use in multi-pixel integrated arrays at terahertz frequencies. Development of wafer-level integrated terahertz receiver front-end by using advanced semiconductor fabrication technologies has progressed very well over the past few years. Novel stacking of micro-machined silicon wafers which allows for the 3-dimensional integration of various terahertz receiver components in extremely small packages has made it possible to design multi-pixel heterodyne arrays. One of the critical technologies to achieve fully integrated system is the antenna arrays compatible with the receiver array architecture. In this paper we explore different receiver and antenna architectures for multi-pixel heterodyne and direct detector arrays for various applications such as multi-pixel high resolution spectrometer and imaging radar at terahertz frequencies.

  4. Terahertz Array Receivers with Integrated Antennas

    NASA Technical Reports Server (NTRS)

    Chattopadhyay, Goutam; Llombart, Nuria; Lee, Choonsup; Jung, Cecile; Lin, Robert; Cooper, Ken B.; Reck, Theodore; Siles, Jose; Schlecht, Erich; Peralta, Alessandro; Thomas, Bertrand; Mehdi, Imran

    2011-01-01

    Highly sensitive terahertz heterodyne receivers have been mostly single-pixel. However, now there is a real need of multi-pixel array receivers at these frequencies driven by the science and instrument requirements. In this paper we explore various receiver font-end and antenna architectures for use in multi-pixel integrated arrays at terahertz frequencies. Development of wafer-level integrated terahertz receiver front-end by using advanced semiconductor fabrication technologies has progressed very well over the past few years. Novel stacking of micro-machined silicon wafers which allows for the 3-dimensional integration of various terahertz receiver components in extremely small packages has made it possible to design multi-pixel heterodyne arrays. One of the critical technologies to achieve fully integrated system is the antenna arrays compatible with the receiver array architecture. In this paper we explore different receiver and antenna architectures for multi-pixel heterodyne and direct detector arrays for various applications such as multi-pixel high resolution spectrometer and imaging radar at terahertz frequencies.

  5. Microstrip antenna arrays with parasitic elements

    NASA Technical Reports Server (NTRS)

    Lee, Kai-Fong

    1996-01-01

    This research was concerned with using parasitic elements to improve the bandwidth, gain and axial ratio characteristics of microstrip antennas and arrays. Significant improvements in these characteristics were obtained using stacked and coplanar parasitic elements. Details of the results are described in a total of 16 journal and 17 conference papers. These are listed in Section four of this report.

  6. Coplanar waveguide fed phased array antenna

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Ponchak, George E.; Lee, R. Q.; Fernandez, N. S.

    1990-01-01

    A K-band four element linear phased array was designed and tested. Coplanar waveguide (CPW) is used for the microwave distribution system. A CPW to twin strip transition is used to interface with the printed dipole antennas. MMIC phased shifters are used for phase control.

  7. Antenna and solar arrays from Soyuz spacecraft

    NASA Image and Video Library

    2013-08-29

    View of antenna and solar arrays (with an Earth limb in the background) taken from a window in the Russian Soyuz spacecraft currently docked to the International Space Station. Photo taken by an Expedition 36 crewmember. Per Twitter message: View out the window to the right of my seat in Soyuz while docked to ISS.

  8. Microelectromechanical Switches for Phased Array Antennas

    NASA Technical Reports Server (NTRS)

    Ponchak, George E.; Simons, Rainee N.; Scardelletti, Maximillian; Varaljay, Nicholas C.

    2000-01-01

    Preliminary results are presented on the fabrication and testing of a MicroElectro-Mechanical (MEM) microstrip series switch. This switch is being developed for use in a K-band phased array antenna that NASA will use for communication links in its Earth orbiting satellites. Preliminary insertion loss and isolation measurements are presented.

  9. Layout and cabling considerations for a large communications antenna array

    NASA Technical Reports Server (NTRS)

    Logan, R. T., Jr.

    1993-01-01

    Layout considerations for a large deep space communications antenna array are discussed. A fractal geometry for the antenna layout is described that provides optimal packing of antenna elements, efficient cable routing, and logical division of the array into identical sub-arrays.

  10. Conformal Impulse Receive Antenna Arrays

    DTIC Science & Technology

    2007-11-02

    equations then becomes the integro - differential equation )26()()(’)’()’( 1 ’)’()’( 0 2 02 0 2...air-dielectric interface and backed by a perfectly conducting plane. We obtained an integro - differential equation for the surface current density on...multi-element array requires that we solve a certain integro - differential equation for the surface current density on the array. This equation

  11. Interleaved arrays antenna technology development

    NASA Technical Reports Server (NTRS)

    1986-01-01

    Phase one and two of a program to further develop and investigate advanced graphite epoxy waveguides, radiators, and components with application to space antennas are discussed. The objective of the two phases were to demonstrate mechanical integrity of a small panel of radiators and parts procured under a previous contract and to develop alternate designs and applications of the technology. Most of the emphasis was on the assembly and test of a 5 x 5 element module. This effort was supported by evaluation of adhesives and waveguide joint configurations. The evaluation and final assembly considered not only mechanical performance but also producibility in large scale.

  12. Feasibility study of a synthesis procedure for array feeds to improve radiation performance of large distorted reflector antennas

    NASA Technical Reports Server (NTRS)

    Stutzman, W. L.; Takamizawa, K.; Lapean, J.

    1993-01-01

    There were several tangible products that resulted from the reflector antenna research program. The initial technical effort was to develop techniques to compensate for distortions over the surface of the main reflector of a large reflector antenna system. An in-depth investigation of this problem resulted in a new technique for the electronic correction of surface errors. A journal article on the findings describe the use of the iterative sampling method. Shortly after the 'Mission to Planet Earth' program started, we began investigating the use of large reflector antennas in geostationary orbit for passive earth remote sensing. A study panel was coordinated by Virginia Tech to set technical goals for the effort. These were used to guide the design of several antennas. The original interest stemmed from an industrial (Reynolds Metals) need and currently involves work with industry (Prodelin Corporation) on high technology, low cost reflectors. The intervening years (1987 - 1993) is the period of this report and Virginia Tech's reflector antenna activity then was exclusively with NASA LaRC.

  13. Phased array antenna with couplers in spatial filter arrangement

    NASA Astrophysics Data System (ADS)

    Lopez, Alfred R.

    1992-02-01

    A lossless spatial filter is provided between the antenna input ports and the elements of an array antenna so that the effective element pattern associated with each input port is primarily within a selected angular region of space. The antenna elements are arranged along a predetermined path and each element is connected to only one output port of the spatial filter. A beam steering unit controls the direction of radiation and includes N phase shifters and means for controlling the phase shifters. Each phase shifter has an input port and an output port which is connected to only one input port of the spatial filter. The antenna also includes a supply means for supplying wave energy signals. The supply means includes a signal generator supplying a power divider having N output signal ports, each output port connected to only one phase shifter input port. In microwave landing systems, this invention provides a non-thinned or fully filled array which may be used to achieve linearity and minimize the field monitor distance for the glide path antenna. A synthesis procedure for a five level non-thinned spatial filter is included.

  14. 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.

  15. 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.

  16. Antenna arrays for producing plane whistler waves

    NASA Astrophysics Data System (ADS)

    Stenzel, Reiner; Urrutia, J. Manuel

    2014-10-01

    Linear whistler modes with ω ~= 0 . 3ωce <<ωpe are excited in a large laboratory plasma with magnetic loop antennas. A single antenna always produces a spatially bounded wave packet whose propagation cannot be directly compared to plane wave theories. By superimposing the fields from spatially separated antennas, the wavenumber along the antenna array can be nearly eliminated. 2D arrays nearly produce plane waves. The angle θ of wave propagation has been varied by a phase shift along the array. The refractive index surface n (θ) has been measured. The parallel phase and group velocities for Gendrin modes has been demonstrated. The interference between two oblique plane whistlers creates a whistler ``waveguide'' mode, i.e. standing waves for k ⊥B0 and propagation for k | |B0 . It also describes the reflection of oblique whistlers from a sharp discontinuity in the refractive index or conductivity. Radial reflections are also a dominant factor in small plasma columns of helicon devices. These results are of interest to space and laboratory plasmas. Work supported by NSF/DOE.

  17. 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.

  18. Phased array antenna beamforming using optical processor

    NASA Technical Reports Server (NTRS)

    Anderson, L. P.; Boldissar, F.; Chang, D. C. D.

    1991-01-01

    The feasibility of optical processor based beamforming for microwave array antennas is investigated. The primary focus is on systems utilizing the 20/30 GHz communications band and a transmit configuration exclusively to serve this band. A mathematical model is developed for computation of candidate design configurations. The model is capable of determination of the necessary design parameters required for spatial aspects of the microwave 'footprint' (beam) formation. Computed example beams transmitted from geosynchronous orbit are presented to demonstrate network capabilities. The effect of the processor on the output microwave signal to noise quality at the antenna interface is also considered.

  19. 802GHz integrated horn antennas imaging array

    NASA Technical Reports Server (NTRS)

    Ali-Ahmad, Walid Y.; Rebeiz, Gabriel M.; Dave, Hemant; Chin, Gordon

    1991-01-01

    Pattern measurements at 802GHz of a single element in 256-element integrated horn imaging array are presented. The integrated-horn antenna consists of a dipole-antenna suspended on a 1-micron dielectric membrane inside a pyramidal cavity etched in silicon. The theoretical far-field patterns, calculated using reciprocity and Floquet-modes representation of the free-space field, agree well with the measured far-field patterns at 802GHz. The associated directivity for a 1.40 lambda horn aperture, calculated from the measured E and H-plane patterns is 12.3dB + or - 0.2dB. This work demonstrates that high-efficiency integrated-horn antennas are easily scalable to terahertz frequencies and could be used for radio-astronomical and plasma-diagnostic applications.

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

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

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

  1. 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.

  2. Arrays of recycled power TM polarized nano-antennas.

    PubMed

    Hattori, Haroldo T; Li, Ziyuan

    2013-07-15

    In recent years, plasmonic nano-antennas have been used in a wide range of applications in sensing, particle detection, imaging and Surface Enhanced Raman Scattering (SERS) detection. Also, arrays of nano-antennas have been recently developed to produce more directional radiation beams or to operate over a wide range of wavelengths. In this article, it is shown that small arrays of nano-antennas can be created by recycling the power that flows through their antenna gaps.

  3. Microstrip Antenna Arrays on Multilayer LCP Substrates

    NASA Technical Reports Server (NTRS)

    Thompson, Dane; Bairavasubramanian, Ramanan; Wang, Guoan; Kingsley, Nickolas D.; Papapolymerou, Ioannis; Tenteris, Emmanouil M.; DeJean, Gerald; Li, RonglLin

    2007-01-01

    A research and development effort now underway is directed toward satisfying requirements for a new type of relatively inexpensive, lightweight, microwave antenna array and associated circuitry packaged in a thin, flexible sheet that can readily be mounted on a curved or flat rigid or semi-rigid surface. A representative package of this type consists of microwave antenna circuitry embedded in and/or on a multilayer liquid- crystal polymer (LCP) substrate. The circuitry typically includes an array of printed metal microstrip patch antenna elements and their feedlines on one or more of the LCP layer(s). The circuitry can also include such components as electrostatically actuated microelectromechanical systems (MEMS) switches for connecting and disconnecting antenna elements and feedlines. In addition, the circuitry can include switchable phase shifters described below. LCPs were chosen over other flexible substrate materials because they have properties that are especially attractive for high-performance microwave applications. These properties include low permittivity, low loss tangent, low water-absorption coefficient, and low cost. By means of heat treatments, their coefficients of thermal expansion can be tailored to make them more amenable to integration into packages that include other materials. The nature of the flexibility of LCPs is such that large LCP sheets containing antenna arrays can be rolled up, then later easily unrolled and deployed. Figure 1 depicts a prototype three- LCP-layer package containing two four-element, dual-polarization microstrip-patch arrays: one for a frequency of 14 GHz, the other for a frequency of 35 GHz. The 35-GHz patches are embedded on top surface of the middle [15-mil (approx.0.13-mm)-thick] LCP layer; the 14- GHz patches are placed on the top surface of the upper [9-mil (approx. 0.23-mm)-thick] LCP layer. The particular choice of LCP layer thicknesses was made on the basis of extensive analysis of the effects of the

  4. 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.

  5. Auxiliary antenna-assisted interference mitigation for radio astronomy arrays

    NASA Astrophysics Data System (ADS)

    Jeffs, B. D.; Li, L.; Warnick, K. F.

    2005-02-01

    Interferometric image synthesis in radio astronomy is plagued by signal corruption from man-made sources. The very weak signals of interest can be overwhelmed by such interference. Recent work has proposed using array signal processing techniques of adaptive beamforming, adaptive filtering, and subspace projection to remove interference prior to image synthesis. In some practical scenarios, we have found poor cancellation performance when using such methods. Because signal-of-interest levels in radio astronomy (RA) are usually well below the noise, even interference to noise ratios (INR) less than unity can affect signal estimation. At these low INRs, it is difficult to estimate interference parameters or statistics with sufficient accuracy for high-performance adaptive cancellation or subspace projection. By adding a few (one to three) low-gain (relative to the primary telescope dishes) "auxiliary" antennas to an array, it is possible to overcome this problem. This paper will show that using such antennas (e.g. commercial-grade 3-m dishes) with an existing array can significantly improve interference rejection. New extensions to subspace projection spatial filtering methods are presented, along with analytical and simulated results for performance comparison.

  6. Optimizing the Antenna Size for the Deep Space Network Array

    NASA Astrophysics Data System (ADS)

    Statman, J. I.; Bagri, D. S.; Yung, C. S.; Weinreb, S.; MacNeal, B. E.

    2004-11-01

    JPL, in conjunction with NASA Headquarters (Code SE), is conducting a feasibility study for a Deep Space Network Array. The DSN Array will have a gain-to-noise temperature ratio (G/T) that is equivalent to ten times the G/T of the 70-m antenna subnet at approximately 8.4 GHz (X-band) by arraying a large number of small antennas. (At approximately 32 GHz (Ka-band), the G/T is four times higher!) Similarly, the DSN Array achieves the flux density of several 20-kW X-band transmitters by arraying smaller transmitters on smaller antennas. The life-cycle cost (LCC) of the DSN Array, including development, installation, and operations, will vary depending on the antenna size. This article updates prior work by Weinreb and MacNeal on optimizing the antenna size for the downlink, and adds a similar study for the uplink antennas. The basic methodology is to compute the antenna-related LCC as a function of antenna diameter and select the antenna diameters that minimize the LCC. The antenna-related LCC is approximated by the sum of the recurring engineering (RE) cost for the antenna-related components and the operations and maintenance (O&M) costs for the antenna part of the DSN Array for 20 years, assuming that the RE is amortized over 20 years as well. To compute the full DSN Array LCC, one has to add the non-recurring engineering (NRE) and the non-antenna RE and O&M costs. The key result is that, for downlink, the selected antenna size is 12 m and, for uplink, the selected antenna size is around 34 m.

  7. Impulse Testing of Corporate-Fed Patch Array Antennas

    NASA Technical Reports Server (NTRS)

    Chamberlain, Neil F.

    2011-01-01

    This paper discusses a novel method for detecting faults in antenna arrays. The method, termed Impulse Testing, was developed for corporate-fed patch arrays where the element is fed by a probe and is shorted at its center. Impulse Testing was devised to supplement conventional microwave measurements in order to quickly verify antenna integrity. The technique relies on exciting each antenna element in turn with a fast pulse (or impulse) that propagates through the feed network to the output port of the antenna. The resulting impulse response is characteristic of the path through the feed network. Using an oscilloscope, a simple amplitude measurement can be made to detect faults. A circuit model of the antenna elements and feed network was constructed to assess various fault scenarios and determine fault-detection thresholds. The experimental setup and impulse measurements for two patch array antennas are presented. Advantages and limitations of the technique are discussed along with applications to other antenna array topologies

  8. Adaptive antenna arrays for satellite communication

    NASA Technical Reports Server (NTRS)

    Gupta, Inder J.

    1989-01-01

    The feasibility of using adaptive antenna arrays to provide interference protection in satellite communications was studied. The feedback loops as well as the sample matric inversion (SMI) algorithm for weight control were studied. Appropriate modifications in the two were made to achieve the required interference suppression. An experimental system was built to test the modified feedback loops and the modified SMI algorithm. The performance of the experimental system was evaluated using bench generated signals and signals received from TVRO geosynchronous satellites. A summary of results is given. Some suggestions for future work are also presented.

  9. An algorithm for signal processing in multibeam antenna arrays

    NASA Astrophysics Data System (ADS)

    Danilevskii, L. N.; Domanov, Iu. A.; Korobko, O. V.

    1980-09-01

    A signal processing method for multibeam antenna arrays is presented which can be used to effectively reduce discrete-phasing sidelobes. Calculations of an 11-element array are presented as an example.

  10. Infrared technology for satellite power conversion. [antenna arrays and bolometers

    NASA Technical Reports Server (NTRS)

    Campbell, D. P.; Gouker, M. A.; Gallagher, J. J.

    1984-01-01

    Successful fabrication of bismuth bolometers led to the observation of antenna action rom array elements. Fabrication of the best antennas arrays was made more facile with finding that increased argon flow during the dc sputtering produced more uniform bismuth films and bonding to antennas must be done with the substrate temperaure below 100 C. Higher temperatures damaged the bolometers. During the testing of the antennas, it was found that the use of a quasi-optical system provided a uniform radiation field. Groups of antennas were bonded in series and in parallel with the parallel configuration showing the greater response.

  11. Azimuth DOA Estimation in Y-bend Antenna Array

    NASA Astrophysics Data System (ADS)

    Sanudin, R.

    2016-11-01

    In smart antenna system, it is extremely crucial to estimate the direction of incoming signals in order to achieve better reception. Reliability of DOA estimation depends on several factors such as the choice of DOA algorithm, size of antenna array as well as array geometry. Therefore, it is particularly desirable to have a configuration of antenna array that could produce an accurate azimuth estimation. In this work, a new planar array is proposed to address the problem of azimuth estimation. This is achieved by having a flexible element position on the x- y plane that improves the steering vector, hence significantly enhances the accuracy of DOA estimation. Besides, a fair distribution of the antenna elements on the x-y plane also helps to eliminates estimation failure in the azimuth range between 240° and 360°. A comparison study between the proposed array and V-shape array is performed in order to gauge the performance of the proposed array in DOA estimation. Simulation results show that the proposed array has acquired better estimation resolution than V-shape array. On top of that, the proposed array has reduced estimation error in V-shape array. It is concluded that the proposed array has shown potential as an excellent choice of antenna array geometry for smart antenna system.

  12. 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.

  13. 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.

  14. Silicon Micromachined Microlens Array for THz Antennas

    NASA Technical Reports Server (NTRS)

    Lee, Choonsup; Chattopadhyay, Goutam; Mehdi, IImran; Gill, John J.; Jung-Kubiak, Cecile D.; Llombart, Nuria

    2013-01-01

    5 5 silicon microlens array was developed using a silicon micromachining technique for a silicon-based THz antenna array. The feature of the silicon micromachining technique enables one to microfabricate an unlimited number of microlens arrays at one time with good uniformity on a silicon wafer. This technique will resolve one of the key issues in building a THz camera, which is to integrate antennas in a detector array. The conventional approach of building single-pixel receivers and stacking them to form a multi-pixel receiver is not suited at THz because a single-pixel receiver already has difficulty fitting into mass, volume, and power budgets, especially in space applications. In this proposed technique, one has controllability on both diameter and curvature of a silicon microlens. First of all, the diameter of microlens depends on how thick photoresist one could coat and pattern. So far, the diameter of a 6- mm photoresist microlens with 400 m in height has been successfully microfabricated. Based on current researchers experiences, a diameter larger than 1-cm photoresist microlens array would be feasible. In order to control the curvature of the microlens, the following process variables could be used: 1. Amount of photoresist: It determines the curvature of the photoresist microlens. Since the photoresist lens is transferred onto the silicon substrate, it will directly control the curvature of the silicon microlens. 2. Etching selectivity between photoresist and silicon: The photoresist microlens is formed by thermal reflow. In order to transfer the exact photoresist curvature onto silicon, there needs to be etching selectivity of 1:1 between silicon and photoresist. However, by varying the etching selectivity, one could control the curvature of the silicon microlens. The figure shows the microfabricated silicon microlens 5 x5 array. The diameter of the microlens located in the center is about 2.5 mm. The measured 3-D profile of the microlens surface has a

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

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

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

  16. Using Antenna Arrays to Motivate the Study of Sinusoids

    ERIC Educational Resources Information Center

    Becker, J. P.

    2010-01-01

    Educational activities involving antenna arrays to motivate the study of sinusoids are described. Specifically, using fundamental concepts related to phase and simple geometric arguments, students are asked to predict the location of interference nulls in the radiation pattern of two-element phased array antennas. The location of the radiation…

  17. Using Antenna Arrays to Motivate the Study of Sinusoids

    ERIC Educational Resources Information Center

    Becker, J. P.

    2010-01-01

    Educational activities involving antenna arrays to motivate the study of sinusoids are described. Specifically, using fundamental concepts related to phase and simple geometric arguments, students are asked to predict the location of interference nulls in the radiation pattern of two-element phased array antennas. The location of the radiation…

  18. Calculating Directivities of Planar-Array Antenna Feeds

    NASA Technical Reports Server (NTRS)

    Rahmat-Samii, Y.; Lee, S. W.

    1986-01-01

    Design of planar-array antennas and antenna feeds aided by new approach to calculation of array directivity. Technique takes into account polarizations, asymmetries in element patterns, nonuniform element spacings, and arbitrary excitations. Gives numerical results faster than previous integration methods, and results agree with those obtained by older methods.

  19. Highly Directive Reflect Array Antenna Design for Wireless Power Transfer

    DTIC Science & Technology

    2017-04-14

    AFRL-AFOSR-JP-TR-2017-0033 Highly Directive Reflect Array Antenna Design for Wireless Power Transfer Siddhartha Prakash Duttagupta INDIAN INSTITUTE...Directive Reflect Array Antenna Design for Wireless Power Transfer 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA2386-14-1-4076 5c.  PROGRAM ELEMENT NUMBER...Antenna Design for Wireless Power Principal Investigator: SP Duttagupta Email: sdgupta@ee.iitb.ac.in Institution: Indian Institute of Technology

  20. Discrete cyclic porphyrin arrays as artificial light-harvesting antenna.

    PubMed

    Aratani, Naoki; Kim, Dongho; Osuka, Atsuhiro

    2009-12-21

    The importance of photosynthesis has driven researchers to seek ways to mimic its fundamental features in simplified systems. The absorption of a photon by light-harvesting (antenna) complexes made up of a large number of protein-embedded pigments initiates photosynthesis. Subsequently the many pigments within the antenna system shuttle that photon via an efficient excitation energy transfer (EET) until it encounters a reaction center. Since the 1995 discovery of the circularly arranged chromophoric assemblies in the crystal structure of light-harvesting antenna complex LH2 of purple bacteria Rps. Acidophila, many designs of light-harvesting antenna systems have focused on cyclic porphyrin wheels that allow for efficient EET. In this Account, we review recent research in our laboratories in the synthesis of covalently and noncovalently linked discrete cyclic porphyrin arrays as models of the photosynthetic light-harvesting antenna complexes. On the basis of the silver(I)-promoted oxidative coupling strategy, we have prepared a series of extremely long yet discrete meso-meso-linked porphyrin arrays and covalently linked large porphyrin rings. We examined the photophysical properties of these molecules using steady-state absorption, fluorescence, fluorescence lifetime, fluorescence anisotropy decay, and transient absorption measurements. Both the pump-power dependence on the femtosecond transient absorption and the transient absorption anisotropy decay profiles are directly related to the EET processes within the porphyrin rings. Within these structures, the exciton-exciton annihilation time and the polarization anisotropy rise time are well-described in terms of the Forster-type incoherent energy hopping model. In noncoordinating solvents such as CHCl(3), meso-pyridine-appended zinc(II) porphyrins and their meso-meso-linked dimers spontaneously assemble to form tetrameric porphyrin squares and porphyrin boxes, respectively. In the latter case, we have demonstrated

  1. Structural synthesis of spiral antennas

    NASA Astrophysics Data System (ADS)

    Prigoda, B. A.

    2013-12-01

    This article discusses alternative designs of helical antennas used in space vehicles. The dependence of the beam shape on the number of approaches and the mode of excitation of helical antennas is shown.

  2. Development of impedance matching technologies for ICRF antenna arrays

    SciTech Connect

    Pinsker, R.I.

    1998-03-01

    All high power ICRF heating systems include devices for matching the input impedance of the antenna array to the generator output impedance. For most types of antennas used, the input impedance is strongly time-dependent on timescales as rapid as 10-4 s, while the rf generators used are capable of producing full power only into a stationary load impedance. Hence, the dynamic response of the matching method is of great practical importance. In this paper, world-wide developments in this field over the past decade are reviewed. These techniques may be divided into several classes. The edge plasma parameters that determine the antenna array`s input impedance may be controlled to maintain a fixed load impedance. The frequency of the rf source can be feedback controlled to compensate for changes in the edge plasma conditions, or fast variable tuning elements in the transmission line between the generator output and the antenna input connections can provide the necessary time-varying impedance transformation. In lossy passive schemes, reflected power due to the time-varying impedance of the antenna array is diverted to a dummy load. Each of these techniques can be applied to a pre-existing antenna system. If a new antenna is to be designed, recent advances allow the antenna array to have the intrinsic property of presenting a constant load to the feeding transmission lines despite the varying load seen by each antenna in the array.

  3. Wideband Antenna Arraying Over Long Distances

    NASA Astrophysics Data System (ADS)

    Torre Fernandez, A.

    2013-08-01

    Antennas separated by long distances have large delays and delay rates among them. If wide-bandwidth signals are received, frequency domain beamformers based on filter banks can be used to carry out signal combination. A new scheme based on subband delay compensation is proposed in this article. The main advantages of this scheme are the wider field of view of the array, the reduction of distortion in the transfer function, and the simplification of communications among sites. In order to perform coherent combination, the delay and delay rates need to be estimated. In order to do so, an algorithm is devised to estimate the differential phase, delay, and delay rate between two antennas based on the subband signals. This algorithm is first developed for a stationary case, in which the delay rate is zero. The product of subband signals is averaged and an inverse discrete Fourier transform (IDFT) is carried out to yield an estimate of the cross-correlation. For the nonstationary case, first the delay rate is calculated by means of a two-dimensional IDFT, and from that point a function similar to the one in the stationary case is obtained so as to compute the delay and phase offset.

  4. Smart adaptive array antennas for wireless communcations

    NASA Astrophysics Data System (ADS)

    Christodoulou, Christos G.; Georgiopoulos, Michael

    2001-08-01

    This paper discusses an experimental neural network based smart antenna capable of performing direction finding and the necessary beamforming. The Radial Basis Function Neural Network (RBFNN) algorithm is used for both tasks and for multiple signals. The algorithm operates in two stages. The field of view of the antenna array is divided into spatial sectors, then each network is trained in the first stage to detect signals emanating from sources in that sector. According to the outputs of the first stage, one or more networks of the second stage can be activated so as to estimate the exact location of the sources. No a priori knowledge is required about the number of sources, and the networks can be designed to arbitrary angular resolution. Some experimental results are shown and compared with other algorithms, such as, the Fourier Transform and the MUSIC algorithm. The comparisons show the superior performance of the RBFNN and its ability to overcome many limitations of the conventional and other superresolution techniques, specifically by reducing the computational complexity and the ability to deal with a large number of sources.

  5. Compensation of relector antenna surface distortion using an array feed

    NASA Technical Reports Server (NTRS)

    Cherrette, A. R.; Acosta, R. J.; Lam, P. T.; Lee, S. W.

    1988-01-01

    The dimensional stability of the surface of a large reflector antenna is important when high gain or low sidelobe performance is desired. If the surface is distorted due to thermal or structural reasons, antenna performance can be improved through the use of an array feed. The design of the array feed and its relation to the surface distortion are examined. The sensitivity of antenna performance to changing surface parameters for fixed feed array geometries is also studied. This allows determination of the limits of usefulness for feed array compensation.

  6. Technique for Radiometer and Antenna Array Calibration with Two Antenna Noise Diodes

    NASA Technical Reports Server (NTRS)

    Srinivasan, Karthik; Limaye, Ashutosh; Laymon, Charles; Meyer, Paul

    2011-01-01

    This paper presents a new technique to calibrate a microwave radiometer and phased array antenna system. This calibration technique uses a radiated noise source in addition to an injected noise sources for calibration. The plane of reference for this calibration technique is the face of the antenna and therefore can effectively calibration the gain fluctuations in the active phased array antennas. This paper gives the mathematical formulation for the technique and discusses the improvements brought by the method over the existing calibration techniques.

  7. A phased antenna array for surface plasmons

    PubMed Central

    Dikken, Dirk Jan W.; Korterik, Jeroen P.; Segerink, Frans B.; Herek, Jennifer L.; Prangsma, Jord C.

    2016-01-01

    Surface plasmon polaritons are electromagnetic waves that propagate tightly bound to metal surfaces. The concentration of the electromagnetic field at the surface as well as the short wavelength of surface plasmons enable sensitive detection methods and miniaturization of optics. We present an optical frequency plasmonic analog to the phased antenna array as it is well known in radar technology and radio astronomy. Individual holes in a thick gold film act as dipolar emitters of surface plasmon polaritons whose phase is controlled individually using a digital spatial light modulator. We show experimentally, using a phase sensitive near-field microscope, that this optical system allows accurate directional emission of surface waves. This compact and flexible method allows for dynamically shaping the propagation of plasmons and holds promise for nanophotonic applications employing propagating surface plasmons. PMID:27121099

  8. Optical antenna arrays in the visible range.

    PubMed

    Matthews, Daniel R; Summers, Huw D; Njoh, Kerenza; Chappell, Sally; Errington, Rachel; Smith, Paul

    2007-03-19

    We report on experimental observations of highly collimated beams of radiation generated when a periodic sub-wavelength grating interacts with surface bound plasmon-polariton modes of a thin gold film. We find that the radiation process can be fully described in terms of interference of emission from a dipole antenna array and modeling the structure in this way enables the far-field radiation pattern to be predicted. The directionality, multiplicity and divergence of the beams can be completely described within this framework. Essential to the process are the surface plasmon excitations: these are the driving mechanism behind the beam formation, phase-coupling radiation from the periodic surface structure and thus imposing a spatial coherence. Detailed fitting of the experimental and modeled data indicates the presence of scattering events involving the interaction of two surface plasmon polariton modes.

  9. A phased antenna array for surface plasmons.

    PubMed

    Dikken, Dirk Jan W; Korterik, Jeroen P; Segerink, Frans B; Herek, Jennifer L; Prangsma, Jord C

    2016-04-28

    Surface plasmon polaritons are electromagnetic waves that propagate tightly bound to metal surfaces. The concentration of the electromagnetic field at the surface as well as the short wavelength of surface plasmons enable sensitive detection methods and miniaturization of optics. We present an optical frequency plasmonic analog to the phased antenna array as it is well known in radar technology and radio astronomy. Individual holes in a thick gold film act as dipolar emitters of surface plasmon polaritons whose phase is controlled individually using a digital spatial light modulator. We show experimentally, using a phase sensitive near-field microscope, that this optical system allows accurate directional emission of surface waves. This compact and flexible method allows for dynamically shaping the propagation of plasmons and holds promise for nanophotonic applications employing propagating surface plasmons.

  10. Electronic Switching Spherical Array (ESSA) antenna systems

    NASA Technical Reports Server (NTRS)

    Hockensmith, R. P.

    1984-01-01

    ESSA (Electronic Switching Spherical Array) is an antenna system conceived, developed and qualified for linking satellite data transmissions with NASA's tracking and data relay satellites (TDRSS) and tracking and data acquisition satellites (TDAS). ESSA functions in the S band frequency region, cover 2 pi or more steradians with directional gain and operates in multiple selectable modes. ESSA operates in concert with the NASA's TDRS standard transponder in the retrodirective mode or independently in directional beam, program track and special modes. Organizations and projects to the ESSA applications for NASA's space use are introduced. Coverage gain, weight power and implementation and other performance information for satisfying a wide range of data rate requirements are included.

  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. Phased arrays for satellites and the TDRSS antennas

    NASA Technical Reports Server (NTRS)

    Imbriale, W. A.

    1983-01-01

    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.

  13. Microstrip patch antenna receiving array operating in the Ku band

    NASA Technical Reports Server (NTRS)

    Walcher, Douglas A.

    1996-01-01

    Microstrip patch antennas were first investigated from the idea that it would be highly advantageous to fabricate radiating elements (antennas) on the same dielectric substrate as RF circuitry and transmission lines. Other advantages were soon discovered to be its lightweight, low profile, conformability to shaped surfaces, and low manufacturing costs. Unfortunately, these same patches continually exhibit narrow bandwidths, wide beamwidths, and low antenna gain. This thesis will present the design and experimental results of a microstrip patch antenna receiving array operating in the Ku band. An antenna array will be designed in an attempt to improve its performance over a single patch. Most Ku band information signals are either wide band television images or narrow band data and voice channels. An attempt to improve the gain of the array by introducing parasitic patches on top of the array will also be presented in this thesis.

  14. T-ray profile synthesis using photoconductive emitter array

    NASA Astrophysics Data System (ADS)

    Hattori, Toshiaki; Masuda, Masayoshi; Sakamoto, Masaya; Egawa, Kazuhiro; Itatani, Taro; Ohi, Akihiko

    2007-09-01

    We have observed coherent synthesis of spatial profiles of THz radiation emitted from a photoconductive antenna array. The antenna array is composed of seven independently addressable photoconductive antenna units having interdigitated electrodes. The antennas were pumped by amplified 800 nm femtosecond optical pulses. Emitted THz radiation was focused, and the time-resolved spatial profile of the THz radiation on the focal plane was observed using a newly developed real-time imaging apparatus, which can correct the terahertz field images for nonuniformity in birefringence of the EO crystal. By scanning the delay time, frequency-resolved images were also obtained, which exhibit frequency-dependent field profiles. Field profiles observed were coherent superpositions of terahertz waves emitted from the antenna units constituting the array. By inverting the bias voltage to the central unit of the emitter array, we observed super-resolution beam size of terahertz waves, which are smaller than the diffraction limit.

  15. Adaptive antenna arrays for satellite communications: Design and testing

    NASA Technical Reports Server (NTRS)

    Gupta, I. J.; Swarner, W. G.; Walton, E. K.

    1985-01-01

    When two separate antennas are used with each feedback loop to decorrelate noise, the antennas should be located such that the phase of the interfering signal in the two antennas is the same while the noise in them is uncorrelated. Thus, the antenna patterns and spatial distribution of the auxiliary antennas are quite important and should be carefully selected. The selection and spatial distribution of auxiliary elements is discussed when the main antenna is a center fed reflector antenna. It is shown that offset feeds of the reflector antenna can be used as auxiliary elements of an adaptive array to suppress weak interfering signals. An experimental system is designed to verify the theoretical analysis. The details of the experimental systems are presented.

  16. Photonic Links for High-Performance Arraying of Antennas

    NASA Technical Reports Server (NTRS)

    Huang, Shouhua; Tjoelker, Robert

    2009-01-01

    An architecture for arraying microwave antennas in the next generation of NASA s Deep Space Network (DSN) involves the use of all photonic links between (1) the antennas in a given array and (2) a signal processing center. In this architecture, all affected parts at each antenna pedestal [except a front-end low-noise amplifier for the radio-frequency (RF) signal coming from the antenna and an optical transceiver to handle monitor and control (M/C) signals] would be passive optical parts

  17. Integrated Solar-Panel Antenna Array for CubeSats

    NASA Technical Reports Server (NTRS)

    Baktur, Reyhan

    2016-01-01

    The goal of the Integrated Solar-Panel Antenna Array for CubeSats (ISAAC) project is to design and demonstrate an effective and efficien toptically transparent, high-gain, lightweight, conformal X-band antenna array that is integrated with the solar panels of a CubeSat. The targeted demonstration is for a Near Earth Network (NEN)radio at X-band, but the design can be easilyscaled to other network radios for higher frequencies. ISAAC is a less expensive and more flexible design for communication systemscompared to a deployed dish antenna or the existing integrated solar panel antenna design.

  18. An efficient synthesis approach for electromagnetic near- and far-field contoured patterns using alternative narrow-beam field functions transformed from the radiations of linearly excited array antennas with least computational complexity

    NASA Astrophysics Data System (ADS)

    Chou, Hsi-Tseng

    2015-05-01

    This paper presents an effective scheme to accelerate the computational efficiency in synthesizing the electromagnetic contoured patterns spanned by the radiations of phased array antennas, which is applicable to synthesize both the near- and far-field patterns. The core concept is to adapt/create closed-form and simple formulations with least computational unknowns to be used in the iterative synthesis procedure. The efficiency is assured by avoiding the cumbersome numerical integration/summation for the radiation fields in the synthesis procedure. Thus, the scheme first transforms the conventional field basis functions (FBFs) defined by the radiations of every array elements into a set of global FBFs arising from the radiations of a set of overlapped virtual arrays, where each of the virtual arrays is properly excited by a Gaussian taper to avoid the ray caustic problems encountered in the asymptotic evaluations. The new FBFs (NFBFs) created by this transformation have radiation fields focused in narrow spans in contrast to the wide patterns of conventional FBFs and may reduce the number of FBFs in the computation if a small coverage area is considered. Furthermore, the closed-form formulations of global NFBFs are obtained by asymptotic evaluation and may dramatically reduce the computational time. This approach is implemented with the use of successive projection method, which also provides closed-form formulations to update the excitations in each iterative step, to synthesize the near- and far-field contoured patterns to demonstrate the feasibility and efficiency.

  19. Multilayer Microstrip Slot And Dipole Array Antenna

    NASA Technical Reports Server (NTRS)

    Tulintseff, Ann N.

    1994-01-01

    Multilayer antenna structure contains interleaved linear subarrays of microstrip dipole and slot radiating antenna elements to provide compact, dual-band antenna. Structure also contains associated microstrip transmission lines, plus high-power amplifiers for transmission and low-noise amplifiers for reception. Overall function is to transmit in horizontal polarization at frequency of 29.634 GHz and receive in vertical polarization at 19.914 GHz, in direction 44 degrees from broadside to antenna. Antenna structure is part of apparatus described in "Steerable K/Ka-band Antenna for Land-Mobile Satellite Applications," NPO-18772.

  20. Study of the characteristics of reconfigurable plasma antenna array

    SciTech Connect

    Alias, Nur Salihah; Dagang, Ahmad Nazri; Ali, Mohd Tarmizi

    2015-04-24

    This paper presents a design and simulation of a reconfigurable array of plasma antenna. The plasma column is used as radiating elements instead of metal to create an antenna. The advantages of the plasma antenna over the conventional antenna are its possible to change the operating parameters, such as the working pressure, input power, radius of the discharge tube, resonant frequency, and length of the plasma column. In addition, plasma antenna can be reconfigurable with respect to shape, frequency and radiation parameters in a very short time. The plasma discharge tube was designed with a length of 200 mm, the radius of the plasma column was 2.5 mm and the coupling sleeve was connected to the SMA as the ground. This simulation was performed by using the simulation software Computer Simulation Technology (CST). The frequency is set in the range of 1 GHz to 10 GHz. The performance of the designed antenna was analyzed in term of return loss, gain and radiation pattern. For reconfigurable plasma antenna array, it shows that the gain is increase when the number of antenna element is increase. The combination of the discharge tube and metal rod as an antenna array has been done, and the result shows that an array with the plasma element can achieve higher gain.

  1. Characterization of tapered slot antenna feeds and feed arrays

    NASA Technical Reports Server (NTRS)

    Kim, Young-Sik; Yngvesson, K. Sigfrid

    1990-01-01

    A class of feed antennas and feed antenna arrays used in the focal plane of paraboloid reflectors and exhibiting higher than normal levels of cross-polarized radiation in the diagonal planes is addressed. A model which allows prediction of element gain and aperture efficiency of the feed/reflector system is presented. The predictions are in good agreement with experimental results. Tapered slot antenna (TSA) elements are used an example of an element of this type. It is shown that TSA arrays used in multibeam systems with small beam spacings are competitive in terms of aperture efficiency with other, more standard types of arrays incorporating waveguide type elements.

  2. An optically controlled Ka-band phased array antenna

    NASA Astrophysics Data System (ADS)

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

    1992-08-01

    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.

  3. 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.

  4. 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).

  5. Linearly tapered slot antenna circular array for mobile communications

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Kelly, Eron; Lee, Richard Q.; Taub, Susan R.

    1993-01-01

    The design, fabrication and testing of a conformal K-band circular array is presented. The array consists of sixteen linearly tapered slot antennas (LTSA). It is fed by a 1:16 microstrip line power splitter via electromagnetic coupling. The array has an omni-directional pattern in the azimuth plane. In the elevation plane the beam is displaced above the horizon.

  6. An adaptive array antenna for mobile satellite communications

    NASA Technical Reports Server (NTRS)

    Milne, Robert

    1990-01-01

    The design of an adaptive array antenna for land vehicle operation and its performance in an operational satellite system is described. Linear and circularly polarized antenna designs are presented. The acquisition and tracking operation of a satellite is described and the effect on the communications signal is discussed. A number of system requirements are examined that have a major impact on the antenna design. The results of environmental, power handling, and RFI testing are presented and potential problems are identified.

  7. Photonic spin-controlled multifunctional shared-aperture antenna array

    NASA Astrophysics Data System (ADS)

    Maguid, Elhanan; Yulevich, Igor; Veksler, Dekel; Kleiner, Vladimir; Brongersma, Mark L.; Hasman, Erez

    2016-06-01

    The shared-aperture phased antenna array developed in the field of radar applications is a promising approach for increased functionality in photonics. The alliance between the shared-aperture concepts and the geometric phase phenomenon arising from spin-orbit interaction provides a route to implement photonic spin-control multifunctional metasurfaces. We adopted a thinning technique within the shared-aperture synthesis and investigated interleaved sparse nanoantenna matrices and the spin-enabled asymmetric harmonic response to achieve helicity-controlled multiple structured wavefronts such as vortex beams carrying orbital angular momentum. We used multiplexed geometric phase profiles to simultaneously measure spectrum characteristics and the polarization state of light, enabling integrated on-chip spectropolarimetric analysis. The shared-aperture metasurface platform opens a pathway to novel types of nanophotonic functionality.

  8. Integrated Solar Array and Reflectarray Antenna for High Bandwidth Cubesats

    NASA Technical Reports Server (NTRS)

    Lewis, Dorothy; Martinez, Andres; Petro, Andrew

    2015-01-01

    The Integrated Solar Array and Reflectarray Antenna (ISARA) mission will demonstrate a reflectarray antenna that increases downlink data rates for Cube- Sats from the existing baseline rate of 9.6 kilobits per second (kbps) to more than 100 megabits per second (Mbps). The ISARA spacecraft is slated for launch no earlier than Dec. 1, 2015.

  9. Reproducible, high performance patch antenna array apparatus and method of fabrication

    DOEpatents

    Strassner, II, Bernd H.

    2007-01-23

    A reproducible, high-performance patch antenna array apparatus includes a patch antenna array provided on a unitary dielectric substrate, and a feed network provided on the same unitary substrate and proximity coupled to the patch antenna array. The reproducibility is enhanced by using photolithographic patterning and etching to produce both the patch antenna array and the feed network.

  10. 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.

  11. Linear antenna array optimization using flower pollination algorithm.

    PubMed

    Saxena, Prerna; Kothari, Ashwin

    2016-01-01

    Flower pollination algorithm (FPA) is a new nature-inspired evolutionary algorithm used to solve multi-objective optimization problems. The aim of this paper is to introduce FPA to the electromagnetics and antenna community for the optimization of linear antenna arrays. FPA is applied for the first time to linear array so as to obtain optimized antenna positions in order to achieve an array pattern with minimum side lobe level along with placement of deep nulls in desired directions. Various design examples are presented that illustrate the use of FPA for linear antenna array optimization, and subsequently the results are validated by benchmarking along with results obtained using other state-of-the-art, nature-inspired evolutionary algorithms such as particle swarm optimization, ant colony optimization and cat swarm optimization. The results suggest that in most cases, FPA outperforms the other evolutionary algorithms and at times it yields a similar performance.

  12. 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.

  13. 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.

  14. Antenna-coupled bolometer arrays using transition-edgesensors

    SciTech Connect

    Myers, Michael J.; Ade, Peter; Engargiola, Greg; Holzapfel,William; Lee,Adrian T.; O'Brient, Roger; Richards, Paul L.; Smith, Andy; Spieler, Helmuth; Tran, Huan

    2004-06-08

    We describe the development of an antenna-coupled bolometer array for use in a Cosmic Microwave Background polarization experiment. Prototype single pixels using double-slot dipole antennas and integrated microstrip band defining filters have been built and tested. Preliminary results of optical testing and simulations are presented. A bolometer array design based on this pixel will also be shown and future plans for application of the technology will be discussed.

  15. Compact antenna arrays with wide bandwidth and low sidelobe levels

    SciTech Connect

    Strassner, II, Bernd H.

    2014-09-09

    Highly efficient, low cost, easily manufactured SAR antenna arrays with lightweight low profiles, large instantaneous bandwidths and low SLL are disclosed. The array topology provides all necessary circuitry within the available antenna aperture space and between the layers of material that comprise the aperture. Bandwidths of 15.2 GHz to 18.2 GHz, with 30 dB SLLs azimuthally and elevationally, and radiation efficiencies above 40% may be achieved. Operation over much larger bandwidths is possible as well.

  16. Multibeam Phased-Array Antennas Developed and Characterized

    NASA Technical Reports Server (NTRS)

    Lee, Richard Q.; Lambert, Kevin M.

    2003-01-01

    Fixed-formation microsatellites have been proposed for future NASA missions to lower costs and improve data collection and reliability. Achieving seamless connectivity communications between these satellites requires the use of multibeam array antennas. As a result of NASA Glenn Research Center s collaborative efforts with the University of Colorado and Texas A&M University, two prototype multibeam array antennas have been developed and demonstrated at Ka-band frequencies. These arrays are designed to be dual-beam, dual-frequency arrays, with two fixed scan beams at around +/- 30 . They can be used in both ground and space systems for transmit and receive functions.

  17. Microstrip Yagi array for MSAT vehicle antenna application

    NASA Technical Reports Server (NTRS)

    Huang, John; Densmore, Arthur; Pozar, David

    1990-01-01

    A microstrip Yagi array was developed for the MSAT system as a low-cost mechanically steered medium-gain vehicle antenna. Because its parasitic reflector and director patches are not connected to any of the RF power distributing circuit, while still contributing to achieve the MSAT required directional beam, the antenna becomes a very efficient radiating system. With the complete monopulse beamforming circuit etched on a thin stripline board, the planar microstrip Yagi array is capable of achieving a very low profile. A theoretical model using the Method of Moments was developed to facilitate the ease of design and understanding of this antenna.

  18. Antenna-coupled arrays of voltage-biased superconducting bolometers

    SciTech Connect

    Myers, Michael J.; Lee, Adrian T.; Richards, P.L.; Schwan, D.; Skidmore, J.T.; Smith, A.D.; Spieler, H.; Yoon, Jongsoo

    2001-07-23

    We report on the development of antenna-coupled Voltage-biased Superconducting Bolometers (VSBs) which use Transition-edge Sensors (TES). Antenna coupling can greatly simplify the fabrication of large multi-frequency bolometer arrays compared to horn-coupled techniques. This simplification can make it practical to implement 1000+ element arrays that fill the focal plane of mm/sub-mm wave telescopes. We have designed a prototype device with a double-slot dipole antenna, integrated band-defining filters, and a membrane-suspended bolometer. A test chip has been constructed and will be tested shortly.

  19. Technique for Radiometer and Antenna Array Calibration - TRAAC

    NASA Technical Reports Server (NTRS)

    Meyer, Paul; Sims, William; Varnavas, Kosta; McCracken, Jeff; Srinivasan, Karthik; Limaye, Ashutosh; Laymon, Charles; Richeson. James

    2012-01-01

    Highly sensitive receivers are used to detect minute amounts of emitted electromagnetic energy. Calibration of these receivers is vital to the accuracy of the measurements. Traditional calibration techniques depend on calibration reference internal to the receivers as reference for the calibration of the observed electromagnetic energy. Such methods can only calibrate errors in measurement introduced by the receiver only. The disadvantage of these existing methods is that they cannot account for errors introduced by devices, such as antennas, used for capturing electromagnetic radiation. This severely limits the types of antennas that can be used to make measurements with a high degree of accuracy. Complex antenna systems, such as electronically steerable antennas (also known as phased arrays), while offering potentially significant advantages, suffer from a lack of a reliable and accurate calibration technique. The proximity of antenna elements in an array results in interaction between the electromagnetic fields radiated (or received) by the individual elements. This phenomenon is called mutual coupling. The new calibration method uses a known noise source as a calibration load to determine the instantaneous characteristics of the antenna. The noise source is emitted from one element of the antenna array and received by all the other elements due to mutual coupling. This received noise is used as a calibration standard to monitor the stability of the antenna electronics.

  20. The conical conformal MEMS quasi-end-fire array antenna

    NASA Astrophysics Data System (ADS)

    Cong, Lin; Xu, Lixin; Li, Jianhua; Wang, Ting; Han, Qi

    2017-03-01

    The microelectromechanical system (MEMS) quasi-end-fire array antenna based on a liquid crystal polymer (LCP) substrate is designed and fabricated in this paper. The maximum radiation direction of the antenna tends to the cone axis forming an angle less than 90∘, which satisfies the proximity detection system applied at the forward target detection. Furthermore, the proposed antenna is fed at the ended side in order to save internal space. Moreover, the proposed antenna takes small covering area of the proximity detection system. The proposed antenna is fabricated by using the flexible MEMS process, and the measurement results agree well with the simulation results. This is the first time that a conical conformal array antenna is fabricated by the flexible MEMS process to realize the quasi-end-fire radiation. A pair of conformal MEMS array antennas resonates at 14.2 GHz with its mainlobes tending to the cone axis forming a 30∘ angle and a 31∘ angle separately, and the gains achieved are 1.82 dB in two directions, respectively. The proposed antenna meets the performance requirements for the proximity detection system which has vast application prospects.

  1. Microstrip Yagi array antenna for mobile satellite vehicle application

    NASA Technical Reports Server (NTRS)

    Huang, John; Densmore, Arthur C.

    1991-01-01

    A novel antenna structure formed by combining the Yagi-Uda array concept and the microstrip radiator technique is discussed. This antenna, called the microstrip Yagi array, has been developed for the mobile satellite (MSAT) system as a low-profile, low-cost, and mechanically steered medium-gain land-vehicle antenna. With the antenna's active patches (driven elements) and parasitic patches (reflector and director elements) located on the same horizontal plane, the main beam of the array can be tilted, by the effect of mutual coupling, in the elevation direction providing optimal coverage for users in the continental United States. Because the parasitic patches are not connected to any of the lossy RF power distributing circuit the antenna is an efficient radiating system. With the complete monopulse beamforming and power distributing circuits etched on a single thin stripline board underneath the microstrip Yagi array, the overall L-band antenna system has achieved a very low profile for vehicle's rooftop mounting, as well as a low manufacturing cost. Experimental results demonstrate the performance of this antenna.

  2. Microstrip Yagi array antenna for mobile satellite vehicle application

    NASA Technical Reports Server (NTRS)

    Huang, John; Densmore, Arthur C.

    1991-01-01

    A novel antenna structure formed by combining the Yagi-Uda array concept and the microstrip radiator technique is discussed. This antenna, called the microstrip Yagi array, has been developed for the mobile satellite (MSAT) system as a low-profile, low-cost, and mechanically steered medium-gain land-vehicle antenna. With the antenna's active patches (driven elements) and parasitic patches (reflector and director elements) located on the same horizontal plane, the main beam of the array can be tilted, by the effect of mutual coupling, in the elevation direction providing optimal coverage for users in the continental United States. Because the parasitic patches are not connected to any of the lossy RF power distributing circuit the antenna is an efficient radiating system. With the complete monopulse beamforming and power distributing circuits etched on a single thin stripline board underneath the microstrip Yagi array, the overall L-band antenna system has achieved a very low profile for vehicle's rooftop mounting, as well as a low manufacturing cost. Experimental results demonstrate the performance of this antenna.

  3. Suspended Patch Antenna Array With Electromagnetically Coupled Inverted Microstrip Feed

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.

    2000-01-01

    The paper demonstrates a four-element suspended patch antenna array, with a parasitic patch layer and an electromagnetically coupled inverted microstrip feed, for linear polarization at K-Band frequencies. This antenna has the following advantages over conventional microstrip antennas: First, the inverted microstrip has lower attenuation than conventional microstrip; hence, conductor loss associated with the antenna corporate feed is lower resulting in higher gain and efficiency. Second, conventional proximity coupled patch antennas require a substrate for the feed and a superstrate for the patch. However, the inverted microstrip fed patch antenna makes use of a single substrate, and hence, is lightweight and low cost. Third, electromagnetic coupling results in wider bandwidth. Details regarding the design and fabrication will be presented as well as measured results including return loss, radiation patterns and cross-polarization levels.

  4. Miniaturized GPS Antenna Array and Test Results

    DTIC Science & Technology

    2006-01-01

    elements on its surface, and a superstrate on top of the elements. The dielectric constant of the substrate is increased so that the size of the... superstrate , the mutual coupling between the antenna elements is minimized and the reduced antenna spacing is scaled so that it appears to be effectively λ/2

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

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

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

  6. 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

  7. Design of Frequency Tunable Compact Antenna and Millimeter to Terahertz Array Antennas

    NASA Astrophysics Data System (ADS)

    Damman, Rafid Noel

    As increased bandwidth demands continue to rise and overly crowded existing bands need be relieved, the study of frequency tunable and higher frequency array antennas is needed. By tuning the resonant frequency of an antenna, the bandwidth increases since the operating frequency has increased from the tuning. Also, higher frequency antenna designs are beginning to take flight to alleviate the lower bands and allow for an increase in bandwidth. Both the methods can bring a solution to the increased bandwidth demand. Thesis work begins with the design of a novel single feed planar antenna with 4G tunable bands and consistent upper LTE bands. This antenna is simulated using full wave analysis tool, fabricated and measured. This antenna shows near omni-directional radiation pattern exhibiting gain levels from -4.25dBi in the lower band to 2.69dBi in the upper band. The impedance matching for the lower band can be tuned from 690 MHz - 970 MHz while the higher band is consistently present between 1.29 GHz - 2.05 GHz, both based on S 11 ≤ - 6dBi. To begin the stepping stone for higher frequency planar array antenna designs, first an 8x8 array antenna is designed in the Ka band. The impedance matching for this design is measured 28.34 GHz - 32.09 GHz having fractional bandwidth of 12.41% based on S11 ? - 10dB. This array antenna was fabricated and experimentally verified for its impedance matching and radiation performances. Next, a 4x4 antenna array is designed for operation in the 5G wireless band and using 0.07mm quartz material. The design has matching band from 53.6 GHz - 54.0 GHz having fractional bandwidth of 0.7435% based on S 11 ≤ -10dB. Finally, a 2x2 array antenna having a center frequency of 300 GHz with fractional bandwidth of 11.2% based on S11 ≤ -10dB is designed. This 2x2 array antenna was also designed using 0.07mm thick quartz substrate material so as to fabricate using the photolithography method due to the limitations of the standard method of

  8. Design and control of phased ICRF antenna arrays

    SciTech Connect

    Goulding, R.H.; Baity, F.W.; Hoffman, D.J.

    1993-11-01

    Phased antenna arrays operating in the ion cyclotron range of frequencies (ICRF) are used to produce highly directional wave spectra, primarily for use in current drive experiments. RF current drive using phased antennas has been demonstrated in both the JET and DIII-D tokamaks, and both devices are planning to operate new four-element arrays beginning early next year. Features of antenna design that are relevant to phased operation and production of directional spectra are reviewed. Recent advances in the design of the feed circuits and the related control systems for these arrays should substantially improve their performance, by reducing the coupling seen by the matching networks and rf power supplies caused by the mutual impedance of the array elements. The feed circuit designs for the DIII-D and JET phased antenna arrays are compared. The two configurations differ significantly due to the fact that one power amplifier is used for the entire array in the former case, and one per element in the latter. The JET system uses automatic feedback control of matching, phase and amplitude of antenna currents, and the transmitter power balance. The design of this system is discussed, and a time dependent model used to predict its behavior is described.

  9. Phased array-fed antenna configuration study: Technology assessment

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

    Spacecraft array fed reflector antenna systems were assessed for particular application to a multiple fixed spot beam/multiple scanning spot beam system. Reflector optics systems are reviewed in addition to an investigation of the feasibility of the use of monolithic microwave integrated circuit power amplifiers and phase shifters in each element of the array feed.

  10. The structure of the antenna pattern of an adaptive array

    NASA Technical Reports Server (NTRS)

    Zohar, S.

    1982-01-01

    The antenna pattern of a receiving adaptive array is investigated for the case of its operation in an environment of one desirable narrow-band signal and (K-1) narrow-band jammers. Results show that the adapted (voltage) antenna pattern of the array is a linear combination of k (or less) basis-patterns, each of which is a function of one source only. It is determined that these basis-patterns have a simple physical meaning in that the k-th basis-pattern is the pattern formed by the array when the transmission of source k is considered a desired signal and all other sources are turned off.

  11. Multifunctional reconfigurable antennas and arrays operating at 60 GHz band

    NASA Astrophysics Data System (ADS)

    Khalat, Abdurazag Mohamed

    To meet the ever increasing demand of high data rate, millimeter-wave (mm-wave) wireless communication has become an area of intense research due to the capability of offering very broad bandwidth. However, the propagation losses increase as a function of operation frequency. Therefore, there is need for antenna systems with high gain and beam-steering capability at elevated frequencies, which comes at the expense of high cost and increased complexity. This dissertation demonstrates the design, micro-fabrication, and characterization of two different antennas and two different antenna arrays. A broadband patch antenna operating within (57 - 66) GHz band, which works as a building block to create a multifunctional reconfigurable antenna (MRA) that is capable of beam steering in three directions pertaining to theta epsilon {-30 0, 00, 300}; φ = 900. These standalone antennas were then put in a linear formation to create a 2x8 planar array and a 4x1 multifunctional recon-figurable antenna array (MRAA) to increase the gain further and to offer wider bandwidth. The proposed novel MRA and MRAA possess variable element factors, which potentially can feature as the main building blocks of mm-wave reconfigurable wireless communication systems with reduced cost and complexity.

  12. Modern Design of Resonant Edge-Slot Array Antennas

    NASA Technical Reports Server (NTRS)

    Gosselin, R. B.

    2006-01-01

    Resonant edge-slot (slotted-waveguide) array antennas can now be designed very accurately following a modern computational approach like that followed for some other microwave components. This modern approach makes it possible to design superior antennas at lower cost than was previously possible. Heretofore, the physical and engineering knowledge of resonant edge-slot array antennas had remained immature since they were introduced during World War II. This is because despite their mechanical simplicity, high reliability, and potential for operation with high efficiency, the electromagnetic behavior of resonant edge-slot antennas is very complex. Because engineering design formulas and curves for such antennas are not available in the open literature, designers have been forced to implement iterative processes of fabricating and testing multiple prototypes to derive design databases, each unique for a specific combination of operating frequency and set of waveguide tube dimensions. The expensive, time-consuming nature of these processes has inhibited the use of resonant edge-slot antennas. The present modern approach reduces costs by making it unnecessary to build and test multiple prototypes. As an additional benefit, this approach affords a capability to design an array of slots having different dimensions to taper the antenna illumination to reduce the amplitudes of unwanted side lobes. The heart of the modern approach is the use of the latest commercially available microwave-design software, which implements finite-element models of electromagnetic fields in and around waveguides, antenna elements, and similar components. Instead of building and testing prototypes, one builds a database and constructs design curves from the results of computational simulations for sets of design parameters. The figure shows a resonant edge-slot antenna designed following this approach. Intended for use as part of a radiometer operating at a frequency of 10.7 GHz, this antenna

  13. Flexible 16 Antenna Array for Microwave Breast Cancer Detection.

    PubMed

    Bahramiabarghouei, Hadi; Porter, Emily; Santorelli, Adam; Gosselin, Benoit; Popović, Milica; Rusch, Leslie A

    2015-10-01

    Radar-based microwave imaging has been widely studied for breast cancer detection in recent times. Sensing dielectric property differences of tissues has been studied over a wide frequency band for this application. We design single- and dual-polarization antennas for wireless ultrawideband breast cancer detection systems using an inhomogeneous multilayer model of the human breast. Antennas made from flexible materials are more easily adapted to wearable applications. Miniaturized flexible monopole and spiral antennas on a 50-μm Kapton polyimide are designed, using a high-frequency structure simulator, to be in contact with biological breast tissues. The proposed antennas are designed to operate in a frequency range of 2-4 GHz (with reflection coefficient (S11) below -10 dB). Measurements show that the flexible antennas have good impedance matching when in different positions with different curvature around the breast. Our miniaturized flexible antennas are 20 mm × 20 mm. Furthermore, two flexible conformal 4 × 4 ultrawideband antenna arrays (single and dual polarization), in a format similar to that of a bra, were developed for a radar-based breast cancer detection system. By using a reflector for the arrays, the penetration of the propagated electromagnetic waves from the antennas into the breast can be improved by factors of 3.3 and 2.6, respectively.

  14. Null-steering techniques for application to large array antennas

    NASA Astrophysics Data System (ADS)

    Hockham, G. A.; Cho, C.; Parr, J. C.; Wolfson, R. I.

    A multimode waveguide can be employed to design an antenna which produces a beam for each propagating mode. A dual-beam waveguide slot array is particularly attractive. The antenna is compact, highly efficient, and has lower sidelobe-level performance than can be achieved with conventional monopulse techniques. Adaptive phase steering for jammer nulling is considered, taking into account a large phased array using a series feed system. The considered configuration was selected for computer simulation. A description is presented of a multiple beam antenna with independent steerable nulls. The multiple beam low-sidelobe antenna configuration has the ability to provide a radiation pattern with multiple and independently-located nulls, with minimal effect on the sidelobes of the unperturbed pattern.

  15. Theoretical and practical limits of superdirective antenna arrays

    NASA Astrophysics Data System (ADS)

    Haskou, Abdullah; Sharaiha, Ala; Collardey, Sylvain

    2017-02-01

    Some applications as Wireless Power Transfer (WPT) require compact and directive antennas. However, Electrically Small Antennas (ESAs) have low efficiencies and quasi-isotropic radiation patterns. Superdirective ESA arrays can be an interesting solution to cope with both constraints (the compactness and the directivity). In this paper, the theoretical and practical limits of superdirective antennas will be presented. These limits can be summarized by the directivity sensitivity toward the excitation coefficients changes and the radiation efficiency decrement as the inter-element decreases. The need for negative resistances is also a practical limit for transforming these arrays into parasitic ones. The necessary trade-offs between the antenna total dimensions (the number of elements and the inter-element distance) and the attainable directivity and efficiency are also analyzed throughout this paper. xml:lang="fr"

  16. Modulation transfer function of antenna-coupled infrared detector arrays.

    PubMed

    Boreman, G D; Dogariu, A; Christodoulou, C; Kotter, D

    1996-11-01

    Individual antenna-coupled IR bolometers have recently been demonstrated at wavelengths near 10 μm. If focal-plane arrays (FPA's) of antenna-coupled detectors can be fabricated, enhancement of IR-imager performance is possible. A first step in the design process is to analyze the image-quality potential of antenna-coupled, FPA-based imagers in terms of the modulation transfer function (MTF). The key step in our analysis is development of a cross-talk MTF that accounts for the electromagnetic coupling between adjacent antennas in the FPA. We find that electromagnetic cross talk will not be a significant image-quality factor in antenna-coupled IR FPA's.

  17. Slot-Antenna Coupled Microbolometer Arrays for THz Radiation

    DTIC Science & Technology

    2000-09-29

    properties for 2.5THz-CH 3OH laser radiation were microbolometers ), and each bolometer is connected in investigated at room temperature . The detected voltage...configuration of the infrared frequency region, because of its room - single slot antenna coupled microbolometer . The temperature operation and easy...Vol. X 3 slot antenna coupled microbolometer array and a 3 pp.773-776, Jun.1979. 2. D. F. Filpovic, W. Y. Ali-Ahmad, and G. M. Rebeiz, " Millimeter - two

  18. Phased-Array Antenna With Optoelectronic Control Circuits

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

    Prototype phased-array antenna features control of amplitude and phase at each radiating element. Amplitude- and phase-control signals transmitted on optical fiber to optoelectronic interface circuit (OEIC), then to monolithic microwave integrated circuit (MMIC) at each element. Offers advantages of flexible, rapid electronic steering and shaping of beams. Furthermore, greater number of elements, less overall performance of antenna degraded by malfunction in single element.

  19. Accurate Insertion Loss Measurements of the Juno Patch Array Antennas

    NASA Technical Reports Server (NTRS)

    Chamberlain, Neil; Chen, Jacqueline; Hodges, Richard; Demas, John

    2010-01-01

    This paper describes two independent methods for estimating the insertion loss of patch array antennas that were developed for the Juno Microwave Radiometer instrument. One method is based principally on pattern measurements while the other method is based solely on network analyzer measurements. The methods are accurate to within 0.1 dB for the measured antennas and show good agreement (to within 0.1dB) of separate radiometric measurements.

  20. Design and fabrication of microstrip antenna arrays

    NASA Technical Reports Server (NTRS)

    1978-01-01

    A microstrip array project was conducted to demonstrate the feasibility of designing and fabricating simple, low cost, low sidelobe phased arrays with circular disk microstrip radiating elements. Design data were presented for microstrip elements and arrays including the effects of the protective covers, the mutual interaction between elements, and stripline feed network design. Low cost multilayer laminate fabrication techniques were also investigated. Utilizing this design data two C-band low sidelobe arrays were fabricated and tested: an eight-element linear and a sixty-four element planar array. These arrays incorporated stripline Butler matrix feed networks to produce a low sidelobe broadside beam.

  1. Multi-carrier mobile TDMA system with active array antenna

    NASA Technical Reports Server (NTRS)

    Suzuki, Ryutaro; Matsumoto, Yasushi; Hamamoto, Naokazu

    1990-01-01

    A multi-carrier time division multiple access (TDMA) is proposed for the future mobile satellite communications systems that include a multi-satellite system. This TDMA system employs the active array antenna in which the digital beam forming technique is adopted to control the antenna beam direction. The antenna beam forming is carried out at the base band frequency by using the digital signal processing technique. The time division duplex technique is applied for the TDM/TDMA burst format, in order not to overlap transmit and receive timing.

  2. A 32 GHz microstrip array antenna for microspacecraft application

    NASA Technical Reports Server (NTRS)

    Huang, J.

    1994-01-01

    JPL/NASA is currently developing microspacecraft systems for future deep space applications. One of the frequency bands being investigated for microspacecraft is the Ka-band (32 GHz), which can be used with smaller equipment and provides a larger bandwidth. This article describes the successful development of a circularly polarized microstrip array with 28 dBic of gain at 32 GHz. This antenna, which is thin, flat, and small, can be surface-mounted onto the microspacecraft and, hence, takes very little volume and mass of the spacecraft. The challenges in developing this antenna are minimizing the microstrip antenna's insertion loss and maintaining a reasonable frequency bandwidth.

  3. A 20 GHz circularly polarized, fan beam slot array antenna

    NASA Astrophysics Data System (ADS)

    Weikle, D. C.

    1982-03-01

    An EHF waveguide slot array was developed for possible use as a receive-only paging antenna for ground mobile terminals. The design, fabrication, and measured performance of this antenna are presented. The antenna generates a circularly polarized fan beam that is narrow in azimuth and broad in elevation. When mechanically rotated in azimuth, it can receive a 20 GHz satellite transmission independent of mobile terminal direction. Azimuth plane sidelobe levels, which are typically <-40 dB from the main lobe, provide for discrimination against ground and airborne jammers.

  4. Thin conformal antenna array for microwave power conversions

    NASA Technical Reports Server (NTRS)

    Dickinson, R. M. (Inventor)

    1978-01-01

    A structure of a circularly polarized, thin conformal, antenna array which may be mounted integrally with the skin of an aircraft employs microstrip elliptical elements and interconnecting feed lines spaced from a circuit ground plane by a thin dielectric layer. The feed lines are impedance matched to the elliptical antenna elements by selecting a proper feedpoint inside the periphery of the elliptical antenna elements. Diodes connected between the feed lines and the ground plane rectify the microwave power, and microstrip filters (low pass) connected in series with the feed lines provide dc current to a microstrip bus. Low impedance matching strips are included between the elliptical elements and the rectifying and filtering elements.

  5. 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.

  6. MIMO communications within the HF band using compact antenna arrays

    NASA Astrophysics Data System (ADS)

    Gunashekar, S. D.; Warrington, E. M.; Feeney, S. M.; Salous, S.; Abbasi, N. M.

    2010-12-01

    Measurements have been made over a 255 km radio path between Durham and Leicester in the UK in order to investigate the potential applicability of multiple input multiple output (MIMO) techniques to communications within the HF band. This paper describes the results from experiments in which compact heterogeneous antenna arrays have been employed. The results of these experiments indicate that traditional spaced HF antenna arrays can be replaced by compact, active, heterogeneous arrays in order to achieve the required levels of decorrelation between the various antenna elements. An example case study is also presented which highlights the importance of the variable nature of the ionosphere in the context of HF-MIMO radio links.

  7. Hydrostar Thermal and Structural Deformation Analyses of Antenna Array Concept

    NASA Technical Reports Server (NTRS)

    Amundsen, Ruth M.; Hope, Drew J.

    1998-01-01

    The proposed Hydrostar mission used a large orbiting antenna array to demonstrate synthetic aperture technology in space while obtaining global soil moisture data. In order to produce accurate data, the array was required to remain as close as possible to its perfectly aligned placement while undergoing the mechanical and thermal stresses induced by orbital changes. Thermal and structural analyses for a design concept of this antenna array were performed. The thermal analysis included orbital radiation calculations, as well as parametric studies of orbit altitude, material properties and coating types. The thermal results included predicted thermal distributions over the array for several cases. The structural analysis provided thermally-driven deflections based on these cases, as well as based on a 1-g inertial load. In order to minimize the deflections of the array in orbit, the use of XN70, a carbon-reinforced polycyanate composite, was recommended.

  8. Research on calibration error of carrier phase against antenna arraying

    NASA Astrophysics Data System (ADS)

    Sun, Ke; Hou, Xiaomin

    2016-11-01

    It is the technical difficulty of uplink antenna arraying that signals from various quarters can not be automatically aligned at the target in deep space. The size of the far-field power combining gain is directly determined by the accuracy of carrier phase calibration. It is necessary to analyze the entire arraying system in order to improve the accuracy of the phase calibration. This paper analyzes the factors affecting the calibration error of carrier phase of uplink antenna arraying system including the error of phase measurement and equipment, the error of the uplink channel phase shift, the position error of ground antenna, calibration receiver and target spacecraft, the error of the atmospheric turbulence disturbance. Discuss the spatial and temporal autocorrelation model of atmospheric disturbances. Each antenna of the uplink antenna arraying is no common reference signal for continuous calibration. So it must be a system of the periodic calibration. Calibration is refered to communication of one or more spacecrafts in a certain period. Because the deep space targets are not automatically aligned to multiplexing received signal. Therefore the aligned signal should be done in advance on the ground. Data is shown that the error can be controlled within the range of demand by the use of existing technology to meet the accuracy of carrier phase calibration. The total error can be controlled within a reasonable range.

  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. 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

  11. 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

  12. A study of microstrip array antennas with the feed network

    NASA Astrophysics Data System (ADS)

    Levine, Ely; Malamud, Gabi; Shtrikman, Shmuel; Treves, David

    1989-04-01

    The radiation and losses in microstrip antennas with a corporate feed network are studied. A surface current approach is applied in which the electrical currents in the feed lines are modeled as ideal transmission lines. The free-space radiation and the surface-wave excitation of typical segments in printed feed networks are studied. A four-element array antenna with its printed feed network is analyzed, and predicted radiation patterns, directivity, and gain are presented and compared with experimental results. The gain and directivity of large arrays of 16, 64, 256, and 1024 elements are calculated, and measurements in the frequency range of 10 to 35 GHz are reported.

  13. On intermodulation beams of satellite DBF transmitting multibeam array antenna

    NASA Astrophysics Data System (ADS)

    Zhao, Hongmei; Wang, Huali; Mu, Shanxiang

    2007-11-01

    Digital beamforming (DBF) transmitting multibeam planar array antenna with nonlinear behaviors of solid-state power amplifiers (SSPA) is discussed. This paper investigates the intermodulation beams produced by the nonlinearity characteristics of the SSPA with multiple carrier components. The Shimbo model is simplified to describe the nonlinear behaviors of SSPA. The optimal SSPA input back-off (IBO) point which is given the desired the carrier and the intermodulatin ratio (C/IM) is simulated. And the tradeoffs between linearity and efficiency of the power amplifier which influence this IBO is also discussed, helping to selecting suitable SSPA device and reducing the dc power consumption in satellite array antenna system.

  14. Novel array-feed distortion compensation techniques for reflector antennas

    NASA Technical Reports Server (NTRS)

    Rahmat-Samii, Yahya

    1991-01-01

    Degradation of antenna performance by reflector surface distortion, which lowers gain and increases sidelobe levels, is addressed. Distortion compensation concepts based on the applications of properly matched array feeds are presented. Results of conceptual developments, numerical simulations, and measurement verifications are presented in support of this approach, with particular attention to the measurement technique. It is shown that the concept is most useful for overcoming the deterioration effects of slowly varying surface distortions, which would make the method very useful for future large space and ground antennas. It is further shown that for a typical, slowly varying thermal or gravitational surface distortion, a 19-element array feed can improve the reflector performance considerably.

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

    NASA Astrophysics Data System (ADS)

    Vescovo, Roberto; Pajewski, Lara; Tosti, Fabio

    2016-04-01

    The aim of this contribution is to offer an overview on the antenna arrays for GPR systems, current trends and open issues. Antennas are a critical hardware component of a radar system, dictating its performance in terms of capability to detect targets. Nevertheless, most of the research efforts in the Ground-Penetrating Radar (GPR) area focus on the use of this imaging technique in a plethora of different applications and on the improvement of modelling/inversion/processing techniques, whereas a limited number of studies deal with technological issues related to the design of novel systems, including the synthesis, optimisation and characterisation of advanced antennas. Even fewer are the research activities carried out to develop innovative antenna arrays. GPR antennas operate in a strongly demanding environment and should satisfy a number of requirements, somehow unique and very different than those of conventional radar antennas. The same applies to GPR antenna arrays. The first requirement is an ultra-wide frequency band: the radar has to transmit and receive short-duration time-domain waveforms, in the order of a few nanoseconds, the time-duration of the emitted pulses being a trade-off between the desired radar resolution and penetration depth. Furthermore, GPR antennas should have a linear phase characteristic over the whole operational frequency range, predictable polarisation and gain. Due to the fact that a subsurface imaging system is essentially a short-range radar, the coupling between transmitting and receiving antennas has to be low and short in time. GPR antennas should have quick ring-down characteristics, in order to prevent masking of targets and guarantee a good resolution. The radiation patterns should ensure minimal interference with unwanted objects, usually present in the complex operational environment; to this aim, antennas should provide high directivity and concentrate the electromagnetic energy into a narrow solid angle. As GPR

  16. Emerging Array Antenna Technologies at JPL

    NASA Technical Reports Server (NTRS)

    Huang, J.

    1998-01-01

    JPL/NASA's Earth remote sensing and deep-space exploration programs have been placing emphasis on their spacecraft's high-gain and large-aperture antennas. At the same time, however, low mass and small storage volume are demanded in order to reduce payload weight and reduce shroud size and thus reduce launch cost.

  17. Spectral performance of Square Kilometre Array Antennas - II. Calibration performance

    NASA Astrophysics Data System (ADS)

    Trott, Cathryn M.; de Lera Acedo, Eloy; Wayth, Randall B.; Fagnoni, Nicolas; Sutinjo, Adrian T.; Wakley, Brett; Punzalan, Chris Ivan B.

    2017-09-01

    We test the bandpass smoothness performance of two prototype Square Kilometre Array (SKA) SKA1-Low log-periodic dipole antennas, SKALA2 and SKALA3 ('SKA Log-periodic Antenna'), and the current dipole from the Murchison Widefield Array (MWA) precursor telescope. Throughout this paper, we refer to the output complex-valued voltage response of an antenna when connected to a low-noise amplifier, as the dipole bandpass. In Paper I, the bandpass spectral response of the log-periodic antenna being developed for the SKA1-Low was estimated using numerical electromagnetic simulations and analysed using low-order polynomial fittings, and it was compared with the HERA antenna against the delay spectrum metric. In this work, realistic simulations of the SKA1-Low instrument, including frequency-dependent primary beam shapes and array configuration, are used with a weighted least-squares polynomial estimator to assess the ability of a given prototype antenna to perform the SKA Epoch of Reionisation (EoR) statistical experiments. This work complements the ideal estimator tolerances computed for the proposed EoR science experiments in Trott & Wayth, with the realized performance of an optimal and standard estimation (calibration) procedure. With a sufficient sky calibration model at higher frequencies, all antennas have bandpasses that are sufficiently smooth to meet the tolerances described in Trott & Wayth to perform the EoR statistical experiments, and these are primarily limited by an adequate sky calibration model and the thermal noise level in the calibration data. At frequencies of the Cosmic Dawn, which is of principal interest to SKA as one of the first next-generation telescopes capable of accessing higher redshifts, the MWA dipole and SKALA3 antenna have adequate performance, while the SKALA2 design will impede the ability to explore this era.

  18. Optimization of an antenna array using genetic algorithms

    SciTech Connect

    Kiehbadroudinezhad, Shahideh; Noordin, Nor Kamariah; Sali, A.; Abidin, Zamri Zainal

    2014-06-01

    An array of antennas is usually used in long distance communication. The observation of celestial objects necessitates a large array of antennas, such as the Giant Metrewave Radio Telescope (GMRT). Optimizing this kind of array is very important when observing a high performance system. The genetic algorithm (GA) is an optimization solution for these kinds of problems that reconfigures the position of antennas to increase the u-v coverage plane or decrease the sidelobe levels (SLLs). This paper presents how to optimize a correlator antenna array using the GA. A brief explanation about the GA and operators used in this paper (mutation and crossover) is provided. Then, the results of optimization are discussed. The results show that the GA provides efficient and optimum solutions among a pool of candidate solutions in order to achieve the desired array performance for the purposes of radio astronomy. The proposed algorithm is able to distribute the u-v plane more efficiently than GMRT with a more than 95% distribution ratio at snapshot, and to fill the u-v plane from a 20% to more than 68% filling ratio as the number of generations increases in the hour tracking observations. Finally, the algorithm is able to reduce the SLL to –21.75 dB.

  19. Synthesis of a large communications aperture using small antennas

    NASA Technical Reports Server (NTRS)

    Resch, George M.; Cwik, T. W.; Jamnejad, V.; Logan, R. T.; Miller, R. B.; Rogstad, Dave H.

    1994-01-01

    In this report we compare the cost of an array of small antennas to that of a single large antenna assuming both the array and single large antenna have equal performance and availability. The single large antenna is taken to be one of the 70-m antennas of the Deep Space Network. The cost of the array is estimated as a function of the array element diameter for three different values of system noise temperature corresponding to three different packaging schemes for the first amplifier. Array elements are taken to be fully steerable paraboloids and their cost estimates were obtained from commercial vendors. Array loss mechanisms and calibration problems are discussed. For array elements in the range 3 - 35 m there is no minimum in the cost versus diameter curve for the three system temperatures that were studied.

  20. 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.

  1. Inflatable Antennas for a Lunar Low Frequency Array

    NASA Astrophysics Data System (ADS)

    Jones, Dayton L.

    2012-05-01

    During the past decade several schemes for deploying large numbers of low frequency radio antennas on the lunar surface have been investigated. The primary scientific motivation is an eventual large array on the lunar far side to image the cosmic Dark Ages using the highly redshifted neutral hydrogen signal. This goal requires an array with thousands of individual antenna elements, requiring a simple, robust, low mass, and rapid deployment system. Several concepts are currently being studied, including rovers (autonomous or tele-operated), ballistically deployed anchors and pulleys, and shape memory materials. This paper considers the use of inflatable antennas consisting of a thin conducting layer on a tubular polyimide structure. Based on previously deployed inflatable structures in space, it seems likely that tube lengths of at least 50 meters could be unrolled on the lunar surface. A major advantage of a lunar surface location is that deflation shortly after deployment is not a problem, and no rigidization techniques are required. A fundamental constraint is the maximum distance over which an inflating tube can unroll across the lunar surface. This can be tested at lunar analog sites on Earth. An additional application of inflatable structures may be self-supporting, vertical towers to support high frequency antennas for data transport between array antenna sites. In this case post-inflation rigidization would be necessary. This work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  10. Analysis of the ICE combiner for multiple antenna arraying

    NASA Technical Reports Server (NTRS)

    Foster, C.; Marina, M.

    1987-01-01

    The passage of the International Cometary Explorer (ICE) through the tail of comet Giacobini-Zinner took place on September 11, 1985, at approximately 11:04 GMT. The signal-to-noise ratio of the data received from the ICE spacecraft during the comet encounter was improved by arraying the 64-m antenna channels A and B (RCP and LCP) with the two 34-m antennas. Specially designed combiners were built to combine the signals received by the three antennas at the different DSN sites to ensure that the spacecraft's weak signal was received. Although the ICE spacecraft was built with a 5-W transmitter and with a small antenna designed to provide data from no farther than 1 million miles, these combiners provided enough signal margin during the encounter to receive the ICE transmitted data from within the tail of comet Giacobini-Zinner, 44 million miles from earth.

  11. 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.

  12. An adaptive array antenna for mobile satellite communications

    NASA Technical Reports Server (NTRS)

    Milne, Robert

    1988-01-01

    The adaptive array is linearly polarized and consists essentially of a driven lambda/4 monopole surrounded by an array of parasitic elements all mounted on a ground plane of finite size. The parasitic elements are all connected to ground via pin diodes. By applying suitable bias voltages, the desired parasitic elements can be activated and made highly reflective. The directivity and pointing of the antenna beam can be controlled in both the azimuth and elevation planes using high speed digital switching techniques. The antenna RF losses are neglible and the maximum gain is close to the theoretical value determined by the effective aperture size. The antenna is compact, has a low profile, is inexpensive to manufacture and can handle high transmitter power.

  13. Optical Links and RF Distribution for Antenna Arrays

    NASA Technical Reports Server (NTRS)

    Huang, Shouhua; Calhoun, Malcolm; Tjoelker, Robert

    2006-01-01

    An array of three antennas has recently been developed at the NASA Jet Propulsion Laboratory capable of detecting signals at X and Ka band. The array requires a common frequency reference and high precision phase alignment to correlate received signals. Frequency and timing references are presently provided from a remotely located hydrogen maser and clock through a combination of commercially and custom developed optical links. The selected laser, photodetector, and fiber components have been tested under anticipated thermal and simulated antenna rotation conditions. The resulting stability limitations due to thermal perturbations or induced stress on the optical fiber have been characterized. Distribution of the X band local oscillator includes a loop back and precision phase monitor to enable correlation of signals received from each antenna.

  14. Antenna-coupled TES bolometer arrays for CMB polarimetry

    NASA Astrophysics Data System (ADS)

    Kuo, C. L.; Bock, J. J.; Bonetti, J. A.; Brevik, J.; Chattopadhyay, G.; Day, P. K.; Golwala, S.; Kenyon, M.; Lange, A. E.; LeDuc, H. G.; Nguyen, H.; Ogburn, R. W.; Orlando, A.; Transgrud, A.; Turner, A.; Wang, G.; Zmuidzinas, J.

    2008-07-01

    We describe the design and performance of polarization selective antenna-coupled TES arrays that will be used in several upcoming Cosmic Microwave Background (CMB) experiments: SPIDER, BICEP-2/SPUD. The fully lithographic polarimeter arrays utilize planar phased-antennas for collimation (F/4 beam) and microstrip filters for band definition (25% bandwidth). These devices demonstrate high optical efficiency, excellent beam shapes, and well-defined spectral bands. The dual-polarization antennas provide well-matched beams and low cross polarization response, both important for high-fidelity polarization measurements. These devices have so far been developed for the 100 GHz and 150 GHz bands, two premier millimeter-wave atmospheric windows for CMB observations. In the near future, the flexible microstrip-coupled architecture can provide photon noise-limited detection for the entire frequency range of the CMBPOL mission. This paper is a summary of the progress we have made since the 2006 SPIE meeting in Orlando, FL.

  15. Focusing light with orbital angular momentum by circular array antenna.

    PubMed

    Arikawa, Takashi; Morimoto, Shohei; Tanaka, Koichiro

    2017-06-12

    We experimentally demonstrated focusing of light with orbital angular momentum (OAM) using an 8-element circular array of linear antennas. A spiral phase plate was used to generate a vortex beam with an OAM of ħ in the terahertz (THz) frequency region. We used THz near-field microscope to directly measure the phase vortex. A beam profile with a center dark spot and 2π phase rotation was observed in the small center gap region of the circular array antenna after the vortex beam excitation. The beam size is reduced by a factor of 3.4 ± 0.2. Half-wave resonance of the antenna element is responsible for the focusing function, indicating the scalability of this method to other frequency regions. This method will enable deep subwavelength focusing of light with OAM and eliminate the obstacle for the observation of the dipole forbidden transition with finite OAM of the vortex beam.

  16. Steerable Beam Array Antenna for Use in ATS-6 Test Program

    DTIC Science & Technology

    1976-05-01

    Departmnent of Transportati~on Transp~rtation Systems Center Kendall Square024 The design and development of an advanced L-Band microstrip phased array...development of the microstrip radiator, array configuration, diode phase shifter and the antenna control unit is described. The array design is considered in...Statement array antenna, aic~f antenna, Document is available to the public microstrip antenna, diode phase’ through the National Technical shifter, sale

  17. Ultrasensitive molecular absorption detection using metal slot antenna arrays.

    PubMed

    Ahn, Kwang Jun; Bahk, Young-Mi; Kim, Dai-Sik; Kyoung, Jisoo; Rotermund, Fabian

    2015-07-27

    We theoretically study the transmission reduction of light passing through absorptive molecules embedded in a periodic metal slot array in a near infrared wavelength regime. From the analytically solved transmitted light, we present a simple relation given by the attenuation length of light at the resonance wavelength of the slot antennas with respect to the spectral width of the resonant transmission peak. This relation clearly explains that the control of the transmission reduction even with very low absorptive materials is possible. We investigate also the transmission reduction by absorptive molecules in a real metallic slot antenna array on a dielectric substrate and compare the results with finite difference time domain calculations. In numerical calculations, we demonstrate that the same amount of transmission reduction by a bulk absorptive material can be achieved only with one-hundredth thickness of the same material when it is embedded in an optimized Fano-resonant slot antenna array. Our relation presented in this study can contribute to label-free chemical and biological sensing as an efficient design and performance criterion for periodic slot antenna arrays.

  18. Technique for Radiometer and Antenna Array Calibration with a Radiated Noise Diode

    NASA Technical Reports Server (NTRS)

    Srinivasan, Karthik; Limaye, Ashutosh; Laymon, Charles; Meyer, Paul

    2009-01-01

    This paper presents a new technique to calibrate a microwave radiometer and antenna array system. This calibration technique uses a radiated noise source in addition to two calibration sources internal to the radiometer. The method accurately calibrates antenna arrays with embedded active devices (such as amplifiers) which are used extensively in active phased array antennas.

  19. Toward a photoconducting semiconductor RF optical fiber antenna array.

    PubMed

    Davis, R; Rice, R; Ballato, A; Hawkins, T; Foy, P; Ballato, J

    2010-09-20

    Recently, optical fibers comprising a crystalline semiconductor core in a silica cladding have been successfully drawn by a conventional drawing process. These fibers are expected to exhibit a photoconductive response when illuminated by photons more energetic than the band gap of the core. In the photoconducting state, such a fiber can be expected to support driven RF currents so as to function as an antenna element, much as a plasma antenna. In this paper, we report the first device-related results on a crystalline semiconductor core optical fiber potentially useful in a photoconducting optical fiber antenna array; namely, optically induced changes to the electrical conductivity of a glass-clad germanium-core optical fiber. Since DC photoconduction measurements were masked by a photovoltaic effect, RF measurements at 5 MHz were used to determine the magnitude of the induced photoconductive effect. The observed photoconductivity, though not large in the present experiment, was comparable to that measured for the bulk crystals from which the fibers were drawn. The absorbed pumping light generated photo-carriers, thereby transforming the core from a dielectric material to a conductor. This technology could thus enable a class of transient antenna elements useful in low observable and reconfigurable antenna array applications.

  20. GNSS antenna array-aided CORS ambiguity resolution

    NASA Astrophysics Data System (ADS)

    Li, Bofeng; Teunissen, Peter J. G.

    2014-04-01

    Array-aided precise point positioning is a measurement concept that uses GNSS data, from multiple antennas in an array of known geometry, to realize improved GNSS parameter estimation proposed by Teunissen (IEEE Trans Signal Process 60:2870-2881, 2012). In this contribution, the benefits of array-aided CORS ambiguity resolution are explored. The mathematical model is formulated to show how the platform-array data can be reduced and how the variance matrix of the between-platform ambiguities can profit from the increased precision of the reduced platform data. The ambiguity resolution performance will be demonstrated for varying scenarios using simulation. We consider single-, dual- and triple-frequency scenarios of geometry-based and geometry-free models for different number of antennas and different standard deviations of the ionosphere-weighted constraints. The performances of both full and partial ambiguity resolution (PAR) are presented for these different scenarios. As the study shows, when full advantage is taken of the array antennas, both full and partial ambiguity resolution can be significantly improved, in some important cases even enabling instantaneous ambiguity resolution. PAR widelaning and its suboptimal character are hereby also illustrated.

  1. Inflatably Deployed Membrane Waveguide Array Antenna for Space

    NASA Technical Reports Server (NTRS)

    Lichodziejewski, David; Cravey, Robin; Hopkins, Glenn

    2003-01-01

    As an alternative to parabolic antennas and Synthetic Aperture Radar (SAR) systems, waveguide arrays offer another method of providing RF transmit/receive communication apertures for spacecraft. The advantage of the membrane waveguide array concept, in addition to its lightweight and low packaged volume, is its inherent shape. Relative to parabolic antennas, the requirement to make an accurate doubly curved surface is removed. L'Garde and Langley Research Center (LaRC), are currently working in this area to develop lightweight waveguide array technologies utilizing thin film membrane structures. Coupled with an ultra-lightweight inflatably deployed rigidizable planar support structure, the system offers a very compelling technology in the fields of space-based radar, communications, and earth resource mapping.

  2. 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.

  3. The steady-state antenna patterns of adaptive arrays

    NASA Technical Reports Server (NTRS)

    Zohar, S.

    1983-01-01

    A decomposition of the adapted pattern generated by an adaptive array operating in an environment with one narrowband signal, K-1 narrowband jammers, and programmed to produce the maximum SNR is presented. The antenna voltage pattern is demonstrated to be a linear combination of K (or less) basis patterns, each from a sole source, and the kth basis pattern becomes the desired signal realized by the array. Isotropic array patterns result in retrodirective basis patterns, and the decomposition can be configured to obtain the retrodirective beams for all K.

  4. Optical beam forming techniques for phased array antennas

    NASA Technical Reports Server (NTRS)

    Wu, Te-Kao; Chandler, Charles W.

    1993-01-01

    Three optical beam forming techniques are identified as applicable to large spaceborne phased array antennas. They are 1) the fiber replacement of conventional RF phased array distribution and control components, 2) spatial beam forming, and 3) optical beam splitting techniques. Two novel optical beam forming approaches, i.e., the spatial beam forming with a 'smart pixel' spatial light modulator (SLM) and the optical beam splitting approaches are conceived with integrated quasi-optical components. Also presented are the transmit and receive array architectures with the new SLM.

  5. Algorithm for Aligning an Array of Receiving Radio Antennas

    NASA Technical Reports Server (NTRS)

    Rogstad, David

    2006-01-01

    A digital-signal-processing algorithm (somewhat arbitrarily) called SUMPLE has been devised as a means of aligning the outputs of multiple receiving radio antennas in a large array for the purpose of receiving a weak signal transmitted by a single distant source. As used here, aligning signifies adjusting the delays and phases of the outputs from the various antennas so that their relatively weak replicas of the desired signal can be added coherently to increase the signal-to-noise ratio (SNR) for improved reception, as though one had a single larger antenna. The method was devised to enhance spacecraft-tracking and telemetry operations in NASA's Deep Space Network (DSN); the method could also be useful in such other applications as both satellite and terrestrial radio communications and radio astronomy. Heretofore, most commonly, alignment has been effected by a process that involves correlation of signals in pairs. This approach necessitates the use of a large amount of hardware most notably, the N(N - 1)/2 correlators needed to process signals from all possible pairs of N antennas. Moreover, because the incoming signals typically have low SNRs, the delay and phase adjustments are poorly determined from the pairwise correlations. SUMPLE also involves correlations, but the correlations are not performed in pairs. Instead, in a partly iterative process, each signal is appropriately weighted and then correlated with a composite signal equal to the sum of the other signals (see Figure 1). One benefit of this approach is that only N correlators are needed; in an array of N much greater than 1 antennas, this results in a significant reduction of the amount of hardware. Another benefit is that once the array achieves coherence, the correlation SNR is N - 1 times that of a pair of antennas.

  6. 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

  7. 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.

  8. Performance evaluation of antenna arrays with noisy carrier reference

    NASA Technical Reports Server (NTRS)

    Yan, T. Y.; Clare, L. P.

    1981-01-01

    The performance evaluation of coherent receivers with noisy carrier references and multiple antennas is presented. The received signal is assumed to be residual carrier BPSK, with a PLL used for extracting the carrier. Explicit relationships between the error probabilities and the various system parameters are given. Specific results are given for the performance gain of combined carrier referencing over baseband only combining when the channel alignment process is ideal. A simple asymptotic expression for the performance gain is determined when the number of antennas used is increased without bound. Examples using Deep Space Network receivers illustrate the performance of each arraying structure.

  9. Monopole antenna arrays for optical trapping, spectroscopy, and sensing

    NASA Astrophysics Data System (ADS)

    Ćetin, A. E.; Yanik, Ahmet Ali; Yilmaz, Cihan; Somu, Sivasubramanian; Busnaina, Ahmed; Altug, Hatice

    2011-03-01

    We introduce a nanoplasmonic platform merging multiple modalities for optical trapping, nanospectroscopy, and biosensing applications. Our platform is based on surface plasmon polariton driven monopole antenna arrays combining complementary strengths of localized and extended surface plasmons. Tailoring of spectrally narrow resonances lead to large index sensitivities (S˜675 nm/RIU) with record high figure of merits (FOM˜112.5). These monopole antennas supporting strong light localization with easily accessible near-field enhanced hotspots are suitable for vibrational nanospectroscopy and optical trapping. Strong optical forces (350 pN/W/μm2) are shown at these hotspots enabling directional control with incident light polarization.

  10. Space Power Amplification with Active Linearly Tapered Slot Antenna Array

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Lee, Richard Q.

    1993-01-01

    A space power amplifier composed of active linearly tapered slot antennas (LTSA's) has been demonstrated and shown to have a gain of 30 dB at 20 GHz. In each of the antenna elements, a GaAs monolithic microwave integrated circuit (MMIC) three-stage power amplifier is integrated with two LTSA's. The LTSA and the MMIC power amplifier has a gain of 11 dB and power added efficiency of 14 percent respectively. The design is suitable for constructing a large array using monolithic integration techniques.

  11. Spatial frequency multiplier with active linearly tapered slot antenna array

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Lee, Richard Q.

    1994-01-01

    A frequency multiplier with active linearly tapered slot antennas (LTSA's) has been demonstrated at the second harmonic frequency. In each antenna element, a GaAs monolithic microwave integrated circuit (MMIC) distributed amplifier is integrated with two LTSA's. The multiplier has a very wide bandwidth and large dynamic range. The fundamental-to-second harmonic conversion efficiency is 8.1 percent. The spatially combined second harmonic signal is 50 dB above the noise level. The design is suitable for constructing a large array using monolithic integration techniques.

  12. 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.

  13. Interplanetary navigation using a continental baseline large antenna arrays

    NASA Technical Reports Server (NTRS)

    Haeberle, Dennis W.; Spencer, David B.; Ely, Todd A.

    2004-01-01

    Navigation is a key component of interplanetary missions and must continue to be precise with the changing landscape of antenna design. Improvements for the Deep Space Network (DSN) may include the use of antenna arrays to simulate the power of a larger single antenna at much lower operating and construction costs. Therefore, it is necessary to test the performance of arrayed antennas from a navigational point-of-view. This initial investigation focuses on the performance of arrayed antennas from a navigational point-of-view. This initial investigation focuses on the performance of delta one-way range measurements using a shorter baseline with more data collection then current systems use. With all other parameter equal, the longer the baseline, the better the accuracy for navigation making the number of data packets very important. This trade study compares baseline distances ranging from 1 to 1000km with an in use baseline, looking at a due east baseline, a due north baseline at 45 degrees East of North. The precision of the baseline systems can be found through a simulated created for this purpose using the Jet Propulsion Lab based Monte navigation and mission design tool. The simulation combines the delta one-way range measurements with two-range and two-way Doppler measurements and puts the measurements through a Kalman filter to determine an orbit solution. Noise is added along with initial errors to give the simulation realism. This study is an important step towards the assessment of the utility of arrays for navigational purposes. The preliminary results have showed a decrease in reliability as the baseline is shortened but the larger continental baselines show comparable results t that of the current Goldstone to Canberra.

  14. Estimating Transmitted-Signal Phase Variations for Uplink Array Antennas

    NASA Technical Reports Server (NTRS)

    Paal, Leslie; Mukai, Ryan; Vilntrotter, Victor; Cornish, Timothy; Lee, Dennis

    2009-01-01

    A method of estimating phase drifts of microwave signals distributed to, and transmitted by, antennas in an array involves the use of the signals themselves as phase references. The method was conceived as part of the solution of the problem of maintaining precise phase calibration required for proper operation of an array of Deep Space Network (DSN) antennas on Earth used for communicating with distant spacecraft at frequencies between 7 and 8 GHz. The method could also be applied to purely terrestrial phased-array radar and other radio antenna array systems. In the DSN application, the electrical lengths (effective signal-propagation path lengths) of the various branches of the system for distributing the transmitted signals to the antennas are not precisely known, and they vary with time. The variations are attributable mostly to thermal expansion and contraction of fiber-optic and electrical signal cables and to a variety of causes associated with aging of signal-handling components. The variations are large enough to introduce large phase drifts at the signal frequency. It is necessary to measure and correct for these phase drifts in order to maintain phase calibration of the antennas. A prior method of measuring phase drifts involves the use of reference-frequency signals separate from the transmitted signals. A major impediment to accurate measurement of phase drifts over time by the prior method is the fact that although DSN reference-frequency sources separate from the transmitting signal sources are stable and accurate enough for most DSN purposes, they are not stable enough for use in maintaining phase calibrations, as required, to within a few degrees over times as long as days or possibly even weeks. By eliminating reliance on the reference-frequency subsystem, the present method overcomes this impediment. In a DSN array to which the present method applies (see figure), the microwave signals to be transmitted are generated by exciters in a signal

  15. Slotline fed microstrip antenna array modules

    NASA Technical Reports Server (NTRS)

    Lo, Y. T.; Oberhart, M. L.; Brenneman, J. S.; Aoyagi, P.; Moore, J.; Lee, R. Q. H.

    1988-01-01

    A feed network comprised of a combination of coplanar waveguide and slot transmission line is described for use in an array module of four microstrip elements. Examples of the module incorporating such networks are presented as well as experimentally obtained impedance and radiation characteristics.

  16. 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.

  17. Optically addressed ultra-wideband phased antenna array

    NASA Astrophysics Data System (ADS)

    Bai, Jian

    Demands for high data rate and multifunctional apertures from both civilian and military users have motivated development of ultra-wideband (UWB) electrically steered phased arrays. Meanwhile, the need for large contiguous frequency is pushing operation of radio systems into the millimeter-wave (mm-wave) range. Therefore, modern radio systems require UWB performance from VHF to mm-wave. However, traditional electronic systems suffer many challenges that make achieving these requirements difficult. Several examples includes: voltage controlled oscillators (VCO) cannot provide a tunable range of several octaves, distribution of wideband local oscillator signals undergo high loss and dispersion through RF transmission lines, and antennas have very limited bandwidth or bulky sizes. Recently, RF photonics technology has drawn considerable attention because of its advantages over traditional systems, with the capability of offering extreme power efficiency, information capacity, frequency agility, and spatial beam diversity. A hybrid RF photonic communication system utilizing optical links and an RF transducer at the antenna potentially provides ultra-wideband data transmission, i.e., over 100 GHz. A successful implementation of such an optically addressed phased array requires addressing several key challenges. Photonic generation of an RF source with over a seven-octave bandwidth has been demonstrated in the last few years. However, one challenge which still remains is how to convey phased optical signals to downconversion modules and antennas. Therefore, a feed network with phase sweeping capability and low excessive phase noise needs to be developed. Another key challenge is to develop an ultra-wideband array antenna. Modern frontends require antennas to be compact, planar, and low-profile in addition to possessing broad bandwidth, conforming to stringent space, weight, cost, and power constraints. To address these issues, I will study broadband and miniaturization

  18. Tracking antenna arrays for near-millimeter waves

    NASA Technical Reports Server (NTRS)

    Tong, P. P.; Neikirk, D. P.; Psaltis, D.; Rutledge, D. B.; Wagner, K.; Young, P. E.

    1983-01-01

    A two-dimensional monolithic array has been developed that gives the elevation and azimuth of point source targets. The array is an arrangement of rows and columns of antennas and bismuth bolometer detectors on a fused quartz substrate. Energy is focused onto the array through a lens placed on the back side of the substrate. At 1.38 mm with a 50 mm diameter objective lens, the array has demonstrated a positioning accuracy of 26 arcmin. In a differential mode this precision improves to 9 arcsec, limited by the mechanics of the rotating stage. This tracking could be automated to a fast two-step procedure where a source is first located to the nearest row and column, and then precisely located by scanning. With signal processing the array should be able to track multiple sources.

  19. 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

  20. Blind identification and equalization for wireless communications using antenna arrays

    NASA Astrophysics Data System (ADS)

    Li, Ye; Liu, Kuo Juey R.

    1997-10-01

    Antenna arrays can be used in wireless communication systems to increase system capacity and improve communication quality. The antenna arrays, which receive several signals at the same time and frequency domain, can be modeled as a multiple-input/multiple- output (MIMO) system. To separate and recover multiple signals from arrays, the parameters of the system have to be identified explicitly or implicitly. In the first part of this paper, we deal with blind parameter identification based on second-order statistics. We investigate the identifiability of the MIMO FIR channels, and obtain a necessary and sufficient condition for second-order based identifiability of the MIMO FIR channels. Then, we extend the identification algorithms for single-input/multiple- output (FIR-SIMO) channels, such as the algebraic algorithm and the subspace algorithms to the identification of the MIMO FIR channels. The MIMO systems can also be directly equalized using blind techniques. We then investigate blind algorithms to separate multiple signals received by antenna arrays. We analyze the CMA equalizer used in the MIMO systems. According to our analysis, for the MIMO FIR channels satisfying certain conditions, the MIMO-CMA FIR equalizer is able to recover one of input signals and remove the intersymbol interference and co-channel interference regardless of the initial setting of the equalizer. To recover all input signals simultaneously, a novel MIMO channel blind equalization algorithm is developed in this paper. The global convergence of the new algorithm for MIMO channels is proved. Hence, the new blind equalization algorithm for MIMO channels can be applied to separate and equalize the signals received by antenna arrays in communication systems.

  1. Adaptive Algorithms for HF Antenna Arrays.

    DTIC Science & Technology

    1987-07-01

    SUBJECT TERMS (Contnue on reverse dfnoceaq and identiy by bkICk numnber) FIELD GROUP SUB-GROUP HP Adaptive Arrays HrF Comunications Systems 4 HP...Although their heavy computational load renders them impractical *1 for many applications, the advancements in cheap, fast digital hardware have...or digital form. For many applications, the LMS algorithm represents a good trade off between speed of convergence* and implementational The speed of

  2. 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.

  3. Coplanar waveguide feeds for phased array antennas

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Lee, Richard Q.

    1991-01-01

    The design and performance is presented of the following Coplanar Waveguides (CPW) microwave distribution networks for linear as well as circularly polarized microstrip patches and dipole arrays: (1) CPW/Microstrip Line feed; (2) CPW/Balanced Stripline feed; (3) CPW/Slotline feed; (4) Grounded CPW/Balanced coplanar stripline feed; and (5) CPW/Slot coupled feed. Typical measured radiation patterns are presented, and their relative advantages and disadvantages are compared.

  4. Coplanar waveguide feeds for phased array antennas

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Lee, Richard Q.

    1991-01-01

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

  5. 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.

  6. Cylindrical Antenna With Partly Adaptive Phased-Array Feed

    NASA Technical Reports Server (NTRS)

    Hussein, Ziad; Hilland, Jeff

    2003-01-01

    A proposed design for a phased-array fed cylindrical-reflector microwave antenna would enable enhancement of the radiation pattern through partially adaptive amplitude and phase control of its edge radiating feed elements. Antennas based on this design concept would be attractive for use in radar (especially synthetic-aperture radar) and other systems that could exploit electronic directional scanning and in which there are requirements for specially shaped radiation patterns, including ones with low side lobes. One notable advantage of this design concept is that the transmitter/ receiver modules feeding all the elements except the edge ones could be identical and, as a result, the antenna would cost less than in the cases of prior design concepts in which these elements may not be identical.

  7. 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

  8. A Laboratory Approximation of Whistler Mode Antenna Arrays

    NASA Astrophysics Data System (ADS)

    Urrutia, J. M. M.; Stenzel, R.

    2014-12-01

    Magnetic loop antennas whose dipole moment, n, is oriented both along and across B0,are used to excite cw whistler modes in a large laboratory plasma for parameters ω ≈ 0.3 ωce « ωpe. These whistler "vortices" resemble m = 0 helicons in bounded plasmas when n parallel to B0 and m = 1 helicon modes when n is perpendicular to B0. Both dipole orientations produce conical phase fronts that cannot be directly compared to plane wave theories and are inclined at the Gendrin angle. The magnetic field topology exhibits evidence of linkage and helicity, whose sign is defined by propagation direction. The wave fields are force free. Using linear superposition, as demonstrated in Physics of Plasmas 7, 519-526 (2000), the measured fields are added in a variety of configurations to produce, for example, directional radiation patterns, whistler standing waves, and nearly plane whistler waves. The configurations are produced by adding the spatially and temporally shifted observed single-antenna magnetic field topology. The directional antenna configuration is shown to be more efficient than rotating field antennas. Whistler standing waves produce no perfect nodes and have wave polarizations varying spatially between linear and circular. Nearly plane whistler waves are created when the angle θ of wave propagation has been varied by a phase shift along an array of spatially separated antennas. These results are of interest to space and laboratory plasmas. (Work supported by DOE/NSF.)

  9. UHF Microstrip Antenna Array for Synthetic- Aperture Radar

    NASA Technical Reports Server (NTRS)

    Thomas, Robert F.; Huang, John

    2003-01-01

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

  10. Frequency translating phase conjugation circuit for active retrodirective antenna array

    NASA Astrophysics Data System (ADS)

    Chernoff, R.

    1980-11-01

    An active retrodirective antenna array which has central phasing from a reference antenna element through a "tree" structured network of transmission lines utilizes a number of phase conjugate circuits (PCCs) at each node and a phase reference regeneration circuit (PRR) at each node except the initial node. Each node virtually coincides with an element of the array. A PCC generates the exact conjugate phase of an incident signal using a phase locked loop which combines the phases in an up converter, divides the sum by 2 and mixes the result with the phase in a down converter for phase detection. The PRR extracts the phase from the conjugate phase. Both the PCC and the PRR are not only exact but also free from mixer degeneracy.

  11. 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.

  12. Model Experiments with Slot Antenna Arrays for Imaging

    NASA Technical Reports Server (NTRS)

    Johansson, J. F.; Yngvesson, K. S.; Kollberg, E. L.

    1985-01-01

    A prototype imaging system at 31 GHz was developed, which employs a two-dimensional (5x5) array of tapered slot antennas, and integrated detector or mixer elements, in the focal plane of a prime-focus paraboloid reflector, with an f/D=1. The system can be scaled to shorter millimeter waves and submillimeter waves. The array spacing corresponds to a beam spacing of approximately one Rayleigh distance and a two-point resolution experiment showed that two point-sources at the Rayleigh distance are well resolved.

  13. Adaptive feed array compensation system for reflector antenna surface distortion

    NASA Technical Reports Server (NTRS)

    Acosta, Roberto J.; Zaman, A.

    1989-01-01

    The feasibility of a closed loop adaptive feed array system for compensating reflector surface deformations has been investigated. The performance characteristics (gain, sidelobe level, pointing, etc.) of large communication antenna systems degrade as the reflector surface distorts mainly due to thermal effects from a varying solar flux. The compensating systems described in this report can be used to maintain the design performance characteristics independent of thermal effects on the reflector surface. The proposed compensating system employs the concept of conjugate field matching to adjust the feed array complex excitation coefficients.

  14. 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.

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

    DOEpatents

    Strassner, II, Bernd H.

    2015-12-22

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

  16. Development of horn antenna mixer array with internal local oscillator module for microwave imaging diagnostics

    SciTech Connect

    Kuwahara, D.; Ito, N.; Nagayama, Y.; Yoshinaga, T.; Yamaguchi, S.; Yoshikawa, M.; Kohagura, J.; Sugito, S.; Kogi, Y.; Mase, A.

    2014-11-15

    A new antenna array is proposed in order to improve the sensitivity and complexity of microwave imaging diagnostics systems such as a microwave imaging reflectometry, a microwave imaging interferometer, and an electron cyclotron emission imaging. The antenna array consists of five elements: a horn antenna, a waveguide-to-microstrip line transition, a mixer, a local oscillation (LO) module, and an intermediate frequency amplifier. By using an LO module, the LO optics can be removed, and the supplied LO power to each element can be equalized. We report details of the antenna array and characteristics of a prototype antenna array.

  17. Development of horn antenna mixer array with internal local oscillator module for microwave imaging diagnostics.

    PubMed

    Kuwahara, D; Ito, N; Nagayama, Y; Yoshinaga, T; Yamaguchi, S; Yoshikawa, M; Kohagura, J; Sugito, S; Kogi, Y; Mase, A

    2014-11-01

    A new antenna array is proposed in order to improve the sensitivity and complexity of microwave imaging diagnostics systems such as a microwave imaging reflectometry, a microwave imaging interferometer, and an electron cyclotron emission imaging. The antenna array consists of five elements: a horn antenna, a waveguide-to-microstrip line transition, a mixer, a local oscillation (LO) module, and an intermediate frequency amplifier. By using an LO module, the LO optics can be removed, and the supplied LO power to each element can be equalized. We report details of the antenna array and characteristics of a prototype antenna array.

  18. Development of horn antenna mixer array with internal local oscillator module for microwave imaging diagnostics

    NASA Astrophysics Data System (ADS)

    Kuwahara, D.; Ito, N.; Nagayama, Y.; Yoshinaga, T.; Yamaguchi, S.; Yoshikawa, M.; Kohagura, J.; Sugito, S.; Kogi, Y.; Mase, A.

    2014-11-01

    A new antenna array is proposed in order to improve the sensitivity and complexity of microwave imaging diagnostics systems such as a microwave imaging reflectometry, a microwave imaging interferometer, and an electron cyclotron emission imaging. The antenna array consists of five elements: a horn antenna, a waveguide-to-microstrip line transition, a mixer, a local oscillation (LO) module, and an intermediate frequency amplifier. By using an LO module, the LO optics can be removed, and the supplied LO power to each element can be equalized. We report details of the antenna array and characteristics of a prototype antenna array.

  19. An Intelligent Fault Detection and Isolation Architecture for Antenna Arrays

    NASA Astrophysics Data System (ADS)

    Rahnamai, K.; Arabshahi, P.; Yan, T.-Y.; Pham, T.; Finley, S. G.

    1997-10-01

    This article describes a general architecture for fault modeling, diagnosis, and isolation of the DSN antenna array based on computationally intelligent techniques(neural networks and fuzzy logic). It encompasses a suite of intelligent test and diagnosis algorithms in software. By continuously monitoring the health of the highly complex and nonlinear array observables, the automated diagnosis software will be able to identify and isolate the most likely causes of system failure in cases of faulty operation. Furthermore, it will be able to recommend a series of corresponding corrective actions and effectively act as an automated real-time and interactive system supervisor. In so doing, it will enhance the array capability by reducing the operational workload, increasing science information availability, reducing the overall cost of operation by reducing system downtimes, improving risk management, and making mission planning much more reliable. Operation of this architecture is illustrated using examples from observables available from the 34-meter arraying task.

  20. Pros and Cons of Using Arrays of Small Antennas Versus Large Single Dish Antennas for the Deep Space Network

    NASA Technical Reports Server (NTRS)

    Bagri, Durgadas S.

    2009-01-01

    This paper briefly describes pros and cons of using arrays of small antennas instead of large single dish antennas for spacecraft telemetry, command, and tracking (TT and C) - communications and navigation (C and N) - and science support that the Deep Space Network (DSN) normally provides. It considers functionality and performance aspects, mainly for TT and C, though it also considers science. It only briefly comments on the cost aspects that seem to favor arrays of small antennas over large single antennas, at least for receiving (downlinks).

  1. Pros and Cons of Using Arrays of Small Antennas Versus Large Single Dish Antennas for the Deep Space Network

    NASA Technical Reports Server (NTRS)

    Bagri, Durgadas S.

    2009-01-01

    This paper briefly describes pros and cons of using arrays of small antennas instead of large single dish antennas for spacecraft telemetry, command, and tracking (TT and C) - communications and navigation (C and N) - and science support that the Deep Space Network (DSN) normally provides. It considers functionality and performance aspects, mainly for TT and C, though it also considers science. It only briefly comments on the cost aspects that seem to favor arrays of small antennas over large single antennas, at least for receiving (downlinks).

  2. Planar, Faceted and Curved Array Antenna Research at Tno Physics and Electronics Laboratory

    NASA Astrophysics Data System (ADS)

    Visser, H. J.

    An overview is presented of research carried out at TNO Physics and Electronics Laboratory in the field of phased array antennas. Started is with a brief historical overview and a presentation of the antenna measurement facilities. Then full wave analysis methods for infinite planar waveguide arrays are discussed and ways to use these methods for analyzing finite arrays. A design approach for microstrip patch array antennas, employing reduced analysis methods and commercially available full wave software is discussed next, followed by a presentation of analysis techniques for faceted and curved array antennas, together with the first reduced analysis results.

  3. Aligning a Receiving Antenna Array to Reduce Interference

    NASA Technical Reports Server (NTRS)

    Jongeling, Andre P.; Rogstad, David H.

    2009-01-01

    A digital signal-processing algorithm has been devised as a means of aligning (as defined below) the outputs of multiple receiving radio antennas in a large array for the purpose of receiving a desired weak signal transmitted by a single distant source in the presence of an interfering signal that (1) originates at another source lying within the antenna beam and (2) occupies a frequency band significantly wider than that of the desired signal. In the original intended application of the algorithm, the desired weak signal is a spacecraft telemetry signal, the antennas are spacecraft-tracking antennas in NASA s Deep Space Network, and the source of the wide-band interfering signal is typically a radio galaxy or a planet that lies along or near the line of sight to the spacecraft. The algorithm could also afford the ability to discriminate between desired narrow-band and nearby undesired wide-band sources in related applications that include satellite and terrestrial radio communications and radio astronomy. The development of the present algorithm involved modification of a prior algorithm called SUMPLE and a predecessor called SIMPLE. SUMPLE was described in Algorithm for Aligning an Array of Receiving Radio Antennas (NPO-40574), NASA Tech Briefs Vol. 30, No. 4 (April 2006), page 54. To recapitulate: As used here, aligning signifies adjusting the delays and phases of the outputs from the various antennas so that their relatively weak replicas of the desired signal can be added coherently to increase the signal-to-noise ratio (SNR) for improved reception, as though one had a single larger antenna. Prior to the development of SUMPLE, it was common practice to effect alignment by means of a process that involves correlation of signals in pairs. SIMPLE is an example of an algorithm that effects such a process. SUMPLE also involves correlations, but the correlations are not performed in pairs. Instead, in a partly iterative process, each signal is appropriately weighted

  4. Beam shaping with satellite phased array antennas: Inmarsat-3 requirements - A case study

    NASA Astrophysics Data System (ADS)

    Rupp, Werner M.

    1990-10-01

    The performance requirements of the Inmarsat-3 communication satellites regarding the L-band spot coverages can be met optimally with a directly radiating phased array antenna. A novel approach to the synthesis of patterns for planar arrays is used to provide contoured beams which match the required spot coverage areas. The variation in gain over each spot beam coverage area is less than the allowed 5 dB. The required isolation of at least 18 dB regarding unwanted radiation on other coverage areas or land masses can be satisfied. The results are presented in graphical form as contour plots of the beam shapes for various coverage areas. Also shown contour plots of the aperture distribution over the planar array in magnitude and phase. The directivity for the various spot beams is calculated for an array of circular horn antennas as well as circular microstrip patches as radiating elements. Thereby, the array size is kept constant while the number of elements and their spacing is changed.

  5. Distributed Antenna-Coupled TES for FIR Detectors Arrays

    NASA Technical Reports Server (NTRS)

    Day, Peter K.; Leduc, Henry G.; Dowell, C. Darren; Lee, Richard A.; Zmuidzinas, Jonas

    2007-01-01

    We describe a new architecture for a superconducting detector for the submillimeter and far-infrared. This detector uses a distributed hot-electron transition edge sensor (TES) to collect the power from a focal-plane-filling slot antenna array. The sensors lay directly across the slots of the antenna and match the antenna impedance of about 30 ohms. Each pixel contains many sensors that are wired in parallel as a single distributed TES, which results in a low impedance that readily matches to a multiplexed SQUID readout These detectors are inherently polarization sensitive, with very low cross-polarization response, but can also be configured to sum both polarizations. The dual-polarization design can have a bandwidth of 50The use of electron-phonon decoupling eliminates the need for micro-machining, making the focal plane much easier to fabricate than with absorber-coupled, mechanically isolated pixels. We discuss applications of these detectors and a hybridization scheme compatible with arrays of tens of thousands of pixels.

  6. Mutual coupling, channel model, and BER for curvilinear antenna arrays

    NASA Astrophysics Data System (ADS)

    Huang, Zhiyong

    This dissertation introduces a wireless communications system with an adaptive beam-former and investigates its performance with different antenna arrays. Mutual coupling, real antenna elements and channel models are included to examine the system performance. In a beamforming system, mutual coupling (MC) among the elements can significantly degrade the system performance. However, MC effects can be compensated if an accurate model of mutual coupling is available. A mutual coupling matrix model is utilized to compensate mutual coupling in the beamforming of a uniform circular array (UCA). Its performance is compared with other models in uplink and downlink beamforming scenarios. In addition, the predictions are compared with measurements and verified with results from full-wave simulations. In order to accurately investigate the minimum mean-square-error (MSE) of an adaptive array in MC, two different noise models, the environmental and the receiver noise, are modeled. The minimum MSEs with and without data domain MC compensation are analytically compared. The influence of mutual coupling on the convergence is also examined. In addition, the weight compensation method is proposed to attain the desired array pattern. Adaptive arrays with different geometries are implemented with the minimum MSE algorithm in the wireless communications system to combat interference at the same frequency. The bit-error-rate (BER) of systems with UCA, uniform rectangular array (URA) and UCA with center element are investigated in additive white Gaussian noise plus well-separated signals or random direction signals scenarios. The output SINR of an adaptive array with multiple interferers is analytically examined. The influence of the adaptive algorithm convergence on the BER is investigated. The UCA is then investigated in a narrowband Rician fading channel. The channel model is built and the space correlations are examined. The influence of the number of signal paths, number of the

  7. Mutual coupling effects in antenna arrays, volume 1

    NASA Technical Reports Server (NTRS)

    Collin, R. E.

    1986-01-01

    Mutual coupling between rectangular apertures in a finite antenna array, in an infinite ground plane, is analyzed using the vector potential approach. The method of moments is used to solve the equations that result from setting the tangential magnetic fields across each aperture equal. The approximation uses a set of vector potential model functions to solve for equivalent magnetic currents. A computer program was written to carry out this analysis and the resulting currents were used to determine the co- and cross-polarized far zone radiation patterns. Numerical results for various arrays using several modes in the approximation are presented. Results for one and two aperture arrays are compared against published data to check on the agreement of this model with previous work. Computer derived results are also compared against experimental results to test the accuracy of the model. These tests of the accuracy of the program showed that it yields valid data.

  8. Reconfigurable time-steered array-antenna beam former.

    PubMed

    Frankel, M Y; Esman, R D

    1997-12-10

    We present and analyze a hardware-optimized technique that provides true-time-delay steering for broadband two-dimensional array-antenna applications. The technique improves on previous approaches by the reduction of the two-dimensional beam-former architecture complexity, by the provision of flexibility in time-delay unit selection, and by the potential reduction of optical loss. The technique relies on a one-dimensional bank of time-delay units to form the required time-delay gradient for proper off-broadside angle steering. A reconfigurable optical interconnection fabric is used to reassign dynamically the connections between the time-delay units and individual array elements of a two-dimensional array to effect the proper steering angle along the off-broadside cone.

  9. Transformation from a Single Antenna to a Series Array Using Push/Pull Origami.

    PubMed

    Shah, Syed Imran Hussain; Lim, Sungjoon

    2017-08-26

    We propose a push/pull origami antenna, transformable between a single antenna element and a three-element array. In limited space, the proposed origami antenna can work as a single antenna. When the space is not limited and a higher gain is required, the proposed origami antenna can be transformed to a series antenna array by pulling the frame. In order to push the antenna array back to a single antenna, the frame for each antenna element size must be different. The frame and supporting dielectric materials are built using a three-dimensional (3D) printer. The conductive patterns are inkjet-printed on paper. Thus, the proposed origami antenna is built using hybrid printing technology. The 10-dB impedance bandwidth is 2.5-2.65 GHz and 2.48-2.62 GHz for the single-antenna and array mode, respectively, and the peak gains in the single-antenna and array mode are 5.8 dBi and 7.6 dBi, respectively. The proposed antenna can be used for wireless remote-sensing applications.

  10. Bandwidth enhancement using Polymeric Grid Array Antenna for millimeter-wave application

    NASA Astrophysics Data System (ADS)

    Muhamad, Wan Asilah Wan; Ngah, Razali; Jamlos, Mohd Faizal; Soh, Ping Jack; Ali, Mohd Tarmizi

    2017-01-01

    A new grid array antenna designed on a polymeric polydimethylsiloxane (PDMS) substrate is presented. A good relative permittivity of the PDMS substrate increases the antenna bandwidth. The PDMS surface is also hardened to protect the proposed grid array antenna's radiating element. A SMA coaxial connector is used to feed the 36 × 35 mm2 antenna from its bottom. A bandwidth enhancement of 72.1% is obtained compared to conventional antenna. Besides, its efficiency is increased up to 70%. The simulated and measured results agreed well and the proposed antenna is validated to suit millimeter-wave applications.

  11. 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.

  12. 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.

  13. Microstrip Antennas with Polarization Diversity across a Wide Frequency Range and Phased Array Antennas for Radar and Satellite Communications

    NASA Astrophysics Data System (ADS)

    Ho, Kevin Ming-Jiang

    The thesis comprises of 3 projects; an L-band microstrip antenna with frequency agility and polarization diversity, X-band phased array antennas incorporating commercially packaged RFIC phased array chips, and studies for Ku/Ka-band shared aperture antenna array. The first project features the use of commercially packaged RF-MEMS SPDT switches, that boasts of high reliability, high linearity, low losses, hermetically packaged and fully compatible for SMTA processes for mass-assembly and production. Using the switches in a novel manner for the feed network, microstrip antennas with polarization diversity are presented. Frequency agility is achieved with the use of tuning diodes to provide capacitive loading to the antenna element. Additional inductance effects from surface-mounted capacitors, and its impact, is introduced. Theoretical cross-polarization of probe-fed antenna elements is presented for both linear and circular polarized microstrip antennas. Designs and measurements are presented, for microstrip antennas with polarization diversity, wide frequency tuning range, and both features. Replacement of the tuning diodes with commercially-packaged high Q RF MEMS tunable capacitors will allow for significant improvements to the radiation efficiency. In another project, multi-channel CMOS RFIC phased-array receiver chips are assembled in QFN packages and directly integrated on the same multi-layered PCB stack-up with the antenna arrays. Problems of isolation from the PCB-QFN interface, and potential performance degradation on antenna array from the use of commercial-grade laminates for assembly requirements, namely potential scan blindness and radiation efficiency, are presented. Causes for apparent drift of dielectric constant for microstrip circuits, and high conductor losses observed in measurements, are introduced. Finally, studies are performed for the design of a Ku/Ka-Band shared aperture array. Different approaches for developing dual-band shared apertures

  14. Optical characterization of Jerusalem cross-shaped nanoaperture antenna arrays

    NASA Astrophysics Data System (ADS)

    Turkmen, Mustafa; Aslan, Ekin; Aslan, Erdem

    2014-03-01

    Recent advances in nanofabrication and computational electromagnetic design techniques have enabled the realization of metallic nanostructures in different shapes and sizes with adjustable resonance frequencies. To date, many metamaterial designs in various geometries with the used of different materials have been presented for the applications of surface plasmons, cloaking, biosensing, and frequency selective surfaces1-5. Surface plasmons which are collective electron oscillations on metal surfaces ensure that plasmonic nanoantennas can be used in many applications like biosensing at infrared (IR) and visible regions. The nanostructure that we introduce has a unit cell that consists of Jerusalem crossshaped nanoaperture on a gold layer, which is standing on suspended SiNx, Si or glass membranes. The proposed nanoaperture antenna array has a regular and stable spectral response. In this study, we present sensitivity of the resonance characteristics of Jerusalem cross-shaped nanoaperture antenna arrays to the changes in substrate parameters and metal thickness. We demonstrate that resonance frequency values can be adjusted by changing the thicknesses and types of the dielectric substrate and the metallic layer. Numerical calculations on spectral response of the nanoantenna array are performed by using Finite Difference Time Domain (FDTD) method6. The results of the simulations specify that resonance frequencies, the reflectance and transmittance values at resonances, and the band gap vary by the change of substrate parameters and metal thicknesses. These variations is a sign of that the proposed nanoantenna can be employed for sensing applications.

  15. Adaptive array antenna for satellite cellular and direct broadcast communications

    NASA Technical Reports Server (NTRS)

    Horton, Charles R.; Abend, Kenneth

    1993-01-01

    Adaptive phased-array antennas provide cost-effective implementation of large, light weight apertures with high directivity and precise beamshape control. Adaptive self-calibration allows for relaxation of all mechanical tolerances across the aperture and electrical component tolerances, providing high performance with a low-cost, lightweight array, even in the presence of large physical distortions. Beam-shape is programmable and adaptable to changes in technical and operational requirements. Adaptive digital beam-forming eliminates uplink contention by allowing a single electronically steerable antenna to service a large number of receivers with beams which adaptively focus on one source while eliminating interference from others. A large, adaptively calibrated and fully programmable aperture can also provide precise beam shape control for power-efficient direct broadcast from space. Advanced adaptive digital beamforming technologies are described for: (1) electronic compensation of aperture distortion, (2) multiple receiver adaptive space-time processing, and (3) downlink beam-shape control. Cost considerations for space-based array applications are also discussed.

  16. Ka-band Dielectric Waveguide Antenna Array for Millimeter Wave Active Imaging System

    NASA Astrophysics Data System (ADS)

    Fang, Weihai; Fei, Peng; Nian, Feng; Yang, Yujie; Feng, Keming

    2014-11-01

    Ka-band compact dielectric waveguide antenna array for active imaging system is given. Antenna array with WR28 metal waveguide direct feeding is specially designed with small size, high gain, good radiation pattern, easy realization, low insertion loss and low mutual coupling. One practical antenna array for 3-D active imaging system is shown with theoretic analysis and experimental results. The mutual coupling of transmitting and receiving units is less than -30dB, the gain from 26.5GHz to 40GHz is (12-16) dB. The results in this paper provide guidelines for the designing of millimeter wave dielectric waveguide antenna array.

  17. 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.

  18. Optimization of Positioning of Interferometric Array Antennas Using Division Algorithm for Radio Astronomy Applications

    NASA Astrophysics Data System (ADS)

    Kiehbadroudinezhad, Shahideh; Valente, Daniela; Cada, Michael; Kamariah Noordin, Nor; Shahabi, Adib

    2017-10-01

    The Square Kilometre Array (SKA) ushers in the new generation of large radio telescopes that will work at wavelengths between meters and centimeters. In order to competitively design interferometric antenna arrays such as SKA, it is crucial to focus on the optimization of system performance. In this paper, we contribute to the solution by introducing a new optimization algorithm called Division Algorithm (DA). This algorithm finds the optimal positions of antennas to simultaneously maximize u–v coverage and decrease sidelobe level (SLL). The DA is able to optimize the configuration of the interferometric array in both snapshot and Earth rotation synthesis observations. To demonstrate its efficiency, the DA is applied to configure an optimum 30-element array for the Giant Metrewave Radio Telescope. The proposed algorithm is able to improve the overlapped samples parameter by about 4% and the unsampled cells parameter by about 12%, at snapshot observation, compared to the Genetic Algorithm (GA). DA is able to improve these two parameters for a 6-hr tracking observation as well. Finally, the proposed algorithm is compared with the GA for different source declination. Results show that the DA is able to decrease the SLL better than the GA.

  19. Air shower measurements with the LOPES radio antenna array

    NASA Astrophysics Data System (ADS)

    Lopes Collaboration; Haungs, A.; Apel, W. D.; Arteaga, J. C.; Asch, T.; Auffenberg, J.; Badea, F.; Bähren, L.; Bekk, K.; Bertaina, M.; Biermann, P. L.; Blümer, J.; Bozdog, H.; Brancus, I. M.; Brüggemann, M.; Buchholz, P.; Buitink, S.; Cantoni, E.; Chiavassa, A.; Cossavella, F.; Daumiller, K.; de Souza, V.; di Pierro, F.; Doll, P.; Engel, R.; Falcke, H.; Finger, M.; Fuhrmann, D.; Gemmeke, H.; Ghia, P. L.; Glasstetter, R.; Grupen, C.; Heck, D.; Hörandel, J. R.; Horneffer, A.; Huege, T.; Isar, P. G.; Kampert, K.-H.; Kang, D.; Kickelbick, D.; Kolotaev, Y.; Krömer, O.; Kuijpers, J.; Lafebre, S.; Łuczak, P.; Mathes, H. J.; Mayer, H. J.; Milke, J.; Mitrica, B.; Morello, C.; Navarra, G.; Nehls, S.; Nigl, A.; Oehlschläger, J.; Over, S.; Petcu, M.; Pierog, T.; Rautenberg, J.; Rebel, H.; Roth, M.; Saftoiu, A.; Schieler, H.; Schmidt, A.; Schröder, F.; Sima, O.; Singh, K.; Stümpert, M.; Toma, G.; Trinchero, G. C.; Ulrich, H.; Walkowiak, W.; Weindl, A.; Wochele, J.; Wommer, M.; Zabierowski, J.; Zensus, J. A.; LOPES Collaboration

    2009-06-01

    LOPES is set up at the location of the KASCADE-Grande extensive air shower experiment in Karlsruhe, Germany and aims to measure and investigate radio pulses from extensive air showers. Since radio waves suffer very little attenuation, radio measurements allow the detection of very distant or highly inclined showers. These waves can be recorded day and night, and provide a bolometric measure of the leptonic shower component. LOPES is designed as a digital radio interferometer using high bandwidths and fast data processing and profits from the reconstructed air shower observables of KASCADE-Grande. The LOPES antennas are absolutely amplitude calibrated allowing to reconstruct the electric field strength which can be compared with predictions from detailed Monte-Carlo simulations. We report about the analysis of correlations present in the radio signals measured by the LOPES 30 antenna array. Additionally, LOPES operates antennas of a different type (LOPESSTAR) which are optimized for an application at the Pierre Auger Observatory. Status, recent results of the data analysis and further perspectives of LOPES and the possible large scale application of this new detection technique are discussed.

  20. Active Antenna Development for the Long Wavelength Array

    NASA Astrophysics Data System (ADS)

    Stewart, K. P.; Hicks, B. C.; Crane, P. C.; Ray, P. S.; Gross, C.; Polisensky, E. J.; Erickson, W. C.

    2005-12-01

    We are developing and testing active baluns and electrically short dipoles for possible use as the primary wideband receiving elements in the Long Wavelength Array (LWA) for HF-VHF radio astronomy. Several dipoles of various designs and dimensions have been built and tested. Their useful range occurs when the dipole arms are approximately 1/8 to one wavelength long and the feedpoint is less than 1/2 wavelength above ground. An eight-element NRL LWA Test Array (NLTA) interferometer has been built and fringes have been observed from the brightest celestial sources in the frequency range from 10 MHz to 50 MHz. The antenna temperatures vary from about 10% to 100% of the average brightness temperature of the galactic background. With these parameters it is easy to make the amplifier noise levels low enough that final system temperature is dominated by the galactic background.

  1. The Digital Motion Control System for the Submillimeter Array Antennas

    NASA Astrophysics Data System (ADS)

    Hunter, T. R.; Wilson, R. W.; Kimberk, R.; Leiker, P. S.; Patel, N. A.; Blundell, R.; Christensen, R. D.; Diven, A. R.; Maute, J.; Plante, R. J.; Riddle, P.; Young, K. H.

    2013-09-01

    We describe the design and performance of the digital servo and motion control system for the 6-meter parabolic antennas of the Submillimeter Array (SMA) on Mauna Kea, Hawaii. The system is divided into three nested layers operating at a different, appropriate bandwidth. (1) A rack-mounted, real-time Unix system runs the position loop which reads the high resolution azimuth and elevation encoders and sends velocity and acceleration commands at 100 Hz to a custom-designed servo control board (SCB). (2) The microcontroller-based SCB reads the motor axis tachometers and implements the velocity loop by sending torque commands to the motor amplifiers at 558 Hz. (3) The motor amplifiers implement the torque loop by monitoring and sending current to the three-phase brushless drive motors at 20 kHz. The velocity loop uses a traditional proportional-integral-derivative (PID) control algorithm, while the position loop uses only a proportional term and implements a command shaper based on the Gauss error function. Calibration factors and software filters are applied to the tachometer feedback prior to the application of the servo gains in the torque computations. All of these parameters are remotely adjustable in the software. The three layers of the control system monitor each other and are capable of shutting down the system safely if a failure or anomaly occurs. The Unix system continuously relays the antenna status to the central observatory computer via reflective memory. In each antenna, a Palm Vx hand controller displays the complete system status and allows full local control of the drives in an intuitive touchscreen user interface. The hand controller can also be connected outside the cabin, a major convenience during the frequent reconfigurations of the interferometer. Excellent tracking performance ( 0.3‧‧ rms) is achieved with this system. It has been in reliable operation on 8 antennas for over 10 years and has required minimal maintenance.

  2. Computer simulation of the effects of a distributed array antenna on synthetic aperture radar images

    NASA Technical Reports Server (NTRS)

    Estes, J. M.

    1985-01-01

    The ARL:UT orbital SAR simulation has been upgraded to use three-dimensional antenna gain patterns. This report describes the modifications and presents quantitative image analyses of a simulation using antenna patterns generated from the modeling of a distributed array antenna.

  3. A finite element-boundary integral method for conformal antenna arrays on a circular cylinder

    NASA Technical Reports Server (NTRS)

    Kempel, Leo C.; Volakis, John L.; Woo, Alex C.; Yu, C. Long

    1992-01-01

    Conformal antenna arrays offer many cost and weight advantages over conventional antenna systems. In the past, antenna designers have had to resort to expensive measurements in order to develop a conformal array design. This is due to the lack of rigorous mathematical models for conformal antenna arrays, and as a result the design of conformal arrays is primarily based on planar antenna design concepts. Recently, we have found the finite element-boundary integral method to be very successful in modeling large planar arrays of arbitrary composition in a metallic plane. Herewith we shall extend this formulation for conformal arrays on large metallic cylinders. In this we develop the mathematical formulation. In particular we discuss the finite element equations, the shape elements, and the boundary integral evaluation, and it is shown how this formulation can be applied with minimal computation and memory requirements. The implementation shall be discussed in a later report.

  4. Quasi-optical antenna-mixer-array design for terahertz frequencies

    NASA Technical Reports Server (NTRS)

    Guo, Yong; Potter, Kent A.; Rutledge, David B.

    1992-01-01

    A new quasi-optical antenna-mixer-array design for terahertz frequencies is presented. In the design, antenna and mixer are combined into an entity, based on the technology in which millimeter-wave horn antenna arrays have been fabricated in silicon wafers. It consists of a set of forward- and backward-looking horns made with a set of silicon wafers. The front side is used to receive incoming signal, and the back side is used to feed local oscillator signal. Intermediate frequency is led out from the side of the array. Signal received by the horn array is picked up by antenna probes suspended on thin silicon-oxynitride membranes inside the horns. Mixer diodes will be located on the membranes inside the horns. Modeling of such an antenna-mixer-array design is done on a scaled model at microwave frequencies. The impedance matching, RF and LO isolation, and patterns of the array have been tested and analyzed.

  5. A finite element-boundary integral method for conformal antenna arrays on a circular cylinder

    NASA Technical Reports Server (NTRS)

    Kempel, Leo C.; Volakis, John L.

    1992-01-01

    Conformal antenna arrays offer many cost and weight advantages over conventional antenna systems. In the past, antenna designers have had to resort to expensive measurements in order to develop a conformal array design. This was due to the lack of rigorous mathematical models for conformal antenna arrays. As a result, the design of conformal arrays was primarily based on planar antenna design concepts. Recently, we have found the finite element-boundary integral method to be very successful in modeling large planar arrays of arbitrary composition in a metallic plane. We are extending this formulation to conformal arrays on large metallic cylinders. In doing so, we will develop a mathematical formulation. In particular, we discuss the finite element equations, the shape elements, and the boundary integral evaluation. It is shown how this formulation can be applied with minimal computation and memory requirements.

  6. Overview of newly installed surface antennas in the Askaryan Radio Array

    NASA Astrophysics Data System (ADS)

    Stockham, Mark

    2013-04-01

    The Askaryan Radio Array (ARA) located at the South Pole is in a period of expansion. This season eight surface antennas located at two sites were added to the existing array. These surface antennas are copper dipole antennas with nominal frequency response from 30-1000 MHz that will be sensitive to Askaryan effect neutrino signals as well as cosmic ray produced extensive air shower signals and will allow for coincident detection with in-ice antenna channels. A review of these surface antennas will be presented.

  7. Electromagnetic Wave Absorbing Technique Using Periodic Patterns for Low RCS Patch Array Antenna

    NASA Astrophysics Data System (ADS)

    Jang, Hong-Kyu; Lee, Yeon-Gwan; Shin, Jae-Hwan; Kim, Chun-Gon

    2013-07-01

    This paper presents an electromagnetic wave absorbing technique to reduce a radar cross-section (RCS) of a patch array antenna without compromising their antenna performance. The technique is based on periodic patterns, which is made of resistive materials. The 2×2 patch array antenna with a resonance frequency of 3.0 GHz was designed and fabricated. To reduce the RCS of the patch array antenna, the periodic patterns using a square patch element were proposed and applied to the surface between the four antenna patches. The printed lossy periodic patterns have radar absorbing performance at 12.0 GHz frequency. The measured results show that the lossy periodic patterns have no significant effect on the antenna radiation performance. On the other hand, the RCS is reduced by more than 98% compared to the conventional antenna at the target frequency.

  8. Phase-locked laser array through global antenna mutual coupling

    SciTech Connect

    Kao, Tsung -Yu; Reno, John L.; Hu, Qing

    2016-01-01

    Here, phase locking of an array of lasers is a highly effective way in beam shaping, to increase the output power, and to reduce lasing threshold. In this work, we present a novel phase-locking mechanism based on "antenna mutual coupling" wherein laser elements interact through far-field radiations with definite phase relations. This allows long-range global coupling among array elements to achieve robust 2-dimensional phase-locked laser array. The new scheme is ideal for lasers with deep sub-wavelength confined cavity such as nanolasers, where the divergent beam pattern could be used to form strong coupling among elements in the array. We experimentally demonstrated such a scheme using sub-wavelength short-cavity surface-emitting lasers at terahertz frequency. More than 37 laser elements are phase-locked to each other, delivering up to 6.5 mW single-mode radiations at ~3 terahertz, with maximum 450-mW/A slope efficiency and near diffraction limit beam divergence.

  9. Phase-locked laser array through global antenna mutual coupling

    DOE PAGES

    Kao, Tsung -Yu; Reno, John L.; Hu, Qing

    2016-01-01

    Here, phase locking of an array of lasers is a highly effective way in beam shaping, to increase the output power, and to reduce lasing threshold. In this work, we present a novel phase-locking mechanism based on "antenna mutual coupling" wherein laser elements interact through far-field radiations with definite phase relations. This allows long-range global coupling among array elements to achieve robust 2-dimensional phase-locked laser array. The new scheme is ideal for lasers with deep sub-wavelength confined cavity such as nanolasers, where the divergent beam pattern could be used to form strong coupling among elements in the array. We experimentallymore » demonstrated such a scheme using sub-wavelength short-cavity surface-emitting lasers at terahertz frequency. More than 37 laser elements are phase-locked to each other, delivering up to 6.5 mW single-mode radiations at ~3 terahertz, with maximum 450-mW/A slope efficiency and near diffraction limit beam divergence.« less

  10. 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.

  11. The DESDynI Synthetic Aperture Radar Array-Fed Reflector Antenna

    NASA Technical Reports Server (NTRS)

    Chamberlain, Neil; Ghaemi, Hirad; Giersch, Louis; Harcke, Leif; Hodges, Richard; Hoffman, James; Johnson, William; Jordan, Rolando; Khayatian, Behrouz; Rosen, Paul; Sadowy, Gregory; Shaffer, Scott; Shen, Yuhsyen; Veilleux, Louise; Wu, Patrick

    2010-01-01

    DESDynI is a mission being developed by NASA with radar and lidar instruments for Earth-orbit remote sensing. This paper focuses on the design of a largeaperture antenna for the radar instrument. The antenna comprises a deployable reflector antenna and an active switched array of patch elements fed by transmit/ receive modules. The antenna and radar architecture facilitates a new mode of synthetic aperture radar imaging called 'SweepSAR'. A system-level description of the antenna is provided, along with predictions of antenna performance.

  12. Advanced Antenna-Coupled Superconducting Detector Arrays for CMB Polarimetry

    NASA Astrophysics Data System (ADS)

    Bock, James

    2014-01-01

    We are developing high-sensitivity millimeter-wave detector arrays for measuring the polarization of the cosmic microwave background (CMB). This development is directed to advance the technology readiness of the Inflation Probe mission in NASA's Physics of the Cosmos program. The Inflation Probe is a fourth-generation CMB satellite that will measure the polarization of the CMB to astrophysical limits, characterizing the inflationary polarization signal, mapping large-scale structure based on polarization induced by gravitational lensing, and mapping Galactic magnetic fields through measurements of polarized dust emission. The inflationary polarization signal is produced by a background of gravitational waves from the epoch of inflation, an exponential expansion of space-time in the early universe, with an amplitude that depends on the physical mechanism producing inflation. The inflationary polarization signal may be distinguished by its unique 'B-mode' vector properties from polarization from the density variations that predominantly source CMB temperature anisotropy. Mission concepts for the Inflation Probe are being developed in the US, Europe and Japan. The arrays are based on planar antennas that provide integral beam collimation, polarization analysis, and spectral band definition in a compact lithographed format that eliminates discrete fore-optics such as lenses and feedhorns. The antennas are coupled to transition-edge superconducting bolometers, read out with multiplexed SQUID current amplifiers. The superconducting sensors and readouts developed in this program share common technologies with NASA X-ray and FIR detector applications. Our program targets developments required for space observations, and we discuss our technical progress over the past two years and plans for future development. We are incorporating arrays into active sub-orbital and ground-based experiments, which advance technology readiness while producing state of the art CMB

  13. Enhanced Nonlinear Effect of Lithium Niobate Based Periodic Nano-antenna Array

    NASA Astrophysics Data System (ADS)

    Pei, X. L.; Bai, S. A.; Tian, J. Y.; Ghosh, P.; Li, Q.; Qiu, M.

    2017-06-01

    We report nonlinear properties of lithium niobate based periodic nano-antenna array. The resonances of this nano-antenna array can be engineered by tuning the geometrical parameters. The nonlinear effect gets enhanced when the electric and magnetic resonances overlap.

  14. Antenna coupled detectors for 2D staring focal plane arrays

    NASA Astrophysics Data System (ADS)

    Gritz, Michael A.; Kolasa, Borys; Lail, Brian; Burkholder, Robert; Chen, Leonard

    2013-06-01

    Millimeter-wave (mmW)/sub-mmW/THz region of the electro-magnetic spectrum enables imaging thru clothing and other obscurants such as fog, clouds, smoke, sand, and dust. Therefore considerable interest exists in developing low cost millimeter-wave imaging (MMWI) systems. Previous MMWI systems have evolved from crude mechanically scanned, single element receiver systems into very complex multiple receiver camera systems. Initial systems required many expensive mmW integrated-circuit low-noise amplifiers. In order to reduce the cost and complexity of the existing systems, attempts have been made to develop new mmW imaging sensors employing direct detection arrays. In this paper, we report on Raytheon's recent development of a unique focal plane array technology, which operates broadly from the mmW through the sub-mmW/THz region. Raytheon's innovative nano-antenna based detector enables low cost production of 2D staring mmW focal plane arrays (mmW FPA), which not only have equivalent sensitivity and performance to existing MMWI systems, but require no mechanical scanning.

  15. SALSA - A Synthesis Array for Lunar Submillimeter Astronomy

    NASA Technical Reports Server (NTRS)

    Mahoney, M. J.; Marsh, K. A.

    1991-01-01

    A conceptual design is described for a lunar submillimeter wavelength interferometer called SALSA, a Synthesis Array for Lunar Submillimeter Astronomy. Its design is greatly simplified over conventional submillimeter wavelength arrays because it takes advantage of a beam waveguide to relay signals to a centrally-located receiver system. The array is optimized to synthesize images at wavelengths between 60 and 300 microns, and it has an angular resolution of 10 milliarcsecs at 60 microns. Observations in this region provide unique insights into fundamental issues in astrophysics such as star formation, but are impossible from the earth's surface because of atmospheric absorption. The baseline design for SALSA consists of twelve, 3.5-meter diameter antennas arranged in a Y-shaped configuration consisting of three 0.5-km long arms, each with four antennas distributed according to a power-law function of distance. Such a beam-waveguide approach has significant advantages, since all the high-power-consumption items (active cryogenics, correlator) are at a central location and could share a single power source. In addition, the antennas can be quite simple and maintenance is greatly reduced. The primary technology challenges for developing such an array are the coherent detectors (mixers and local oscillator sources), and ensuring the dimensional stability of the optical elements under the extreme lunar thermal environment (85-385 K).

  16. SALSA - A Synthesis Array for Lunar Submillimeter Astronomy

    NASA Technical Reports Server (NTRS)

    Mahoney, M. J.; Marsh, K. A.

    1991-01-01

    A conceptual design is described for a lunar submillimeter wavelength interferometer called SALSA, a Synthesis Array for Lunar Submillimeter Astronomy. Its design is greatly simplified over conventional submillimeter wavelength arrays because it takes advantage of a beam waveguide to relay signals to a centrally-located receiver system. The array is optimized to synthesize images at wavelengths between 60 and 300 microns, and it has an angular resolution of 10 milliarcsecs at 60 microns. Observations in this region provide unique insights into fundamental issues in astrophysics such as star formation, but are impossible from the earth's surface because of atmospheric absorption. The baseline design for SALSA consists of twelve, 3.5-meter diameter antennas arranged in a Y-shaped configuration consisting of three 0.5-km long arms, each with four antennas distributed according to a power-law function of distance. Such a beam-waveguide approach has significant advantages, since all the high-power-consumption items (active cryogenics, correlator) are at a central location and could share a single power source. In addition, the antennas can be quite simple and maintenance is greatly reduced. The primary technology challenges for developing such an array are the coherent detectors (mixers and local oscillator sources), and ensuring the dimensional stability of the optical elements under the extreme lunar thermal environment (85-385 K).

  17. Investigation of certain characteristics of thinned antenna arrays with digital signal processing

    NASA Astrophysics Data System (ADS)

    Danilevskii, L. V.; Domanov, Iu. A.; Korobko, O. V.; Tauroginskii, B. I.

    1983-11-01

    A thinned array with correlation processing of input signals is examined. It is shown that amplitude quantization does not change the signal at the thinned-array input as compared with the complete antenna array. The discreteness of time delay causes the thinned and complete arrays to become nonequivalent. Computer-simulation results are presented.

  18. The study of microstrip antenna arrays and related problems

    NASA Technical Reports Server (NTRS)

    Lo, Y. T.

    1984-01-01

    The physical layout of the array elements and the proximity of the microstrip feed network makes the input impedance and radiation pattern values dependent upon the effects of mutual coupling, feedline discontinuities and feed point location. The extent of these dependences was assessed and a number of single patch and module structures were constructed and measured at an operating frequency of approximately 4.0 GHz. The empirical results were compared with the ones which were theoretically predicted by the cavity model of thin microstrip antennas. Each element was modelled as an independent radiating patch and each microstrip feedline as an independent, quasi-TEM transmission line. The effects of the feedline discontinuities are approximated by lumped L-C circuit models.

  19. Characterization of MMIC devices for active array antennas

    NASA Astrophysics Data System (ADS)

    Smetana, J.; Farr, E.; Mittra, R.

    1985-01-01

    Certain aspects of monlithic microwave integrated circuit (MMIC) interconnectivity were investigated. Considerations that lead to preserving the inherently reproducible characteristics of the MMIC are proposed. It is shown that at radio frequencies (RF) greater than 20 GHz, the transition from the MMIC device to other transmission media must be an accurate RF match. It is proposed that the RF match is sufficiently critical to include the transition as part of the delivered MMIC package. The model to analyze several transitions is presented. This model consists of a succession of abrupt discontinuities in printed circuit transmission lines. The analysis of these discontinuities is achieved by the Spectral Galerkin technique, to establish the modes and mode that special effects should be coordinated by the active array antenna industry toward standardization of MMIC packaging and characterization.

  20. 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.

  1. Characterization of MMIC devices for active array antennas

    NASA Technical Reports Server (NTRS)

    Smetana, J.; Farr, E.; Mittra, R.

    1984-01-01

    Certain aspects of monolithic microwave integrated circuit (MMIC) interconnectivity were investigated. Considerations that lead to preserving the inherently reproducible characteristics of the MMIC are proposed. It is shown that at radio frequencies (RF) greater than 20 GHz, the transition from the MMIC device to other transmission media must be an accurate RF match. It is proposed that the RF match is sufficiently critical to include the transition as part of the delivered MMIC package. The model to analyze several transitions is presented. This model consists of a succession of abrupt discontinuities in printed circuit transmission lines. The analysis of these discontinuities is achieved by the Spectral Galerkin technique, to establish the modes and mode matching, to generate the generalized S parameters of the individual discontinuities. Preliminary results achieved with this method are presented. It is concluded that special effects should be coordinated by the active array antenna industry toward standardization of MMIC packaging and characterization.

  2. Monolithic microwave integrated circuit devices for active array antennas

    NASA Technical Reports Server (NTRS)

    Mittra, R.

    1984-01-01

    Two different aspects of active antenna array design were investigated. The transition between monolithic microwave integrated circuits and rectangular waveguides was studied along with crosstalk in multiconductor transmission lines. The boundary value problem associated with a discontinuity in a microstrip line is formulated. This entailed, as a first step, the derivation of the propagating as well as evanescent modes of a microstrip line. The solution is derived to a simple discontinuity problem: change in width of the center strip. As for the multiconductor transmission line problem. A computer algorithm was developed for computing the crosstalk noise from the signal to the sense lines. The computation is based on the assumption that these lines are terminated in passive loads.

  3. Design investigation for a microstrip phased array antenna for the ORION satellite

    NASA Astrophysics Data System (ADS)

    Smith, Mark B.

    1988-06-01

    Students at the Naval Postgraduate School are designing a general purpose mini-satellite that can be launched from a Get-Away-Special cannister located in the cargo bay of the Space Shuttle and will be compatible with expendable launch vehicles as well. This thesis defines preliminary antenna systems and the design parameters for the telemetry system of the ORION mini-satellite. These antenna design parameters may be used for investigations of various proposed antenna systems and the design parameters also allow for trade-off studies with the mission capabilities and subsystems of the satellite. An investigation is made into the feasibility of using conformal microstrip patch array antennas for the telemetry, tracking and command (TT&C) systems. It is necessary to have two separate microstrip patch array antennas for the telemetry system: one uplink and one downlink antenna. The microstrip patch array antenna can operate as either an omnidirectional antenna or a directional antenna by changing the phase of the individual patch feeds. This feature gives the microstrip patch array antenna more flexibility for meeting the needs of potential users.

  4. Surface-enhanced infrared spectroscopy using metal oxide plasmonic antenna arrays.

    PubMed

    Abb, Martina; Wang, Yudong; Papasimakis, Nikitas; de Groot, C H; Muskens, Otto L

    2014-01-08

    We successfully demonstrate surface-enhanced infrared spectroscopy using arrays of indium tin oxide (ITO) plasmonic nanoantennas. The ITO antennas show a strongly reduced plasmon wavelength, which holds promise for ultracompact antenna arrays and extremely subwavelength metamaterials. The strong plasmon confinement and reduced antenna cross section allows ITO antennas to be integrated at extremely high densities with no loss in performance due to long-range transverse interactions. By further reducing the spacing of antennas in the arrays, we access the regime of plasmonic near field coupling where the response is enhanced for both Au and ITO devices. Ultracompact ITO antennas with high spatial and spectral selectivity in spectroscopic applications offer a viable new platform for infrared plasmonics, which may be combined with other functionalities of these versatile materials in devices.

  5. A microfabricated low-profile wideband antenna array for terahertz communications.

    PubMed

    Luk, K M; Zhou, S F; Li, Y J; Wu, F; Ng, K B; Chan, C H; Pang, S W

    2017-04-28

    While terahertz communications are considered to be the future solutions for the increasing demands on bandwidth, terahertz equivalents of radio frequency front-end components have not been realized. It remains challenging to achieve wideband, low profile antenna arrays with highly directive beams of radiation. Here, based on the complementary antenna approach, a wideband 2 × 2 cavity-backed slot antenna array with a corrugated surface is proposed. The approach is based on a unidirectional antenna with a cardiac radiation pattern and stable frequency characteristics that is achieved by integrating a series-resonant electric dipole with a parallel-resonant magnetic dipole. In this design, the slots work as magnetic dipoles while the corrugated surface radiates as an array of electric dipoles. The proposed antenna is realized at 1 THz operating frequency by stacking multiple metallized layers using the microfabrication technology. S-parameter measurements of this terahertz low-profile metallic antenna array demonstrate high efficiency at terahertz frequencies. Fractional bandwidth and gain are measured to be 26% and 14 dBi which are consistent with the simulated results. The proposed antenna can be used as the building block for larger antenna arrays with more directive beams, paving the way to develop high gain low-profile antennas for future communication needs.

  6. Multibeam Spatially-Fed Antenna Arrays with Amplitude-Controlled Beam Steering

    DTIC Science & Technology

    2003-09-01

    connections between antenna pair feeds corresponding to the two linear polarizations. The lens array designed for this study is a cylindrical 45-element...multibeam array that can be designed to have low loss for large numbers of elements for two orthogonal well-isolated (30dB) polarizations. In a transmitter...This loss can be significantly reduced if the lens array and the receiving antenna are designed as a system, which was attempted in the case of the 10

  7. Graphene circular polarization analyzer based on spiral metal triangle antennas arrays.

    PubMed

    Zhu, Bofeng; Ren, Guobin; Gao, Yixiao; Wu, Beilei; Wan, Chenglong; Jian, Shuisheng

    2015-09-21

    In this paper we propose a circular polarization analyzer based on spiral metal triangle antenna arrays deposited on graphene. Via the dipole antenna resonances, plasmons are excited on graphene surface and the wavefront can be tailed by arranging metal antennas into linetype, circular or spiral arrays. Especially, for spiral antenna arrays, the geometric phase effect can be cancelled by or superposed on the chirality carried within circular polarization incidence, producing spatially separated solid dot or donut shape fields at the center. Such a phenomenon enables the graphene based spiral metal triangle antennas arrays to achieve functionality as a circular polarization analyzer. Extinction ratio over 550 can be achieved and the working wavelength can be tuned by adjusting graphene Fermi level dynamically. The proposed analyzer may find applications in analyzing chiral molecules using different circularly polarized waves.

  8. Active feed array compensation for reflector antenna surface distortions. Ph.D. Thesis - Akron Univ., Ohio

    NASA Technical Reports Server (NTRS)

    Acosta, Roberto J.

    1988-01-01

    The feasibility of electromagnetic compensation for reflector antenna surface distortions is investigated. The performance characteristics of large satellite communication reflector antenna systems degrade as the reflector surface distorts, mainly due to thermal effects from solar radiation. The technique developed can be used to maintain the antenna boresight directivity and sidelobe level independent of thermal effects on the reflector surface. With the advent of monolithic microwave integrated circuits (MMIC), a greater flexibility in array fed reflector antenna systems can be achieved. MMIC arrays provide independent control of amplitude and phase for each of the many radiating elements in the feed array. By assuming a known surface distortion profile, a simulation study is carried out to examine the antenna performance as a function of feed array size and number of elements. Results indicate that the compensation technique can effectively control boresight directivity and sidelobe level under peak surface distortion in the order of tenth of a wavelength.

  9. New design concept of monopole antenna array for UHF 7T MRI.

    PubMed

    Hong, Suk-Min; Park, Joshua Haekyun; Woo, Myung-Kyun; Kim, Young-Bo; Cho, Zang-Hee

    2014-05-01

    We have developed and evaluated a monopole antenna array that can increase sensitivity at the center of the brain for 7T MRI applications. We have developed a monopole antenna array that has half the length of a conventional dipole antenna with eight channels for brain imaging with a 7T MRI. The eight-channel monopole antenna array and conventional eight-channel transceiver surface coil array were evaluated and compared in terms of transmit properties, specific absorption ratio (SAR), and sensitivity. The sensitivity maps were generated by dividing the SNR map by the flip angle distribution. A single surface coil provides asymmetric sensitivity resulting in reduced sensitivity at the center of the brain. In contrast, a single monopole antenna provides higher sensitivity at the center of the brain. Moreover, the monopole antenna array provides uniform sensitivity over the entire brain, and the sensitivity gain was 1.5 times higher at the center of the brain compared with the surface coil array. The monopole antenna array is a promising candidate for MRI applications, especially for brain imaging in a 7T MRI because it provides increased sensitivity at the center of the brain. Copyright © 2013 Wiley Periodicals, Inc.

  10. Enhancing isolation of antenna arrays by simultaneously blocking and guiding magnetic field lines using magnetic metamaterials

    NASA Astrophysics Data System (ADS)

    Liu, Zhaotang; Wang, Jiafu; Qu, Shaobo; Zhang, Jieqiu; Ma, Hua; Xu, Zhuo; Zhang, Anxue

    2016-10-01

    In this article, we propose to enhance the isolation of antenna arrays by manipulating the near-field magnetic coupling between adjacent antennas using magnetic metamaterials (MMs). Due to the artificially designed negative or large permeability, MMs can concentrate or block the magnetic field lines where they are located, which allows us to tune the near-field magnetic coupling strengths between antennas. MMs can play a two-fold role in enhancing antenna isolation. On one hand, the magnetic fields can be blocked in gaps between adjacent antennas using MMs with negative permeability; on the other hand, the magnetic fields can be pulled towards the borders of the antenna array using MMs with large permeability. As an example, we demonstrated a four-element patch antenna array with split-ring resonators (SRR) integrated in the substrate. The measured results show that the isolation can be enhanced by more than 10 dB with the integration of SRRs, even if the gap between antennas is only about 0.082λ. This work provides an effective alternative to the design of high-isolation antenna arrays.

  11. Antenna-Coupled Bolometer Arrays for Measurement of the Cosmic Microwave Background Polarization

    NASA Astrophysics Data System (ADS)

    Myers, M. J.; Arnold, K.; Ade, P.; Engargiola, G.; Holzapfel, W.; Lee, A. T.; Meng, X.; O'Brient, R.; Richards, P. L.; Spieler, H.; Tran, H. T.

    2008-04-01

    We are building antenna-coupled Transition Edge Sensor bolometer arrays to measure the polarization of the cosmic microwave background. 217 GHz prototype pixels have previously been characterized and showed promising performance (Myers et al. in Appl. Phys. Lett. 86:114103, [2005]). Our design uses a double slot dipole antenna and an integrated microstrip band defining filter. New devices have been tested which include on-chip test structures to improve our understanding of detector performance and guide future development. In parallel with this, large arrays of bolometers based on the prototype pixel design have also been constructed. The array pixels are a heterogeneous mixture of single band pixels at 90 GHz, 150 GHz, and 220 GHz and now incorporate dual-polarization antennas (Chattopadhyay and Zmuidzinas in IEEE Trans. Antennas Propag. 46:736, [1998]). Preliminary results from optical testing of array pixels are presented. These bolometer arrays will be used in the upcoming CMB polarization experiment P olarbear.

  12. 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

  13. 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

  14. Antenna array connections for efficient performance of distributed microbolometers in the IR.

    PubMed

    Silva-López, Manuel; Cuadrado, Alexander; Llombart, Nuria; Alda, Javier

    2013-05-06

    Optical antennas and resonant structures have been extensively investigated due to its potential for electromagnetic detection and energy harvesting applications. However their integration into large arrays and the role of connection lines between individual antennas has drawn little attention. This is necessary if we want to exploit its potential constructively and to enable economical large-scale fabrication. In this contribution we point out some features that an efficient antenna array should address. Experimental measurements on aluminum microbolometers are compared to electromagnetic simulations, it is shown that the finite size of a real array and the interconnection lines interact and affect the global performance.

  15. Mechanical Development of a Very Non-Standard Patch Array Antenna for Extreme Environments

    NASA Technical Reports Server (NTRS)

    Hughes, Richard; Chamberlain, Neil; Jakoboski, Julie; Petkov, Mihail

    2012-01-01

    This paper describes the mechanical development of patch antenna arrays for the Juno mission. The patch arrays are part of a six-frequency microwave radiometer instrument that will be used to measure thermal emissions from Jupiter. The very harsh environmental conditions in Jupiter orbit, as well as a demanding launch environment, resulted in a design that departs radically from conventional printed circuit patch antennas. The paper discusses the development and qualification of the Juno patch array antennas, with emphasis on the materials approach that was devised to mitigate the effects of electron charging in Jupiter orbit.

  16. Low Average Sidelobe Slot Array Antennas for Radiometer Applications

    NASA Technical Reports Server (NTRS)

    Rengarajan, Sembiam; Zawardzki, Mark S.; Hodges, Richard E.

    2012-01-01

    In radiometer applications, it is required to design antennas that meet low average sidelobe levels and low average return loss over a specified frequency bandwidth. It is a challenge to meet such specifications over a frequency range when one uses resonant elements such as waveguide feed slots. In addition to their inherent narrow frequency band performance, the problem is exacerbated due to modeling errors and manufacturing tolerances. There was a need to develop a design methodology to solve the problem. An iterative design procedure was developed by starting with an array architecture, lattice spacing, aperture distribution, waveguide dimensions, etc. The array was designed using Elliott s technique with appropriate values of the total slot conductance in each radiating waveguide, and the total resistance in each feed waveguide. Subsequently, the array performance was analyzed by the full wave method of moments solution to the pertinent integral equations. Monte Carlo simulations were also carried out to account for amplitude and phase errors introduced for the aperture distribution due to modeling errors as well as manufacturing tolerances. If the design margins for the average sidelobe level and the average return loss were not adequate, array architecture, lattice spacing, aperture distribution, and waveguide dimensions were varied in subsequent iterations. Once the design margins were found to be adequate, the iteration was stopped and a good design was achieved. A symmetric array architecture was found to meet the design specification with adequate margin. The specifications were near 40 dB for angular regions beyond 30 degrees from broadside. Separable Taylor distribution with nbar=4 and 35 dB sidelobe specification was chosen for each principal plane. A non-separable distribution obtained by the genetic algorithm was found to have similar characteristics. The element spacing was obtained to provide the required beamwidth and close to a null in the E

  17. Design of a low-loss series-fed microstrip array antenna

    NASA Technical Reports Server (NTRS)

    Mahbub, M. R.; Christodoulou. C. G.; Bailey, M. C.

    1998-01-01

    The design and analysis of a series-fed, low-loss, inverted microstrip array antenna, operating at 1.413 GHz is presented. The array antenna is composed of two sub arrays. Each sub array consists of an equal number of microstrip patches all connected together through a series microstrip line. The first element of each sub array is coaxially fed but 180 degree out of phase. This approach ensures a symmetric radiation pattern. The design approach, is accomplished using the IE3D code that utilizes the method of moments. All experimental and simulated data are presented and discussed.

  18. Circular patch microstrip array antenna on NiCoAl ferrite substrate in C-band

    NASA Astrophysics Data System (ADS)

    Kumar, Dheeraj; Pourush, P. K. S.

    2010-05-01

    The problem of a 4×4 circular disc array antenna (CDAA) printed on a uniaxially anisotropic ferrite (NiCoAl) substrate is treated. The effect of anisotropy on the resonant frequency of the antenna is investigated. Radiation and scattering characteristics of the antenna with normal magnetic bias field to the direction of wave propagation in the plane of ferrite are described. Calculated result for the radar cross section (RCS) of antenna presented, and it is shown that the peaks in the RCS can be moved with respect to angle of incidence by changing the magnetic bias field. This effect offers a way of minimizing the radar visibility of microstrip antennas and arrays. Results are obtained from cavity modal solutions for a circular patch antenna at its TM 11 mode.

  19. Parasitic antenna effect in terahertz plasmon detector array for real-time imaging system

    NASA Astrophysics Data System (ADS)

    Yang, Jong-Ryul; Lee, Woo-Jae; Ryu, Min Woo; Rok Kim, Kyung; Han, Seong-Tae

    2015-10-01

    The performance uniformity of each pixel integrated with a patch antenna in a terahertz plasmon detector array is very important in building the large array necessary for a real-time imaging system. We found a parasitic antenna effect in the terahertz plasmon detector whose response is dependent on the position of the detector pixel in the illumination area of the terahertz beam. It was also demonstrated that the parasitic antenna effect is attributed to the physical structure consisting of signal pads, bonding wires, and interconnection lines on a chip and a printed circuit board. Experimental results show that the performance of the detector pixel is determined by the sum of the effects of each parasitic antenna and the on-chip integrated antenna designed to detect signals at the operating frequency. The parasitic antenna effect can be minimized by blocking the interconnections with a metallic shield.

  20. Yagi-Uda optical antenna array collimated laser based on surface plasmons

    NASA Astrophysics Data System (ADS)

    Ma, Long; Lin, Jie; Ma, Yuan; Liu, Bin; Tan, Jiubin; Jin, Peng

    2016-06-01

    The divergence and directivity of a laser with a periodic Yagi-Uda optical antenna array modulated surface are investigated by finite element method. The nanoparticle optical antenna arrays are optimized to achieve the high directivity and the small divergence by using of Helmholtz's reciprocity theorem. When the nanoparticle antenna replaced by a Yagi-Uda antenna with same size, the directivity and the signal-to-noise ratio of the modulated laser beam are notably enhanced. The main reason is that the directors of the Yagi-Uda antennas induce more energy to propagate towards the antenna transmitting direction. The results can provide valuable guidelines in designing collimated laser, which can be widely applied in the field of biologic detection, spatial optical communication and optical measurement.

  1. System-Level Performance of Antenna Arrays in CDMA-Based Cellular Mobile Radio Systems

    NASA Astrophysics Data System (ADS)

    Czylwik, Andreas; Dekorsy, Armin

    2004-12-01

    Smart antennas exploit the inherent spatial diversity of the mobile radio channel, provide an antenna gain, and also enable spatial interference suppression leading to reduced intracell as well as intercell interference. Especially, for the downlink of future CDMA-based mobile communications systems, transmit beamforming is seen as a well-promising smart antenna technique. The main objective of this paper is to study the performance of diverse antenna array topologies when applied for transmit beamforming in the downlink of CDMA-based networks. In this paper, we focus on uniform linear array (ULA) and uniform circular array (UCA) topologies. For the ULA, we consider three-sector base stations with one linear array per sector. While recent research on downlink beamforming is often restricted to one single cell, this study takes into account the important impact of intercell interference on the performance by evaluating complete networks. Especially, from the operator perspective, system capacity and system coverage are very essential parameters of a cellular system so that there is a clear necessity of intensive system level investigations. Apart from delivering assessments on the performance of the diverse antenna array topologies, in the paper also different antenna array parameters, such as element spacing and beamwidth of the sector antennas, are optimized. Although we focus on the network level, fast channel fluctuations are taken into account by including them analytically into the signal-to-interference calculation.

  2. Design of 4x1 microstrip patch antenna array for 5.8 GHz ISM band applications

    NASA Astrophysics Data System (ADS)

    Valjibhai, Gohil Jayesh; Bhatia, Deepak

    2013-01-01

    This paper describes the new design of four element antenna array using corporate feed technique. The proposed antenna array is developed on the Rogers 5880 dielectric material. The antenna array works on 5.8 GHz ISM band. The industrial, scientific and medical (ISM) radio bands are radio bands (portions of the radio spectrum) reserved internationally for the use of radio frequency (RF) energy for industrial, scientific and medical purposes other than communications. The array antennas have VSWR < 1.6 from 5.725 - 5.875 GHz. The simulated return loss characteristic of the antenna array is - 39.3 dB at 5.8 GHz. The gain of the antenna array is 12.3 dB achieved. The directivity of the broadside radiation pattern is 12.7 dBi at the 5.8 GHz operating frequency. The antenna array is simulated using High frequency structure simulation software.

  3. Directional antenna array (DAA) for communications, control, and data link protection

    NASA Astrophysics Data System (ADS)

    Molchanov, Pavlo A.; Contarino, Vincent M.

    2013-06-01

    A next generation of Smart antennas with point-to-point communication and jam, spoof protection capability by verification of spatial position is offered. A directional antenna array (DAA) with narrow irradiation beam provides counter terrorism protection for communications, data link, control and GPS. Communications are "invisible" to guided missiles because of 20 dB smaller irradiation outside the beam and spatial separation. This solution can be implemented with current technology. Directional antennas have higher gain and can be multi-frequency or have wide frequency band in contrast to phase antenna arrays. This multi-directional antenna array provides a multi-functional communication network and simultaneously can be used for command control, data link and GPS.

  4. Unidirectional waveguide grating antennas with uniform emission for optical phased arrays.

    PubMed

    Raval, Manan; Poulton, Christopher V; Watts, Michael R

    2017-07-01

    We demonstrate millimeter-scale optical waveguide grating antennas with unidirectional emission for integrated optical phased arrays. Unidirectional emission eliminates the fundamental problem of blind spots in the element factor of a phased array caused by reflections of antenna radiation within the substrate. Over 90% directionality is demonstrated using a design consisting of two silicon nitride layers. Furthermore, the perturbation strength along the antenna is apodized to achieve uniform emission for the first time, to the best of our knowledge, on a millimeter scale. This allows for a high effective aperture and receiving efficiency. The emission profile of the measured 3 mm long antenna has a standard deviation of 8.65% of the mean. These antennas are state of the art and will allow for integrated optical phased arrays with blind-spot-free high transmission output power and high receiving efficiency for LIDAR and free-space communication systems.

  5. 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.

  6. Performance Analysis of High Frequency Single-Site-Location Antenna Arrays Using Numerical Electromagnetic Modeling

    DTIC Science & Technology

    1990-09-01

    interferometer and if it employs more than 2 antenna elements it is called multiple baseline interferometer. Interferometers have the advantage of not...of a signal can be determined with greater precision. The resolution of a multiple baseline interferometer is given by the widest antenna pair...baseline). This study will analyze a multiple baseline phase-interferometer antenna array developed by SWRI. In this interferometer the 3-dimensional angle

  7. 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.

  8. Quasi-isotropic VHF antenna array design study for the International Ultraviolet Explorer satellite

    NASA Technical Reports Server (NTRS)

    Raines, J. K.

    1975-01-01

    Results of a study to design a quasi-isotropic VHF antenna array for the IUE satellite are presented. A free space configuration was obtained that has no nulls deeper than -6.4 dbi in each of two orthogonal polarizations. A computer program named SOAP that analyzes the electromagnetic interaction between antennas and complicated conducting bodies, such as satellites was developed.

  9. Terahertz coded aperture mask using vanadium dioxide bowtie antenna array

    NASA Astrophysics Data System (ADS)

    Nadri, Souheil; Percy, Rebecca; Kittiwatanakul, Lin; Arsenovic, Alex; Lu, Jiwei; Wolf, Stu; Weikle, Robert M.

    2014-09-01

    Terahertz imaging systems have received substantial attention from the scientific community for their use in astronomy, spectroscopy, plasma diagnostics and security. One approach to designing such systems is to use focal plane arrays. Although the principle of these systems is straightforward, realizing practical architectures has proven deceptively difficult. A different approach to imaging consists of spatially encoding the incoming flux of electromagnetic energy prior to detection using a reconfigurable mask. This technique is referred to as "coded aperture" or "Hadamard" imaging. This paper details the design, fabrication and testing of a prototype coded aperture mask operating at WR-1.5 (500-750 GHz) that uses the switching properties of vanadium dioxide(VO2). The reconfigurable mask consists of bowtie antennas with vanadium dioxide VO2 elements at the feed points. From the symmetry, a unit cell of the array can be represented by an equivalent waveguide whose dimensions limit the maximum operating frequency. In this design, the cutoff frequency of the unit cell is 640 GHz. The VO2 devices are grown using reactive-biased target ion beam deposition. A reflection coefficient (S11) measurement of the mask in the WR-1.5 (500-750 GHz) band is conducted. The results are compared with circuit models and found to be in good agreement. A simulation of the transmission response of the mask is conducted and shows a transmission modulation of up to 28 dB. This project is a first step towards the development of a full coded aperture imaging system operating at WR-1.5 with VO2 as the mask switching element.

  10. 12. NEAR FIELD HORN (TESTING DEVICE FOR EMIITER/ANTENNA ARRAY SYSTEM) ...

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

    12. NEAR FIELD HORN (TESTING DEVICE FOR EMIITER/ANTENNA ARRAY SYSTEM) AT FACE "A" - VIEW IS LOOKING SOUTH 20° EAST. - Cape Cod Air Station, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  11. Antennas for the array-based Deep Space Network: current status and future designs

    NASA Technical Reports Server (NTRS)

    Imbriale, William A.; Gama, Eric

    2005-01-01

    Development of very large arrays1,2 of small antennas has been proposed as a way to increase the downlink capability of the NASA Deep Space Network DSN) by two or three orders of magnitude thereby enabling greatly increased science data from currently configured missions or enabling new mission concepts. The current concept is for an array of 400 x 12-m antennas at each of three longitudes. The DSN array will utilize radio astronomy sources for phase calibration and will have wide bandwidth correlation processing for this purpose. NASA has undertaken a technology program to prove the performance and cost of a very large DSN array. Central to that program is a 3-element interferometer to be completed in 2005. This paper describes current status of the low cost 6-meter breadboard antenna to be used as part of the interferometer and the RF design of the 12-meter antenna.

  12. Performance Test of Various Types of Antenna Arrays in Real Propagation Environment

    NASA Astrophysics Data System (ADS)

    Budiyanto, Setiyo; Nugraha, Beny; WidiAstuti, Dian

    2016-01-01

    The research was conducted on various types of antenna arrays namely Uniform Array, Binomial Array, Dolph-Chebyshev Array, and Taylor Array. This research is done in the real propagation environment in order to define precisely the number of antenna elements, the distance between the elements, the angle of the antenna arrays, the side lobe level and the n-bar array distribution. The testing process is done by using Matlab and the Non-Uniform Array Simulation Program. The results obtained for various types of antenna arrays are as follows: On Uniform Array produces Half Power Beam Width (HPBW) of 10.152° and directivity of l0 dB, on Binomial Array generates Half Power Beam Width (HPBW) of 20.245° and directivity of 7.47 dB, on Dolph-Chebyshev Arrayproduces Half Power Beam Width (HPBW) of 20.304° and directivity of 4.0185 dB, and on Taylor Arrayproduces Half Power Beam Width (HPBW) of 12.78° and directivity of 8.9 dB.

  13. Compensation of static deformation and vibrations of antenna arrays

    NASA Astrophysics Data System (ADS)

    Knott, Peter; Loecker, Claudius; Algermissen, Stephan; Sekora, Robert

    2012-11-01

    The effect of vibrations and static deformations on aerospace platforms and their influence on the performance of radar, navigation or communication systems are currently studied in the scope of the NATO Research Task Groups SET-131. The deformations may be caused by different effects, e.g. aerodynamic loads, vehicle motion, moving parts such as rudders or turbines, or the impact of a collision. Depending on their strength and the function of the wireless system, they may have a significant impact on the system performance. Structural aspects of the platform such as mechanical or thermal stability, aerodynamics or outer appearance are of great importance. The present paper gives an overview of the scope of work of the group and on-going investigations on system performance analysis and compensation methods such as adaptive signal processing or electronic phase compensation for military key applications such as RADAR, Communication, Electronic Support Measures (ESM) or Command and Control (C2). In addition, the development of an antenna array demonstrator with active vibration compensation using piezo sensors and actuators and control algorithms will be shown, including simulated as well as experimental results.

  14. Experimental and theoretical investigation of silver-coated ZnO nanorod arrays as antennas for the visible and near-IR spectral range

    NASA Astrophysics Data System (ADS)

    Kaidashev, E. M.; Lyanguzov, N. V.; Lerer, A. M.; Raspopova, E. A.

    2014-04-01

    A new design of optical antennas consisting of zinc oxide (ZnO) nanorods covered by a thin metal film is proposed. Arrays of highly oriented ZnO nanorods perpendicular to a substrate and covered by a thin silver film have been obtained using methods of carbothermal synthesis and magnetron sputtering. The problems of electromagnetic wave diffraction on a single metal/dielectric nanovibrator (situated at the interface of dielectrics) and on a two-dimensional periodic array of these nanovibrators have been solved. The results of calculations of the electrodynamic characteristics of optical antennas with various lengths have been compared to experimental data.

  15. Omnidirectional 3D nanoplasmonic optical antenna array via soft-matter transformation.

    PubMed

    Ross, Benjamin M; Wu, Liz Y; Lee, Luke P

    2011-07-13

    Inspired by the natural processes during morphogenesis, we demonstrate the transformation capability of active soft-matter to define nanoscale metal-on-polymer architectures below the resolution limit of conventional lithography. Specifically, using active polymers, we fabricate and characterize ultradense nanoplasmonic antenna arrays with sub-10 nm tip-to-tip nanogaps. In addition, the macroscale morphology can be independently manipulated into arbitrary three-dimensional geometries, demonstrated with the fabrication of an omnidirectional nanoplasmonic optical antenna array.

  16. An array fed dual reflector antenna for limited sector electronic beam scanning

    NASA Astrophysics Data System (ADS)

    Pearson, R. A.; Davies, D. E. N.; Cullen, A. L.

    A dual reflector configuration capable of electronic beam deflection is described. It was found that, in two dimensions, the performance of a confocal reflector arrangement can be significantly improved by shaping the subreflector. A computationally efficient method for analyzing the three-dimensional antenna has been demonstrated which combines an accurate array representation with a minimal amount of ray tracing to overcome the difficulties of modeling the array fed dual reflector antenna.

  17. The design and fabrication of microstrip omnidirectional array antennas for aerospace applications

    NASA Technical Reports Server (NTRS)

    Campbell, T. G.; Appleton, M. W.; Lusby, T. K.

    1976-01-01

    A microstrip antenna design concept was developed that will provide quasi-omnidirectional radiation pattern characteristics about cylindrical and conical aerospace structures. L-band and S-band antenna arrays were designed, fabricated, and, in some cases, flight tested for rocket, satellite, and aircraft drone applications. Each type of array design is discussed along with a thermal cover design that was required for the sounding rocket applications.

  18. Nonlinear gain of a millimetre wave antenna array mounted on a re-entry vehicle

    NASA Astrophysics Data System (ADS)

    Sharma, Ashok Kumar; Kumar, Ashok

    2007-04-01

    A millimetre wave antenna array, mounted on a space vehicle re-entering the Earth's atmosphere, encounters a high density plasma around it. At high antenna power, the millimetre wave field heats the electrons nonuniformly. The electron temperature, Te, follows the antenna pattern, being maximum along the direction of the principal maximum (z-axis) and falling off rapidly across it. The ambipolar plasma diffusion under the pressure gradient force creates a refractive index profile with maximum on the z-axis, leading to self-convergence of the millimetre wave and enhancement in the effective gain of the antenna.

  19. Receiving antenna array element with extended bandwidth toward low frequencies

    NASA Astrophysics Data System (ADS)

    Balzovsky, E. V.; Buyanov, Yu I.; Koshelev, V. I.; Nekrasov, E. S.

    2017-08-01

    An ultrawideband antenna based on a short dielectric dipole has been developed to sound dielectric layered media and to search objects including those hidden behind a dielectric barrier. In contrast to the previously presented antennas, the new one has an unbalanced output and contains a built-in balanced-to-unbalanced unit. As a result of optimization of the antenna geometry and topology of active elements, the lower frequency boundary was shifted toward low frequencies. The antenna records short nanosecond pulses with the spectrum ranging from 150 MHz to 2 GHz with small waveform distortions.

  20. 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.

  1. Nonactive antenna compensation for fixed-array microwave imaging--Part I: Model development.

    PubMed

    Paulsen, K D; Meaney, P M

    1999-06-01

    Fixed-array microwave imaging with multisensor data acquisition can suffer from nonactive antenna element interactions which cause distortions in the measurements. In Part I of a two-part paper, we develop a nonactive antenna compensation model for incorporation in model-based near-field microwave image reconstruction methods. The model treats the nonactive members of the antenna array as impedance boundary conditions applied over a cylindrical surface of finite radius providing two parameters, the effective antenna radius and impedance factor, which can be determined empirically from measured data. Results show that the effective radius and impedance factor provide improved fits to experimental data in homogeneous phantoms where measurements are obtained with and without the presence of the nonactive antenna elements. Once deduced, these parameters are incorporated into the nonactive antenna compensation model and lead to systematic data-model match improvements in heterogeneous phantoms. While the improvements afforded by the nonactive antenna model are small on a per measurement basis, they are not insignificant. As shown in Part II, inclusion of this new model for nonactive antenna compensation produces significantly higher quality image reconstructions from measurements obtained with a fixed-array data acquisition system over the frequency band 500-900 MHz.

  2. An active K/Ka-band antenna array for the NASA ACTS mobile terminal

    NASA Technical Reports Server (NTRS)

    Tulintseff, A.; Crist, R.; Densmore, Art; Sukamto, L.

    1993-01-01

    An active K/Ka-band antenna array is currently under development for NASA's ACTS Mobile Terminal (AMT). The AMT task will demonstrate voice, data, and video communications to and from the AMT vehicle in Los Angeles, California, and a base station in Cleveland, Ohio, via the ACTS satellite at 30 and 20 GHz. Satellite tracking for the land-mobile vehicular antenna system involves 'mechanical dithering' of the antenna, where the antenna radiates a fixed beam 46 deg. above the horizon. The antenna is to transmit horizontal polarization and receive vertical polarization at 29.634 plus or minus 0.15 GHz and 19.914 plus or minus 0.15 GHz, respectively. The active array will provide a minimum of 22 dBW EIRP transmit power density and a -8 dB/K deg. receive sensitivity.

  3. Miniaturized dual-band antenna array with double-negative (DNG) metamaterial for wireless applications

    NASA Astrophysics Data System (ADS)

    Alqadami, Abdulrahman Shueai Mohsen; Jamlos, Mohd Faizal; Soh, Ping Jack; Rahim, Sharul Kamal Abdul; Vandenbosch, Guy A. E.; Narbudowicz, Adam

    2017-01-01

    A miniaturized dual-band antenna array using a negative index metamaterial is presented for WiMAX, LTE, and WLAN applications. This left-handed metamaterial plane is located behind the antenna array, and its unit cell is a combination of split-ring resonator, square electric ring resonator, and rectangular electrical coupled resonator. This enables the achievement of a metamaterial structure exhibiting both negative permittivity and permeability, which results in antenna size miniaturization, efficiency, and gain enhancement. Moreover, the proposed metamaterial antenna has realized dual-band operating frequencies compared to a single frequency for normal antenna. The measured reflection coefficient (S11) shows a 50.25% bandwidth in the lower band (from 2.119 to 3.058 GHz) and 4.27% in the upper band (from 5.058 to 5.276 GHz). Radiation efficiency obtained in the lower and upper band are >95 and 80%, respectively.

  4. High-Efficiency Wide-Band Suspended Patch Antenna Array Demonstrated

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.

    2001-01-01

    A four-element, suspended patch antenna array that has a parasitic patch layer on top and is electromagnetically coupled to an inverted microstrip feed for linear polarization was demonstrated at K-band frequencies. The layout of the array is shown in the following figure. The antenna has the following advantages over conventional microstrip antennas: 1. The inverted microstrip has lower losses, which result in higher gain and efficiency. 2. The inverted microstrip is easier to fabricate, because the strip width is wider for a given characteristic impedance. 3. A conventional proximity-coupled patch antenna requires a substrate for the feed and a superstrate for the patch. However, the inverted microstrip-fed patch antenna makes use of a single substrate and, hence, is lightweight and inexpensive. 4. Electromagnetic coupling results in a wider bandwidth.

  5. An active K/Ka-band antenna array for the NASA ACTS mobile terminal

    NASA Astrophysics Data System (ADS)

    Tulintseff, A.; Crist, R.; Densmore, Art; Sukamto, L.

    An active K/Ka-band antenna array is currently under development for NASA's ACTS Mobile Terminal (AMT). The AMT task will demonstrate voice, data, and video communications to and from the AMT vehicle in Los Angeles, California, and a base station in Cleveland, Ohio, via the ACTS satellite at 30 and 20 GHz. Satellite tracking for the land-mobile vehicular antenna system involves 'mechanical dithering' of the antenna, where the antenna radiates a fixed beam 46 deg. above the horizon. The antenna is to transmit horizontal polarization and receive vertical polarization at 29.634 plus or minus 0.15 GHz and 19.914 plus or minus 0.15 GHz, respectively. The active array will provide a minimum of 22 dBW EIRP transmit power density and a -8 dB/K deg. receive sensitivity.

  6. Implementation of an Antenna Array Signal Processing Breadboard for the Deep Space Network

    NASA Technical Reports Server (NTRS)

    Navarro, Robert

    2006-01-01

    The Deep Space Network Large Array will replace/augment 34 and 70 meter antenna assets. The array will mainly be used to support NASA's deep space telemetry, radio science, and navigation requirements. The array project will deploy three complexes in the western U.S., Australia, and European longitude each with 400 12m downlink antennas and a DSN central facility at JPL. THis facility will remotely conduct all real-time monitor and control for the network. Signal processing objectives include: provide a means to evaluate the performance of the Breadboard Array's antenna subsystem; design and build prototype hardware; demonstrate and evaluate proposed signal processing techniques; and gain experience with various technologies that may be used in the Large Array. Results are summarized..

  7. A patch antenna design for application in a phased-array head and neck hyperthermia applicator.

    PubMed

    Paulides, Margarethus M; Bakker, Jurriaan F; Chavannes, Nicolas; Van Rhoon, Gerard C

    2007-11-01

    In this paper, we describe a specifically designed patch antenna that can be used as the basis antenna element of a clinical phased-array head and neck hyperthermia applicator. Using electromagnetic simulations we optimized the dimensions of a probe-fed patch antenna design for operation at 433 MHz. By several optimization steps we could converge to a theoretical reflection of -38 dB and a bandwidth (-15 dB) of 20 MHz (4.6%). Theoretically, the electrical performance of the antenna was satisfactory over a temperature range of 15 degrees C-35 degrees C, and stable for patient-antenna distances to as low as 4 cm. In an experimental cylindrical setup using six elements of the final patch design, we measured the impedance characteristics of the antenna 1) to establish its performance in the applicator and 2) to validate the simulations. For this experimental setup we simulated and measured comparable values: -21 dB reflection at 433 MHz and a bandwidth of 18.5 MHz. On the basis of this study, we anticipate good central interference of the fields of multiple antennas and conclude that this patch antenna design is very suitable for the clinical antenna array. In future research we will verify the electrical performance in a prototype applicator.

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

    NASA Astrophysics Data System (ADS)

    Venkatesh, Vijay

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

  9. Eight-Element Antenna Array for LTE 3.4-3.8 GHz Mobile Handset Applications

    NASA Astrophysics Data System (ADS)

    Yang, Lingsheng; Ji, Ming; Cheng, Biyu; Ni, Bo

    2017-09-01

    In this letter, an eight-element Multiple-input multiple-output (MIMO) antenna system for LTE mobile handset applications is proposed. The antenna array consists of eight 3D inverted F-shaped antennas (3D-IFA), and the measured -10 dB impedance bandwidth is 3.2-3.9 GHz which can cover the LTE bands 42 and 43 (3.4-3.8 GHz). By controlling the rotation of the antenna elements, no less than 10 dB isolation between antenna elements can be obtained. After using the specially designed meandered slots on the ground as decoupling structures, the measured isolation can be further improved to higher than 13 dB between the antenna elements at the whole operating band.

  10. System concepts for transmit arrays of parabolic antennas for deep space uplinks

    NASA Technical Reports Server (NTRS)

    Hurd, William J.

    2005-01-01

    Phased arrays of parabolic antennas are a potentially lower-cost way to provide uplink transmission to distant spacecraft, compared to the 34-m and 70-m antennas now used by the NASA Deep Space Network. A large transmit array could provide very high EIRP when needed for spacecraft emergencies, such as the equivalent of 1 MW radiated from a 70-m antenna. Cost-effectiveness is realized by dividing the array into smaller arrays to provide routine support to many spacecraft simultaneously. The antennas might be as small as 12-m in diameter, with as many as 100 antennas covering an area of 0.5 km to 1 km in extent. Such arrays present significant technical challenges in phase alignment, which must be maintained at close to 1 mm. The concept requires a very stable system with accurately known antenna phase center locations. The system is first calibrated by transmitting from all antennas, and observing the signals at a target located in the far fields of the individual antennas. The antennas are then pointed to the operational targets, with the signal phases and time delays set to reinforce in the target directions. This requires accurate knowledge of the target directions and calculation of the required phases. The system must be phase-stable for all directions and over the time between calibrations, which is desired to be at least one day. In this paper, a system concept is presented, the major error sources are identified, a rough error budget is established, and key elements of the system are discussed. A calibration method is recommended which uses satellites as radar targets. The performance goal is to achieve a combining loss of less than 0.2 dB in good weather, and of less than 1 dB in all but extremely bad weather.

  11. Reconfigurable Array Antenna Using Microelectromechanical Systems (MEMS) Actuators

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Chun, Donghoon; Katehi, Linda P. B.

    2001-01-01

    The paper demonstrates a patch antenna integrated with a novel microelectromechanical systems (MEMS) actuator for reconfiguring the operating frequency. Experimental results demonstrate that the center frequency can be reconfigured by as much as 1.6 percent of the nominal operating frequency at K-Band In addition, a novel on-wafer antenna pattern measurement technique is demonstrated.

  12. Multi-Band Miniaturized Patch Antennas for a Compact, Shielded Microwave Breast Imaging Array

    PubMed Central

    Aguilar, Suzette M.; Al-Joumayly, Mudar A.; Burfeindt, Matthew J.; Behdad, Nader; Hagness, Susan C.

    2014-01-01

    We present a comprehensive study of a class of multi-band miniaturized patch antennas designed for use in a 3D enclosed sensor array for microwave breast imaging. Miniaturization and multi-band operation are achieved by loading the antenna with non-radiating slots at strategic locations along the patch. This results in symmetric radiation patterns and similar radiation characteristics at all frequencies of operation. Prototypes were fabricated and tested in a biocompatible immersion medium. Excellent agreement was obtained between simulations and measurements. The trade-off between miniaturization and radiation efficiency within this class of patch antennas is explored via a numerical analysis of the effects of the location and number of slots, as well as the thickness and permittivity of the dielectric substrate, on the resonant frequencies and gain. Additionally, we compare 3D quantitative microwave breast imaging performance achieved with two different enclosed arrays of slot-loaded miniaturized patch antennas. Simulated array measurements were obtained for a 3D anatomically realistic numerical breast phantom. The reconstructed breast images generated from miniaturized patch array data suggest that, for the realistic noise power levels assumed in this study, the variations in gain observed across this class of multi-band patch antennas do not significantly impact the overall image quality. We conclude that these miniaturized antennas are promising candidates as compact array elements for shielded, multi-frequency microwave breast imaging systems. PMID:25392561

  13. Method and apparatus for self-calibration and phasing of array antenna

    NASA Technical Reports Server (NTRS)

    Wu, C. (Inventor)

    1984-01-01

    A technique for self-calibrating and phasing a lens-feed array antenna, while normal operation is stopped, utilizes reflected energy of a continuous and coherent wave broadcast by a transmitter through a central feed while a phase controller advances the phase angles of reciprocal phase shifters in radiation electronics of the array elements at different rates to provide a distinct frequency modulation of electromagnetic wave energy returned by reflection in one mode and leakage in another mode from the radiation electronics of each array element. The composite return signal received by a synchronous receiver goes through a Fourier transform processing system and produces a response function for each antenna element. Compensation of the phase angles for the antenna elements required to conform the antenna response to a precomputed array pattern is derived from the reciprocal square root of the response functions for the antenna elements which, for a rectangular array of NXM elements, is a response function T(n,m). A third mode of calibration uses an external pilot tone from a separate antenna element. Respective responses are thus obtained from the three modes of calibration.

  14. Multi-Band Miniaturized Patch Antennas for a Compact, Shielded Microwave Breast Imaging Array.

    PubMed

    Aguilar, Suzette M; Al-Joumayly, Mudar A; Burfeindt, Matthew J; Behdad, Nader; Hagness, Susan C

    2013-12-18

    We present a comprehensive study of a class of multi-band miniaturized patch antennas designed for use in a 3D enclosed sensor array for microwave breast imaging. Miniaturization and multi-band operation are achieved by loading the antenna with non-radiating slots at strategic locations along the patch. This results in symmetric radiation patterns and similar radiation characteristics at all frequencies of operation. Prototypes were fabricated and tested in a biocompatible immersion medium. Excellent agreement was obtained between simulations and measurements. The trade-off between miniaturization and radiation efficiency within this class of patch antennas is explored via a numerical analysis of the effects of the location and number of slots, as well as the thickness and permittivity of the dielectric substrate, on the resonant frequencies and gain. Additionally, we compare 3D quantitative microwave breast imaging performance achieved with two different enclosed arrays of slot-loaded miniaturized patch antennas. Simulated array measurements were obtained for a 3D anatomically realistic numerical breast phantom. The reconstructed breast images generated from miniaturized patch array data suggest that, for the realistic noise power levels assumed in this study, the variations in gain observed across this class of multi-band patch antennas do not significantly impact the overall image quality. We conclude that these miniaturized antennas are promising candidates as compact array elements for shielded, multi-frequency microwave breast imaging systems.

  15. A synthesis array for lunar submillimeter astronomy

    NASA Technical Reports Server (NTRS)

    Mahoney, M. J.

    1990-01-01

    This paper describes a system concept for a synthesis array for lunar submillimeter astronomy (SALSA). It includes a brief discussion of the science objectives and the advantages of a placing such an array on the moon, the system concept, and a top-level discussion of the various subsystems, including the technology drivers associated with each.

  16. A synthesis array for lunar submillimeter astronomy

    NASA Technical Reports Server (NTRS)

    Mahoney, M. J.

    1990-01-01

    This paper describes a system concept for a synthesis array for lunar submillimeter astronomy (SALSA). It includes a brief discussion of the science objectives and the advantages of a placing such an array on the moon, the system concept, and a top-level discussion of the various subsystems, including the technology drivers associated with each.

  17. Radar jammer with an antenna array of pseudo-randomly spaced radiating elements

    SciTech Connect

    Hacker, P.S.

    1984-08-21

    Disclosed herein is a radar jammer which utilizes an electronically agile, sparsely populated, phase controlled antenna array of pseudo-randomly spaced radiating elements to form a high gain, single narrow beam of radiation directed at a detected threat radar, but containing only a small fraction of the available transmitting power, While providing simultaneously therewith effective jamming radiation over a wide coverage region. Preferably, the plurality of radiating elements are sparsely disposed pseudo-randomly over an area surface to form an antenna array, the number of radiating elements in the array being less than the value of the surface area divided by the transmitting carrier wavelength (lambda) squared.

  18. Maintenance Optimization Model for One kind of Three-Dimensional Radar Antenna Array

    NASA Astrophysics Data System (ADS)

    Wang, Min; Yang, Jiang-ping; Wang, Yong-pan; Liu, Wei-jian

    2017-07-01

    For three-dimensional radar, maintenance cost is high and maintenance time is difficult to be determined. What’s more, model simulation computing is significantly complex. The subject of this paper is a new generation of meter wave active, phased array 3D radar. We put forth a concept that maintenance should be done after dividing into several regions to the asymmetrical distribution planar array antenna. First, a failure model of array elements is built to analyze the influence from the element to antenna. Second, the maintenance optimization model is established. Finally, computer simulations are conducted to verify the feasibility and effectiveness of the proposed model.

  19. Multifrequency and multidirection optimizations of antenna arrays using heuristic algorithms and the multilevel fast multipole algorithm

    NASA Astrophysics Data System (ADS)

    Önol, Can; Alkış, Sena; Gökçe, Özer; Ergül, Özgür

    2016-07-01

    We consider fast and efficient optimizations of arrays involving three-dimensional antennas with arbitrary shapes and geometries. Heuristic algorithms, particularly genetic algorithms, are used for optimizations, while the required solutions are carried out accurately and efficiently via the multilevel fast multipole algorithm (MLFMA). The superposition principle is employed to reduce the number of MLFMA solutions to the number of array elements per frequency. The developed mechanism is used to optimize arrays for multifrequency and/or multidirection operations, i.e., to find the most suitable set of antenna excitations for desired radiation characteristics simultaneously at different frequencies and/or directions. The capabilities of the optimization environment are demonstrated on arrays of bowtie and Vivaldi antennas.

  20. 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.

  1. Dynamic null steering in an ultrawideband time-steered array antenna.

    PubMed

    Frankel, M Y; Esman, R D

    1998-08-10

    We develop a method for forming squint-free wideband nulls in the antenna pattern of an ultrawideband array antenna. The technique uses an optical dispersive-prism beam former to provide time-delayed microwave signals to each antenna element for forming a squint-free main beam. The amplitude-modulated optical carrier is propagated through a set of optical links. Each link feeds an array element and includes an amount of dispersion proportional to element position. Tuning the wavelength of the optical carrier controls the microwave signal's arrival-time delay gradient across the array. A dispersive-prism tapped delay-line microwave filter is used to frequency shape a nulling signal. The wideband nulls do not significantly distort the main beam and are steered independently of the main beam. The technique is applied to sidelobe nulling for a transmitter and for jammer suppression for a receiver array.

  2. DSN Antenna Array Architectures Based on Future NASA Mission Needs

    NASA Technical Reports Server (NTRS)

    MacNeal, Bruce E.; Abraham, Douglas S.; Cesarone, Robert J.

    2007-01-01

    A flexible method of parametric, full life-cycle cost analysis has been combined with data on NASA's future communication needs to estimate the required number and operational dates of new antennas for the Deep Space Network (DSN). The requirements were derived from a subset of missions in the Integrated Mission Set database of NASA's Space Communications Architecture Working Group. Assuming that no new antennas are 'constructed', the simulation shows that the DSN is unlikely to meet more than 20% of mission requirements by 2030. Minimum full life-cycle costs result when antennas in the diameter range, 18m-34m, are constructed. Architectures using a mixture of antenna diameters produce a slightly lower full life-cycle cost.

  3. Development And Test of A Digitally Steered Antenna Array for The Navigator GPS Receiver

    NASA Technical Reports Server (NTRS)

    Pinto, Heitor David; Valdez, Jennifer E.; Winternitz, Luke M. B.; Hassouneh, Munther A.; Price, Samuel R.

    2012-01-01

    Global Positioning System (GPS)-based navigation has become common for low-Earth orbit spacecraft as the signal environment is similar to that on the Earth s surface. The situation changes abruptly, however, for spacecraft whose orbital altitudes exceed that of the GPS constellation. Visibility is dramatically reduced and signals that are present may be very weak and more susceptible to interference. GPS receivers effective at these altitudes require increased sensitivity, which often requires a high-gain antenna. Pointing such an antenna can pose a challenge. One efficient approach to mitigate these problems is the use of a digitally steered antenna array. Such an antenna can optimally allocate gain toward desired signal sources and away from interferers. This paper presents preliminary results in the development and test of a digitally steered antenna array for the Navigator GPS research program at NASA s Goddard Space Flight Center. In particular, this paper highlights the development of an array and front-end electronics, the development and test of a real-time software GPS receiver, and implementation of three beamforming methods for combining the signals from the array. Additionally, this paper discusses the development of a GPS signal simulator which produces digital samples of the GPS L1C/A signals as they would be received by an arbitrary antenna array configuration. The simulator models transmitter and receiver dynamics, near-far and multipath interference, and has been a critical component in both the development and test of the GPS receiver. The GPS receiver system was tested with real and simulated GPS signals. Preliminary results show that performance improvement was achieved in both the weak signal and interference environments, matching analytical predictions. This paper summarizes our initial findings and discusses the advantages and limitations of the antenna array and the various beamforming methods.

  4. Directions of arrival estimation with planar antenna arrays in the presence of mutual coupling

    NASA Astrophysics Data System (ADS)

    Akkar, Salem; Harabi, Ferid; Gharsallah, Ali

    2013-06-01

    Directions of arrival (DoAs) estimation of multiple sources using an antenna array is a challenging topic in wireless communication. The DoAs estimation accuracy depends not only on the selected technique and algorithm, but also on the geometrical configuration of the antenna array used during the estimation. In this article the robustness of common planar antenna arrays against unaccounted mutual coupling is examined and their DoAs estimation capabilities are compared and analysed through computer simulations using the well-known MUltiple SIgnal Classification (MUSIC) algorithm. Our analysis is based on an electromagnetic concept to calculate an approximation of the impedance matrices that define the mutual coupling matrix (MCM). Furthermore, a CRB analysis is presented and used as an asymptotic performance benchmark of the studied antenna arrays. The impact of the studied antenna arrays geometry on the MCM structure is also investigated. Simulation results show that the UCCA has more robustness against unaccounted mutual coupling and performs better results than both UCA and URA geometries. The performed simulations confirm also that, although the UCCA achieves better performance under complicated scenarios, the URA shows better asymptotic (CRB) behaviour which promises more accuracy on DoAs estimation.

  5. Adaptive Nulling at HF Using a Compact Array of Active Parasitic Antennas.

    DTIC Science & Technology

    1985-03-01

    elements with variable complex terminations. Such an ar- ray would provide anti -jaming (AJ) capabilities in a very tiny aperture, using less electronic... nature of the parasitic array could cause an unstable oscillation to start. The issue of stability is taken up in detail in Section 4.2. The...various impedances between the antennas of the array. 2-11 7 Another aspect of parasitic arrays is the inherent non-linear nature of any control

  6. Polymer (PDMS-Fe3O4) magneto-dielectric substrate for a MIMO antenna array

    NASA Astrophysics Data System (ADS)

    Alqadami, Abdulrahman Shueai Mohsen; Jamlos, Mohd Faizal; Soh, Ping Jack; Kamarudin, Muhammad Ramlee

    2016-01-01

    This paper presents the design of a 2 × 4 multiple-input multiple-output (MIMO) antenna array fabricated on a nanocomposite magneto-dielectric polymer substrate. The 10-nm iron oxide (Fe3O4) nanoparticles and polydimethylsiloxane (PDMS) composite is used as substrate to enhance the performance of a MIMO antenna array. The measured results showed up to 40.8 % enhancement in terms of bandwidth, 9.95 dB gain, and 57 % of radiation efficiency. Furthermore, it is found that the proposed magneto-dielectric (PDMS-Fe3O4) composite substrate provides excellent MIMO parameters such as correlation coefficient, diversity gain, and mutual coupling. The prototype of the proposed antenna is transparent, flexible, lightweight, and resistant against dust and corrosion. Measured results indicate that the proposed antenna is suitable for WLAN and ultra-wideband biomedical applications within frequency range of 5.33-7.70 GHz.

  7. Efficient second harmonic generation using nonlinear substrates patterned by nano-antenna arrays.

    PubMed

    Bar-Lev, Doron; Scheuer, Jacob

    2013-12-02

    We study theoretically various design considerations for efficient generation of second harmonic using a nonlinear substrate patterned with nano-antennas. The analysis is focused on a gap Bowtie nano-antenna array recessed in LiNbO₃ which is shown to be preferable over on surface structures due to field enhancement, field profile and linear and non-linear polarization considerations. In addition, we develop the nano-antenna counterpart of the Boyd-Klienmann model in order to analyze the impact of a Gaussian shaped fundamental beam on the generated second harmonic. Finally, we show that the dielectric properties of the substrate lead to preferable directions for the incident fundamental harmonic and the emission of the second harmonic. Our analyses lead to several design rules which can enhance second and high harmonic generation from nano-antennas arrays by several orders of magnitude.

  8. Ultra-small single-negative electric metamaterials for electromagnetic coupling reduction of microstrip antenna array.

    PubMed

    Xu, He-Xiu; Wang, Guang-Ming; Qi, Mei-Qing; Zeng, Hui-Yong

    2012-09-24

    We report initially the design, fabrication and measurement of using waveguided electric metamaterials (MTM) in the design of closely-spaced microtrip antenna arrays with mutual coupling reduction. The complementary spiral ring resonators (CSRs) which exhibit single negative resonant permittivity around 3.5GHz are used as the basic electric MTM element. For verification, two CSRs with two and three concentric rings are considered, respectively. By properly arranging these well engineered waveguided MTMs between two H-plane coupled patch antennas, both numerical and measured results indicate that more than 8.4 dB mutual coupling reduction is obtained. The mechanism has been studied from a physical insight. The electric MTM element is electrically small, enabling the resultant antenna array to exhibit a small separation (λo/8 at the operating wavelength) and thus a high directivity. The proposed strategy opens an avenue to new types of antenna with super performances and can be generalized for other electric resonators.

  9. Novel Compact Mushroom-Type EBG Structure for Electromagnetic Coupling Reduction of Microstrip Antenna array

    NASA Astrophysics Data System (ADS)

    Hu, Lizhong; Wang, Guangming; Liang, Jiangang; Zhang, Chenxin

    2015-03-01

    A novel compact electromagnetic bandgap (EBG) structure consisting of two turns complementary spiral resonator (CSR) and conventional mushroom EBG (CM-EBG) structure is introduced to suppress the mutual coupling in antenna arrays for multiple-input and multiple-output (MIMO) applications. Eigenmode calculation is used to investigate the proposed CSR-loaded mushroom-type EBG (MT-EBG), which proved to exhibit bandgap property and a miniaturization of 48.9% is realized compared with the CM-EBG. By inserting the proposed EBG structure between two E-plane coupled microstrip antennas, a mutual coupling reduction of 8.13 dB has been achieved numerically and experimentally. Moreover, the EBG-loaded antenna has better far-field radiation patterns compared with the reference antenna. Thus, this novel EBG structure with advantages of compactness and high decoupling efficiency opens an avenue to new types of antennas with super performances.

  10. Dual-Polarization, Multi-Frequency Antenna Array for use with Hurricane Imaging Radiometer

    NASA Technical Reports Server (NTRS)

    Little, John

    2013-01-01

    Advancements in common aperture antenna technology were employed to utilize its proprietary genetic algorithmbased modeling tools in an effort to develop, build, and test a dual-polarization array for Hurricane Imaging Radiometer (HIRAD) applications. Final program results demonstrate the ability to achieve a lightweight, thin, higher-gain aperture that covers the desired spectral band. NASA employs various passive microwave and millimeter-wave instruments, such as spectral radiometers, for a range of remote sensing applications, from measurements of the Earth's surface and atmosphere, to cosmic background emission. These instruments such as the HIRAD, SFMR (Stepped Frequency Microwave Radiometer), and LRR (Lightweight Rainfall Radiometer), provide unique data accumulation capabilities for observing sea surface wind, temperature, and rainfall, and significantly enhance the understanding and predictability of hurricane intensity. These microwave instruments require extremely efficient wideband or multiband antennas in order to conserve space on the airborne platform. In addition, the thickness and weight of the antenna arrays is of paramount importance in reducing platform drag, permitting greater time on station. Current sensors are often heavy, single- polarization, or limited in frequency coverage. The ideal wideband antenna will have reduced size, weight, and profile (a conformal construct) without sacrificing optimum performance. The technology applied to this new HIRAD array will allow NASA, NOAA, and other users to gather information related to hurricanes and other tropical storms more cost effectively without sacrificing sensor performance or the aircraft time on station. The results of the initial analysis and numerical design indicated strong potential for an antenna array that would satisfy all of the design requirements for a replacement HIRAD array. Multiple common aperture antenna methodologies were employed to achieve exceptional gain over the entire

  11. RF Photonic, In-Situ, Real-Time Phased Array Antenna Calibration System

    DTIC Science & Technology

    2010-11-22

    physical length of fiber. After photodetection , the RF calibration signals are applied directly to an array of electrically small dipole antennas...allows static adjustment over both the amplitude and phase. After photodetection , the RF signal is placed across the ESDA antenna located at each unit...fed using a double Marchand balun. The Marchand balun consists of a microstrip (unbalanced)-to-slotline ( balanced ) transition. The balun design uses

  12. Understanding and optimizing microstrip patch antenna cross polarization radiation on element level for demanding phased array antennas in weather radar applications

    NASA Astrophysics Data System (ADS)

    Vollbracht, D.

    2015-11-01

    The antenna cross polarization suppression (CPS) is of significant importance for the accurate calculation of polarimetric weather radar moments. State-of-the-art reflector antennas fulfill these requirements, but phased array antennas are changing their CPS during the main beam shift, off-broadside direction. Since the cross polarization (x-pol) of the array pattern is affected by the x-pol element factor, the single antenna element should be designed for maximum CPS, not only at broadside, but also for the complete angular electronic scan (e-scan) range of the phased array antenna main beam positions. Different methods for reducing the x-pol radiation from microstrip patch antenna elements, available from literature sources, are discussed and summarized. The potential x-pol sources from probe fed microstrip patch antennas are investigated. Due to the lack of literature references, circular and square shaped X-Band radiators are compared in their x-pol performance and the microstrip patch antenna size variation was analyzed for improved x-pol pattern. Furthermore, the most promising technique for the reduction of x-pol radiation, namely "differential feeding with two RF signals 180° out of phase", is compared to single fed patch antennas and thoroughly investigated for phased array applications with simulation results from CST MICROWAVE STUDIO (CST MWS). A new explanation for the excellent port isolation of dual linear polarized and differential fed patch antennas is given graphically. The antenna radiation pattern from single fed and differential fed microstrip patch antennas are analyzed and the shapes of the x-pol patterns are discussed with the well-known cavity model. Moreover, two new visual based electromagnetic approaches for the explanation of the x-pol generation will be given: the field line approach and the surface current distribution approach provide new insight in understanding the generation of x-pol component in microstrip patch antenna radiation

  13. Integrated Antenna/Solar Array Cell (IA/SAC) System for Flexible Access Communications

    NASA Technical Reports Server (NTRS)

    Lee, Ricard Q.; Clark, Eric B.; Pal, Anna Maria T.; Wilt, David M.; Mueller, Carl H.

    2004-01-01

    Present satellite communications systems normally use separate solar cells and antennas. Since solar cells generally account for the largest surface area of the spacecraft, co-locating the antenna and solar cells on the same substrate opens the possibility for a number of data-rate-enhancing communications link architecture that would have minimal impact on spacecraft weight and size. The idea of integrating printed planar antenna and solar array cells on the same surface has been reported in the literature. The early work merely attempted to demonstrate the feasibility by placing commercial solar cells besides a patch antenna. Recently, Integrating multiple antenna elements and solar cell arrays on the same surface was reported for both space and terrestrial applications. The application of photovoltaic solar cell in a planar antenna structure where the radiating patch antenna is replaced by a Si solar cell has been demonstrated in wireless communication systems (C. Bendel, J. Kirchhof and N. Henze, 3rd Would Photovotaic Congress, Osaka, Japan, May 2003). Based on a hybrid approach, a 6x1 slot array with circularly polarized crossdipole elements co-located on the same surface of the solar cells array has been demonstrated (S. Vaccaro, J. R. Mosig and P. de Maagt, IEEE Trans. Ant. and Propag., Vol. 5 1, No. 8, Aug. 2003). Amorphous silicon solar cells with about 5-10% efficiency were used in these demonstrations. This paper describes recent effort to integrate advanced solar cells with printed planar antennas. Compared to prior art, the proposed WSAC concept is unique in the following ways: 1) Active antenna element will be used to achieve dynamic beam steering; 2) High efficiency (30%) GaAs multi-junction solar cells will be used instead of Si, which has an efficiency of about 15%; 3) Antenna and solar cells are integrated on a common GaAs substrate; and 4) Higher data rate capability. The IA/SAC is designed to operate at X-band (8-12 GH) and higher frequencies

  14. Integrated Antenna/Solar Array Cell (IA/SAC) System for Flexible Access Communications

    NASA Technical Reports Server (NTRS)

    Lee, Ricard Q.; Clark, Eric B.; Pal, Anna Maria T.; Wilt, David M.; Mueller, Carl H.

    2004-01-01

    Present satellite communications systems normally use separate solar cells and antennas. Since solar cells generally account for the largest surface area of the spacecraft, co-locating the antenna and solar cells on the same substrate opens the possibility for a number of data-rate-enhancing communications link architecture that would have minimal impact on spacecraft weight and size. The idea of integrating printed planar antenna and solar array cells on the same surface has been reported in the literature. The early work merely attempted to demonstrate the feasibility by placing commercial solar cells besides a patch antenna. Recently, Integrating multiple antenna elements and solar cell arrays on the same surface was reported for both space and terrestrial applications. The application of photovoltaic solar cell in a planar antenna structure where the radiating patch antenna is replaced by a Si solar cell has been demonstrated in wireless communication systems (C. Bendel, J. Kirchhof and N. Henze, 3rd Would Photovotaic Congress, Osaka, Japan, May 2003). Based on a hybrid approach, a 6x1 slot array with circularly polarized crossdipole elements co-located on the same surface of the solar cells array has been demonstrated (S. Vaccaro, J. R. Mosig and P. de Maagt, IEEE Trans. Ant. and Propag., Vol. 5 1, No. 8, Aug. 2003). Amorphous silicon solar cells with about 5-10% efficiency were used in these demonstrations. This paper describes recent effort to integrate advanced solar cells with printed planar antennas. Compared to prior art, the proposed WSAC concept is unique in the following ways: 1) Active antenna element will be used to achieve dynamic beam steering; 2) High efficiency (30%) GaAs multi-junction solar cells will be used instead of Si, which has an efficiency of about 15%; 3) Antenna and solar cells are integrated on a common GaAs substrate; and 4) Higher data rate capability. The IA/SAC is designed to operate at X-band (8-12 GH) and higher frequencies

  15. Performance, operational limits, of an Electronic Switching Spherical Array (ESSA) antenna

    NASA Technical Reports Server (NTRS)

    Stockton, R.

    1979-01-01

    The development of a microprocessor controller which provides multimode operational capability for the Electronic Switching Spherical Array (ESSA) Antenna is described. The best set of operating conditions were determined and the performance of an ESSA antenna was demonstrated in the following modes: (1) omni; (2) acquisition/track; (3) directive; and (4) multibeam. The control algorithms, software flow diagrams, and electronic circuitry were developed. The microprocessor and control electronics were built and interfaced with the antenna to carry out performance testing. The acquisition/track mode for users in the Tracking and Data Relay Satellite System is emphasized.

  16. 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.

  17. Optical antenna arrays on a fiber facet for in situ surface-enhanced Raman scattering detection.

    PubMed

    Smythe, Elizabeth J; Dickey, Michael D; Bao, Jiming; Whitesides, George M; Capasso, Federico

    2009-03-01

    This paper reports a bidirectional fiber optic probe for the detection of surface-enhanced Raman scattering (SERS). One facet of the probe features an array of gold optical antennas designed to enhance Raman signals, while the other facet of the fiber is used for the input and collection of light. Simultaneous detection of benzenethiol and 2-[(E)-2-pyridin-4-ylethenyl]pyridine is demonstrated through a 35 cm long fiber. The array of nanoscale optical antennas was first defined by electron-beam lithography on a silicon wafer. The array was subsequently stripped from the wafer and then transferred to the facet of a fiber. Lithographic definition of the antennas provides a method for producing two-dimensional arrays with well-defined geometry, which allows (i) the optical response of the probe to be tuned and (ii) the density of "hot spots" generating the enhanced Raman signal to be controlled. It is difficult to determine the Raman signal enhancement factor (EF) of most fiber optic Raman sensors featuring hot spots because the geometry of the Raman enhancing nanostructures is poorly defined. The ability to control the size and spacing of the antennas enables the EF of the transferred array to be estimated. EF values estimated after focusing a laser directly onto the transferred array ranged from 2.6 x 10(5) to 5.1 x 10(5).

  18. The revised solar array synthesis computer program

    NASA Technical Reports Server (NTRS)

    1970-01-01

    The Revised Solar Array Synthesis Computer Program is described. It is a general-purpose program which computes solar array output characteristics while accounting for the effects of temperature, incidence angle, charged-particle irradiation, and other degradation effects on various solar array configurations in either circular or elliptical orbits. Array configurations may consist of up to 75 solar cell panels arranged in any series-parallel combination not exceeding three series-connected panels in a parallel string and no more than 25 parallel strings in an array. Up to 100 separate solar array current-voltage characteristics, corresponding to 100 equal-time increments during the sunlight illuminated portion of an orbit or any 100 user-specified combinations of incidence angle and temperature, can be computed and printed out during one complete computer execution. Individual panel incidence angles may be computed and printed out at the user's option.

  19. Bandwidth enhancement of a multilayered polymeric comb array antenna for millimeter-wave applications

    NASA Astrophysics Data System (ADS)

    Muhamad, Wan Asilah Wan; Ngah, Razali; Jamlos, Mohd Faizal; Soh, Ping Jack; Ali, Mohd Tarmizi; Narbudowicz, Adam

    2017-01-01

    This paper introduces a new multilayered polymeric comb array antenna fabricated on a polydimethylsiloxane (PDMS) dielectric substrate. PDMS is selected due to its excellent electrical and mechanical properties such as low permittivity, water resistance and robustness. The polymeric comb array antenna consists of a zigzag array aligned at -90° with respect to the radiating patch with full ground plane. The radiating patch is embedded inside the PDMS substrate while the coaxial connector is located at the bottom of the transmission line. The proposed antenna functions from 22.649 to 27.792 GHz. Simulated and measured reflection coefficients and radiation patterns agreed well. A maximum gain of 9.856 dB is recorded at 25 GHz, indicating suitability for implementation in millimeter-wave applications.

  20. Bandwidth enhancement of an array antenna using slotted artificial magnetic conductors

    NASA Astrophysics Data System (ADS)

    Lago, Herwansyah; Jamlos, Mohd Faizal; Soh, Ping Jack; Muslim, M. H.; Vandenbosch, Guy A. E.; Narbudowicz, Adam

    2017-01-01

    An artificial magnetic conductor (AMC)-integrated array antenna operating at 9.41 GHz is proposed in this work. The AMC plane consists of an array of 9 × 12 rectangular elements slotted using four circular slots. The rectangular circular-slotted AMC unit cell acts as a metamaterial with high permeability of 10.05 and non-unity permittivity of 1.52, respectively. The integration of the AMC plane into a reference array antenna operating at 9.41 GHz increases the impedance bandwidth by 76%, from 1.12 to 1.98 GHz. Besides that, the efficiency is also enhanced from 95.91 to 96.31%. Both reference and proposed antenna show a satisfactory agreement in terms of simulated and measured reflection coefficients and radiation patterns.

  1. Determining Direction of Arrival at a Y-Shaped Antenna Array

    NASA Technical Reports Server (NTRS)

    Starr, Stan

    2003-01-01

    An algorithm computes the direction of arrival (both azimuth and elevation angles) of a lightning-induced electromagnetic signal from differences among the times of arrival of the signal at four antennas in a Y-shaped array on the ground. In the original intended application of the algorithm, the baselines of the array are about 90 m long and the array is part of a lightning-detection-and-ranging (LDAR) system. The algorithm and its underlying equations can also be used to compute directions of arrival of impulsive phenomena other than lightning on arrays of sensors other than radio antennas: for example, of an acoustic pulse arriving at an array of microphones.

  2. Airborne electronically steerable phased array. [steerable antennas - systems analysis

    NASA Technical Reports Server (NTRS)

    Coats, R.

    1975-01-01

    Results of a study directed to the design of a lightweight high-gain, spaceborne communications array are presented. The array includes simultaneous transmission and receiving, automatic acquisition and tracking of a signal within a 60-degree cone from the array normal, and provides for independent forming of the transmit and receive beams. Application for this array is the space shuttle, space station, or any of the advanced manned (or unmanned) orbital vehicles. Performance specifications are also given.

  3. Feed array metrology and correction layer for large antenna systems in ASIC mixed signal technology

    NASA Astrophysics Data System (ADS)

    Centureli, F.; Scotti, G.; Tommasino, P.; Trifiletti, A.; Romano, F.; Cimmino, R.; Saitto, A.

    2014-08-01

    The paper deals with a possible use of the feed array present in a large antenna system, as a layer for measuring the antenna performance with a self-test procedure and a possible way to correct residual errors of the Antenna geometry and of the antenna distortions. Focus has been concentrated on a few key critical elements of a possible feed array metrology program. In particular, a preliminary contribution to the design and development of the feed array from one side, and the subsystem dedicated to antenna distortion monitoring and control from the other, have been chosen as the first areas of investigation. Scalability and flexibility principles and synergic approach with other coexistent technologies have been assumed of paramount importance to ensure ease of integrated operation and therefore allowing in principle increased performance and efficiency. The concept is based on the use of an existing feed array grid to measure antenna distortion with respect to the nominal configuration. Measured data are then processed to develop a multilayer strategy to control the mechanical movable devices (when existing) and to adjust the residual fine errors through a software controlled phase adjustment of the existing phase shifter The signal from the feed array is converted passing through a FPGA/ASIC level to digital data channels. The kind of those typically used for the scientific experiments. One additional channel is used for monitoring the antenna distortion status. These data are processed to define the best correction strategy, based on a software managed control system capable of operating at three different levels of the antenna system: reflector rotation layer, sub reflector rotation and translation layer (assuming the possibility of controlling a Stewart machine), phase shifter of the phased array layer. The project is at present in the design phase, a few elements necessary for a sound software design of the control subsystem have been developed at a

  4. 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

  5. Precise calibration of a GNSS antenna array for adaptive beamforming applications.

    PubMed

    Daneshmand, Saeed; Sokhandan, Negin; Zaeri-Amirani, Mohammad; Lachapelle, Gérard

    2014-05-30

    The use of global navigation satellite system (GNSS) antenna arrays for applications such as interference counter-measure, attitude determination and signal-to-noise ratio (SNR) enhancement is attracting significant attention. However, precise antenna array calibration remains a major challenge. This paper proposes a new method for calibrating a GNSS antenna array using live signals and an inertial measurement unit (IMU). Moreover, a second method that employs the calibration results for the estimation of steering vectors is also proposed. These two methods are applied to the receiver in two modes, namely calibration and operation. In the calibration mode, a two-stage optimization for precise calibration is used; in the first stage, constant uncertainties are estimated while in the second stage, the dependency of each antenna element gain and phase patterns to the received signal direction of arrival (DOA) is considered for refined calibration. In the operation mode, a low-complexity iterative and fast-converging method is applied to estimate the satellite signal steering vectors using the calibration results. This makes the technique suitable for real-time applications employing a precisely calibrated antenna array. The proposed calibration method is applied to GPS signals to verify its applicability and assess its performance. Furthermore, the data set is used to evaluate the proposed iterative method in the receiver operation mode for two different applications, namely attitude determination and SNR enhancement.

  6. Precise Calibration of a GNSS Antenna Array for Adaptive Beamforming Applications

    PubMed Central

    Daneshmand, Saeed; Sokhandan, Negin; Zaeri-Amirani, Mohammad; Lachapelle, Gérard

    2014-01-01

    The use of global navigation satellite system (GNSS) antenna arrays for applications such as interference counter-measure, attitude determination and signal-to-noise ratio (SNR) enhancement is attracting significant attention. However, precise antenna array calibration remains a major challenge. This paper proposes a new method for calibrating a GNSS antenna array using live signals and an inertial measurement unit (IMU). Moreover, a second method that employs the calibration results for the estimation of steering vectors is also proposed. These two methods are applied to the receiver in two modes, namely calibration and operation. In the calibration mode, a two-stage optimization for precise calibration is used; in the first stage, constant uncertainties are estimated while in the second stage, the dependency of each antenna element gain and phase patterns to the received signal direction of arrival (DOA) is considered for refined calibration. In the operation mode, a low-complexity iterative and fast-converging method is applied to estimate the satellite signal steering vectors using the calibration results. This makes the technique suitable for real-time applications employing a precisely calibrated antenna array. The proposed calibration method is applied to GPS signals to verify its applicability and assess its performance. Furthermore, the data set is used to evaluate the proposed iterative method in the receiver operation mode for two different applications, namely attitude determination and SNR enhancement. PMID:24887043

  7. 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.

  8. Nullspace MUSIC and Improved Radio Frequency Emitter Geolocation from a Mobile Antenna Array

    NASA Astrophysics Data System (ADS)

    Kintz, Andrew L.

    This work advances state-of-the-art Radio Frequency (RF) emitter geolocation from an airborne or spaceborne antenna array. With an antenna array, geolocation is based on Direction of Arrival (DOA) estimation algorithms such as MUSIC. The MUSIC algorithm applies to arbitrary arrays of polarization sensitive antennas and yields high resolution. However, MUSIC fails to obtain its theoretical resolution for simultaneous, closely spaced, co-frequency signals. We propose the novel Nullspace MUSIC algorithm, which outperforms MUSIC and its existing modifications while maintaining MUSIC(apostrophe)s fundamental orthogonality test. Nullspace MUSIC applies a divide-and-conquer approach and estimates a single DOA at a time. Additionally, an antenna array on an aircraft cannot be perfectly calibrated. RF waves are blocked, reflected, and scattered in a time-varying fashion by the platform around the antenna array. Consequently, full-wave electromagnetics simulations or demanding measurements of the entire platform cannot eliminate the mismatch between the true, in-situ antenna patterns and the antenna patterns that are available for DOA estimation (the antenna array manifold). Platform-induced manifold mismatch severely degrades MUSIC(apostrophe)s resolution and accuracy. We show that Nullspace MUSIC improves DOA accuracy for well separated signals that are incident on an airborne antenna array. Conventionally, geolocation from a mobile platform draws Lines of Bearing (LOB) from the antenna array along the DOAs to find the locations where the DOAs intersect with the ground. However, averaging the LOBs in the global coordinate system yields large errors due to geometric dilution of precision. Since averaging positions fails, a single emitter is typically located by finding the position on the ground that yields the Minimum Apparent Angular Error (MAAE) for the DOA estimates over a flight. We extend the MAAE approach to cluster LOBs from multiple emitters. MAAE clustering

  9. 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.

  10. 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.

  11. Usage of the antenna array for radio communication in locomotive engines in Russian Railways

    NASA Astrophysics Data System (ADS)

    Myakochin, Yu O.

    2017-01-01

    The paper presents the realization of the antenna array for arranging the digital communication in the locomotives of Russian Railways. The provided approach allows setting up steady digital communication without expensive updating of the current technique at the substations. The antenna array described in the article has a gain coefficient from 17dB to 18dB at 150MHz. The paper analyzes the data of possible application of digital standards of data transfer without significant modernization of base-load stations used in Russian Railways.

  12. A L-Band Superstrate Lens Enhanced Antenna and Array for Tactical Operations

    DTIC Science & Technology

    2013-07-01

    JUL 2013 2. REPORT TYPE 3. DATES COVERED 00-00-2013 to 00-00-2013 4. TITLE AND SUBTITLE A L-Band Superstrate Lens Enhanced Antenna and Array for...unlimited 13. SUPPLEMENTARY NOTES 14. ABSTRACT The design of a 1.2 GHz microstrip antenna utilizing a superstrate layer for gain enhancement is...dB of gain enhancement in simulation through the use of the superstrate lens. The 4 x 1 superstrate array achieves approximately 2.5 dB of gain

  13. Electric arc localization based on antenna arrays and MUSIC direction of arrival estimation

    NASA Astrophysics Data System (ADS)

    Paun, Mirel; Digulescu, Angela; Tamas, Razvan; Ioana, Cornel

    2015-02-01

    This paper presents an application of antenna arrays and MUSIC algorithm for estimating the location of an electric arc source. The proposed technique can be used to localize arc faults in photovoltaic arrays and their associated transformation stations. The technique was implemented and tested in the laboratory. For this purpose, an experimental setup consisting of 4 antennas, a digital storage oscilloscope with computer connectivity and a PC (Personal Computer) for data processing was built. The results proved that the proposed method is able to estimate the direction of the electric arc source with reasonable accuracy.

  14. Conformal Antenna and Array Design Using Novel Electronic Materials

    DTIC Science & Technology

    2010-03-31

    4. Miniature conformal spirals on textured/ metamaterial ferrite substrates (middle) to replace traditional blade antennas that protrude nearly...waves (as photonic crystal modes) in textured or layered dielectric media ( metamaterials ). Of importance is that these modes are non- reflecting at...low loss ferrites within the substrate of the printed coupled lines will significantly enhance bandwidth and radiation. A concept that includes

  15. Applications of Microwave Antenna Array for Wireless Power Transmission and Radar Imaging in Complex Environment

    NASA Astrophysics Data System (ADS)

    Zhang, Ce

    The focus of my research interests lies in the application of microwave antenna array system and array signal processing techniques to problems in wireless power transmission and radar imaging. The two research areas share the same underlying mathematical principle of time reversality of electromagnetic wave propagation. Based on this principle, the array antenna system and the associated signal processing algorithm are further improved to adapt to different scenarios. In my dissertation, the rest part presents an optimal algorithm for wireless power transmission with beamforming array. The optimal weight distribution on antenna array elements is found based on time reversal eigenmode technique. Our method is adaptive to the medium of the channel and can be applied to arbitrarily positioned antenna without degradation of efficiency. This novel method is analytically studied and verified with numerical electromagnetic simulations. The second part presents a new problem called "Hard-Wall Radar Imaging" (HWRI) has been proposed when the electromagnetic waves cannot penetrate the shielding walls (such as metallic walls). The research methodology involves algorithm development combined with experimental results to gain more insights into the real microwave imaging system. First, we implemented the imaging system with the conventional time reversal DORT (Decomposition of Time-Reversal Operator) imaging algorithm and adapted it into a new signal processing technique (multiplicative array technique) to obtain the image in the proposed scenario. Second, after having identified the drawbacks of the rest imaging system, the imaging system is improved to distributed MIMO radar configuration. The new imaging algorithm is also developed based on the techniques of Direction-of-Arrival(DoA) estimation and adaptive nulling. From this algorithm, the experimental results show that the new imaging system can localize two targets correctly. To resolve the problem of spurious clutter

  16. Development of Local Oscillator Integrated Antenna Array for Electron Cyclotron Emission Imaging Diagnostics

    NASA Astrophysics Data System (ADS)

    Kuwahara, Daisuke; Ito, Naoki; Nagayama, Yoshio; Tsuchiya, Hayato; Yoshikawa, Masayuki; Kohagura, Junko; Yoshinaga, Tomokazu; Yamaguchi, Soichiro; Kogi, Yuichiro; Mase, Atsushi

    2016-10-01

    Microwave imaging systems include difficulties in terms of multi-channelization and cost. Our group solved these problems by developing a Horn-antenna Mixer Array (HMA), a 50 - 110 GHz 1-D heterodyne-type antenna array, which can be easily stacked as a 2-D receiving array. However, the HMA still evidenced problems owing to the requirement for local oscillation (LO) optics and an expensive high-power LO source. To solve this problem, we have developed an upgraded HMA, named the Local Integrated Antenna array (LIA), in which each channel has an internal LO supply using a frequency multiplier integrated circuit. Therefore, the proposed antenna array eliminates the need for both the LO optics and the high-power LO source. However, the LIA still has problems, that the instabilities of the sensitivity and poor channel isolation. This paper describes the principle of the LIA, and solutions of above-mentioned problems. This work is performed with the support and under the auspices of the NIFS Collaborative Research Program (NIFS15KOAP029 and NIFS16KUGM115).

  17. Development of local oscillator integrated antenna array for microwave imaging diagnostics

    NASA Astrophysics Data System (ADS)

    Kuwahara, D.; Ito, N.; Nagayama, Y.; Tsuchiya, H.; Yoshikawa, M.; Kohagura, J.; Yoshinaga, T.; Yamaguchi, S.; Kogi, Y.; Mase, A.; Shinohara, S.

    2015-12-01

    Microwave imaging diagnostics are powerful tools that are used to obtain details of complex structures and behaviors of such systems as magnetically confined plasmas. For example, microwave imaging reflectometry and microwave imaging interferometers are suitable for observing phenomena that are involved with electron density fluctuations; moreover, electron cyclotron emission imaging diagnostics enable us to accomplish the significant task of observing MHD instabilities in large tokamaks. However, microwave imaging systems include difficulties in terms of multi-channelization and cost. Recently, we solved these problems by developing a Horn-antenna Mixer Array (HMA), a 50 - 110 GHz 1-D heterodyne- type antenna array, which can be easily stacked as a 2-D receiving array, because it uses an end-fire element. However, the HMA still evidenced problems owing to the requirement for local oscillation (LO) optics and an expensive high-power LO source. To solve this problem, we have developed an upgraded HMA, named the Local Integrated Antenna array (LIA), in which each channel has an internal LO supply using a frequency multiplier integrated circuit. Therefore, the proposed antenna array eliminates the need for both the LO optics and the high-power LO source. This paper describes the principle of the LIA, and provides details about an 8 channel prototype LIA.

  18. Noise performance of very large antenna arrays. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Lin, H. C.

    1975-01-01

    The maximum size and resolution of receiving antenna arrays is found to be limited by signal-to-noise ratio considerations. For square arrays containing no active elements, a practical limit at 30 GHz appears to be on the order of 10 meters for communications and one to two meters for radiometry. These limitations can be overcome by use of active devices at various levels of the array organization. The nature of the resulting tradeoffs is indicated. Explicit formulas are developed for both passive and active arrays, and sample computations and the computer programs are given.

  19. New method for the time calibration of an interferometric radio antenna array

    NASA Astrophysics Data System (ADS)

    Schröder, F. G.; Asch, T.; Bähren, L.; Blümer, J.; Bozdog, H.; Falcke, H.; Haungs, A.; Horneffer, A.; Huege, T.; Isar, P. G.; Krömer, O.; Nehls, S.

    2010-04-01

    Digital radio antenna arrays, like LOPES (LOFAR PrototypE Station), detect high-energy cosmic rays via the radio emission from atmospheric extensive air showers. LOPES is an array of dipole antennas placed within and triggered by the KASCADE-Grande experiment on site of the Karlsruhe Institute of Technology, Germany. The antennas are digitally combined to build a radio interferometer by forming a beam into the air shower arrival direction which allows measurements even at low signal-to-noise ratios in individual antennas. This technique requires a precise time calibration. A combination of several calibration steps is used to achieve the necessary timing accuracy of about 1 ns. The group delays of the setup are measured, the frequency dependence of these delays (dispersion) is corrected in the subsequent data analysis, and variations of the delays with time are monitored. We use a transmitting reference antenna, a beacon, which continuously emits sine waves at known frequencies. Variations of the relative delays between the antennas can be detected and corrected for at each recorded event by measuring the phases at the beacon frequencies.

  20. 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.

  1. Large-Scale Arrays of Bowtie Nanoaperture Antennas for Nanoscale Dynamics in Living Cell Membranes.

    PubMed

    Flauraud, Valentin; van Zanten, Thomas S; Mivelle, Mathieu; Manzo, Carlo; Garcia Parajo, Maria F; Brugger, Jürgen

    2015-06-10

    We present a novel blurring-free stencil lithography patterning technique for high-throughput fabrication of large-scale arrays of nanoaperture optical antennas. The approach relies on dry etching through nanostencils to achieve reproducible and uniform control of nanoantenna geometries at the nanoscale, over millimeter-sizes in a thin aluminum film. We demonstrate the fabrication of over 400 000 bowtie nanoaperture (BNA) antennas on biocompatible substrates, having gap sizes ranging from (80 ± 5) nm down to (20 ± 10) nm. To validate their applicability on live cell research, we used the antenna substrates as hotspots of localized illumination to excite fluorescently labeled lipids on living cell membranes. The high signal-to-background afforded by the BNA arrays allowed the recording of single fluorescent bursts corresponding to the passage of freely diffusing individual lipids through hotspot excitation regions as small as 20 nm. Statistical analysis of burst length and intensity together with simulations demonstrate that the measured signals arise from the ultraconfined excitation region of the antennas. Because these inexpensive antenna arrays are fully biocompatible and amenable to their integration in most fluorescence microscopes, we foresee a large number of applications including the investigation of the plasma membrane of living cells with nanoscale resolution at endogenous expression levels.

  2. 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.

  3. Analysis of Active Phased Antenna Array Parameters for the Gurt Radio Telescope

    NASA Astrophysics Data System (ADS)

    Tokarsky, P. L.; Konovalenko, A. A.; Yerin, S. N.

    2015-06-01

    The calculation technique results of numerical analysis of parameters of active phased antenna array (APAA) of the Giant Ukrainian Radio Telescope (GURT) of decameter and meter wavelengths which is being built now nearby Kharkiv at the area of S. Ya. Braude Radio Astronomy Observatory of the Institute of Radio Astronomy of the National Academy of Sciences of Ukraine are presented. The technique is based on the matrix theory of antenna arrays which combines an electromagnetic approach to analysis of radiators array with the methods of microwave multiport theory for the APAA feed network description. The results of numerical calculation of the APAA effective area and its gain, which in case of passive array is associated with its efficiency, are given and analyzed for a wide scan range within 10 to 80 MHz.

  4. Spectral shaping and phase control of a fast-wave current drive antenna array

    SciTech Connect

    Baity, F.W.; Gardner, W.L.; Goulding, R.H.; Hoffman, D.J.; Ryan, P.M.

    1989-01-01

    The requirements for antenna design and phase control circuitry for a fast-wave current drive (FWCD) array operating in the ion cyclotron range of frequencies are considered. The design of a phase control system that can operate at arbitrary phasing over a wide range of plasma-loading and strap-coupling values is presented for a four-loop antenna array, prototypical of an array planned for the DIII-D tokamak (General Atomics, San Diego, California). The goal is to maximize the power launched with the proper polarization for current drive while maintaining external control of phase. Since it is desirable to demonstrate the feasibility of FWCD prior to ITER, a four-strap array has been designed for DIII-D to operate with the existing 2-MW transmitter at 60 MHz. 3 refs., 6 figs.

  5. Phased-array antenna control by a monolithic photonic integrated circuit, COMPASS

    SciTech Connect

    Kravitz, S.H.; Hietala, V.M.; Vawter, G.A.; Meyer, W.J.

    1991-01-01

    Phased-array antenna systems are well known for rapid beam steering and their ability to bring high power to the target. Such systems are also quite complex and heavy, which have limited their usefulness. The issues of weight, size, power use, and complexity have been addressed through a system named COMPASS (Coherent Optical Monolithic Phased Array Steering System). All phased-array antenna systems need: (1) small size; (2) low power use; (3) high-speed beam steering; and (4) digitally-controlled phase shifting. COMPASS meets these basic requirements, and provides some very desirable additional features. These are: (1) phase control separate from the transmit/receive module; (2) simple expansion to large arrays; (3) fiber optic interconnect for reduced sensitivity to EMI; (4) an intrinsically radiation-hard GaAs chip; and (5) optical power provided by a commercially available continuous wave (CW) laser. 4 refs., 8 figs.

  6. Dual-mode antenna array for microwave heating and noninvasive thermometry of superficial tissue disease

    NASA Astrophysics Data System (ADS)

    Stauffer, Paul R.; Jacobsen, Svein; Rossetto, Francesca; Diederich, Chris J.; Neuman, Daniel

    1999-05-01

    Hyperthermia therapy of superficial skin disease has proven clinically useful, but current heating equipment is clumsy and technically inadequate for many patients. The present effort describes a dual purpose multielement conformal array microwave applicator that is fabricated from flexible printed circuit board (PCB) material to facilitate heating of large surface areas overlying contoured anatomy. Preliminary studies document the feasibility of combining concentric spiral microstrip antennas within multilayer PCB material in order to achieve tissue heating simultaneously with non-invasive thermometry by radiometric sensing of blackbody radiation from the target tissue under the applicator. Results demonstrate that superficial tissue regions may be heated uniformly above 50% of SARmax out to the periphery of 915 MHz conformal array applicators made from arrays of Dual Concentric Conductor apertures. Finally the data clearly demonstrate that separate complimentary antenna structures may be combined together in thin and lightweight conformal arrays to provide heating simultaneously with microwave radiometry based temperature monitoring of superficial tissue.

  7. The 20 GHz circularly polarized, high temperature superconducting microstrip antenna array

    NASA Technical Reports Server (NTRS)

    Morrow, Jarrett D.; Williams, Jeffery T.; Long, Stuart A.; Wolfe, John C.

    1994-01-01

    The primary goal was to design and characterize a four-element, 20 GHz, circularly polarized microstrip patch antenna fabricated from YBa2Cu3O(x) superconductor. The purpose is to support a high temperature superconductivity flight communications experiment between the space shuttle orbiter and the ACTS satellite. This study is intended to provide information into the design, construction, and feasibility of a circularly polarized superconducting 20 GHz downlink or cross-link antenna. We have demonstrated that significant gain improvements can be realized by using superconducting materials for large corporate fed array antennas. In addition, we have shown that when constructed from superconducting materials, the efficiency, and therefore the gain, of microstrip patches increases if the substrate is not so thick that the dominant loss mechanism for the patch is radiation into the surface waves of the conductor-backed substrate. We have considered two design configurations for a superconducting 20 GHz four-element circularly polarized microstrip antenna array. The first is the Huang array that uses properly oriented and phased linearly polarized microstrip patch elements to realize a circularly polarized pattern. The second is a gap-coupled array of circularly polarized elements. In this study we determined that although the Huang array operates well on low dielectric constant substrates, its performance becomes extremely sensitive to mismatches, interelement coupling, and design imperfections for substrates with high dielectric constants. For the gap-coupled microstrip array, we were able to fabricate and test circularly polarized elements and four-element arrays on LaAlO3 using sputtered copper films. These antennas were found to perform well, with relatively good circular polarization. In addition, we realized a four-element YBa2Cu3O(x) array of the same design and measured its pattern and gain relative to a room temperature copper array. The patterns were

  8. Radiation characteristics of two-element array of circular patch microstrip antenna in a warm plasma

    NASA Astrophysics Data System (ADS)

    Saxena, V. K.; Dinesh, Abhinav; Gupta, Raj Kumar

    1989-08-01

    The radiation properties of a two-element array of circular patch microstrip antenna in an ionized medium are studied. Expressions for the far zone EM-mode and P-mode radiation fields using hydrodynamic equations and potential function techniques are derived. The results are computed for the ionized media as well as for free space and compared with those of single-element circular patch microstrip antenna. It is observed that EM-mode field patterns are modified to a great extent, whereas the P-mode field patterns show discrete raylike structure similar to those of other antennas. Antenna parameters like radiation conductivity, radiation efficiency, directivity and quality factor are also computed for different ratios of plasma to source frequency.

  9. Low Frequency End Performance of a Symmetrical Configuration Antenna for the Square Kilometre Array (SKA)

    NASA Astrophysics Data System (ADS)

    Cortés-Medellín, Germán

    2004-06-01

    The frequency specifications of the Square Kilometre Array (SKA) call for an optimum operation of the antenna elements from 25 down to 100 MHz. The current 12 m diameter US-SKA design is specified from 500 up to 25 GHz, with an upper goal of 35 GHz. At the low frequency end of the band (i.e., 100 MHz), a 12 m reflector antenna is about four wavelengths in diameter. Then, the question is: how well can you do, at this low frequency end of the specified band of operation for the SKA, with a symmetric reflector configuration using an ultra-wide-band prime focus feed? This paper presents the analysis of the antenna performance, in terms of Aeff/TA, of three symmetric configurations of the 12 m US-SKA antenna design between 100 and 200 MHz.

  10. High Sensitivity Terahertz Detection through Large-Area Plasmonic Nano-Antenna Arrays

    NASA Astrophysics Data System (ADS)

    Yardimci, Nezih Tolga; Jarrahi, Mona

    2017-02-01

    Plasmonic photoconductive antennas have great promise for increasing responsivity and detection sensitivity of conventional photoconductive detectors in time-domain terahertz imaging and spectroscopy systems. However, operation bandwidth of previously demonstrated plasmonic photoconductive antennas has been limited by bandwidth constraints of their antennas and photoconductor parasitics. Here, we present a powerful technique for realizing broadband terahertz detectors through large-area plasmonic photoconductive nano-antenna arrays. A key novelty that makes the presented terahertz detector superior to the state-of-the art is a specific large-area device geometry that offers a strong interaction between the incident terahertz beam and optical pump at the nanoscale, while maintaining a broad operation bandwidth. The large device active area allows robust operation against optical and terahertz beam misalignments. We demonstrate broadband terahertz detection with signal-to-noise ratio levels as high as 107 dB.

  11. High Sensitivity Terahertz Detection through Large-Area Plasmonic Nano-Antenna Arrays

    PubMed Central

    Yardimci, Nezih Tolga; Jarrahi, Mona

    2017-01-01

    Plasmonic photoconductive antennas have great promise for increasing responsivity and detection sensitivity of conventional photoconductive detectors in time-domain terahertz imaging and spectroscopy systems. However, operation bandwidth of previously demonstrated plasmonic photoconductive antennas has been limited by bandwidth constraints of their antennas and photoconductor parasitics. Here, we present a powerful technique for realizing broadband terahertz detectors through large-area plasmonic photoconductive nano-antenna arrays. A key novelty that makes the presented terahertz detector superior to the state-of-the art is a specific large-area device geometry that offers a strong interaction between the incident terahertz beam and optical pump at the nanoscale, while maintaining a broad operation bandwidth. The large device active area allows robust operation against optical and terahertz beam misalignments. We demonstrate broadband terahertz detection with signal-to-noise ratio levels as high as 107 dB. PMID:28205615

  12. Phase conjugation method and apparatus for an active retrodirective antenna array

    NASA Technical Reports Server (NTRS)

    Tausworthe, R. C.; Chernoff, R. C. (Inventor)

    1979-01-01

    An active retrodirective antenna array wherein a reference array element is used to generate a phase reference which is replicated at succeeding elements of the array. Each element of the array is associated with a phase regeneration circuit and the phase conjugation circuitry of an adjacent element. In one implementation, the phase reference circuit operates on the input signal at the reference element, a voltage controlled oscillator (VCO) output signal and the input pilot signal at the next array element received from a transmission line. By proper filtering and mixing, a phase component may be produced to which the VCO may be locked to produce the phase conjugate of the pilot signal at the next array element plus a transmission line delay. In another implementation, particularly suited for large arrays in space, two different input pilot frequencies are employed.

  13. 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).

  14. Microstrip patch array antenna on photonic crystal substrate at terahertz frequency

    NASA Astrophysics Data System (ADS)

    Jha, Kumud Ranjan; Singh, G.

    2012-01-01

    Recent advancement in the fabrication and packaging technology has led to the micrometer and nanometer-scale device modeling. This technological development and subsequent reduction in the dimension of devices like modulators, detectors and antennas has brought a thought of increasing the operating frequency of the system to the extent of sub-millimeter wavelength. In the view of the technical breakthrough in the area of fabrication and packaging, we have explored a printed antenna array on the photonic crystal in the terahertz spectrum in this paper. An equivalent circuit model of the antenna has been proposed and a methodology to investigate various electrical parameters is discussed. Tunable parameters of the structure have been explored to optimize the electrical performance of the proposed antenna. The analysis is also compared by using two simulators: (a) CST Microwave Studio based on finite integral technique and (b) Ansoft HFSS based on finite element method. The effect of the photonic crystal as substrate to enhance the gain of this kind of the antenna has also been demonstrated. The gain, directivity, front-to-back ratio (F/B ratio), and the radiation efficiency of the proposed antenna at 600 GHz is 16.88 dBi, 17.19 dBi, 14.77 dB and 89.72%, respectively. Finally, the performance of the antenna has been compared with the reported literature.

  15. Multilevel photonic modules for millimeter-wave phased-array antennas

    NASA Astrophysics Data System (ADS)

    Paolella, Arthur C.; Joshi, Abhay M.; Wright, James G.; Coryell, Louis A.

    1998-11-01

    Optical signal distribution for phased array antennas in communication system is advantageous to designers. By distributing the microwave and millimeter wave signal through optical fiber there is the potential for improved performance and lower weight. In addition when applied to communication satellites this weight saving translates into substantially reduced launch costs. The goal of the Phase I Small Business Innovation Research (SBIR) Program is the development of multi-level photonic modules for phased array antennas. The proposed module with ultimately comprise of a monolithic, InGaAs/InP p-i-n photodetector-p-HEMT power amplifier, opto-electronic integrated circuit, that has 44 GHz bandwidth and output power of 50 mW integrated with a planar antenna. The photodetector will have a high quantum efficiency and will be front-illuminated, thereby improved optical performance. Under Phase I a module was developed using standard MIC technology with a high frequency coaxial feed interconnect.

  16. Integrated patch and slot array antenna for terahertz quantum cascade lasers at 4.7 THz

    SciTech Connect

    Bonzon, C. Benea Chelmus, I. C.; Ohtani, K.; Geiser, M.; Beck, M.; Faist, J.

    2014-04-21

    Our work presents a slot and a patch array antenna at the front facet of a 4.7 THz quantum cascade laser as extractor, decreasing the facet reflectivity down to 2.6%. The resulting output power increases by a factor 2 and the slope efficiency by a factor 4. The simulated and the measured far-fields are in good agreement.

  17. 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.

  18. An Active K/K-Band Antenna Array for the NASA ACTS Mobile Terminal

    NASA Technical Reports Server (NTRS)

    Tulintseff, A.; Crist, R.; Densmore, A.; Sukamto, L.

    1993-01-01

    An active K/K-band antenna array is currently under development for NASA's ACTS Mobile Terminal (AMT). The AMT task will demonstrate voice, data, and video communications to and from the AMT vehicle in Los Angeles, California, and a base station in Cleveland, Ohio, via the ACTS satellite at 30 and 20 GHz.

  19. 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.

  20. 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.

  1. 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.

  2. Comparison of RF Photonics-Based Beamformers for Super-Wide Bandwidth Phased Array Antennas

    NASA Astrophysics Data System (ADS)

    Belkin, M.; Sigov, A.; Tyschuk, Y.; Golovin, V.

    2017-05-01

    We demonstrate the NI AWRDE E-CAD tool-based simulation experiments to compare the three arrangements of photonic beam forming networks. The results confirm clearly the benefits of the proposed arrangement based on combination of multichannel fiber Bragg grating and switchable optical delay lines providing super-wide operating bandwidth and the better economical characteristics of microwave-band phased array antennas.

  3. A new optimization technique for adaptive antenna arrays

    NASA Astrophysics Data System (ADS)

    Ohnishi, Katsumi; Milton, Robert T.

    1993-05-01

    This paper describes a new adaptive nulling algorithm for adjusting the array weights under the 'soft' constraint based on the measured correlations between the array and element outputs. The algorithm can be regarded as an extension of the constrained LMS algorithm. The present algorithm is derived from the same concept of signal and noise subspaces defined in the well-known MUSIC algorithm. One of the unique features of the present algorithm is that the number of the iterations required to adapt the array weights to form nulls is exactly equal to the number of interferers.

  4. Array feed/reflector antenna design for intense microwave beams

    NASA Astrophysics Data System (ADS)

    Blank, Stephen J.

    1990-04-01

    It is shown that a planar-array feed has excellent potential as a solution to paraboloidal reflector distortion problems and beam-steering requirements. Numerical results from an algorithmic procedure are presented which show that, for a range of distortion models, appreciable on-axis gain restoration can be achieved with as few as seven elements. For beam-steering to + or - 1 MW, 19 elements are required. For arrays with either seven or 19 elements, high effective aperture elements give higher system gain than elements having lower effective apertures. With 37 elements, excellent gain and beam-steering performance to + or - 1.5 BW is obtained independently of assumed effective aperture of the array element. A few simple rules of thumb are presented for the design of the planar-array feed configuration.

  5. Measuring phased-array antenna beampatterns with high dynamic range for the Murchison Widefield Array using 137 MHz ORBCOMM satellites

    NASA Astrophysics Data System (ADS)

    Neben, A. R.; Bradley, R. F.; Hewitt, J. N.; Bernardi, G.; Bowman, J. D.; Briggs, F.; Cappallo, R. J.; Deshpande, A. A.; Goeke, R.; Greenhill, L. J.; Hazelton, B. J.; Johnston-Hollitt, M.; Kaplan, D. L.; Lonsdale, C. J.; McWhirter, S. R.; Mitchell, D. A.; Morales, M. F.; Morgan, E.; Oberoi, D.; Ord, S. M.; Prabu, T.; Shankar, N. Udaya; Srivani, K. S.; Subrahmanyan, R.; Tingay, S. J.; Wayth, R. B.; Webster, R. L.; Williams, A.; Williams, C. L.

    2015-07-01

    Detection of the fluctuations in a 21 cm line emission from neutral hydrogen during the Epoch of Reionization in thousand hour integrations poses stringent requirements on calibration and image quality, both of which necessitate accurate primary beam models. The Murchison Widefield Array (MWA) uses phased-array antenna elements which maximize collecting area at the cost of complexity. To quantify their performance, we have developed a novel beam measurement system using the 137 MHz ORBCOMM satellite constellation and a reference dipole antenna. Using power ratio measurements, we measure the in situ beampattern of the MWA antenna tile relative to that of the reference antenna, canceling the variation of satellite flux or polarization with time. We employ angular averaging to mitigate multipath effects (ground scattering) and assess environmental systematics with a null experiment in which the MWA tile is replaced with a second-reference dipole. We achieve beam measurements over 30 dB dynamic range in beam sensitivity over a large field of view (65% of the visible sky), far wider and deeper than drift scans through astronomical sources allow. We verify an analytic model of the MWA tile at this frequency within a few percent statistical scatter within the full width at half maximum. Toward the edges of the main lobe and in the sidelobes, we measure tens of percent systematic deviations. We compare these errors with those expected from known beamforming errors.

  6. Beam-forming Errors in Murchison Widefield Array Phased Array Antennas and their Effects on Epoch of Reionization Science

    NASA Astrophysics Data System (ADS)

    Neben, Abraham R.; Hewitt, Jacqueline N.; Bradley, Richard F.; Dillon, Joshua S.; Bernardi, G.; Bowman, J. D.; Briggs, F.; Cappallo, R. J.; Corey, B. E.; Deshpande, A. A.; Goeke, R.; Greenhill, L. J.; Hazelton, B. J.; Johnston-Hollitt, M.; Kaplan, D. L.; Lonsdale, C. J.; McWhirter, S. R.; Mitchell, D. A.; Morales, M. F.; Morgan, E.; Oberoi, D.; Ord, S. M.; Prabu, T.; Udaya Shankar, N.; Srivani, K. S.; Subrahmanyan, R.; Tingay, S. J.; Wayth, R. B.; Webster, R. L.; Williams, A.; Williams, C. L.

    2016-03-01

    Accurate antenna beam models are critical for radio observations aiming to isolate the redshifted 21 cm spectral line emission from the Dark Ages and the Epoch of Reionization (EOR) and unlock the scientific potential of 21 cm cosmology. Past work has focused on characterizing mean antenna beam models using either satellite signals or astronomical sources as calibrators, but antenna-to-antenna variation due to imperfect instrumentation has remained unexplored. We characterize this variation for the Murchison Widefield Array (MWA) through laboratory measurements and simulations, finding typical deviations of the order of ±10%-20% near the edges of the main lobe and in the sidelobes. We consider the ramifications of these results for image- and power spectrum-based science. In particular, we simulate visibilities measured by a 100 m baseline and find that using an otherwise perfect foreground model, unmodeled beam-forming errors severely limit foreground subtraction accuracy within the region of Fourier space contaminated by foreground emission (the “wedge”). This region likely contains much of the cosmological signal, and accessing it will require measurement of per-antenna beam patterns. However, unmodeled beam-forming errors do not contaminate the Fourier space region expected to be free of foreground contamination (the “EOR window”), showing that foreground avoidance remains a viable strategy.

  7. BEAM-FORMING ERRORS IN MURCHISON WIDEFIELD ARRAY PHASED ARRAY ANTENNAS AND THEIR EFFECTS ON EPOCH OF REIONIZATION SCIENCE

    SciTech Connect

    Neben, Abraham R.; Hewitt, Jacqueline N.; Dillon, Joshua S.; Goeke, R.; Morgan, E.; Bradley, Richard F.; Bernardi, G.; Bowman, J. D.; Briggs, F.; Cappallo, R. J.; Corey, B. E.; Lonsdale, C. J.; McWhirter, S. R.; Deshpande, A. A.; Greenhill, L. J.; Hazelton, B. J.; Morales, M. F.; Johnston-Hollitt, M.; Kaplan, D. L.; Mitchell, D. A.; and others

    2016-03-20

    Accurate antenna beam models are critical for radio observations aiming to isolate the redshifted 21 cm spectral line emission from the Dark Ages and the Epoch of Reionization (EOR) and unlock the scientific potential of 21 cm cosmology. Past work has focused on characterizing mean antenna beam models using either satellite signals or astronomical sources as calibrators, but antenna-to-antenna variation due to imperfect instrumentation has remained unexplored. We characterize this variation for the Murchison Widefield Array (MWA) through laboratory measurements and simulations, finding typical deviations of the order of ±10%–20% near the edges of the main lobe and in the sidelobes. We consider the ramifications of these results for image- and power spectrum-based science. In particular, we simulate visibilities measured by a 100 m baseline and find that using an otherwise perfect foreground model, unmodeled beam-forming errors severely limit foreground subtraction accuracy within the region of Fourier space contaminated by foreground emission (the “wedge”). This region likely contains much of the cosmological signal, and accessing it will require measurement of per-antenna beam patterns. However, unmodeled beam-forming errors do not contaminate the Fourier space region expected to be free of foreground contamination (the “EOR window”), showing that foreground avoidance remains a viable strategy.

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

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

  9. Reconfigurable antenna pattern verification

    NASA Technical Reports Server (NTRS)

    Drexler, Jerome P. (Inventor); Becker, Robert C. (Inventor); Meyers, David W. (Inventor); Muldoon, Kelly P. (Inventor)

    2013-01-01

    A method of verifying programmable antenna configurations is disclosed. The method comprises selecting a desired antenna configuration from a plurality of antenna configuration patterns, with the selected antenna configuration forming at least one reconfigurable antenna from reconfigurable antenna array elements. The method validates the formation of the selected antenna configuration to determine antenna performance of the at least one reconfigurable antenna.

  10. Enhanced vibrational spectroscopy, intracellular refractive indexing for label-free biosensing and bioimaging by multiband plasmonic-antenna array.

    PubMed

    Chen, Cheng-Kuang; Chang, Ming-Hsuan; Wu, Hsieh-Ting; Lee, Yao-Chang; Yen, Ta-Jen

    2014-10-15

    In this study, we report a multiband plasmonic-antenna array that bridges optical biosensing and intracellular bioimaging without requiring a labeling process or coupler. First, a compact plasmonic-antenna array is designed exhibiting a bandwidth of several octaves for use in both multi-band plasmonic resonance-enhanced vibrational spectroscopy and refractive index probing. Second, a single-element plasmonic antenna can be used as a multifunctional sensing pixel that enables mapping the distribution of targets in thin films and biological specimens by enhancing the signals of vibrational signatures and sensing the refractive index contrast. Finally, using the fabricated plasmonic-antenna array yielded reliable intracellular observation was demonstrated from the vibrational signatures and intracellular refractive index contrast requiring neither labeling nor a coupler. These unique features enable the plasmonic-antenna array to function in a label-free manner, facilitating bio-sensing and imaging development.

  11. Four-to-one power combiner for 20 GHz phased array antenna using RADC MMIC phase shifters

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The design and microwave simulation of two-to-one microstrip power combiners is described. The power combiners were designed for use in a four element phase array receive antenna subarray at 20 GHz. Four test circuits are described which were designed to enable testing of the power combiner and the four element phased array antenna. Test Circuit 1 enables measurement of the two-to-one power combiner. Test Circuit 2 enables measurement of the four-to-one power combiner. Test Circuit 3 enables measurement of a four element antenna array without phase shifting MMIC's in order to characterize the power combiner with the antenna patch-to-microstrip coaxial feedthroughs. Test circuit 4 is the four element phased array antenna including the RADC MMIC phase shifters and appropriate interconnects to provide bias voltages and control phase bits.

  12. 1x2 Array of U-Slotted Rectangular Patch Antennas for HighSpeed LTE Mobile Networks

    NASA Astrophysics Data System (ADS)

    Daud, P.; H, Sri.; Mahmudin, D.; Estu, T. T.; Fathnan, A. A.; Wijayanto, Y. N.; Armi, N.

    2016-01-01

    Microstrip antenna is a shaped thin board of antenna and capable for working at high frequencies. Microstrip antenna has a pattern strip shape in a various form, one of which is a rectangular shape. Microstrip antennas have some shortcomings which have narrow bandwidth and small gain, to cover the shortfall, the antenna is made using an array to increase the gain and u - slot to widen the bandwidth. In this paper will discuss the results of the antenna simulation using Ansoft HFSS software applications and their compliance with specifications designed antenna. In this issues we analysis the results of the design and simulation microstrip antenna at a frequency of 2.6 - 2.7 GHz for LTE applications

  13. Deployable reflector antenna performance optimization using automated surface correction and array-feed compensation

    NASA Technical Reports Server (NTRS)

    Schroeder, Lyle C.; Bailey, M. C.; Mitchell, John L.

    1992-01-01

    Methods for increasing the electromagnetic (EM) performance of reflectors with rough surfaces were tested and evaluated. First, one quadrant of the 15-meter hoop-column antenna was retrofitted with computer-driven and controlled motors to allow automated adjustment of the reflector surface. The surface errors, measured with metric photogrammetry, were used in a previously verified computer code to calculate control motor adjustments. With this system, a rough antenna surface (rms of approximately 0.180 inch) was corrected in two iterations to approximately the structural surface smoothness limit of 0.060 inch rms. The antenna pattern and gain improved significantly as a result of these surface adjustments. The EM performance was evaluated with a computer program for distorted reflector antennas which had been previously verified with experimental data. Next, the effects of the surface distortions were compensated for in computer simulations by superimposing excitation from an array feed to maximize antenna performance relative to an undistorted reflector. Results showed that a 61-element array could produce EM performance improvements equal to surface adjustments. When both mechanical surface adjustment and feed compensation techniques were applied, the equivalent operating frequency increased from approximately 6 to 18 GHz.

  14. Planar array antenna with director on indium phosphide substrate for 300GHz wireless link

    NASA Astrophysics Data System (ADS)

    Kanaya, Haruichi; Oda, Tomoki; Iizasa, Naoto; Kato, Kazutoshi

    2016-02-01

    This paper presents a design and fabrication of 1 x 4 one-sided directional slot array antenna with director metal layer on indium phosphide (InP) substrate for 300 GHz wireless link. The floating metal and polyimide dielectric layer are stacked on InP. Antenna is designed on the top metal layer. By optimizing the length of the bottom floating metal layer, one-sided directional radiation can be realized. The branched coplanar wave guide (CPW) transmission line is connected to each antenna element with the same electrical length. The size of the 1 x 4 array antenna is 2,550 µm x 1,217 µm x 18 µm. In order to enhance the gain of forward direction, director metal layer is placed over 83 µm from top metal layer. Simulated realized gain in peak direction of our antenna is 9.23 dBi. The measured center frequency is almost the same as that of the simulation results.

  15. Optimized hyper beamforming of linear antenna arrays using collective animal behaviour.

    PubMed

    Ram, Gopi; Mandal, Durbadal; Kar, Rajib; Ghoshal, Sakti Prasad

    2013-01-01

    A novel optimization technique which is developed on mimicking the collective animal behaviour (CAB) is applied for the optimal design of hyper beamforming of linear antenna arrays. Hyper beamforming is based on sum and difference beam patterns of the array, each raised to the power of a hyperbeam exponent parameter. The optimized hyperbeam is achieved by optimization of current excitation weights and uniform interelement spacing. As compared to conventional hyper beamforming of linear antenna array, real coded genetic algorithm (RGA), particle swarm optimization (PSO), and differential evolution (DE) applied to the hyper beam of the same array can achieve reduction in sidelobe level (SLL) and same or less first null beam width (FNBW), keeping the same value of hyperbeam exponent. Again, further reductions of sidelobe level (SLL) and first null beam width (FNBW) have been achieved by the proposed collective animal behaviour (CAB) algorithm. CAB finds near global optimal solution unlike RGA, PSO, and DE in the present problem. The above comparative optimization is illustrated through 10-, 14-, and 20-element linear antenna arrays to establish the optimization efficacy of CAB.

  16. Optimized Hyper Beamforming of Linear Antenna Arrays Using Collective Animal Behaviour

    PubMed Central

    Ram, Gopi; Mandal, Durbadal; Kar, Rajib; Ghoshal, Sakti Prasad

    2013-01-01

    A novel optimization technique which is developed on mimicking the collective animal behaviour (CAB) is applied for the optimal design of hyper beamforming of linear antenna arrays. Hyper beamforming is based on sum and difference beam patterns of the array, each raised to the power of a hyperbeam exponent parameter. The optimized hyperbeam is achieved by optimization of current excitation weights and uniform interelement spacing. As compared to conventional hyper beamforming of linear antenna array, real coded genetic algorithm (RGA), particle swarm optimization (PSO), and differential evolution (DE) applied to the hyper beam of the same array can achieve reduction in sidelobe level (SLL) and same or less first null beam width (FNBW), keeping the same value of hyperbeam exponent. Again, further reductions of sidelobe level (SLL) and first null beam width (FNBW) have been achieved by the proposed collective animal behaviour (CAB) algorithm. CAB finds near global optimal solution unlike RGA, PSO, and DE in the present problem. The above comparative optimization is illustrated through 10-, 14-, and 20-element linear antenna arrays to establish the optimization efficacy of CAB. PMID:23970843

  17. Simulation and Testing of a Linear Array of Modified Four-Square Feed Antennas for the Tianlai Cylindrical Radio Telescope

    NASA Astrophysics Data System (ADS)

    Cianciara, Aleksander J.; Anderson, Christopher J.; Chen, Xuelei; Chen, Zhiping; Geng, Jingchao; Li, Jixia; Liu, Chao; Liu, Tao; Lu, Wing; Peterson, Jeffrey B.; Shi, Huli; Steffel, Catherine N.; Stebbins, Albert; Stucky, Thomas; Sun, Shijie; Timbie, Peter T.; Wang, Yougang; Wu, Fengquan; Zhang, Juyong

    A wide bandwidth, dual polarized, modified four-square antenna is presented as a feed antenna for radio astronomical measurements. A linear array of these antennas is used as a line-feed for cylindrical reflectors for Tianlai, a radio interferometer designed for 21cm intensity mapping. Simulations of the feed antenna beam patterns and scattering parameters are compared to experimental results at multiple frequencies across the 650-1420MHz range. Simulations of the beam patterns of the combined feed array/reflector are presented as well.

  18. Design and characterisation of a phased antenna array for intact breast hyperthermia.

    PubMed

    Curto, Sergio; Garcia-Miquel, Aleix; Suh, Minyoung; Vidal, Neus; Lopez-Villegas, Jose M; Prakash, Punit

    2017-06-28

    Currently available hyperthermia technology is not well suited to treating cancer malignancies in the intact breast. This study investigates a microwave applicator incorporating multiple patch antennas, with the goal of facilitating controllable power deposition profiles for treating lesions at diverse locations within the intact breast. A 3D-computational model was implemented to assess power deposition profiles with 915 MHz applicators incorporating a hemispheric groundplane and configurations of 2, 4, 8, 12, 16 and 20 antennas. Hemispheric breast models of 90 mm and 150 mm diameter were considered, where cuboid target volumes of 10 mm edge length (1 cm(3)) and 30 mm edge length (27 cm(3)) were positioned at the centre of the breast, and also located 15 mm from the chest wall. The average power absorption (αPA) ratio expressed as the ratio of the PA in the target volume and in the full breast was evaluated. A 4-antenna proof-of-concept array was fabricated and experimentally evaluated. Computational models identified an optimal inter-antenna spacing of 22.5° along the applicator circumference. Applicators with 8 and 12 antennas excited with constant phase presented the highest αPA at centrally located and deep-seated targets, respectively. Experimental measurements with a 4-antenna proof-of-concept array illustrated the potential for electrically steering power deposition profiles by adjusting the relative phase of the signal at antenna inputs. Computational models and experimental results suggest that the proposed applicator may have potential for delivering conformal thermal therapy in the intact breast.

  19. Taiwanese antennas for the Sub-Millimeter Array: a progress report

    NASA Astrophysics Data System (ADS)

    Raffin, Phillippe A.; Liu, Ching-Tang; Cervera, Mathieu; Chang, Chi-Ling; Chen, Ming-Tang; Lee, Cheng-Ching; Lee, Typhoon; Lo, Kwok-Yung; Ma, Rwei-Ping; Martin, Robert N.; Martin-Cocher, Pierre; Ong, Ching-Long; Park, Yong-Sun; Tsai, Rong-Den; Wu, Enboa; Yang, Shun-Cheng; Yang, Tien-Szu

    2000-07-01

    The Academia Sinica, Institute for Astronomy and Astrophysics (ASIAA) is building two antennas to be added to the six antennas of the Sub-Millimeter Array (SMA) of the Smithsonian Astrophysical Observatory (SAO). The antennas have been designed at SAO and are currently under construction at Mauna Kea. ASIAA's two antennas are made in Taiwan from parts manufactured locally and imported from Europe and from the USA. This report will focus on the manufacturing and testing of 2 major components: the alidade and the reflector. We will emphasize the work done on the composite parts used in the 6- meter reflectors, namely the carbon fiber tubes for the backup structure, the carbon fiber legs of the quadrupod and the composite central hub. We will discuss the modal testing and pointing tests of the antennas. Finally this report will show how the Taiwanese industry was able to respond to the high manufacturing standards required to build sub-millimeter antennas. The design and manufacturing capabilities of the Aeronautical Research Laboratories and China Shipbuilding Corporation have made possible the construction of the telescopes in Taiwan.

  20. Using a focal-plane array to estimate antenna pointing errors

    NASA Technical Reports Server (NTRS)

    Zohar, S.; Vilnrotter, V. A.

    1991-01-01

    The use of extra collecting horns in the focal plane of an antenna as a means of determining the Direction of Arrival (DOA) of the signal impinging on it, provided it is within the antenna beam, is considered. Our analysis yields a relatively simple algorithm to extract the DOA from the horns' outputs. An algorithm which, in effect, measures the thermal noise of the horns' signals and determines its effect on the uncertainty of the extracted DOA parameters is developed. Both algorithms were implemented in software and tested in simulated data. Based on these tests, it is concluded that this is a viable approach to the DOA determination. Though the results obtained are of general applicability, the particular motivation for the present work is their application to the pointing of a mechanically deformed antenna. It is anticipated that the pointing algorithm developed for a deformed antenna could be obtained as a small perturbation of the algorithm developed for an undeformed antenna. In this context, it should be pointed out that, with a deformed antenna, the array of horns and its associated circuitry constitute the main part of the deformation-compensation system. In this case, the pointing system proposed may be viewed as an additional task carried out by the deformation-compensation hardware.

  1. Simple Switched-Beam Array Antenna System for Mobile Satellite Communications

    NASA Astrophysics Data System (ADS)

    Basari; Purnomo, M. Fauzan E.; Saito, Kazuyuki; Takahashi, Masaharu; Ito, Koichi

    This paper presents a simple antenna system for land vehicle communication aimed at Engineering Test Satellite-VIII (ETS-VIII) applications. The developed antenna system which designed for mounting in a vehicle is compact, light weight and offers simple satellite-tracking operation. This system uses a microstrip patch array antenna, which includes onboard-power divider and switching circuit for antenna feeding control, due to its low profile. A Global Positioning System (GPS) receiver is constructed to provide accurate information on the vehicle's position and bearing during traveling. The personal computer (PC) interfaces as the control unit and data acquisition, which were specifically designed for this application, allow the switching circuit control as well as the retrieving of the received power levels. In this research, the antenna system was firstly examined in an anechoic chamber for S parameter, axial ratio, and radiation characteristics. Satisfactory characteristics were obtained. As for beam-tracking of antenna, it was examined in the anechoic chamber with the gain above 5dBic and the axial ratio below 3dB. Moreover, good received power levels for tracking the ETS-VIII satellite in outdoor measurement, were confirmed.

  2. High Power Terahertz Fields Generated by an Arrayed Photoconductive Antenna Structure

    NASA Astrophysics Data System (ADS)

    Graber, Benjamin; Wu, Dong Ho; Kim, Christopher

    Terahertz spectroscopy has a wide array of scientific, commercial, and industrial applications. However, to date, terahertz signal strength of available commercial systems is limited to less than 100 uW in average terahertz power. It is expected that with enhanced terahertz power one may be able to obtain better terahertz spectral information, and enable more practical terahertz applications in real environments. In order to achieve this goal we experimentally constructed an arrayed photoconductive antenna structure, in which terahertz signals from a few photoconductive antennas are combined by adjusting every terahertz signals to be in phase. The collected signals from the multiple emitters are concentrated onto a small area so that the combined terahertz signal strength is over 1mW in average power and peak electric field over 16kV/m. The terahertz frequency spectrum of combined signals is unaltered and exactly the same as that of each individual photoconductive antenna, which spans from 100GHz to 3THz. Experimental details regarding power measurement, time domain signals, and frequency spectra analysis will be discussed. This prototype array structure appears to scale linearly with the addition of photoconductive antennas.

  3. The study of microstrip antenna arrays and related problems

    NASA Technical Reports Server (NTRS)

    Lo, R. Q.

    1984-01-01

    The work on rectangular microstrip antennas for dual frequency operation is reported on. The principle of this approach is based on the excitation of a patch for two or more different modes which correspond to different frequencies. However, for a given geometry, the modal frequencies have a fixed relationship; therefore, the usefulness of such a design is greatly limited. In this study three different methods have been contrived to control the frequency ratio over a wide range. First, as found prevously, if shorting pins are inserted at certain locations in the patch, the low frequency can be raised substantially. Second, if slots are cut in the patch, the high frequency can be lowered considerably. By using both techniques, the two frequency ratio can be varied approximately from 3 to 1.3. After that, the addition of more pins or slots becomes ineffective.

  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. Reduction of Mutual Coupling in Small Dipole Array Antennas

    DTIC Science & Technology

    2003-03-01

    few elements near the edge. The effect near the end of the array is known as the edge - effect . For a majority of the elements in a large phased......modification will reduce the edge effect , producing an active element pattern at the edge elements that is similar to that of elements away from the

  6. 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.

  7. Cost and reliability study for a large array of small reflector antennas for JPL/NASA Deep Space Network (DSN)

    NASA Technical Reports Server (NTRS)

    Jamnejad, Vahraz; Cwik, Tom; Resch, George

    1993-01-01

    A study performed to estimate the cost of an array of small aperture reflector antennas to be used instead of or in conjunction with the current large reflector antennas of the JPL/NASA Deep Space Network (DSN) is described. The arrays are used for servicing present and future NASA missions that involve smaller spacecraft with limited power and smaller, lower-gain antennas. The advantages of the array configuration in terms of cost and reliability are discussed. A probabilistic determination of the reliability and availability of the array as a function of the number of array elements and the availability of individual array elements is made. The impact of additional marginal elements on the operational availability of the array is studied. Parametric cost and reliability plots are presented and directions for further investigation are outlined.

  8. Aperture-coupled thin-membrane microstrip array antenna for beam scanning application

    NASA Technical Reports Server (NTRS)

    Huang, John; Sadowy, Gregory; Derksen, Chuck; Del Castillo, Linda; Smith, Phil; Hoffman, Jim; Hatake, Toshiro; Moussessian, Alina

    2005-01-01

    A microstrip array using aperture-slot-coupling technique with very thin membranes has been developed at the L-band frequency for beam scanning application. This technology-demonstration array with 4 x 2 elements achieved a relatively wide bandwidth of 100 MHz (8%) and +/-45(deg) beam scan. Very narrow coupling slots were used with each having an aspect ratio of 160 (conventional slot aspect ratio is between 10 to 30) for coupling through very thin membrane (0.05mm thickness). This thin-membrane aperture-coupling technique allows the array antenna elements to be more easily integrated with transmit/receive amplifier (T/R) and phase shifter modules. This paper addresses only the radiator portion of the array. The array and active components will be presented in a separate pape.

  9. Dual polarized receiving steering antenna array for measurement of ultrawideband pulse polarization structure

    NASA Astrophysics Data System (ADS)

    Balzovsky, E. V.; Buyanov, Yu. I.; Koshelev, V. I.; Nekrasov, E. S.

    2016-03-01

    To measure simultaneously two orthogonal components of the electromagnetic field of nano- and subnano-second duration, an antenna array has been developed. The antenna elements of the array are the crossed dipoles of dimension 5 × 5 cm. The arms of the dipoles are connected to the active four-pole devices to compensate the frequency response variations of a short dipole in the frequency band ranging from 0.4 to 4 GHz. The dipoles have superimposed phase centers allowing measuring the polarization structure of the field in different directions. The developed antenna array is the linear one containing four elements. The pattern maximum position is controlled by means of the switched ultrawideband true time delay lines. Discrete steering in seven directions in the range from -40° to +40° has been realized. The error at setting the pattern maximum position is less than 4°. The isolation of the polarization exceeds 29 dB in the direction orthogonal to the array axis and in the whole steering range it exceeds 23 dB. Measurement results of the polarization structure of radiated and scattered pulses with different polarization are presented as well.

  10. Design and analysis of a large cylinder antenna array in Tianlai

    NASA Astrophysics Data System (ADS)

    Chen, Z. P.; Wang, R. L.; Peterson, J.; Chen, X. L.; Zhang, J. Y.; Shi, H. L.

    2016-07-01

    In order to make a large area survey, detect a large scale structure and understand dark energy, a large radio interference array with a large number of feeds is required. However, cost and deformation control are main considerations in designing a large antenna array. In this paper we designed a cylinder parabolic structure for antenna array 45m x 40m of "Tianlai" project in Xinjiang, China in 2015. In order to largely reduce weight and cost, the antenna was divided into many assemble units, their structure was optimized by MSC.Patran/Nastran and their reflector deformation under various load cases of gravity, snow and wind was analyzed. For the feed support, we compared different types of structure such as arch-bridge, tower, cable and pole, and by mechanical simulations we found that the arch-bridge structure is very helpful to achieve large span, decrease weight and improve stability, for example, the total weight of optimized structure can be reduced to 43.7% of before. Finally some deformation measurement and experiment methods were discussed, which can be extended to array 100m×100m in the future.

  11. Dual polarized receiving steering antenna array for measurement of ultrawideband pulse polarization structure.

    PubMed

    Balzovsky, E V; Buyanov, Yu I; Koshelev, V I; Nekrasov, E S

    2016-03-01

    To measure simultaneously two orthogonal components of the electromagnetic field of nano- and subnano-second duration, an antenna array has been developed. The antenna elements of the array are the crossed dipoles of dimension 5 × 5 cm. The arms of the dipoles are connected to the active four-pole devices to compensate the frequency response variations of a short dipole in the frequency band ranging from 0.4 to 4 GHz. The dipoles have superimposed phase centers allowing measuring the polarization structure of the field in different directions. The developed antenna array is the linear one containing four elements. The pattern maximum position is controlled by means of the switched ultrawideband true time delay lines. Discrete steering in seven directions in the range from -40° to +40° has been realized. The error at setting the pattern maximum position is less than 4°. The isolation of the polarization exceeds 29 dB in the direction orthogonal to the array axis and in the whole steering range it exceeds 23 dB. Measurement results of the polarization structure of radiated and scattered pulses with different polarization are presented as well.

  12. Dual polarized receiving steering antenna array for measurement of ultrawideband pulse polarization structure

    SciTech Connect

    Balzovsky, E. V.; Buyanov, Yu. I.; Koshelev, V. I. Nekrasov, E. S.

    2016-03-15

    To measure simultaneously two orthogonal components of the electromagnetic field of nano- and subnano-second duration, an antenna array has been developed. The antenna elements of the array are the crossed dipoles of dimension 5 × 5 cm. The arms of the dipoles are connected to the active four-pole devices to compensate the frequency response variations of a short dipole in the frequency band ranging from 0.4 to 4 GHz. The dipoles have superimposed phase centers allowing measuring the polarization structure of the field in different directions. The developed antenna array is the linear one containing four elements. The pattern maximum position is controlled by means of the switched ultrawideband true time delay lines. Discrete steering in seven directions in the range from −40° to +40° has been realized. The error at setting the pattern maximum position is less than 4°. The isolation of the polarization exceeds 29 dB in the direction orthogonal to the array axis and in the whole steering range it exceeds 23 dB. Measurement results of the polarization structure of radiated and scattered pulses with different polarization are presented as well.

  13. An experimental SMI adaptive antenna array for weak interfering signals

    NASA Technical Reports Server (NTRS)

    Dilsavor, R. L.; Gupta, I. J.

    1989-01-01

    A modified sample matrix inversion (SMI) algorithm designed to increase the suppression of weak interference is implemented on an existing experimental array system. The algorithm itself is fully described as are a number of issues concerning its implementation and evaluation, such as sample scaling, snapshot formation, weight normalization, power calculation, and system calibration. Several experiments show that the steady state performance (i.e., many snapshots are used to calculate the array weights) of the experimental system compares favorably with its theoretical performance. It is demonstrated that standard SMI does not yield adequate suppression of weak interference. Modified SMI is then used to experimentally increase this suppression by as much as 13dB.

  14. Evaluation of Two Dimensional HF Adaptive Antenna Arrays

    DTIC Science & Technology

    1974-10-01

    CONVENTIONAL WEIGHTS 2. J. ADAPTIVE WEIGHTS 1. 4 RECEIVER ERRORS 2.4. 1 Error Analysis 2.4.2 Simulation SIMULATION RESULTS 3. i PROPERTIES OF...conditions, to document the research which has been done on the properties ot lov-redundancy sparse arrays when used with adaptive beam- formers...optimum processor*! a d.-grading effect on the resolution propertier . near a discrete source is noted. As McOonough notes, the effec of

  15. 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.

  16. Terahertz epsilon-near-zero cut-through metal-slit array antenna

    NASA Astrophysics Data System (ADS)

    Suzuki, Takehito; Kimura, Tatsuya; Togashi, Takahisa; Kitahara, Hideaki; Ishihara, Koki; Sato, Tatsuya

    2017-02-01

    Metamaterials can give rise to unprecedented refractive indices and drive the rapid development of metadevices with on-demand electromagnetic properties. Recent advances in terahertz science demand high-performance optical elements beyond conventional designs of naturally occurring materials in the terahertz wave band. However, how an epsilon-near-zero (ENZ) structure can exploit terahertz metadevices is still not fully demonstrated based on a physical analysis. Here, inspired by the ENZ concept, we demonstrate a design guideline of a terahertz ENZ cut-through metal-slit array antenna. Measurements by a terahertz imager visualize the beam profile of a terahertz wave, and the measured permittivity of 0.26 agrees well with that of 0.27 obtained by simulation and theory. The terahertz ENZ antenna provides a wide range of potential applications such as high-directivity antennas, beam dividers, beam-steering elements, phase-control devices, and novel filters.

  17. Theoretical and measured electric field distributions within an annular phased array: consideration of source antennas.

    PubMed

    Zhang, Y; Joines, W T; Jirtle, R L; Samulski, T V

    1993-08-01

    The magnitude of E-field patterns generated by an annular array prototype device has been calculated and measured. Two models were used to describe the radiating sources: a simple linear dipole and a stripline antenna model. The stripline model includes detailed geometry of the actual antennas used in the prototype and an estimate of the antenna current based on microstrip transmission line theory. This more detailed model yields better agreement with the measured field patterns, reducing the rms discrepancy by a factor of about 6 (from approximately 23 to 4%) in the central region of interest where the SEM is within 25% of the maximum. We conclude that accurate modeling of source current distributions is important for determining SEM distributions associated with such heating devices.

  18. Enhancing resolution properties of array antennas via field extrapolation: application to MIMO systems

    NASA Astrophysics Data System (ADS)

    Reggiannini, Ruggero

    2015-12-01

    This paper is concerned with spatial properties of linear arrays of antennas spaced less than half wavelength. Possible applications are in multiple-input multiple-output (MIMO) wireless links for the purpose of increasing the spatial multiplexing gain in a scattering environment, as well as in other areas such as sonar and radar. With reference to a receiving array, we show that knowledge of the received field can be extrapolated beyond the actual array size by exploiting the finiteness of the interval of real directions from which the field components impinge on the array. This property permits to increase the performance of the array in terms of angular resolution. A simple signal processing technique is proposed allowing formation of a set of beams capable to cover uniformly the entire horizon with an angular resolution better than that achievable by a classical uniform-weighing half-wavelength-spaced linear array. Results are also applicable to active arrays. As the above approach leads to arrays operating in super-directive regime, we discuss all related critical aspects, such as sensitivity to external and internal noises and to array imperfections, and bandwidth, so as to identify the basic design criteria ensuring the array feasibility.

  19. System for tunerless operation of a four-element phased array antenna for fast wave current drive

    SciTech Connect

    Pinsker, R.I.; Cary, W.P.; Petty, C.C.; Callis, R.W.; Grassie, J.S. de; Baity, F.W.; Martin, W.C.

    1997-11-01

    A simple transmission line configuration for powering a four-element phased antenna array is described. This system, called the balanced feed configuration (BFC) is suitable for co- or counter- Fast Wave Current Drive (FWCD) applications. It has the property of presenting a constant matched load to the transmitter despite wide variations in the antenna load impedance without the use of variable tuning elements. This system has been implemented on a 2 MW 60 MHz FWCD antenna on the DIII-D tokamak.

  20. Power compensators for phased operation of antenna arrays on JET and DIII-D

    SciTech Connect

    Goulding, R.H.; Hoffman, D.J.; Ryan, P.M. ); Bosia, G.; Bures, M.; Start, D.; Wade, T. ); Petty, C.C.; Pinsker, R.I. )

    1994-10-15

    A system has been designed to allow operation of the JET A2 antenna arrays with phasing between elements of other than 0 or [pi] at increased power. The system uses a hybrid coupler to transfer power in the direction opposite to that occurring at the antenna elements. This results in nearly equal currents and voltages on the feed lines and antenna structures, with nearly equal input powers at the rf generators. The direction and magnitude of the power transfer is controlled by adjustable tuning elements mounted on two of the four coupler ports. Much insight has been gained on optimization of the circuit design to maximize bandwidth ([similar to]10 MHz for the present JET design with 20 MHz a possibility) and power-handling capability. The concept has been tested initially on the DIII-D tokamak, with a compensator installed in the feed circuit for the four-element FWCD antenna array. In this application it acts to equalize input impedances, and will eventually be used to allow operation with multiple transmitters.

  1. Power compensators for phased operation of antenna arrays on JET and DIII-D

    SciTech Connect

    Goulding, R.H.; Hoffman, D.J.; Ryan, P.M.; Bosia, G.; Bures, M.; Start, D.; Wade, T.; Petty, C.C.; Pinsker, R.I.

    1993-06-01

    A system has been designed to allow operation of the JET A2 antenna arrays with phasing between elements of other than 0 or {pi} at increased power. The system uses a hybrid coupler to transfer power in the direction opposite to that occurring at the antenna elements. This results in nearly equal currents and voltages on the feed lines and antenna structures, with nearly equal input powers at the rf generators. The direction and magnitude of the power transfer is controlled by adjustable tuning elements mounted on two of the four coupler ports. Much insight has been gained on optimization of the circuit design to maximize bandwidth ({approximately}10 MHz for the present JET design with 20 MHz a possibility) and power-handling capability. The concept has been tested initially on the DIII-D tokamak, with a compensator installed in the feed circuit for the four-element FWCD antenna array. In this application it acts to equalize input impedances, and will eventually be used to allow operation with multiple transmitters.

  2. Power compensators for phased operation of antenna arrays on JET and DIII-D

    SciTech Connect

    Goulding, R.H.; Hoffman, D.J.; Ryan, P.M. ); Bosia, G.; Bures, M.; Start, D.; Wade, T. ); Petty, C.C.; Pinsker, R.I. )

    1993-01-01

    A system has been designed to allow operation of the JET A2 antenna arrays with phasing between elements of other than 0 or [pi] at increased power. The system uses a hybrid coupler to transfer power in the direction opposite to that occurring at the antenna elements. This results in nearly equal currents and voltages on the feed lines and antenna structures, with nearly equal input powers at the rf generators. The direction and magnitude of the power transfer is controlled by adjustable tuning elements mounted on two of the four coupler ports. Much insight has been gained on optimization of the circuit design to maximize bandwidth ([approximately]10 MHz for the present JET design with 20 MHz a possibility) and power-handling capability. The concept has been tested initially on the DIII-D tokamak, with a compensator installed in the feed circuit for the four-element FWCD antenna array. In this application it acts to equalize input impedances, and will eventually be used to allow operation with multiple transmitters.

  3. Superconducting Quantum Arrays for Wideband Antennas and Low Noise Amplifiers

    NASA Technical Reports Server (NTRS)

    Mukhanov, O.; Prokopemko, G.; Romanofsky, Robert R.

    2014-01-01

    Superconducting Quantum Iinetference Filters (SQIF) consist of a two-dimensional array of niobium Josephson Junctions formed into N loops of incommensurate area. This structure forms a magnetic field (B) to voltage transducer with an impulse like response at B0. In principle, the signal-to-noise ratio scales as the square root of N and the noise can be made arbitrarily small (i.e. The SQIF chips are expected to exhibit quantum limited noise performance). A gain of about 20 dB was recently demonstrated at 10 GHz.

  4. Single and dual-Gregorian reflector antenna shaped beam far-field synthesis

    NASA Astrophysics Data System (ADS)

    Mehler, M. J.

    The direct far-field G.O. synthesis of shaped beam reflector antennas has recently been treated by Mehler, Tun and Adatia (1986). These authors use a synthesis technique which exploits complex coordinates and which is based on a method originally considered by Norris and Westcott (1976). They describe the synthesis of single reflector antennas which radiate both elliptical beams and European coverage patterns. Here this technique is extended to consider a class of dual reflector antennas which possess shaped main reflectors and conic subreflectors. An example is given of a Gregorian duel reflector antenna which radiates a cross-polar field significantly smaller than that radiated by single shaped reflector antennas. In addition, the behavior of the radiation pattern as a function of the reflector diameter is investigated.

  5. Hyperbolic Positioning with Antenna Arrays and Multi-Channel Pseudolite for Indoor Localization

    PubMed Central

    Fujii, Kenjirou; Sakamoto, Yoshihiro; Wang, Wei; Arie, Hiroaki; Schmitz, Alexander; Sugano, Shigeki

    2015-01-01

    A hyperbolic positioning method with antenna arrays consisting of proximately-located antennas and a multi-channel pseudolite is proposed in order to overcome the problems of indoor positioning with conventional pseudolites (ground-based GPS transmitters). A two-dimensional positioning experiment using actual devices is conducted. The experimental result shows that the positioning accuracy varies centimeter- to meter-level according to the geometric relation between the pseudolite antennas and the receiver. It also shows that the bias error of the carrier-phase difference observables is more serious than their random error. Based on the size of the bias error of carrier-phase difference that is inverse-calculated from the experimental result, three-dimensional positioning performance is evaluated by computer simulation. In addition, in the three-dimensional positioning scenario, an initial value convergence analysis of the non-linear least squares is conducted. Its result shows that initial values that can converge to a right position exist at least under the proposed antenna setup. The simulated values and evaluation methods introduced in this work can be applied to various antenna setups; therefore, by using them, positioning performance can be predicted in advance of installing an actual system. PMID:26437405

  6. Operating the Upgraded NSTX HHFW Antenna Array in an Environment with Li-coated Surfaces

    SciTech Connect

    Ryan, Philip Michael; Ellis, R.; Hosea, J.; Kung, C. C.; LeBlanc, B; Pinsker, R.; Taylor, G.; Wilson, J. R.; NSTX Team,

    2011-01-01

    The single-feed, end-grounded straps of the NSTX 12-strap HHFW antenna array have been replaced with double-feed, center-grounded straps to reduce the voltages in the vicinity of the Faraday shield (FS) for a given strap current. The strap spacings to the FS and to the back plate were increased by 3 mm to decrease the electric fields for a given voltage. The electric fields near the FS have been roughly halved for the same strap currents, permitting a direct examination of the roles that internal fields play in determining antenna power limits in plasmas. Extensive RF/plasma conditioning of the antenna was required to remove enough of the evaporated Li deposits from prior wall conditioning to permit coupling in excess of 4 MW to L- and H-mode plasmas in 2009. Most arcs were associated with expulsion of Li from the FS/antenna frame surfaces. The center-grounded straps were less susceptible to arcing during ELMing Hmode plasmas. Reliable operation above 2 MW was difficult after the installation of the Liquid Lithium Divertor (LLD) in 2010. Li-compound dust was found in the antennas after this run and is believed to have contributed to the reduced power limit.

  7. Operating The Upgraded NSTX HHFW Antenna Array In An Environment With Li-coated Surfaces

    SciTech Connect

    Ryan, P. M.; Ellis, R.; Hosea, J. C.; Kung, C. C.; LeBlanc, B. P.; Taylor, G.; Wilson, J. R.; Pinsker, R. I.

    2011-12-23

    The single-feed, end-grounded straps of the NSTX 12-strap HHFW antenna array have been replaced with double-feed, center-grounded straps to reduce the voltages in the vicinity of the Faraday shield (FS) for a given strap current. The strap spacings to the FS and to the back plate were increased by 3 mm to decrease the electric fields for a given voltage. The electric fields near the FS have been roughly halved for the same strap currents, permitting a direct examination of the roles that internal fields play in determining antenna power limits in plasmas. Extensive RF/plasma conditioning of the antenna was required to remove enough of the evaporated Li deposits from prior wall conditioning to permit coupling in excess of 4 MW to L- and H-mode plasmas in 2009. Most arcs were associated with expulsion of Li from the FS/antenna frame surfaces. The center-grounded straps were less susceptible to arcing during ELMing H-mode plasmas. Reliable operation above 2 MW was difficult after the installation of the Liquid Lithium Divertor (LLD) in 2010. Li-compound 'dust' was found in the antennas after this run and is believed to have contributed to the reduced power limit.

  8. Hyperbolic Positioning with Antenna Arrays and Multi-Channel Pseudolite for Indoor Localization.

    PubMed

    Fujii, Kenjirou; Sakamoto, Yoshihiro; Wang, Wei; Arie, Hiroaki; Schmitz, Alexander; Sugano, Shigeki

    2015-09-30

    A hyperbolic positioning method with antenna arrays consisting of proximately-located antennas and a multi-channel pseudolite is proposed in order to overcome the problems of indoor positioning with conventional pseudolites (ground-based GPS transmitters). A two-dimensional positioning experiment using actual devices is conducted. The experimental result shows that the positioning accuracy varies centimeter- to meter-level according to the geometric relation between the pseudolite antennas and the receiver. It also shows that the bias error of the carrier-phase difference observables is more serious than their random error. Based on the size of the bias error of carrier-phase difference that is inverse-calculated from the experimental result, three-dimensional positioning performance is evaluated by computer simulation. In addition, in the three-dimensional positioning scenario, an initial value convergence analysis of the non-linear least squares is conducted. Its result shows that initial values that can converge to a right position exist at least under the proposed antenna setup. The simulated values and evaluation methods introduced in this work can be applied to various antenna setups; therefore, by using them, positioning performance can be predicted in advance of installing an actual system.

  9. Angle resolution of wideband signals received by two slightly diverse linear antenna arrays

    NASA Astrophysics Data System (ADS)

    Bagdasaryan, S. T.; Zinevich, Y. P.

    1984-05-01

    The problem of angle resolution is considered in the case of detection of wideband signals by means of antenna arrays with a discontinuous aperture. The receiver antenna is assumed to be linear and to consist of two separate equidistant arrays of weakly directional elements. The signals are assumed to appear at the receiver on plane electromagnetic waves together with interference and intrinsic noise, both centered stationary Gaussian random processes. Expressions are derived for the energy utilization factor, characterizing the signal to noise interference ratio relative to the signal noise ratio without interference. A comparison of that energy utilization factor corresponding to optimal processing of a narrow band signal and to nonoptimal processing of a wideband signal, respectively, yields the dependence of detectability and angle resolution on the signal bandwidth and the angular spacing of signal sources.

  10. Modeling of systems wireless data transmission based on antenna arrays in underwater acoustic channels

    NASA Astrophysics Data System (ADS)

    Fedosov, V. P.; Lomakina, A. V.; Legin, A. A.; Voronin, V. V.

    2016-05-01

    In this paper the system of wireless transmission of data based on the use an adaptive algorithm for processing spatial-time signals using antenna arrays is presented. In the transmission of data in a multipath propagation of signals have been used such technologies as a MIMO (Multiple input-Multiple output) and OFDM (Orthogonal frequency division multiplexing) to solve the problem of increasing the maximum speed of data transfer and the low probability of errors. The adaptation process is based on the formation of the directional pattern equivalent to the amplitude antenna array in the signal arrival direction with the highest capacity on one of propagation paths in the channel. The simulation results showed that the use of an adaptive algorithm on the reception side can significantly reduce the probability of bit errors, thus to increase throughput in an underwater acoustic data channel.

  11. Frequency translating phase conjugation circuit for active retrodirective antenna array. [microwave transmission

    NASA Technical Reports Server (NTRS)

    Chernoff, R. (Inventor)

    1980-01-01

    An active retrodirective antenna array which has central phasing from a reference antenna element through a "tree" structured network of transmission lines utilizes a number of phase conjugate circuits (PCCs) at each node and a phase reference regeneration circuit (PRR) at each node except the initial node. Each node virtually coincides with an element of the array. A PCC generates the exact conjugate phase of an incident signal using a phase locked loop which combines the phases in an up converter, divides the sum by 2 and mixes the result with the phase in a down converter for phase detection. The PRR extracts the phase from the conjugate phase. Both the PCC and the PRR are not only exact but also free from mixer degeneracy.

  12. Design and Application of Wuhan Ionospheric Oblique Backscattering Sounding System with the Addition of an Antenna Array (WIOBSS-AA).

    PubMed

    Cui, Xiao; Chen, Gang; Wang, Jin; Song, Huan; Gong, Wanlin

    2016-06-15

    The Wuhan Ionospheric Oblique Backscattering Sounding System with the addition of an antenna array (WIOBSS-AA) is the newest member of the WIOBSS family. It is a multi-channel radio system using phased-array antenna technology. The transmitting part of this radio system applies an array composed of five log-periodic antennas to form five beams that span an area to the northwest of the radar site. The hardware and the antenna array of the first multi-channel ionosonde in the WIOBSS family are introduced in detail in this paper. An ionospheric detection experiment was carried out in Chongyang, Hubei province, China on 16 March 2015 to examine the performance of WIOBSS-AA. The radio system demonstrated its ability to obtain ionospheric electron density information over a wide area. The observations indicate that during the experiment, the monitored large-area ionospheric F2-layer was calm and electron density increased with decreasing latitude.

  13. A TSVD Analysis of the Impact of Polarization on Microwave Breast Imaging using an Enclosed Array of Miniaturized Patch Antennas

    PubMed Central

    Mays, R. Owen; Behdad, Nader; Hagness, Susan C.

    2014-01-01

    Microwave breast imaging performance is fundamentally dependent on the quality of information contained within the scattering data. We apply a truncated singular-value decomposition (TSVD) method to evaluate the information contained in a simulated scattering scenario wherein a compact, shielded array of miniaturized patch antennas surrounds an anatomically realistic numerical breast phantom. In particular, we investigate the impact of different antenna orientations (and thus polarizations), namely two array configurations with uniform antenna orientations and one mixed-orientation array configuration. The latter case is of interest because it may offer greater flexibility in antenna and array design. The results of this analysis indicate that mixed-polarization configurations do not degrade information quality compared to uniform-polarization configurations and in fact may enhance imaging performance, and thus represent viable design options for microwave breast imaging systems. PMID:25705136

  14. A TSVD Analysis of the Impact of Polarization on Microwave Breast Imaging using an Enclosed Array of Miniaturized Patch Antennas.

    PubMed

    Mays, R Owen; Behdad, Nader; Hagness, Susan C

    Microwave breast imaging performance is fundamentally dependent on the quality of information contained within the scattering data. We apply a truncated singular-value decomposition (TSVD) method to evaluate the information contained in a simulated scattering scenario wherein a compact, shielded array of miniaturized patch antennas surrounds an anatomically realistic numerical breast phantom. In particular, we investigate the impact of different antenna orientations (and thus polarizations), namely two array configurations with uniform antenna orientations and one mixed-orientation array configuration. The latter case is of interest because it may offer greater flexibility in antenna and array design. The results of this analysis indicate that mixed-polarization configurations do not degrade information quality compared to uniform-polarization configurations and in fact may enhance imaging performance, and thus represent viable design options for microwave breast imaging systems.

  15. Design and Application of Wuhan Ionospheric Oblique Backscattering Sounding System with the Addition of an Antenna Array (WIOBSS-AA)

    PubMed Central

    Cui, Xiao; Chen, Gang; Wang, Jin; Song, Huan; Gong, Wanlin

    2016-01-01

    The Wuhan Ionospheric Oblique Backscattering Sounding System with the addition of an antenna array (WIOBSS-AA) is the newest member of the WIOBSS family. It is a multi-channel radio system using phased-array antenna technology. The transmitting part of this radio system applies an array composed of five log-periodic antennas to form five beams that span an area to the northwest of the radar site. The hardware and the antenna array of the first multi-channel ionosonde in the WIOBSS family are introduced in detail in this paper. An ionospheric detection experiment was carried out in Chongyang, Hubei province, China on 16 March 2015 to examine the performance of WIOBSS-AA. The radio system demonstrated its ability to obtain ionospheric electron density information over a wide area. The observations indicate that during the experiment, the monitored large-area ionospheric F2-layer was calm and electron density increased with decreasing latitude. PMID:27314360

  16. Optical BEAMTAP Beam-Forming and Jammer-Nulling System for Broadband Phased-Array Antennas

    NASA Astrophysics Data System (ADS)

    Kriehn, Gregory; Kiruluta, Andrew; Silveira, Paulo E. X.; Weaver, Sam; Kraut, Shawn; Wagner, Kelvin; Weverka, R. Ted; Griffiths, Lloyd

    2000-01-01

    We present an approach to receive-mode broadband beam forming and jammer nulling for large adaptive antenna arrays as well as its efficient and compact optical implementation. This broadband efficient adaptive method for true-time-delay array processing (BEAMTAP) algorithm decreases the number of tapped delay lines required for processing an N -element phased-array antenna from N to only 2, producing an enormous savings in delay-line hardware (especially for large broadband arrays) while still providing the full NM degrees of freedom of a conventional N -element time-delay-and-sum beam former that requires N tapped delay lines with M taps each. This allows the system to adapt fully and optimally to an arbitrarily complex spatiotemporal signal environment that can contain broadband signals of interest, as well as interference sources and narrow-band and broadband jammers all of which can arrive from arbitrary angles onto an arbitrarily shaped array thus enabling a variety of applications in radar, sonar, and communication. This algorithm is an excellent match with the capabilities of radio frequency (rf) photonic systems, as it uses a coherent optically modulated fiber-optic feed network, gratings in a photorefractive crystal as adaptive weights, a traveling-wave detector for generating time delay, and an acousto-optic device to control weight adaptation. Because the number of available adaptive coefficients in a photorefractive crystal is as large as 10 9 , these photonic systems can adaptively control arbitrarily large one- or two-dimensional antenna arrays that are well beyond the capabilities of conventional rf and real-time digital signal processing techniques or alternative photonic techniques.

  17. Optical BEAMTAP beam-forming and jammer-nulling system for broadband phased-array antennas.

    PubMed

    Kriehn, G; Kiruluta, A; Silveira, P E; Weaver, S; Kraut, S; Wagner, K; Weverka, R T; Griffiths, L

    2000-01-10

    We present an approach to receive-mode broadband beam forming and jammer nulling for large adaptive antenna arrays as well as its efficient and compact optical implementation. This broadband efficient adaptive method for true-time-delay array processing (BEAMTAP) algorithm decreases the number of tapped delay lines required for processing an N-element phased-array antenna from N to only 2, producing an enormous savings in delay-line hardware (especially for large broadband arrays) while still providing the full NM degrees of freedom of a conventional N-element time-delay-and-sum beam former that requires N tapped delay lines with M taps each. This allows the system to adapt fully and optimally to an arbitrarily complex spatiotemporal signal environment that can contain broadband signals of interest, as well as interference sources and narrow-band and broadband jammers--all of which can arrive from arbitrary angles onto an arbitrarily shaped array--thus enabling a variety of applications in radar, sonar, and communication. This algorithm is an excellent match with the capabilities of radio frequency (rf) photonic systems, as it uses a coherent optically modulated fiber-optic feed network, gratings in a photorefractive crystal as adaptive weights, a traveling-wave detector for generating time delay, and an acousto-optic device to control weight adaptation. Because the number of available adaptive coefficients in a photorefractive crystal is as large as 10(9), these photonic systems can adaptively control arbitrarily large one- or two-dimensional antenna arrays that are well beyond the capabilities of conventional rf and real-time digital signal processing techniques or alternative photonic techniques.

  18. 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.

  19. On spatial resolution of quasi-optical focal plane antenna array imagers

    NASA Astrophysics Data System (ADS)

    Volkov, Leonid V.; Voronko, Alexander I.; Volkova, Natalie L.

    2004-08-01

    The spatial resolution of millimeter wave (MMW), submillimeter wave (SMMW) and infrared (IR) quasi-optical imagers based on the usage of focal plane antenna arrays (FPAA) is limited by several common factors. Analytical expressions for the point spread functions (PSF) of FPAA imagers are derived for both coherent and spatially incoherent imaging. The possibility of developing advanced super-resolution imaging algorithms using PSFs determined to a high accuracy is discussed.

  20. Microwave monolithic integrated circuit development for future spaceborne phased array antennas

    NASA Technical Reports Server (NTRS)

    Anzic, G.; Kascak, T. J.; Downey, A. N.; Liu, D. C.; Connolly, D. J.

    1983-01-01

    The development of fully monolithic gallium arsenide (GaAs) receive and transmit modules suitable for phased array antenna applications in the 30/20 gigahertz bands is presented. Specifications and various design approaches to achieve the design goals are described. Initial design and performance of submodules and associated active and passive components are presented. A tradeoff study summary is presented highlighting the advantages of distributed amplifier approach compared to the conventional single power source designs.

  1. 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.

  2. 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.

  3. Restoring Low Sidelobe Antenna Patterns with Failed Elements in a Phased Array Antenna

    DTIC Science & Technology

    2016-02-01

    combination has zeros at the location of the failed elements. Furthermore since each of these low sidelobe beamformers achieve low sidelobes, we...with or without failed elements, the procedure will fail to achieve low sidelobes if the array manifold errors are too large. Using just the KNOWN...vectors, , to achieve low sidelobes are available. The beams in are spaced by a half beamwidth (i.e., sin / ). The manifold errors, , are modeled

  4. Fabrication method of 3D feed horn shape MEMS antenna array using MRPBI system and application for microbolometer

    NASA Astrophysics Data System (ADS)

    Park, Jong-Yeon; Kim, Kuntae; Moon, Sung; Park, Jong-Oh; Oh, Myung-Hwan; Pak, James Jungho

    2001-11-01

    A 3D Feed horn shape MEMS antenna has some attractive features for array application, which can be used to improve microbolometer performance. Since MEMS technology have been faced many difficulties to fabrication of 3D feed horn shape MEMS antenna array itself. The purpose of this paper is to propose a new fabrication method to realize a 3D feed horn shape MEMS antenna array using a MRPBI(Mirror Reflected Parallel Beam Illuminator) system with an ultra-slow-rotated and inclined x-y-z stage. A high-aspect-ratio 300 micrometers sidewalls had been fabricated using SU-8 negative photo resist. It can be demonstrated to feasibility of realize 3D feed horn shape MEMS antenna array fabrication. In order to study the effect of this novel technique, the 3D feed horn shape MEMS antenna array had been simulated with HFSS(High Frequency Structure Simulator) tools and then compared with traditional 3D theoretical antenna models. As a result, it seems possible to use a 3D feed horn shape MEMS antenna at the tera hertz band to improve microbolometer performance and optical MEMS device fabrication.

  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. A Study of Loaded Microstrip Antennas and Their Applications to Arrays

    DTIC Science & Technology

    1989-03-01

    impedance variatio. and magnetic current distribu- tion of the single loaded microstrip antena Patch size 6 x 4 crn , load position (2.25 0.95) feed...RADC-TR-89-10 Final Technical Report March 1999J9 A STUDY OF LOADED MICROSTRIP 0 ANTENNAS AND THEIR APPLICATIONS oo TO ARRAYS𔃻" N University of...if necessary and ,denr, by block number) FIELD GROUP SUB-GROUP Dynamic Impedance Tuning 17 09 Microstrip Elements 20 14 Phased Arrays 19 ABSTRACT

  7. Frequency Tunable Antennas and Novel Phased Array Feeding Networks for Next Generation Communication Systems

    NASA Astrophysics Data System (ADS)

    Avser, Bilgehan

    The thesis presents three dual-band frequency tunable antennas for carrier aggregation systems and two new feeding networks for reducing the number of phase shifters in limited-scan arrays. First, single- and dual-feed, dual-frequency, low-profile antennas with independent frequency tuning using varactor diodes are presented. The dual-feed planar inverted F-antenna (PIFA) has two operating frequencies which are independently tuned at 0.7--1.1 GHz and at 1.7--2.3 GHz with better than 10 dB impedance match. The isolation between the high-band and the low-band ports is > 13 dB; hence, one resonant frequency can be tuned without affecting the other. The single-feed contiguous-dual-band antenna has two resonant frequencies, which are independently tuned at 1.2--1.6 GHz at 1.6--2.3 GHz with better than 10 dB impedance match for most of the tuning range. And the single-feed dual-band antenna has two resonant frequencies, which are independently tuned at 0.7--1.0 GHz at 1.7--2.3 GHz with better than 10 dB impedance match for most of the tuning range. The tuning is done using varactor diodes with a capacitance range from 0.8 to 3.8 pF, which is compatible with RF MEMS devices. The antenna volumes are 63 x 100 x 3.15 mm3 on epsilon r = 3.55 substrates and the measured antenna efficiencies vary between 25% and 50% over the tuning range. The application areas are in carrier aggregation systems for fourth generation (4G) wireless systems. Next, a new phased array feeding network that employs random sequences of non-uniform sub-arrays (and a single phase shifter for each sub-array) is presented. When these sequences are optimized, the resulting phased arrays can scan over a wide region with low sidelobe levels. Equations for analyzing the random arrays and an algorithm for optimizing the array sequences are presented. Multiple random-solutions with different number of phase shifters and different set of sub-array groups are analyzed and design guidelines are presented. The

  8. The study of microstrip antenna arrays and related problems

    NASA Technical Reports Server (NTRS)

    Lo, Y. T.

    1986-01-01

    In February, an initial computer program to be used in analyzing the four-element array module was completed. This program performs the analysis of modules composed of four rectangular patches which are corporately fed by a microstrip line network terminated in four identical load impedances. Currently, a rigorous full-wave analysis of various types of microstrip line feed structures and patches is being performed. These tests include the microstrip line feed between layers of different electrical parameters. A method of moments was implemented for the case of a single dielectric layer and microstrip line fed rectangular patches in which the primary source is assumed to be a magnetic current ribbon across the line some distance from the patch. Measured values are compared with those computed by the program.

  9. Antenna-coupled TES bolometers used in BICEP2, Keck Array, and SPIDER

    DOE PAGES

    Ade, P. A. R.; Aikin, R. W.; Amiri, M.; ...

    2015-10-20

    We have developed antenna-coupled transition-edge sensor bolometers for a wide range of cosmic microwave background (CMB) polarimetry experiments, including Bicep2, Keck Array, and the balloon borne Spider. These detectors have reached maturity and this paper reports on their design principles, overall performance, and key challenges associated with design and production. Our detector arrays repeatedly produce spectral bands with 20%–30% bandwidth at 95, 150, or 230 GHz. The integrated antenna arrays synthesize symmetric co-aligned beams with controlled side-lobe levels. Cross-polarized response on boresight is typicallymore » $$\\sim 0.5\\%$$, consistent with cross-talk in our multiplexed readout system. End-to-end optical efficiencies in our cameras are routinely 35% or higher, with per detector sensitivities of NET ~ 300 $$\\mu {{\\rm{K}}}_{\\mathrm{CMB}}\\sqrt{{\\rm{s}}}$$. Thanks to the scalability of this design, we have deployed 2560 detectors as 1280 matched pairs in Keck Array with a combined instantaneous sensitivity of $$\\sim 9\\;\\mu {{\\rm{K}}}_{\\mathrm{CMB}}\\sqrt{{\\rm{s}}}$$, as measured directly from CMB maps in the 2013 season. Furthermore, similar arrays have recently flown in the Spider instrument, and development of this technology is ongoing.« less

  10. Spatio-Temporal Equalizer for a Receiving-Antenna Feed Array

    NASA Technical Reports Server (NTRS)

    Mukai, Ryan; Lee, Dennis; Vilnrotter, Victor

    2010-01-01

    A spatio-temporal equalizer has been conceived as an improved means of suppressing multipath effects in the reception of aeronautical telemetry signals, and may be adaptable to radar and aeronautical communication applications as well. This equalizer would be an integral part of a system that would also include a seven-element planar array of receiving feed horns centered at the focal point of a paraboloidal antenna that would be nominally aimed at or near the aircraft that would be the source of the signal that one seeks to receive (see Figure 1). This spatio-temporal equalizer would consist mostly of a bank of seven adaptive finite-impulse-response (FIR) filters one for each element in the array - and the outputs of the filters would be summed (see Figure 2). The combination of the spatial diversity of the feedhorn array and the temporal diversity of the filter bank would afford better multipath-suppression performance than is achievable by means of temporal equalization alone. The seven-element feed array would supplant the single feed horn used in a conventional paraboloidal ground telemetry-receiving antenna. The radio-frequency telemetry signals re ceiv ed by the seven elements of the array would be digitized, converted to complex baseband form, and sent to the FIR filter bank, which would adapt itself in real time to enable reception of telemetry at a low bit error rate, even in the presence of multipath of the type found at many flight test ranges.

  11. Antenna-coupled TES Bolometers Used in BICEP2, Keck Array, and Spider

    NASA Astrophysics Data System (ADS)

    BICEP2 Collaboration; Keck Array Collaboration; SPIDER Collaboration; Ade, P. A. R.; Aikin, R. W.; Amiri, M.; Barkats, D.; Benton, S. J.; Bischoff, C. A.; Bock, J. J.; Bonetti, J. A.; Brevik, J. A.; Buder, I.; Bullock, E.; Chattopadhyay, G.; Davis, G.; Day, P. K.; Dowell, C. D.; Duband, L.; Filippini, J. P.; Fliescher, S.; Golwala, S. R.; Halpern, M.; Hasselfield, M.; Hildebrandt, S. R.; Hilton, G. C.; Hristov, V.; Hui, H.; Irwin, K. D.; Jones, W. C.; Karkare, K. S.; Kaufman, J. P.; Keating, B. G.; Kefeli, S.; Kernasovskiy, S. A.; Kovac, J. M.; Kuo, C. L.; LeDuc, H. G.; Leitch, E. M.; Llombart, N.; Lueker, M.; Mason, P.; Megerian, K.; Moncelsi, L.; Netterfield, C. B.; Nguyen, H. T.; O'Brient, R.; Ogburn, R. W., IV; Orlando, A.; Pryke, C.; Rahlin, A. S.; Reintsema, C. D.; Richter, S.; Runyan, M. C.; Schwarz, R.; Sheehy, C. D.; Staniszewski, Z. K.; Sudiwala, R. V.; Teply, G. P.; Tolan, J. E.; Trangsrud, A.; Tucker, R. S.; Turner, A. D.; Vieregg, A. G.; Weber, A.; Wiebe, D. V.; Wilson, P.; Wong, C. L.; Yoon, K. W.; Zmuidzinas, J.

    2015-10-01

    We have developed antenna-coupled transition-edge sensor bolometers for a wide range of cosmic microwave background (CMB) polarimetry experiments, including Bicep2, Keck Array, and the balloon borne Spider. These detectors have reached maturity and this paper reports on their design principles, overall performance, and key challenges associated with design and production. Our detector arrays repeatedly produce spectral bands with 20%-30% bandwidth at 95, 150, or 230 GHz. The integrated antenna arrays synthesize symmetric co-aligned beams with controlled side-lobe levels. Cross-polarized response on boresight is typically ˜ 0.5%, consistent with cross-talk in our multiplexed readout system. End-to-end optical efficiencies in our cameras are routinely 35% or higher, with per detector sensitivities of NET ˜ 300 μ {K}{CMB}√{s}. Thanks to the scalability of this design, we have deployed 2560 detectors as 1280 matched pairs in Keck Array with a combined instantaneous sensitivity of ˜ 9 μ {K}{CMB}√{s}, as measured directly from CMB maps in the 2013 season. Similar arrays have recently flown in the Spider instrument, and development of this technology is ongoing.

  12. Evaluation of a hemi-spherical wideband antenna array for breast cancer imaging

    NASA Astrophysics Data System (ADS)

    Klemm, M.; Craddock, I. J.; Preece, A.; Leendertz, J.; Benjamin, R.

    2008-12-01

    Using similar techniques to ground penetrating radars, microwave detection of breast tumors is a potential nonionizing and noninvasive alternative to traditional body-imaging techniques. In order to develop an imaging system, the team at Bristol have been working on a number of antenna array prototypes, based around a stacked-patch element, starting with simple pairs of elements and progressing to fully populated planar arrays. As the system commences human subject trials, a curved breast phantom has been developed along with an approximately hemi-spherical conformal array. This contribution will present details of the conformal array design and initial results from this unique experimental imaging system as applied to an anatomically shaped breast phantom.

  13. 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.

  14. Design for steering accuracy in antenna arrays using shared optical phase shifters

    NASA Technical Reports Server (NTRS)

    Kam, Moshe; Herczfeld, Peter R.; Wilcox, Jeffrey

    1989-01-01

    Uniform linear phased arrays where many radiating elements share a relatively small number of phase shifters are investigated. Such architectures arise in arrays which derive the time delays in the signal paths from a small group of independent phase shifters. In particular, a true time-delay device which has been suggested recently for optically controlled arrays is used as the basic phase shifter. Different architectures, viz. alternative procedures of deriving the necessary time delay for each antenna in the face of phase-shifter inaccuracies, are examined. The variance of the steered beam's direction is used as the performance criterion. The direction-optimal architecture is obtained by means of quadratic programming, and is shown not to be unique. The nonuniqueness of the optimal architecture is exploited to improve other characteristics of the array's beam shape, and the optimal solution is shown to compare favorably with a suboptimal interleaved solution which is easier to implement.

  15. 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.

  16. An Integrated Circuit for Radio Astronomy Correlators Supporting Large Arrays of Antennas

    NASA Technical Reports Server (NTRS)

    D'Addario, Larry R.; Wang, Douglas

    2016-01-01

    Radio telescopes that employ arrays of many antennas are in operation, and ever larger ones are being designed and proposed. Signals from the antennas are combined by cross-correlation. While the cost of most components of the telescope is proportional to the number of antennas N, the cost and power consumption of cross-correlationare proportional to N2 and dominate at sufficiently large N. Here we report the design of an integrated circuit (IC) that performs digital cross-correlations for arbitrarily many antennas in a power-efficient way. It uses an intrinsically low-power architecture in which the movement of data between devices is minimized. In a large system, each IC performs correlations for all pairs of antennas but for a portion of the telescope's bandwidth (the so-called "FX" structure). In our design, the correlations are performed in an array of 4096 complex multiply-accumulate (CMAC) units. This is sufficient to perform all correlations in parallel for 64 signals (N=32 antennas with 2 opposite-polarization signals per antenna). When N is larger, the input data are buffered in an on-chipmemory and the CMACs are re-used as many times as needed to compute all correlations. The design has been synthesized and simulated so as to obtain accurate estimates of the IC's size and power consumption. It isintended for fabrication in a 32 nm silicon-on-insulator process, where it will require less than 12mm2 of silicon area and achieve an energy efficiency of 1.76 to 3.3 pJ per CMAC operation, depending on the number of antennas. Operation has been analyzed in detail up to N = 4096. The system-level energy efficiency, including board-levelI/O, power supplies, and controls, is expected to be 5 to 7 pJ per CMAC operation. Existing correlators for the JVLA (N = 32) and ALMA (N = 64) telescopes achieve about 5000 pJ and 1000 pJ respectively usingapplication-specific ICs in older technologies. To our knowledge, the largest-N existing correlator is LEDA atN = 256; it

  17. An Integrated Circuit for Radio Astronomy Correlators Supporting Large Arrays of Antennas

    NASA Technical Reports Server (NTRS)

    D'Addario, Larry R.; Wang, Douglas

    2016-01-01

    Radio telescopes that employ arrays of many antennas are in operation, and ever larger ones are being designed and proposed. Signals from the antennas are combined by cross-correlation. While the cost of most components of the telescope is proportional to the number of antennas N, the cost and power consumption of cross-correlationare proportional to N2 and dominate at sufficiently large N. Here we report the design of an integrated circuit (IC) that performs digital cross-correlations for arbitrarily many antennas in a power-efficient way. It uses an intrinsically low-power architecture in which the movement of data between devices is minimized. In a large system, each IC performs correlations for all pairs of antennas but for a portion of the telescope's bandwidth (the so-called "FX" structure). In our design, the correlations are performed in an array of 4096 complex multiply-accumulate (CMAC) units. This is sufficient to perform all correlations in parallel for 64 signals (N=32 antennas with 2 opposite-polarization signals per antenna). When N is larger, the input data are buffered in an on-chipmemory and the CMACs are re-used as many times as needed to compute all correlations. The design has been synthesized and simulated so as to obtain accurate estimates of the IC's size and power consumption. It isintended for fabrication in a 32 nm silicon-on-insulator process, where it will require less than 12mm2 of silicon area and achieve an energy efficiency of 1.76 to 3.3 pJ per CMAC operation, depending on the number of antennas. Operation has been analyzed in detail up to N = 4096. The system-level energy efficiency, including board-levelI/O, power supplies, and controls, is expected to be 5 to 7 pJ per CMAC operation. Existing correlators for the JVLA (N = 32) and ALMA (N = 64) telescopes achieve about 5000 pJ and 1000 pJ respectively usingapplication-specific ICs in older technologies. To our knowledge, the largest-N existing correlator is LEDA atN = 256; it

  18. An Integrated Circuit for Radio Astronomy Correlators Supporting Large Arrays of Antennas

    NASA Astrophysics Data System (ADS)

    D'Addario, Larry R.; Wang, Douglas

    2016-03-01

    Radio telescopes that employ arrays of many antennas are in operation, and ever larger ones are being designed and proposed. Signals from the antennas are combined by cross-correlation. While the cost of most components of the telescope is proportional to the number of antennas N, the cost and power consumption of cross-correlation are proportional to N2 and dominate at sufficiently large N. Here, we report the design of an integrated circuit (IC) that performs digital cross-correlations for arbitrarily many antennas in a power-efficient way. It uses an intrinsically low-power architecture in which the movement of data between devices is minimized. In a large system, each IC performs correlations for all pairs of antennas but for a portion of the telescope’s bandwidth (the so-called “FX” structure). In our design, the correlations are performed in an array of 4096 complex multiply-accumulate (CMAC) units. This is sufficient to perform all correlations in parallel for 64 signals (N=32 antennas with two opposite-polarization signals per antenna). When N is larger, the input data are buffered in an on-chip memory and the CMACs are reused as many times as needed to compute all correlations. The design has been synthesized and simulated so as to obtain accurate estimates of the ICs size and power consumption. It is intended for fabrication in a 32nm silicon-on-insulator process, where it will require less than 12mm2 of silicon area and achieve an energy efficiency of 1.76-3.3pJ per CMAC operation, depending on the number of antennas. Operation has been analyzed in detail up to N=4096. The system-level energy efficiency, including board-level I/O, power supplies, and controls, is expected to be 5-7pJ per CMAC operation. Existing correlators for the JVLA (N=32) and ALMA (N=64) telescopes achieve about 5000pJ and 1000pJ, respectively using application-specific ICs (ASICs) in older technologies. To our knowledge, the largest-N existing correlator is LEDA at N=256; it

  19. Shaped beam synthesis with series-fed microstrip patch arrays

    NASA Astrophysics Data System (ADS)

    Strickland, P. C.

    A numerical optimization procedure to minimize the phase-error and temperature sensitivity of series-fed microstrip patch arrays is described and demonstrated. By varying feed line impedance while keeping patch width constant, arrays can be designed to produce shaped beams which do not degrade off the H-plane boresight. Typical results are presented graphically, and the applicability of the arrays produced to the design of a microwave-landing-system azimuth antenna is indicated.

  20. A phased array antenna with a broadly steerable beam based on a low-loss metasurface lens

    NASA Astrophysics Data System (ADS)

    Liu, Yahong; Jin, Xueyu; Zhou, Xin; Luo, Yang; Song, Kun; Huang, Lvhongzi; Zhao, Xiaopeng

    2016-10-01

    A new concept for a gradient phase discontinuity metasurface lens integrated with a phased array antenna possessing a broadly steerable beam is presented in this paper. The metasurface lens is composed of a metallic H-shaped pattern and the metallic square split ring can achieve complete 360° transmission phase coverage at 30° phase intervals. The metasurface can refract an incident plane wave to an angle at will by varying the lattice constant. We demonstrate that the beam steering range of the phased array antenna is between 12° and 85° when the metasurface lens with a refracting electromagnetic wave is employed at 45°. Interestingly, the proposed array antenna has a much higher gain than a conventional phased array antenna at low elevation angles. It is expected that the proposed array antenna will have potential applications in wireless and satellite communications. Furthermore, the proposed array antenna is fabricated easily and is also low in cost due to its microstrip technology.

  1. 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

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

    NASA Astrophysics Data System (ADS)

    Rabbani, Muhammad Saqib; Ghafouri-Shiraz, Hooshang

    2017-05-01

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

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

    NASA Astrophysics Data System (ADS)

    Rabbani, Muhammad Saqib; Ghafouri-Shiraz, Hooshang

    2016-12-01

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

  4. Synthesis Array Topology Metrics in Location Characterization

    NASA Astrophysics Data System (ADS)

    Shanmugha Sundaram, GA

    2015-08-01

    Towards addressing some of the fundamental mysteries in physics at the micro- and macro-cosm level, that form the Key Science Projects (KSPs) for the Square Kilometer Array (SKA; such as Probing the Dark Ages and the Epoch of Reionization in the course of an Evolving Universe; Galaxy Evolution, Cosmology, and Dark Energy; and the Origin and evolution of Cosmic Magnetism) a suitable interfacing of these goals has to be achieved with its optimally designed array configuration, by means of a critical evaluation of the radio imagingcapabilities and metrics. Of the two forerunner sites, viz. Australia and South Africa, where pioneering advancements to state-of-the-art in synthesis array radio astronomy instrumentation are being attempted in the form of pathfinders to the SKA, for its eventual deployment, a diversity of site-dependent topology and design metrics exists. Here, the particular discussion involves those KSPs that relate to galactic morphology and evolution, and explores their suitability as a scientific research goal from the prespective of the location-driven instrument design specification. Relative merits and adaptability with regard to either site shall be presented from invoking well-founded and established array-design and optimization principles designed into a customized software tool.

  5. Design of On-Chip N-Fold Orbital Angular Momentum Multicasting Using V-Shaped Antenna Array

    PubMed Central

    Du, Jing; Wang, Jian

    2015-01-01

    We design a V-shaped antenna array to realize on-chip multicasting from a single Gaussian beam to four orbital angular momentum (OAM) beams. A pattern search assisted iterative (PSI) algorithm is used to design an optimized continuous phase pattern which is further discretized to generate collinearly superimposed multiple OAM beams. Replacing the designed discrete phase pattern with corresponding V-shaped antennas, on-chip N-fold OAM multicasting is achieved. The designed on-chip 4-fold OAM multicasting exploiting V-shaped antenna array shows favorable operation performance with low crosstalk less than -15 dB. PMID:25951325

  6. 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.

  7. An Improved Solution for Integrated Array Optics in Quasi-Optical mm and Submm Receivers: the Hybrid Antenna

    NASA Technical Reports Server (NTRS)

    Buttgenbach, Thomas H.

    1993-01-01

    The hybrid antenna discussed here is defined as a dielectric lens-antenna as a special case of an extended hemi-spherical dielectric lens that is operated in the diffraction limited regime. It is a modified version of the planar antenna on a lens scheme developed by Rutledge. The dielectric lens-antenna is fed by a planar-structure antenna, which is mounted on the flat side of the dielectric lens-antenna using it as a substrate, and the combination is termed a hybrid antenna. Beam pattern and aperture efficiency measurements were made at millimeter and submillimeter wavelengths as a function of extension of the hemi- spherical lens and different lens sizes. An optimum extension distance is found experimentally and numerically for which excellent beam patterns and simultaneously high aperture efficiencies can be achieved. At 115 GHz the aperture efficiency was measured to be (76 4 +/- 6) % for a diffraction limited beam with sidelobes below -17 dB. Results of a single hybrid antenna with an integrated Superconductor-Insulator-Superconductor (SIS) detector and a broad-band matching structure at submillimeter wavelengths are presented. The hybrid antenna is diffraction limited, space efficient in an array due to its high aperture efficiency, and is easily mass produced, thus being well suited for focal plane heterodyne receiver arrays.

  8. An Improved Solution for Integrated Array Optics in Quasi-Optical mm and Submm Receivers: the Hybrid Antenna

    NASA Technical Reports Server (NTRS)

    Buttgenbach, Thomas H.

    1993-01-01

    The hybrid antenna discussed here is defined as a dielectric lens-antenna as a special case of an extended hemi-spherical dielectric lens that is operated in the diffraction limited regime. It is a modified version of the planar antenna on a lens scheme developed by Rutledge. The dielectric lens-antenna is fed by a planar-structure antenna, which is mounted on the flat side of the dielectric lens-antenna using it as a substrate, and the combination is termed a hybrid antenna. Beam pattern and aperture efficiency measurements were made at millimeter and submillimeter wavelengths as a function of extension of the hemi- spherical lens and different lens sizes. An optimum extension distance is found experimentally and numerically for which excellent beam patterns and simultaneously high aperture efficiencies can be achieved. At 115 GHz the aperture efficiency was measured to be (76 4 +/- 6) % for a diffraction limited beam with sidelobes below -17 dB. Results of a single hybrid antenna with an integrated Superconductor-Insulator-Superconductor (SIS) detector and a broad-band matching structure at submillimeter wavelengths are presented. The hybrid antenna is diffraction limited, space efficient in an array due to its high aperture efficiency, and is easily mass produced, thus being well suited for focal plane heterodyne receiver arrays.

  9. Phase Center Stabilization of a Horn Antenna and its Application in a Luneburg Lens Feed Array

    NASA Astrophysics Data System (ADS)

    Simakauskas, Brian H.

    With any reflecting or refracting structure, such as a parabolic reflector or lens antenna, the knowledge of the focal point is critical in the design as it determines the point at which a feeding signal should originate for proper operation. Spherically symmetrical lenses have a distinct advantage over other structure types in that there exists an infinite number of focal points surrounding the lens. Due to this feature, a spherical lens can remain in a fixed position while a beam can be steered to any direction by movement of the feed only. Unlike phased arrays that beam-steer electronically, a spherical lens exhibits no beam deterioration at wide angles. The lens that accomplishes this is in practice called the Luneburg lens which has been studied since the 1940s. Due to the electromechanical properties of the horn antenna, it is often used to feed the above mentioned configurations. In the focusing of any feed antenna, its phase center is an approximate point in space that should be coincident with a reflector or lens's focal point to minimize phase error over the radiating aperture. Although this is often easily accomplished over a narrow bandwidth, over wide bandwidths some antennas have phase centers that vary significantly, making their focusing a challenge. This thesis seeks to explain the problem with focusing a Luneburg lens with a canonical horn antenna and offers a modified horn design that remains nearly focused over a frequency band of 18 -- 45 GHz. In addition to simulating the feed / lens configurations, the lens and feed horn will be fabricated and mounted for far field measurements to be taken in an anechoic antenna range. A final feed design will be implemented in an array configuration with the Luneburg lens, capable of transmitting and receiving multiple beams without requiring any moving parts or complex electronic beam-forming networks. As a tradeoff, a separate receiver or switching network is required to accommodate each feed antenna. This

  10. Synthesis of offset dual shaped subreflector antennas for control of Cassegrain aperture distributions

    NASA Technical Reports Server (NTRS)

    Galindo-Israel, V.; Mittra, R.

    1984-01-01

    The method presented for antenna upgrading involves a redesign of only the subreflector portion of a Cassegrain antenna or the introduction of a subreflector feed system for a paraboloid. A pair of offset subreflectors are synthesized which will produce a controllable high gain amplitude distribution in the aperture of the large paraboloid. The synthesis method is based on the approximate formulation for an offset dual shaped high gain antenna first presented by Galindo-Israel and Mittra (1977). It is pointed out that in their approximate formulation, the geometrical optics energy was scattered from a subreflector and then from a second large reflector, which reflected a uniform phase distribution. In the offset dual shaped subreflector (DSS) antenna proposed here, the second reflection is from a smaller (sub) reflector, and it scatters a spherical wave that feeds a hyperboloid or feeds a large paraboloid directly. The DSS synthesis is tested on the 210-ft-diameter Cassegrain antenna at Goldstone, California.

  11. Integrated Phase Array Antenna/Solar Cell System for Flexible Access Communication (IA/SAC)

    NASA Technical Reports Server (NTRS)

    Clark, E. B.; Lee, R. Q.; Pal, A. T.; Wilt, D. M.; McElroy, B. D.; Mueller, C. H.

    2005-01-01

    This paper describes recent efforts to integrate advanced solar cells with printed planar antennas. Several previous attempts have been reported in the literature, but this effort is unique in several ways. It uses Gallium Arsenide (GaAs) multi-junction solar cell technology. The solar cells and antennas will be integrated onto a common GaAs substrate. When fully implemented, IA/SAC will be capable of dynamic beam steering. In addition, this program targets the X-band (8 - 12 GHz) and higher frequencies, as compared to the 2.2 - 2.9 GHz arrays targeted by other organizations. These higher operating frequencies enable a greater bandwidth and thus higher data transfer rates. The first phase of the effort involves the development of 2 x 2 cm GaAs Monolithically Integrated Modules (MIM) with integrated patch antennas on the opposite side of the substrate. Subsequent work will involve the design and development of devices having the GaAs MIMs and the antennas on the same side of the substrate. Results from the phase one efforts will be presented.

  12. Results of lower hybrid wave experiments using a dielectric loaded waveguide array antenna on TST-2

    NASA Astrophysics Data System (ADS)

    Wakatsuki, T.; Ejiri, A.; Shinya, T.; Takase, Y.; Furui, H.; Hiratsuka, J.; Imamura, K.; Inada, T.; Kakuda, H.; Kasahara, H.; Nagashima, Y.; Nakamura, K.; Nakanishi, A.; Oosako, T.; Saito, K.; Seki, T.; Shimpo, F.; Sonehara, M.; Togashi, H.; Tsuda, S.; Tsujii, N.; Yamaguchi, T.

    2014-02-01

    Lower hybrid current drive experiments were performed on the TST-2 spherical tokamak (R = 0.38 m, a = 0.25 m, Bt = 0.3 T, Ip = 0.1 MA). A waveguide array antenna consisting of four dielectric (alumina, ɛr = 10.0) loaded waveguides was used. The coupling characteristics were investigated over a wide range of input power (0.1 W - 40 kW). The reflection coefficient of this antenna increased when the input power exceeded approximately 1 kW. This result was compared with a numerical simulation based on the finite element method (FEM). The ponderomotive effect was calculated for the wave field calculated by COMSOL [1]. This calculation also showed variation of the reflection coefficient with the input power. Non-inductive plasma current start-up to 10 kA was demonstrated using 40 kW of lower hybrid wave (LHW) power. The current drive figure of merit (ηCD = IpneR/PRF) of this antenna was higher than that obtained using the combline antenna, which is designed to excite a travelling fast wave. The best current drive efficiency was obtained in the case in which the n∥ (= ck∥/ω) spectrum of the excited LHW was peaked around 9 and the toroidal field was higher than in previous experiments.

  13. Aircraft antennas/conformal antennas missile antennas

    NASA Astrophysics Data System (ADS)

    Solbach, Klaus

    1987-04-01

    Three major areas of airborne microwave antennas are examined. The basic system environment for missile telemetry/telecommand and fuze functions is sketched and the basic antenna design together with practical examples are discussed. The principle requirements of modern nose radar flat plate antennas are shown to result from missile/aircraft system requirements. Basic principles of slotted waveguide antenna arrays are sketched and practical antenna designs are discussed. The present early warning system designs are sketched to point out requirements and performance of practical radar warning and jamming antennas (broadband spiral antennas and horn radiators). With respect to newer developments in the ECM scenario, some demonstrated and proposed antenna systems (lens fed arrays, phased array, active array) are discussed.

  14. Antenna-coupled TES bolometer arrays for BICEP2/Keck and SPIDER

    NASA Astrophysics Data System (ADS)

    Orlando, A.; Aikin, R. W.; Amiri, M.; Bock, J. J.; Bonetti, J. A.; Brevik, J. A.; Burger, B.; Chattopadthyay, G.; Day, P. K.; Filippini, J. P.; Golwala, S. R.; Halpern, M.; Hasselfield, M.; Hilton, G. C.; Irwin, K. D.; Kenyon, M.; Kovac, J. M.; Kuo, C. L.; Lange, A. E.; LeDuc, H. G.; Llombart, N.; Nguyen, H. T.; Ogburn, R. W.; Reintsema, C. D.; Runyan, M. C.; Staniszewski, Z.; Sudiwala, R.; Teply, G.; Trangsrud, A. R.; Turner, A. D.; Wilson, P.

    2010-07-01

    BICEP2/Keck and SPIDER are cosmic microwave background (CMB) polarimeters targeting the B-mode polarization induced by primordial gravitational waves from inflation. They will be using planar arrays of polarization sensitive antenna-coupled TES bolometers, operating at frequencies between 90 GHz and 220 GHz. At 150 GHz each array consists of 64 polarimeters and four of these arrays are assembled together to make a focal plane, for a total of 256 dual-polarization elements (512 TES sensors). The detector arrays are integrated with a time-domain SQUID multiplexer developed at NIST and read out using the multi-channel electronics (MCE) developed at the University of British Columbia. Following our progress in improving detector parameters uniformity across the arrays and fabrication yield, our main effort has focused on improving detector arrays optical and noise performances, in order to produce science grade focal planes achieving target sensitivities. We report on changes in detector design implemented to optimize such performances and following focal plane arrays characterization. BICEP2 has deployed a first 150 GHz science grade focal plane to the South Pole in December 2009.

  15. Microwave reconstruction method using a circular antenna array cooperating with an internal transmitter

    NASA Astrophysics Data System (ADS)

    Zhou, Huiyuan; Narayanan, Ram M.; Balasingham, Ilangko

    2016-05-01

    This paper addresses the detection and imaging of a small tumor underneath the inner surface of the human intestine. The proposed system consists of an around-body antenna array cooperating with a capsule carrying a radio frequency (RF) transmitter located within the human body. This paper presents a modified Levenberg-Marquardt algorithm to reconstruct the dielectric profile with this new system architecture. Each antenna around the body acts both as a transmitter and a receiver for the remaining array elements. In addition, each antenna also acts as a receiver for the capsule transmitter inside the body to collect additional data which cannot be obtained from the conventional system. In this paper, the synthetic data are collected from biological objects, which are simulated for the circular phantoms using CST studio software. For the imaging part, the Levenberg-Marquardt algorithm, which is a kind of Newton inversion method, is chosen to reconstruct the dielectric profile of the objects. The imaging process involves a two-part innovation. The first part is the use of a dual mesh method which builds a dense mesh grid around in the region around the transmitter and a coarse mesh for the remaining area. The second part is the modification of the Levenberg-Marquardt method to use the additional data collected from the inside transmitter. The results show that the new system with the new imaging algorithm can obtain high resolution images even for small tumors.

  16. Initial studies of array feeds for the 70-meter antenna at 32 GHz

    NASA Technical Reports Server (NTRS)

    Cramer, P. W.

    1991-01-01

    The results of a study to determine the feasibility of using array feed techniques to improve the performance of the 70 m antenna at 32 GHz are presented. Changing from 8.4 to 32 GHz has the potential of increasing the gain by 11.6 dB, but recent measurements indicate that additional losses of from 3 to 7 dB occur at 32 GHz, depending on the elevation angle. Array feeds were proposed to recover some of the losses by compensating for surface distortions that contribute to these losses. Results for both surface distortion compensation and pointing error correction are discussed. These initial studies, however, had one significant restriction: The mechanical finite element model was used to characterize the surface distortions, not the measured distortions from three angle holography data, which would be more representative of the actual antenna. Further work is required to provide for a more accurate estimate of performance that utilizes holography data and, in particular, one that evaluates the performance in the focal plane region of the antenna.

  17. Engineering the Losses and Beam Divergence in Arrays of Patch Antenna Microcavities for Terahertz Sources

    NASA Astrophysics Data System (ADS)

    Madéo, Julien; Pérez-Urquizo, Joel; Todorov, Yanko; Sirtori, Carlo; Dani, Keshav M.

    2017-07-01

    We perform a comprehensive study on the emission from finite arrays of patch antenna microcavities designed for the terahertz range by using a finite element method. The emission properties including quality factors, far-field pattern, and photon extraction efficiency are investigated for etched and non-etched structures as a function of the number of resonators, the dielectric layer thickness, and period of the array. In addition, the simulations are achieved for lossy and perfect metals and dielectric layers, allowing to extract the radiative and non-radiative contributions to the total quality factors of the arrays. Our study shows that this structure can be optimized to obtain low beam divergence (FWHM <10°) and photon extraction efficiencies >50% while keeping a strongly localized mode. These results show that the use of these microcavities would lead to efficient terahertz emitters with a low divergence vertical emission and engineered losses.

  18. Antennas for Terahertz Applications: Focal Plane Arrays and On-chip Non-contact Measurement Probes

    NASA Astrophysics Data System (ADS)

    Trichopoulos, Georgios C.

    The terahertz (THz) band provides unique sensing opportunities that enable several important applications such as biomedical imaging, remote non-destructive inspection of packaged goods, and security screening. THz waves can penetrate most materials and can provide unique spectral information in the 0.1--10 THz band with high resolution. In contrast, other imaging modalities, like infrared (IR), suffer from low penetration depths and are thus not attractive for non-destructive evaluation. However, state-of-the-art THz imaging systems typically employ mechanical raster scans using a single detector to acquire two-dimensional images. Such devices tend to be bulky and complicated due to the mechanical parts, and are thus rather expensive to develop and operate. Thus, large-format (e.g. 100x100 pixels) and all-electronics based THz imaging systems are badly needed to alleviate the space, weight and power (SWAP) factors and enable cost effective utilization of THz waves for sensing and high-data-rate communications. In contrast, photonic sensors are very compact because light can couple directly to the photodiode without residing to radiation coupling topologies. However, in the THz band, due to the longer wavelengths and much lower photon energies, highly efficient antennas with optimized input impedance have to be integrated with THz sensors. Here, we implement novel antenna engineering techniques that are optimized to take advantage of recent technological advances in solid-state THz sensing devices. For example, large-format focal plane arrays (FPAs) have been the Achilles' heel of THz imaging systems. Typically, optical components (lenses, mirrors) are employed in order to improve the optical performance of FPAs, however, antenna sensors suffer from degraded performance when they are far from the optical axis, thus minimizing the number of useful FPA elements. By modifying the radiation pattern of FPA antennas we manage to alleviate the off-axis aberration

  19. 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.

  20. Definition Study for Space Shuttle Experiments Involving Large, Steerable Millimeter-Wave Antenna Arrays

    NASA Technical Reports Server (NTRS)

    Levis, C. A.

    1976-01-01

    The potential uses and techniques for the shuttle spacelab Millimeter Wave Large Aperture Antenna Experiment (MWLAE) are documented. Potential uses are identified: applications to radio astronomy, the sensing of atmospheric turbulence by its effect on water vapor line emissions, and the monitoring of oil spills by multifrequency radiometry. IF combining is preferable to RF combining with respect to signal to noise ratio for communications receiving antennas of the size proposed for MWLAE. A design approach using arrays of subapertures is proposed to reduce the number of phase shifters and mixers for uses which require a filled aperture. Correlation radiometry and a scheme utilizing synchronous Dicke switches and IF combining are proposed as potential solutions.