Showing papers on "Antenna array published in 1971"
Patent•
20 Jan 1971TL;DR: An antenna array for use with a system for receiving signals from a radio capsule disposed within a patient''s gastrointestinal tract is described in this paper, which includes three mutually perpendicular loop antennas, two of which are ferrite-core loop antennas disposed near the center of the array, the third being a loop antenna surrounding the two ferrite core antennas.
Abstract: An antenna array for use with a system for receiving signals from a radio capsule disposed within a patient''s gastrointestinal tract. The array of antennas comprises three mutually perpendicular loop antennas, two of which are ferrite-core loop antennas disposed near the center of the array, the third being a loop antenna surrounding the two ferrite-core antennas. The antenna array includes means for matching the impedance of the loop antennas to transmission lines to which they are to be connected.
132 citations
TL;DR: In this article, the antenna spacing between two adjacent antennas in a space diversity array is greater than 0.5λ, and the array configuration does not affect the cumulative distribution curves nor the shapes of the level-crossing-rate (LCR) curves, and only slightly affects the signal level at which the maximum LCR occurs.
Abstract: The theoretical analysis in this paper is based on the assumption that the angles of signal arrival on the mobile receiver are uniformly distributed. From the analysis and experimental studies, we find that if the antenna spacing between two adjacent antennas in a space diversity array is greater than 0.5λ the array configuration does not affect the cumulative distribution curves nor the shapes of the level-crossing-rate (LCR) curves, and only slightly affects the signal level at which the maximum LCR occurs. Hence a three-element array with a triangular shape or a four-element array with a rectangular shape can be considered a good arrangement, provided each side (antenna spacing) is greater than 0.5λ. Two slightly better arrangements than those we just mentioned for improving the signal fading are also proposed for three-branch and four-branch diversity signals, respectively.
22 citations
Patent•
09 Sep 1971
TL;DR: In this article, a Van-Atta array antenna device of the type where a plurality of equally spaced antenna elements are disposed in parallel and respective pairs of antenna elements disposed symmetrically with respect to the center of the antenna array are interconnected by feeders of substantially the same length, impedance matching stubs having an adjustable length are connected to substantially the centre of respective feeders in order to enable incoming electromagnetic waves to be reradiated either straight backward or in an opposite direction to that in which they are receiving, without changing the characteristic impedance of feeders.
Abstract: In a Van-Atta array antenna device of the type wherein a plurality of equally spaced antenna elements are disposed in parallel and respective pairs of antenna elements disposed symmetrically with respect to the center of the antenna array are interconnected by feeders of substantially the same length, impedance matching stubs having an adjustable length are connected to substantially the center of respective feeders in order to enable incoming electromagnetic waves to be reradiated either straight backward or in an opposite direction to that in which they are receiving, with respect to the antenna boresight, without changing the characteristic impedance of feeders.
19 citations
Patent•
03 Feb 1971TL;DR: In this paper, the authors proposed a configuration in which each group of radiating elements has approximately the same control of the beamwidth and the steering of its beam of radiation as would be the case if only one of these groups were present.
Abstract: A phased array antenna including within its single electromagnetic radiating aperture two or more groups of radiating elements, each group of radiating elements being distinguished by the polarization and frequency spectrum of its radiation. The radiating elements of each group are of sufficiently small physical size compared to their free space wavelength to permit their being interleaved among the radiating elements of the other groups in a configuration whereby each group of radiating elements has approximately the same control of the beamwidth and the steering of its beam of radiation as would be the case if only one of these groups were present.
19 citations
Patent•
30 Dec 1971TL;DR: In this article, the authors present an approach to a radio angle measurement problem in the context of an antenna array system, which is applicable to RADAR and other detection systems.
Abstract: THIS INVENTION RELATES TO A RADIO ANGLE MEASUREMENT APPARATUS, WHICH IS APPLICABLE TO RADAR AND OTHER DETECTION SYSTEMS AND WHICH UTILIZES ANTENNA ARRAY SYSTEM(S) WITH RADIATOR ELEMENTS DISTRIBUTED AT SPACING LARGER THAN ONE HALF OF THE PROPAGATION WAVELENGTH. AT LEAST TWO VALUES OF D/A (WHERE D IS THE SAID RADIATOR ELEMENTS SPACING. A THE PROPAGATION WAVELENGTH) ARE EMPLOYED. THERE ARE, FURTHERMORE, A SET OF PHASE DISCRIMINATING MEANS, ONE FOR EACH ONE D/A VALUE, FOR DISCRIMINATING THE PHASE DIFFERENCE BETWEEN THE SIGNALS THAT ARE RECEIVED BY NEIGHBORING ELEMENTS OF ANTENNA ARRAYS, AND A PHASE-DIFFERENCE-TO-ANGLE CORRELATING MEANS FOR CORRELATING MEASURED SETS OF SAID PHASE DIFFERENCES TO THE INCIDENT ANGLE OF THE SIGNAL, MAKING USE OF THE EITHER THEORETICALLY OR EXPERIMENTALLY KNOWN RELATIONSHIPS BETWEEN SAID SETS OF PHASE DIFFERENCES AND THE INCIDENT ANGLE OF THE SIGNAL. IN THE ABOVE CORRELATION PROCESS, A CONSIDERATION OF THE ROLE PLAYED BY THE RESOLUTION OF PHASE DISCRIMINATION IS GIVEN, WHICH HELPS TO CONSTRUCT OPTIMAL EMBODIMENTS OF THE INVENTION, TO MAXIMIZE THE POSSIBILITY OF ACCURATE ANGLE MEASUREMENT. D R A W I N G
15 citations
Patent•
23 Mar 1971
TL;DR: In this paper, an antenna system consisting of slotted waveguides for generating radiobeams of the desired shape to provide wide coverage and eliminate false courses is described. But the spacing between the slots and the coupling of the slots to the waveguiders are individually selected to synthesize the desired beam shapes.
Abstract: This specification discloses an antenna system for guiding aircraft during landing. The antenna system comprises slotted waveguides for generating radiobeams of the desired shape to provide wide coverage and eliminate false courses. The spacing between the slots and the coupling of the slots to the waveguides are individually selected to synthesize the desired beam shapes.
12 citations
Patent•
16 Jul 1971
TL;DR: In this article, rod antenna radiating elements having bifilar helix feeds are arranged in a particular concentric circle type array configuration to achieve high gain, improved elipticity and size and weight economies.
Abstract: Disc on rod antenna radiating elements having bifilar helix feeds are arranged in a particular concentric circle type array configuration to achieve high gain, improved elipticity and size and weight economies Element spacing is adjusted to prevent element collecting aperture overlap A collapsible segmented dielectric rod in combination with ring members of radial wire segments are utilized to provide an unfurlable array in one preferred embodiment
11 citations
Patent•
13 Sep 1971TL;DR: An antenna system for reducing co-channel interference in a signal receiving network, comprising; at least four logarithmically periodic antenna elements having corresponding points disposed in a common plane, a first two of said antenna elements also disposed within a horizontal plane, the remaining two also disposed inside a vertical plane, said first two elements being substantially equal first distances from the line of intersection of said horizontal and vertical planes and said remaining two elements were substantially equal second distance from the said line-of- intersection; a support structure; and means for cantilever mounting antenna elements on said structure with
Abstract: An antenna system for reducing co-channel interference in a signal receiving network, said system comprising; at least four logarithmically periodic antenna elements having corresponding points disposed in a common plane, a first two of said antenna elements also disposed within a horizontal plane, the remaining two of said antenna elements also disposed within a vertical plane, said first two elements being substantially equal first distances from the line of intersection of said horizontal and vertical planes and said remaining two elements being substantially equal second distances from the said line of intersection; a support structure; and means for cantilever mounting said antenna elements on said structure with the maximum sensitivities of said antenna elements directed outwardly from said support structure.
11 citations
Patent•
28 Jul 1971
TL;DR: In this paper, a comparison of the responses of the signal processing circuitry to the radar target signals and to two signals with an adjustable known phase difference is made until the result of the comparison is a null.
Abstract: In the measurement of the phase difference (proportional to the elevation angle of a target) provided by the radar target signals that are received by each antenna of an antenna array, a comparison of the responses of the signal processing circuitry to the radar target signals and to two signals with an adjustable known phase difference, causes the known phase difference to change until the result of the comparison is a null. The known phase difference, at the time that the comparison provides a null, is equal to the phase difference provided by the radar target signals and is independent of phase errors introduced by the processing circuitry.
9 citations
Patent•
07 Apr 1971
TL;DR: In this article, a capture effect antenna system was proposed, in which the course and clearance signals are transmitted from a single antenna array, and the clearance carrier signal has a substantial null along the course centerline, to cause significant reduction in the course bends.
Abstract: A capture effect antenna system in which the course and clearance signals are transmitted from a single antenna array. The clearance carrier signal has a substantial null along the course centerline, to thereby cause significant reduction in the course bends.
8 citations
Patent•
26 Oct 1971TL;DR: In this paper, a phase-array antenna system which looks at all positions, rather than at one point, within its field of view, simultaneously is presented, which is accomplished by modulating the incoming wavefront with a repetitive wide band signal in each antenna element.
Abstract: A phase-array antenna system which looks at all positions, rather than at one point, within its field of view, simultaneously. This is accomplished by modulating the incoming wave-front with a repetitive wide band signal in each antenna element. The system comprises a plurality of antennas, a plurality of modulators operatively connected to a modulation signal generator, a signal combiner device and a signal analyzer.
01 Oct 1971
TL;DR: In this article, the angles of arrival of a multimoded signal at an antena array from simultaneous measurements of the amplitude and the phase of the signal in each element of the array is considered.
Abstract: The problem considered is that of clculating the angles of arrival of a multimoded signal at an antena array from simultaneous measurements of the amplitude and the phase of the signal in each element of the array. A general solution with wide application is described.
TL;DR: In this paper, two 48-hour beam-swinging experiments in trans-horizon microwave propagation are presented, where the experimental angular response patterns (antenna scans) averaged over about 3 min are compared with theoretical patterns computed from turbulent scattering theory.
Abstract: Results from two 48-hour beam-swinging experiments in transhorizon microwave propagation are presented. A 3.2-GHz signal was transmitted over a 164-km path and received with a 12-element vertical antenna array (beamwidth 0.29\deg elevation by 5\deg azimuth). The beam was rapidly scanned in elevation. Experimental angular response patterns (antenna scans) averaged over about 3 min are compared with theoretical patterns computed from turbulent scattering theory. There is considerable variability in the experimental patterns for different time periods. The experimental patterns for different time periods are separated into three groups. Signal group 1 patterns resemble the response of the array to a point source. A propagation model based on partial reflection or refraction from a stratified atmospheric layer best describes these signal characteristics. Signal group 2 patterns can be described by a model predicting a smooth decrease in scattered power with scattering angle at a rate inversely proportional to the m th power of the angle with m between 4 and 10. A propagation model based on atmospheric turbulence can describe these signal characteristics only if it includes modifying factors to account for the difference in the exponent m observed at different time periods. Signal group 3 patterns are characterized by broadened maxima, by two or more maxima, or by a maximum which is significantly displaced above the horizon. These signals can be explained only by a model which contains a nonuniform scattering mechanism. A variation in signal characteristics as a function of time of day was evident in both experiments.
Patent•
26 Apr 1971
TL;DR: In this article, a matrix switching system controlled by a code of six fixed digital signals to selectively switch signals energizing two spaced feeds of an antenna array is described. And five different codes are provided to digitally shift the antenna array beam in five discrete steps.
Abstract: A matrix switching system controlled by a code of six fixed digital signals to selectively switch signals energizing two spaced feeds of an antenna array. Five different codes are provided to digitally shift the antenna array beam in five discrete steps.
Patent•
29 Sep 1971
TL;DR: In this paper, a circular or cylindrical scanning antenna array has circumferentially spaced radiating elements fed substantially in phase from a source of a carrier frequency with an imposed reference signal.
Abstract: A circular or cylindrical scanning antenna array having circumferentially spaced radiating elements fed substantially in phase from a source of a carrier frequency with an imposed reference signal. In addition, an additional energy component is coupled in discretely to each radiating element through a fixed phase shifter for each such element. The fixed phase shifters have values beginning at zero for an arbitrary predetermined element location and then increasing in equal steps of theta where theta is the angular radiating element spacing about the perimeter. The additional energy fed through these phase shifters is modulated by a predetermined modulation signal to produce a single sideband. The result is a scanning, or rotating, amplitude modulated pattern similar to that used in the VOR or TACAN system.
TL;DR: In this paper, the concept of interelement mutual coupling was added to a previously presented design technique for aerial arrays, with mutual coupling accounted for, one can realistically design electronically scanned arrays of wire elements that have both maximum gain and a number of independent, steerable nulls in the radiation pattern.
Abstract: This paper adds the concept of interelement mutual coupling to a previously presented design technique for aerial arrays. With mutual coupling accounted for, one can realistically design electronically scanned arrays of wire elements that have both maximum gain and a number of independent, steerable nulls in the radiation pattern.
TL;DR: In this paper, a method for the maximisation of the directivity of an antenna array by phase adjustments under the constraint of a uniform-amplitude excitation is presented, which can be applied readily to both linear and circular arrays.
Abstract: A method is presented for the maximisation of the directivity of an antenna array by phase adjustments under the constraint of a uniform-amplitude excitation. It is a perturbation procedure which can be applied readily to both linear and circular arrays. Typical results are given.
Patent•
15 Dec 1971TL;DR: A TACAN antenna array comprising a central radiating element, providing carrier frequency fc radiation omnidirectionally in the azimuth plane, which is surrounded by two or more concentric arrays of 15Hz and 135Hz modulation radiating elements.
Abstract: A TACAN antenna array comprising a central radiating element, providing carrier frequency fc radiation omnidirectionally in the azimuth plane, which is surrounded by two or more concentric arrays of 15Hz and 135Hz modulation radiating elements. The first concentric array is preferably comprised of 4 elements used to provide a fc + OR - 15Hz modulation and is comprised of two orthogonally disposed antiphased subarrays which are excited with the suppressed carrier sideband energy of a 15Hz modulated carrier frequency fc with the two orthogonally arranged subarrays being excited in phase quadrature with one another. The second concentric array is preferably comprised of 36 radiating elements divided into two subarrays of 18 elements each, which are excited with 135Hz modulated suppressed carrier fc sideband energy. The elements of the two 18 element subarrays are alternately dispersed in a circular pattern. The two subarrays respectively are fed in phase quadrature with adjacent elements of each subarray being fed in antiphase relationship so that as the circumference is traversed a +l, +j, -l, -j phase relationship exists in consecutive sets of four elements around the 36 radiating elements.
TL;DR: In this paper, the effect of moving roots of the polynomial can be represented as a linear sampled-data system problem, which is solved by using a table of Z transforms or by discrete numerical convolution.
Abstract: It is well known that a linear antenna array with equally spaced elements can be represented by a polynomial whose roots correspond to the nulls of its antenna pattern. Since the linear array has equally spaced elements, its polynomial has only integral powers of the variable, so that the array can be represented by a Z transform. Therefore, the effect of moving roots of the polynomial can be represented as a linear sampled-data system problem, which is solved by using a table of Z transforms or by discrete numerical convolution. In this paper, the quantitative effects on the array and its antenna pattern caused by moving roots of the polynomial are determined, and these effects are utilized for array synthesis to produce desired antenna patterns. Examples illustrating the use of this new synthesis technique include modification of a uniform array to obtain low sidelobes in the antenna pattern and synthesis of an array to produce nulls in its antenna pattern in the directions of discrete and spatially distributed interference sources.
Patent•
21 Jul 1971
TL;DR: In this article, an antenna array distribution can be represented as the sum of a symmetric and an antisymmetric function and the radiation at any point in the far field of the aerial array can then be simulated by adding together the symmetric outputs in quadrature with the correct amplitude.
Abstract: Any arbitrary antenna array distribution can be represented as the sum of a symmetric and an antisymmetric function. The radiation at any point in the far field of the aerial array can then be simulated by adding together the symmetric and antisymmetric outputs in quadrature with the correct amplitude. This simplifies the construction of subsequent combining units since these reproduce the far field at any point by amplitude wieghting along without the need for differential phasing.
01 Jun 1971
TL;DR: A novel method is presented in which the admittance matrix representing an antenna array, consisting of both active and passive elements, is extracted from the array's element-pattern data, and enables optimization of the location of both passive and active elements.
Abstract: : The report describes a technique developed to optimize the performance of antenna arrays under realistic, on the vehicle conditions. This technique permits free choice of optimality criteria and design parameters and is applicable to both planar and nonplanar arrays with geometric constraints. The need for an improved Airborne Early Warning (AEW) airplane, the improvement being that of an airborne antenna system with reduced side lobes, was the main impetus for this investigation. The work reported grew from an initial study of the antenna array problem under the assumption of idealized free-space conditions. An experimental-computational approach to the solution of this problem has been formulated in which powerful n-dimensional optimum search methods (i.e., the Davidon algorithm) are applied to experimental data obtained from carefully scaled models of the vehicle and antenna array configuration. The optimization algorithm provides a new design for the antenna array that is then used in the scale model, and the process develops in an iterative fashion. The necessary laboratory setup and data processing techniques used to test the feasibility of this approach are discussed. Experimental results showing encouraging improvements have been obtained on an array of eight elements both with and without an aircraft model. These results indicate that the algorithmic procedure is both stable and convergent. (Author)
Patent•
07 Dec 1971
TL;DR: In this article, a Doppler ILS system consisting of two antenna systems operating in a diplex arrangement is described, and the choice of the line carrying the information in the spectrum of the low frequency signal derived from the signals received from the second antenna system and permitting an accurate measurement is made by means of the information derived from signal received from a signal receiving from the first antenna system.
Abstract: A transmitter for a Doppler ILS system comprises two antenna systems operating in a diplex arrangement; the first antenna system is conventional, and is formed by an array of antennas regularly spaced and by an auxiliary antenna, it allows an angle measurement in a comparatively inaccurate fashion; the second antenna system is formed by an array of antennas regularly spaced with a spacing greater than in the first antenna system (the spacing being in either case being measured using as a unit the wavelength corresponding to the operating frequency of the considered antenna array), and by an auxiliary antenna; it would allow an accurate angle measurement were it not for an indetermination; in the Doppler ILS receiver co-operating with this transmitter the choice of the line carrying the information in the spectrum of the low frequency signal derived from the signals received from the second antenna system and permitting an accurate measurement is made by means of the information derived from the signal received from the first antenna system.
Patent•
26 Apr 1971
TL;DR: In this article, a scanning antenna array with plural antenna units and a digital feed system for reversibly energizing plural ones of said units in unison with groups of different fixed amplitude signals is presented.
Abstract: A scanning antenna array having plural antenna units and a digital feed system for reversibly energizing plural ones of said units in unison with groups of different fixed amplitude signals. The feed system includes fixed power dividers for generating (or receiving) the plural signals, and a multiple tier switching system for applying said different groups of signals to preselected groups of said units in a preselected or desired order.
TL;DR: In this paper, the amplitude-trigonometric interpolation between signals received at a circular antenna array is reexamined, and the accuracy of this class of direction-finding system is limited by interpolation, gain mistracking, and additive-noise errors.
Abstract: Radio direction-finding techniques that use amplitude-trigonometric interpolation between signals received at a circular antenna array are reexamined. The accuracy of this class of direction-finding system is limited by interpolation, gain mistracking, and additive-noise errors. The channel gain mistracking error is shown to be significantly lower than previously estimated. Typical calculations show that the trigonometric interpolation technique is an order of magnitude more accurate than previously supposed.
TL;DR: In this article, a set of arbitrarily located receiving antenna elements, each connected with an appropriate network, can be used to construct a matched filter where the antenna array response results in an autocorrelation of a specified desired signal, correlating over time and space coordinates simultaneously.
Abstract: A set of arbitrarily located receiving antenna elements, each connected with an appropriate network, can be used to construct a matched filter where the antenna array response results in an autocorrelation of a specified desired signal, correlating over time and space coordinates simultaneously. A receiving system using such a signal processing antenna can discard interferences which do not have the same spectral characteristics as the desired signal, or which do not originate from the same point as the desired signal source. Examples of correlating antenna arrays for various arbitrary intelligence modulations of the desired signal are discussed in this communication.