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Showing papers on "Antenna array published in 1992"


Journal ArticleDOI
TL;DR: An adaptive algorithm for radar target detection using an antenna array is proposed that contains a simplified test statistic that is a limiting case of the GLRT detector.
Abstract: An adaptive algorithm for radar target detection using an antenna array is proposed. The detector is derived in a manner similar to that of the generalized likelihood-ratio test (GLRT) but contains a simplified test statistic that is a limiting case of the GLRT detector. This simplified detector is analyzed for performance to signals on boresight, as well as when the signal direction is misaligned with the look direction. >

1,430 citations


Journal ArticleDOI
01 Jan 1992
TL;DR: The history of antennas and some of the most basic radiating elements, demonstrates the fundamental principles of antenna radiation, reviews Maxwell's equations and electromagnetic boundary conditions, and outlines basic procedures and equations of radiation as discussed by the authors.
Abstract: In this review the author traces the history of antennas and some of the most basic radiating elements, demonstrates the fundamental principles of antenna radiation, reviews Maxwell's equations and electromagnetic boundary conditions, and outlines basic procedures and equations of radiation. Modeling of antenna source excitation is illustrated, and antenna parameters and figures-of-merit are reviewed. Theorems, arraying principles, and advanced asymptotic methods for antenna analysis and design are summarized. >

254 citations


Patent
11 Sep 1992
TL;DR: In this article, the authors proposed an improved antenna system that, in one embodiment, includes an antenna array comprised of a plurality of elements, each of which is capable of providing a signal, and a multi-beam beamformer for producing two spatially independent overlapping beams from the signals provided by two different subsets of the antenna array.
Abstract: The present invention provides an improved antenna system that, in one embodiment, includes an antenna array comprised of a plurality of elements, each of which is capable of providing a signal. Also included in the improved antenna system is, a multi-beam beamformer for producing two spatially independent overlapping beams from the signals provided by two different subsets of the antenna array. The phase of the two beams is compared to realize an interferometer that can provide high or fine resolution data on the position of an object relative to the antenna system. The amplitude of the two beams can also be compared to obtain coarse data on the position of the object. The beamformer includes a switching network for selecting which elements of the antenna array form the two subsets. This permits, for example, the position of the beams to moved, the baseline of the two beams to be varied, and/or the beam width of the beams to be altered. To reduce adverse aerodynamic effects in certain applications, the antenna array is located conformal to the exterior surface of the body on which the array is mounted. Further, to reduce temperature related problems associated with high speed movement of the body on which the array is located, the array is located on the side of the body, as opposed to the front of the body. The side location also provides space for other types of sensors that are preferably located adjacent to the front surface of the body.

176 citations


Patent
06 Nov 1992
TL;DR: In this article, the authors extended the range from which transponder replies can be received at a virtual secondary surveillance radar of the type described in U.S. Pat. No. 4,115,771 by replacing the omnidirectional antenna previously utilized to receive replies from transponders within the range of the SSR with a stationary array of a plurality of directive antennas arranged in a circle and having radiation patterns pointing in different directions from the center of and covering a respective sector of the circle, and sequentially switching on the antenna of the array covering the sector in
Abstract: The range from which transponder replies can be received at a virtual secondary surveillance radar of the type described in U.S. Pat. No. 4,115,771 is extended by replacing the omnidirectional antenna previously utilized to receive replies from transponders within the range of the SSR with a stationary array of a plurality of directive antennas arranged in a circle and having radiation patterns pointing in different directions from the center of and covering a respective sector of the circle, and sequentially switching on the antenna of the array covering the sector in which the rotating beam of the associated SSR is then pointing. In an arrangement in which the SSR and PSSR are so widely separated that in certain pointing directions the SSR beam overlies more than one sector of the antenna array, the antennas are sequentially switched on at calculated switching times determined from the pointing direction of the SSR beam and the times it takes in the geometrical arrangement between the SSR beam and the radiation patterns of the antennas of the array, for a given SSR interrogating pulse to propagate, from launch, along the beam until it reaches the line separating the first encountered sector from the next adjacent sector, between second and third sectors, and so on, such that a high gain directive antenna is always pointing in the proper direction to receive reply signals from a transponder intercepted by the scanning beam of the SSR.

154 citations


Journal ArticleDOI
TL;DR: In this paper, the far-field radiation pattern of a 4*4 diagonal horn array, measured at 100 GHz, was calculated by aperture integration, and the results indicated that the fraction of the power radiated into the fundamental Gaussian mode is about 84%.
Abstract: The far-field radiation pattern of a diagonal horn has been calculated by aperture integration. The radiation patterns for a 4*4 diagonal horn array, measured at 100 GHz, agree very well with theoretical predictions. The aperture electric field was also expanded into Gauss-Hermite modes. The results indicate that the fraction of the power radiated into the fundamental Gaussian mode is about 84%. About 10% of the power is radiated in the cross-polarized component. >

123 citations


Journal ArticleDOI
01 Jan 1992
TL;DR: Basic antenna array theory is outlined with major emphasis on pattern analysis and synthesis for periodic linear and planar arrays, phased arrays, and conformal arrays and extension is made to synthesis techniques which use computer algorithms.
Abstract: Basic antenna array theory is outlined with major emphasis on pattern analysis and synthesis for periodic linear and planar arrays, phased arrays, and conformal arrays. Extension is made to synthesis techniques which use computer algorithms. These include arbitrary sidelobe control, shaped beams, and phase-only null steering. The subjects of random errors and phased array quantization errors are outlined. >

117 citations


Patent
11 May 1992
TL;DR: In this article, the authors proposed a method for automatically beamforming a radio frequency transmitter having an array antenna, which is transmitted for the benefit of a target communication unit based upon characteristics of a received signal.
Abstract: A method is offered of automatically beamforming a radio frequency transmitter having an array antenna. The beamformed signal is transmitted for the benefit of a target communication unit based upon characteristics of a received signal. The method includes the steps of determining a transmit equalizer transfer function and receive equalizer transfer function for each array element of the antenna array based, at least in part, upon application of common input signals and comparison of outputs. The method further includes adaptively filtering a received signal, from a communication unit based, at least in part, upon the determined receive equalizer weights, to provide a receive beamform array. A beamformed signal may then be transmitted to the communication unit based upon the transmit equalizer weights and receive beamform array.

103 citations


Journal ArticleDOI
Hisamatsu Nakano1, H. Takeda1, Y. Kitamura1, H. Mimaki1, Junji Yamauchi1 
TL;DR: In this article, a low-profile array antenna composed of two-turn 4 degrees pitch angle helices is designed for a frequency band of 11.7 GHz to 12.0 GHz.
Abstract: A low-profile array antenna composed of two-turn 4 degrees pitch angle helices is designed for a frequency band of 11.7 GHz to 12.0 GHz. The feed wire of each helix is inserted into a radial waveguide through a small hole and excited by a traveling wave flowing in the transverse electromagnetic mode between the two parallel plates of the waveguide. The measured aperture efficiency shows a maximum value of 77% for a beam radiated in the normal direction and 69% for a 30 degrees beam tilt. >

93 citations


Journal ArticleDOI
TL;DR: In this article, a 3*5 element array using Schottky diode mixers with integrated HEMT IF amplifiers is described, which covers the 86-115 GHz frequency range for radio astronomical observations.
Abstract: A focal plane imaging array receiver is described which covers the 86-115 GHz frequency range for radio astronomical observations. The 3*5 element array uses cryogenic Schottky diode mixers with integrated HEMT IF amplifiers. A cold quasi-optical filter selects the desired sideband, and terminates the image at 20 K. Polarization interleaving is used to minimize the array size on the sky. LO power is provided by a frequency tripled YIG tuned oscillator. The average receiver noise temperature of the array pixels varies from 250-350 K SSB depending on the frequency. Only three mechanical tuners are used in the system and all functions are under computer control. >

86 citations


Journal ArticleDOI
01 Jan 1992
TL;DR: An abbreviated view of the topics included in modern array architecture is presented in this article, where the broad subject of architecture includes all the electromagnetic, thermal and mechanical aspects that need to be addressed by the array design team.
Abstract: An abbreviated view of the topics included in modern array architecture is presented. The broad subject of architecture includes all the electromagnetic, thermal and mechanical aspects that need to be addressed by the array design team. The emphasis is on the interaction between the selection of an array aperture organization, corporate feeds, devices and elements, and a discussion of EHF monolithic array architecture is included as an example. >

83 citations


Journal ArticleDOI
01 Jan 1992
TL;DR: In this article, the authors designed antenna array distributions and their associated patterns based on placement of zeros of the array polynomial, and gave an overview of the synthesis processes and evaluated the ultimate pencil beam array, the superdirective array.
Abstract: Antenna array distributions and their associated patterns are now designed on physical principles, based on placement of zeros of the array polynomial. An overview of the synthesis processes is given. Robust and low Q distributions for linear arrays and circular planar arrays that provide variable sidelobe level pencil beam patterns are treated in detail. Associated difference patterns are included. Individual sidelobes or groups of sidelobes may be adjusted in level. The same technique allows synthesis of an efficient shaped beam, with or without sidelobe adjustment. The ultimate pencil beam array, the superdirective array, is evaluated. >

Journal ArticleDOI
TL;DR: In this article, an array of photoconducting antennas which generates electrically controllable millimeter-wave and sub-millimeterwave radiation in free space is described, where the emitted radiation is directional and electrically steerable, and can be scanned through an angle of over 40 degrees.
Abstract: An array of photoconducting antennas which generates electrically controllable millimeter-wave and submillimeter-wave radiation in free space is described. Under quasi-sinusoidal optical illumination, the emitted radiation is directional and electrically steerable, and can be scanned through an angle of over 40 degrees . The center of the scanning range can be adjusted by changing the angle of incidence of the pump beam. The far-field radiation pattern of the array is measured and discussed. Also, some properties of the array under illumination by a short optical pulse are demonstrated. These include electrical control of the frequency content of the signal and mapping of the spatial profile of the applied electric field onto the radiated waveform. The latter property can be used to multiplex information presented in parallel into a train of radiated pulses with a bit spacing of 6 ps. >

Journal ArticleDOI
Kazuhiro Uehara1, K. Miyashita1, K.-I. Natsume1, K. Hatakeyama1, K. Mizuno1 
TL;DR: In this paper, four kinds of lens-coupled antenna imaging arrays for operation at millimeter- and submillimeter-wave frequencies are compared from the viewpoint of matching with detectors and optical systems.
Abstract: The authors have been developing four kinds of lens-coupled antenna imaging arrays for operation at millimeter- and submillimeter-wave frequencies. Dipole antennas, Yagi-Uda trap-loaded antennas, and microstrip patches are compared from the viewpoint of matching with detectors and optical systems. The radiation patterns and input impedance of each antenna have been calculated and measured to attain the optimum matching using model experiments. The trap-loaded antenna arrays have been successfully applied to plasma diagnostics at the Tsukuba GAMMA 10 tandem mirror. >

Journal ArticleDOI
TL;DR: In this paper, the authors present a periodic second-harmonic spatial power combining oscillator, which is achieved by phase locking the oscillators at the fundamental frequency and combining the secondharmonic power in space through an array of microstrip patch antennas.
Abstract: The authors present a periodic second-harmonic spatial power combining oscillator. The power combining is achieved by phase locking the oscillators at the fundamental frequency and combining the second-harmonic power in space through an array of microstrip patch antennas. The effect of moding and multiple device-circuit interaction is investigated. This circuit is planar, and therefore simplifies the design of monolithic circuits, X-band Gunn diodes are used for the purpose of demonstration. >

Journal ArticleDOI
TL;DR: In this paper, the development of integrated horn antennas since their introduction in 1987 is reviewed, and the integrated horn is fabricated by suspending a dipole antenna, on a thin dielectric membrane, in a pyramidal cavity etched in silicon.
Abstract: The development of integrated horn antennas since their introduction in 1987 is reviewed. The integrated horn is fabricated by suspending a dipole antenna, on a thin dielectric membrane, in a pyramidal cavity etched in silicon. Recent progress has resulted in optimized low- and high-gain designs, with single and double polarization for remote-sensing and communication applications. A full-wave analysis technique has resulted in an integrated antenna with performance comparable to that of waveguide-fed corrugated-horn antennas. The integrated horn design can be extended to large arrays, for imaging and phased-array applications, while leaving plenty of room for the RF and IF processing circuitry. Theoretical and experimental results at microwave frequencies and at 90 GHz, 240 GHz, and 802 GHz are presented. >

Journal ArticleDOI
TL;DR: In this paper, the spectral domain moment (SDF) method was used to compute the resonant length, impedance, directivity, efficiency, cross-polarization level, and scan performance of isolated microstrip antennas and infinite arrays of microstrip antenna printed on chiral substrates.
Abstract: 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 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-polarization levels and losses due to surface wave excitation. >

Journal ArticleDOI
TL;DR: A design for a phased array which automatically tracks the aircraft as it flies on station is proposed, which uses a feedback link through the transmitted beam.
Abstract: SHARP (stationary high altitude relay platform) is a proposed airborne platform consisting of a light aircraft powered by microwave energy beamed to it from the ground. A design for a phased array which automatically tracks the aircraft as it flies on station is proposed. It uses a feedback link through the transmitted beam. Computer simulations are presented. >

Patent
26 Aug 1992
TL;DR: In this article, the slotline elements (30, 52) are packed with spacing close enough to allow for electronic beam steering without creating grating lobes in the field at the highest frequency of operation.
Abstract: A missile guidance antenna that is conformal to the missile surface, dual-polarized and broadband. Slotline notch array elements (30, 52) are inclined toward boresight for both the E and H-planes. This inclination directs a greater portion of the energy toward the front of the missile. The additional energy directed forward reduces the nullifying effects of the metallic skin on the tangential E-field and enhances the performance of the other polarization. The slotline elements (30, 52) can be packed with spacing close enough to allow for electronic beam steering without creating grating lobes in the field at the highest frequency of operation.

Journal ArticleDOI
01 Feb 1992
TL;DR: A general method of antenna pattern synthesis using weighted least squares that can be used on nonlinear arrays, for arrays with different element patterns on each element, and for near-field pattern synthesis.
Abstract: A general method of antenna pattern synthesis using weighted least squares is presented. The special case of linear equal spaced arrays is analysed, and three design examples are given. This design technique is compared with Woodward synthesis and with the method of Orchard, Elliott and Stern. An example using unequal spacing is also presented. The method can also be used on nonlinear arrays, for arrays with different element patterns on each element, and for near-field pattern synthesis.

Patent
08 May 1992
TL;DR: In this article, a phased array for transmitting to a microwave powered aircraft is focussed and steered by feedback from the aircraft, and the resulting amplitude modulation of the field at the aircraft is used to calculate a correction to the antenna phase, which is telemetered back to the array system.
Abstract: A phased array for transmitting to a microwave powered aircraft is focussed and steered by feedback from the aircraft. Each antenna of the array is phase modulated in turn, and the resulting amplitude modulation of the field at the aircraft is used to calculate a correction to the antenna phase, which is telemetered back to the array system and applied to the antenna phase shifter.

Journal ArticleDOI
TL;DR: A Hopfield-type neural network approach which leads to an analog circuit for implementing the real-time adaptive antenna array and an optimal array pattern can be steered by updating the weights across the array in order to maximize the output signal-to-noise ratio (SNR).
Abstract: A Hopfield-type neural network approach which leads to an analog circuit for implementing the real-time adaptive antenna array is presented. An optimal array pattern can be steered by updating the weights across the array in order to maximize the output signal-to-noise ratio (SNR). The problem of adjusting the array weights can be characterized as a constrained quadratic nonlinear programming. The adjustment of settings is required to respond to a rapid time-varying environment. A Hopfield-type neural net with a number of graded-response neurons designed to perform the constrained quadratic nonlinear programming would lead to a solution in a time determined by RC time constants, not by algorithmic time complexity. The constrained quadratic programming neural net has associated it with an energy function which the net always seeks to minimize. A fourth-order Runge-Kutta simulation shows that the circuit operates at a much higher speed than conventional techniques and the computation time of solving a linear array of 10 elements is about 0.1 ns for RC=5*10/sup -9/. >

Journal ArticleDOI
TL;DR: In this paper, the effect of subarraying on scan blindness was demonstrated for arrays using two-element subarrays of printed dipoles and microstrip patches, and it was found that the large spacing between sub-arrays leads to a limited scan range.
Abstract: The analysis and scanning characteristics of several different types of infinite arrays composed of subarrayed printed dipole and microstrip patch elements are presented. The analysis is based on full-wave moment method theory, and includes mutual coupling between elements in the subarray as well as between subarrays. The effect of subarraying on scan blindness is demonstrated for arrays using two-element subarrays of printed dipoles and microstrip patches. Results are also given for the amount of power radiated in grating lobes. The effect of a subarray composed of one driven element and one parasitic element, and the use of a four-element synchronous subarray of microstrip patches to generate circular polarization are also considered. Data are given for impedance mismatch, power radiated into grating lobes, and the axial ratio; both square and rectangular patches area considered. Results are also shown for an infinite array of seven-element hexagonal subarrays of printed dipoles, and it is found that the large spacing between subarrays leads to a limited scan range. >

Patent
03 Dec 1992
TL;DR: In this article, an antenna array system is disclosed which uses subarrays of slots and subarray of dipoles on separate planes, where the slots and dipoles respectively are interleaved, and there is minimal overlap between them.
Abstract: An antenna array system is disclosed which uses subarrays of slots and subarrays of dipoles on separate planes. The slots and dipoles respectively are interleaved, which is to say there is minimal overlap between them. Each subarray includes a microstrip transmission line and a plurality of elements extending perpendicular thereto. The dipoles form the transmission elements and the slots form the receive elements. The plane in which the slots are formed also forms a ground plane for the dipoles--hence the feed to the dipole is on the opposite side of this ground plane as the feed to the slots. HPAs are located adjacent the dipoles on one side of the substrate and LNAs are located adjacent the slots on the other side of the substrate. The dipoles and slots are tuned by setting different offsets between each element and the microstrip transmission line.

Journal ArticleDOI
Nabeel A. Riza1
TL;DR: In this paper, a phase-based antenna control for very large phased arrays (e.g. 5000 elements) is presented, with 0-3 pi phase shift measured for a 60-MHz carrier.
Abstract: Nematic liquid crystal (NLC) technology-based optical systems for controlling phased array antennas are presented. These systems can provide low-cost, high-quality (>6-b), phase-based antenna control for very large phased arrays (e.g. 5000 elements). An experiment demonstrating NLC-based antenna phase control is performed, with 0-3 pi phase shift measured for a 60-MHz carrier. A novel time-multiplexed radar beam scanning approach is introduced to counter the slow response of the NLCs, allowing fast 200 beams/s antenna scanning rates. >

Patent
22 Dec 1992
TL;DR: In this article, a monolithically loaded microstrip antenna is provided for a communications function such as a cellular telephone base station, which includes a ground plane and a group of stacked, planar elements.
Abstract: A monolithically loaded microstrip antenna is provided for a communications function, such as a cellular telephone base station. The antenna includes a ground plane and a group of stacked, planar elements. A director element having a rectangular configuration together with monolithic load tabs is connected to a feed line and spaced above the ground plane. A first director element is spaced above the driven element and has lesser length and width dimensions than the driven element. A second director element is spaced above the first director element and likewise has lesser length and width dimensions than the driven element. A group of eight of the antennas are positioned in a column to form an antenna array which has substantial vertical polarization, a relatively wide horizontal beam width, approximately 60° and a relatively narrow vertical beam width, approximately 8.0°. The antenna array has a center frequency of 885 Mhz and a bandwidth of approximately 230 Mhz.

Patent
Frederik Labaar1
27 Oct 1992
TL;DR: In this paper, a system for introducing true time delays in a phased array antenna for pulsed signals comprising an active, recirculating delay time system which is selectively activated to introduce variable delays in the signal path between the signal transceiver and the individual antenna array elements is presented.
Abstract: A system for introducing true time delays in a phased array antenna for pulsed signals comprising an active, recirculating delay time system which is selectively activated to introduce variable delays in the signal path between the signal transceiver and the individual antenna array elements.

Patent
27 Aug 1992
TL;DR: In this paper, a microstrip electronic scan antenna array is provided comprising a hollow elongated octagonal-shaped housing formed by four quadrantially disposed microstrip patch antenna arrays and four filler panels extending between the patch arrays.
Abstract: A microstrip electronic scan antenna array is provided comprising a hollow elongated octagonal-shaped housing formed by four quadrantially-disposed microstrip patch antenna arrays and four filler panels extending between the patch arrays. Three, independently-switchable microstrip Y-junction circulators are tandem interconnected in a double-ended wye configuration on a common dielectric substrate forming an octagonal end cover for the housing. Each of the three circulators acts as a single pole-double throw switch and the sequence of energization of the four microstrip patch antenna arrays is determined by controlling the sequence and direction of circulator coupling action of the three circulators.

Patent
27 May 1992
TL;DR: In this paper, a two-dimensional array of slot antennas which can provide two dimensional quantitative dielectric and conductivity images of formations in the region surrounding an earth borehole is presented.
Abstract: A two-dimensional array of slot antennas which can provide two-dimensional quantitative dielectric and conductivity images of formations in the region surrounding an earth borehole. The antennas are mounted in a wall-engaging member of a logging device that is moveable through the borehole. Selected ones of the antennas are energized at given times to transmit electromagnetic energy into the formations, the electromagnetic energy being received at other antennas for processing to obtain formation properties.

Journal ArticleDOI
TL;DR: In this paper, a complete 915-MHz hyperthermia system with temperature control by microwave radiometry was designed for use in a complete coaxial antennas different in their active length, and the heating patterns were reconstructed from the power deposition associated with the bioheat transfer equation.
Abstract: Coaxial antennas different in their active length have been designed for use in a complete 915-MHz hyperthermia system with temperature control by microwave radiometry. Heating patterns are reconstructed from the power deposition associated with the bioheat transfer equation. Temperature control is effected by means of microwave radiometry and used in order to determine bioheat parameters. Phased arrays are studied allowing heated volume expansion. >

Journal ArticleDOI
TL;DR: In this article, the Cramer-Rao bound (CRB) was used to evaluate the accuracy of the estimated directions of arrival (DOAs), corresponding to the joint estimation of the DOAs, signal covariance matrix, signal polarization parameters, and noise variance.
Abstract: The performance of direction finding systems in a correlated signal environment utilizing diversely polarized antenna arrays is investigated. The Cramer-Rao bound (CRB) is used to evaluate the accuracy of the estimated directions of arrival (DOAs). Compact closed form formulas are presented for the CRB corresponding to the joint estimation of the DOAs, signal covariance matrix, signal polarization parameters, and noise variance. The CRB is evaluated numerically for selected examples, to provide insights into the potential improvement in direction-finding accuracy due to polarization diversity. >