Showing papers on "Reflective array antenna published in 1968"
01 Sep 1968
TL;DR: Tests in which individual failures were simulated indicate that array elements were well isolated from each other, and the impedance of the radiating elements may be well mat to parallel one hundred transistor amplifiers.
Abstract: The advent of many new moderate power solid-state devices has created a renewed interest in the techniques for combining these devices to achieve even higher powers. This paper describes a new technique for combining large numbers of energy sources by using a dense array of radiating elements. The impedance of the radiating elements, as determined theoretically and confirmed using an array simulator, may be well mat to parallel one hundred transistor amplifiers has a net gain of 4.75 dB at 410 MHz with 100-watts output. Tests in which individual failures were simulated indicate that array elements were well isolated from each other.
41 citations
TL;DR: In this article, a relationship between the critical scan angles and phase of the mutual coupling coefficients was found between a large, flat, homogeneous antenna array, and a relationship was analyzed with respect to the phase of mutual coupling coefficient.
Abstract: Mutual coupling between antenna elements in a phased array causes array performance to vary with scan angle. Large impedance mismatch and radiation loss can occur in certain critical directions for which the steering phase advances match the antenna coupling delays. At these critical scan angles, many coupling contributions add inphase to produce a large impedance mismatch and minimum radiation from the array. Several different phased arrays have exhibited scanning "blind" regions that appear to be a consequence of coupling accumulation. A large, flat, homogeneous antenna array is analyzed, and a relationship is found between the critical scan angles and phase of the mutual coupling coefficients. Extensive measurements on arrays of horn antennas have shown radiation minima that correlate with coupling phase measurements and with theory.
40 citations
TL;DR: In this article, it was shown that an equiangular-spiral antenna may be divided into three distinct regions, and that the positions of these regions are frequency independent, and it was also found that for rapidly expanding antennas there are two or more active regions that are characterized by differences in rate of attenuation.
Abstract: According to the behavior of the current, an equiangular-spiral antenna may be divided into three distinct regions. Since the positions of these regions are frequency independent, it is possible to obtain a complete description of the current distribution on almost all practical equiangular-spiral antennas by a set of carves, which is given in this paper. It is also found that for rapidly expanding antennas there are, in general, two or more active regions that are characterized by differences in rate of attenuation. Such a phenomenon is interpreted in terms of the Brillouin diagram. A variational formulation of the input impedance of the antenna is also presented. The variation method using the approximate current provided by the set of curves gives a quick, direct means of finding the input impedances.
40 citations
01 Jul 1968
TL;DR: In this paper, a complete network description for an antenna is realized via a modal decomposition of the electromagnetic fields surrounding the structure, which contains the transmitting, receiving, and radar scattering properties of the antenna.
Abstract: A complete network description for an antenna is realized via a modal decomposition of the electromagnetic fields surrounding the structure. The representation contains the transmitting, receiving, and radar scattering properties of the antenna. A scattering formulation permits the antenna's power gain, directivity, effective area, and radar cross section to be expressed as a functional on the elements of its scattering matrix. For an array of antennas, the excitations which optimize its power gain and the loading network which maximizes its radar cross section are determined. The philosophic approach of circuit theory is employed for describing physical antennas. A set of canonical antenna elements having simple properties is first defined; in addition, an actual physical structure is represented as an array of canonical elements. The method is applied to the case of a Yagi-Uda array. The possibility of loading the array with active impedances is investigated.
30 citations
01 Nov 1968
TL;DR: In this paper, the progress and potential of the discrete increment, semiconductor controlled, microwave phase shifter is reviewed and an attempt is made to review the potential of this system.
Abstract: The electronically controlled phased array radar antenna has received considerable attention in the last decade. Requiring no mechanical motion for steering, it can scan in microseconds or, with some phase control elements, in nanoseconds. Even multiple beams can be formed electronically. In the future, for almost every antenna steering application, the electrically steered array will be desired provided cost, reliability, power handling capability, bandwidth, and insertion loss can be made comparable with the mechanical systems. At present, only the electronic array can be used to achieve microsecond steering. Both ferrite and semiconductor media have undergone serious development to meet the task of controlling rapidly the phase of the signals applied to elemental radiators in the phased array. In this paper, an attempt is made to review the progress and potential of the discrete increment, semiconductor controlled, microwave phase shifter.
27 citations
01 Nov 1968
TL;DR: By means of a Poisson sum formula and an integral-equation technique, an accurate solution for an infinite phased dipole array is obtained in this paper, where the elements of the array are spaced uniformly and are excited with increasing phases.
Abstract: By means of a Poisson sum formula and an integral-equation technique, an accurate solution for an infinite phased dipole array is obtained. The elements of the array are spaced uniformly and are excited with increasing phases. The technique can be applied to an infinite collinear array and to an infinite planar array either in free space or over a ground plane. The integral equation is solved both by a Fourier method and by an approximate five-term procedure. It is found that the latter is as good as the former. The current distributions and the active admittances are investigated.
26 citations
TL;DR: Digital computer predictions of aperture antenna patterns are shown to be far more complete, in terms of information concerning the field vectors over virtually unrestricted angular sectors and even at short distances, when vector rather than scalar diffraction theory is applied.
Abstract: Digital computer predictions of aperture antenna patterns are shown to be far more complete, in terms of information concerning the field vectors over virtually unrestricted angular sectors and even at short distances, when vector rather than scalar diffraction theory is applied.
21 citations
TL;DR: In this paper, a helical log-periodic array is designed considering the same parameters as those used in an existing logperiodic dipole array, and the impedance and radiation characteristics are measured for both arrays.
Abstract: A helical log-periodic array is designed considering the same parameters as those used in an existing log-periodic dipole array. The impedance and radiation characteristics are measured for both arrays. It is observed that the arrays have similar characteristics. Moreover, the advantage of the helical array is that its transverse dimension becomes much smaller.
16 citations
01 Nov 1968
TL;DR: In this article, a two-reflector antenna system is used in its Cassegrain form for many applications because it has considerable versatility in the optimization of its design parameters, such as the ability to make modifications to existing systems at reasonable costs through a redesign of only one subunit in the configuration.
Abstract: The two-reflector antenna system is widely used in its Cassegrain form for many applications because it has considerable versatility in the optimization of its design parameters. By replacing either one of its continuous reflecting surfaces with a discrete-element phased array, additional versatility is created. Both cases are discussed herein and key experiments are reported which verify that such modifications are practical. When the main reflector becomes a phased array, a fairly large region of space can be scanned rapidly. The configuration investigated indicates that a modest reduction in the number of array elements, as compared to conventional arrays, can be obtained by absorption of the array factor grating lobe structure. Excellent monopulse pattern characteristics are also shown throughout the scan region. When the subreflector becomes a phased array, a small region of space can be scanned rapidly with very few array elements. The configuration investigated indicates that phase control based on geometrical optics analyses is sufficient to overcome the usual aperture phase aberrations which occur with displaced and/or multiple feed antenna geometries. Conventional array beam-steering expressions become somewhat complex when exact results are to be implemented. A major advantage of the two-reflector antenna wherein one surface is a phased array is the possibility of making modifications to existing systems at reasonable costs through a redesign of only one subunit in the configuration.
16 citations
Patent•
25 Jul 1968
TL;DR: In this paper, a group of sixteen rooms in a triangular grid are arranged to be symmetric about three axes, each of which has a common intersection and a common separation.
Abstract: AN ARRAY ANTENNA WHEREIN THE RADIATING ELEMENTS ARE QUANTIZED INTO GROUPS OF ELEMENTS. EACH GROUP CONSISTS OF SIXTEEN ELEMENTS IN FIVE ADJACENT COLUMNS OF A TRIANGULAR GRID, HAVING FOUR ELEMENTS IN EACH OF THE THREE INNER COLUMNS AND TWO ELEMENTS IN EACH OF THE OUTER COLUMNS. IN EACH GROUP THE ELEMENTS ARE ARRANGED TO BE SYMMETRICAL ABOUT THREE AXES HAVING A COMMON INTERSECTION AND SEPARATED BY SIXTY DEGREES. THE ELEMENTS THAT COMPRISE EACH GROUP ARE COMMONLY EXCITED AND EACH GROUP OF ELEMENTS IS EXCITED BY A DIFFEERNT BASIC EXCITATION SIGNAL. THIS ARRANGEMENT SUBSTANTIALLY REDUCES THE NUMBER OF BASIC EXCITATION SIGNALS REQUIRED AND PROVIDES EFFICIENT EXCITATION OF EACH ELEMENT WITH LOW QUANTIZATION SIDELOBES.
15 citations
01 Nov 1968
TL;DR: In this paper, the radiation properties of a simple spherical phased array of 16 flat spiral antennas have been investigated experimentally over a frequency range of 0.6 GHz to 3 GHz, and the results indicated that such an array is capable of operating with widely spaced antenna elements.
Abstract: The radiation properties of a simple spherical phased array of 16 flat spiral antennas have been investigated experimentally over a frequency range of 0.6 GHz to 3 GHz. The results obtained indicate that such an array is capable of operating with widely spaced antenna elements. The spherical array surface considerably reduces the grating lobe amplitudes in the pattern, thereby making the array broad-band. The polarization characteristics of the radiation field were also studied.
TL;DR: The feasibility of using a direct numerical integration of physical optics fields for computing radiation patterns of ground-based HF-VHF antennas in the presence of known ground irregularities is examined in this article.
Abstract: The feasibility of using a direct numerical integration of physical optics fields for computing radiation patterns of ground-based HF-VHF antennas in the presence of known ground irregularities is examined The initial study treats a special case of a line source above a perfectly conducting plane with a semicylindrical boss This case permits a comparison of results computed using physical optics formulations to the exact values The agreement is gratifyingly close, which justifies an extension of such a study to a three-dimensional case
TL;DR: In this paper, an element investigation, design, and testing of a backfire log-periodic cavity-backed slot array operating from 2.8 to 5.9 GHz was described.
Abstract: This communication describes the element investigation, design, and testing of a backfire log-periodic cavity-backed slot array operating from 2.8 to 5.9 GHz in a frequency-independent fashion. The gain of the antenna is approximately 10 dB, and the VSWR is below 2.5 to 1. The H -plane power patterns are given with nearfield plots along file array. The advantages of the antenna are a simple stripline feeding system and the fact that the structure protrudes a little because shallow cavities are used.
TL;DR: The principles of operation and the most general applications of one very important class of array antennas are discussed.
Abstract: An array antenna can enlarge the capability of a radar system by contributing beam-pointing agility as well as providing a way of handling large power. The fundamental theory of such antennas was outlined in IEEE Spectrum exactly four years ago.1 Advances in the art have been so impressive that this month's Proceedings of the IEEE is a special issue on Electronic Scanning. The present article discusses the principles of operation and the most general applications of one very important class of array antennas.
TL;DR: The performance of high-power curtain antennas which have been designed for international broadcasting stations is presented along with details of design and construction.
Abstract: The performance of high-power curtain antennas which have been designed for international broadcasting stations is presented along with details of design and construction. The antennas described provide horizontal beamwidths ranging from 190°to 28 °, vertical beamwidths from 4°to 12°, and power gains ranging from 18 to more than 23.5 dB above a half-wave dipole in free space.
TL;DR: In this article, three techniques using partial skew are developed for the smoothing of the pattern of circular arrays with respect to the presence of the supporting structure, and they provide a large flexibility in the choice of dimensions and feeding systems of such antennas.
Abstract: Three techniques using partial skew are developed in this paper. They do not lead to the same degree of smoothing of the patterns of circular arrays as the 90 °skew, but they present the advantage of being less sensitive to the presence of the supporting structure. They also provide a large flexibility in the choice of dimensions and feeding systems of such antennas.
TL;DR: In this paper, the authors extended the five-term method developed for two arbitrarily located parallel antennas (Chang, 1967) to a general antenna array of N parallel elements and showed that the phase of the current along the antenna does not stay constant, as is generally assumed.
Abstract: The five-term method developed for two arbitrarily located parallel antennas (Chang, 1967) has been successfully extended to a general antenna array of N parallel elements. The method can be applied to either planar array or three-dimensional array. The array is characterized either by specifying driving voltages or input currents. Arrays of both half-wave and full-wave elements are discussed. The results reveal that the phase of the current along the antenna does not stay constant, as is generally assumed, even for arrays of half-wave elements. As a consequence, differences between the actual computed field patterns and the ideal patterns computed by assuming sinusoidal currents are not negligible even in the main beam region. The input admittances of the elements vary widely from element to element. For the arrays of half-wave elements, a complete analysis is also carried out with the conventional emf method. The results reveal the inadequacy of the emf method in dealing with these arrays.
TL;DR: In this article, the secondary pattern beamwidth variation is decreased or eliminated over portions of the frequency band of these antennas, by using a parabolic reflector illuminated by a ridge-loaded horn.
Abstract: Broad-band microwave receiving and tracking systems generally require medium to high-gain antennas that have a minimum beamwidth requirement dictated by probability of intercept and acquisition time considerations. This paper discusses a technique whereby the secondary pattern beamwidth variation is decreased or eliminated over portions of the frequency band of these antennas. The antennas consist of a parabolic reflector illuminated by a ridge-loaded horn. A brief analysis, based on empirical antenna equations, is presented along with a description of a pencil-beam antenna and a very broad-band conical-scan tracking antenna that were made possible through the use of this technique.
TL;DR: In this article, it is assumed that the directional antennas are of the type cosn ϕ(-π/2⩽ϕ⩾π/ 2 and zero elsewhere), which are closely approximated by many practical anteunas, and the number of antennas to be uesd determines the value of n.
Abstract: There are many applications on which one would want to obtain an omnidirectional pattern by mounting many directional antennas around a large structure. If the structure is many wave-lengths in size and if the directional antennas are mounted pointing radially out, then the resulting pattern will usually present very rapid excursions in amplitude with very deep nulls. If one assumes that the directional antennas are of the type cosn ϕ(-π/2⩽ϕ⩽π/2 and zero elsewhere), which are closely approximated by many practical anteunas, then it is possible to smooth out considerably the resulting pattern by pointing the directional antennas tangentially to a circle circumscribing the structure and by properly choosing the radius of the circle. The number of antennas to be uesd determines the value of n.
TL;DR: The theory and experimental results for an electronically scanned array antenna using multiple wavelength ferrite aperture elements at millimeter wavelengths were presented in this paper, along with the experimental patterns and curves showing the tradeoffs of aperture size, scan capability and efficiency.
Abstract: The theory and experimental results are presented for an electronically scanned array antenna using multiple wavelength ferrite aperture elements at millimeter wavelengths. The theory for the individual element scanner is given, along with the experimental patterns. Curves showing the tradeoffs of aperture size, scan capability, and efficiency are plotted for the element scanners. A five-element array employing the element scanner as elements was analyzed, constructed, and tested experimentally. The constructed array scanned 50\deg ( \pm25\deg )with a scan speed of 50 milliseconds.
Patent•
12 Apr 1968
01 Sep 1968
Book•
01 Jan 1968
TL;DR: In this article, King and his co-authors developed a theory of the behavior of arrays of rod-shaped antennas such as are used to achieve directive transmission and reception of radio waves for use in communication between points on the earth, between the earth and a space vehicle, or in radio astronomy.
Abstract: In this book, first published in 1968, King and his co-authors develop a theory of the behaviour of arrays of rod-shaped antennas such as are used to achieve directive transmission and reception of radio waves for use in communication between points on the earth, between the earth and a space vehicle, or in radio astronomy. They use quantitative analysis of arrays of practical types and wide range of lengths over a wide frequency band, which makes possible the design of new arrays with desired characteristics. After the introductory chapter reviewing the foundations and conventions antenna theory, each subsequent chapter takes into account the authors own particular theories on isolated antennas, two-coupled antennas, N-element circular array, N-element curtain array of identical elements, to arrays containing elements of different lengths and finally to planar and three-dimensional arrays. The final chapter is concerned with problems of measurement and the correlation of theory with experiment.
TL;DR: In this article, the design of an economical wideband array suitable for low-frequency radio astronomy applications is discussed, which consists of 32 non-uniformly spaced, uniformly excited, log periodic antennae designed to operate over a 2 : 1 frequency band.
Abstract: This paper discusses the design of an economical wideband array suitable for low-frequency radio astronomy applications. The array consists of 32 non-uniformly spaced, uniformly excited, log periodic antennae designed to operate over a 2 : 1 frequency band. At the highest operating frequency, the array has a beam-width of approximately 1° and side-lobes at least 16–5 dB below the main beam level. The theoretical limit to which the'side-lobes of an idealized array, having the same gain and length, can be suppressed is 17 dB.
01 Nov 1968
TL;DR: In this article, a simple equation relating the reflection coefficients of the edge elements and the center elements of a two-dimensional antenna array is derived for TEM-mode parallel-plate horn arrays.
Abstract: A simple equation is derived relating the reflection coefficients of the edge elements and the center elements of a two-dimensional antenna array. Calculated values of the coupling and reflection coefficients are presented for TEM-mode parallel-plate horn arrays. These are compared to published values for arrays with ground planes.
TL;DR: In this paper, a Van Atta reflector consisting of four half-wave dipoles arranged on a line is used to demonstrate that coupling between the array antennas will reduce the reflecting properties of the reflector array.
Abstract: In order to reduce the space occupied by a reflector array, it is desirable to arrange the array antennas as close to each other as possible; however, in this case coupling between the array antennas will reduce the reflecting properties of the reflector array. The purpose of the present communication is to demonstrate that this is true for a Van Atta reflector consisting of four half-wave dipoles arranged on a line. Theoretical results obtained by using the methods described in references are compared with experimental results. In contrast to previous experimental results which have been presented as normalized, the results described are absolute
01 Jun 1968
TL;DR: In this article, critical components of Ku-band phased array antenna for meteorological satellite were analyzed and evaluated for the first time, and a detailed analysis and evaluation of the critical components were presented.
Abstract: Analysis and evaluation of critical components of Ku-band phased array antenna for meteorological satellite
01 Sep 1968