Showing papers on "Coaxial antenna published in 1975"
TL;DR: The Wheeler method and the Q method are used to find the efficiency of electrically small multiturn loop antennas and are applicable at VHF and frequencies below where the design of an antenna range or anechoic chamber becomes increasingly difficult and expensive.
Abstract: Two methods for measuring antenna efficiency are described. The two methods, referred to as the Wheeler method and the Q method, are used to find the efficiency of electrically small multiturn loop antennas. The principal advantage of both methods is that they can be quickly and easily applied. Further, both methods relate the antenna efficiency to the input impedance rather than a far-field pattern integration. Thus, the methods are applicable at VHF and frequencies below where the design of an antenna range or anechoic chamber becomes increasingly difficult and expensive.
191 citations
Patent•
11 Jun 1975
TL;DR: In this article, antenna elements comprised of a dipole reactively coupled to a feed line on a microstrip board are shown to be linearly and circularly polarized arrays of such elements.
Abstract: Herein disclosed are antenna elements comprised of a dipole reactively coupled to a feed line on a microstrip board; and linearly and circularly polarized arrays of such elements.
91 citations
Patent•
03 Nov 1975
TL;DR: In this paper, a dual-frequency circularly polarized antenna was adapted for receiving satellite transmissions and/or for transmitting signals to satellites as for navigation purposes, the antenna being adapted through novel conductive preferably spiral-element configurations of different lengths.
Abstract: This disclosure deals with a novel dual-frequency circularly polarized antenna that is particularly adapted for receiving satellite transmissions and/or for transmitting signals to satellites as for navigation purposes, the antenna being adapted through novel conductive preferably spiral-element configurations of different lengths, to produce substantially omnidirectional horizontal coverage and substantially hemispherical vertical coverage at two or more operating frequencies.
74 citations
TL;DR: In this paper, a linear antenna and a slot antenna were used to provide a relatively isotropic radiation pattern when the dipole is perpendicular to the plane of the slot, and the theoretical far-field radiation pattern of a dipole flanked by a two-element array of slot antennas was formulated.
Abstract: The combination of a linear antenna and slot antenna can be used to provide a relatively isotropic radiation pattern when the dipole is perpendicular to the plane of the slot. The theoretical far-field radiation pattern of a dipole flanked by a two-element array of slot antennas is formulated. The fields for two different phasings between the elements of the combination antenna are calculated and the degree of approximation to an isotropic source in the sense of the total field noted. An experimental antenna was fabricated and the radiated fields measured with good agreement found with the theoretical formulas.
45 citations
Patent•
24 Apr 1975TL;DR: An asymmetrically fed electric microstrip dipole antenna consisting of a n electrically conducting, rectangular-shaped element formed on one surface of a dielectric substrate, the ground plane being on the opposite surface, the length of the element determines the resonant frequency as discussed by the authors.
Abstract: An asymmetrically fed electric microstrip dipole antenna consisting of a n electrically conducting, rectangular-shaped element formed on one surface of a dielectric substrate, the ground plane being on the opposite surface The length of the element determines the resonant frequency The feed point is located along the centerline of the antenna length and the input impedance can be varied by moving the feed point along the centerline from the center point to the end of the antenna without affecting the radiation pattern The antenna bandwidth increases with the width of the element and spacing between the element and ground plane
44 citations
Patent•
12 Feb 1975
TL;DR: In this article, an omnidirectional antenna comprising vertically stacked pairs of folded slot antennas is presented, where each slot antenna is electrically loaded to allow reduction of slot physical dimensions to the point that the diameter of two slots when mounted back-to-back is less than one wavelength.
Abstract: Disclosed is an omnidirectional antenna comprising vertically stacked pairs of folded slot antennas. Each slot antenna is electrically loaded to allow reduction of slot physical dimensions to the point that the diameter of two slots when mounted back-to-back is less than one wavelength. The resulting antenna produces a highly omnidirectional signal having vertical polarization. Vertical beam shaping is achieved by selection of the phase and magnitude of the signal transmitted by each pair of folded slot elements.
42 citations
TL;DR: In this article, a new type of holographic antenna based on the principle of the volume hologram is proposed, which is unique in that the feed point is placed in the plane of the holographic plate.
Abstract: A new type of holographic antenna based on the principle of the volume hologram is proposed. The characteristics of the prototype are examined. The antenna has a unidirectional beam with a front-to-back ratio of 20 dB. The practical frequency handwidth is about 10 percent of the center frequency. The antenna is unique in that the feed point is placed in the plane of the holographic plate so that both feeder and the holographic plate could be made out of one printed circuit board for easy flush mount installation or mass production, although the feeder of the prototype antenna was a pyramidal horn.
38 citations
Patent•
10 Jul 1975
TL;DR: In this paper, the effective element pattern is modified by means of coupling circuits to closely conform to the ideal element pattern required for radiating the antenna beam within a selected angular region of space.
Abstract: Disclosed are array antenna systems wherein the effective element pattern is modified by means of coupling circuits to closely conform to the ideal element pattern required for radiating the antenna beam within a selected angular region of space. Use of the coupling circuits in the embodiment of a scanning beam antenna significantly reduces the number of phase shifters required as compared to prior art array antennas.
36 citations
Patent•
20 Oct 1975
TL;DR: In this article, a planar spiral antenna modified by having the outer ends of its arms terminated by a bifilar helix is presented, which can effectively cover the entire bandwidth of from about 0.5 GHz to about 18 GHz.
Abstract: A circularly polarized, broad-beamed antenna system capable of effectively covering the entire bandwidth of from about 0.5 GHz to about 18 GHz or higher. The system provided comprises a generally conventional planar spiral antenna modified by having the outer ends of its arms terminated by a bifilar helix. The bifilar helix is positioned behind the planar spiral and at 90° to it. By proper coupling of the two antenna portions, it has been found that within the 2 to 18 GHz range, the planar spiral operates as if the helix were not present, while below 2 GHz, the spiral functions as a transmission line feeding the helix and the helix radiates essentially all of the energy from the antenna. The antenna system provided is approximately the same size as conventional 2 to 18 GHz cavity backed spiral antennas and generally satisfies all of the physical constraints and limitations placed upon airborne radar-warning systems.
34 citations
02 Jun 1975
34 citations
Patent•
18 Feb 1975
TL;DR: In this paper, a coaxial cable feed circuit that divides the power between horizontal and vertical dipole radiating elements was proposed to discriminate against interfering signals having any given polarization characteristics.
Abstract: Interference from polarized signals is minimized by controlling the polarization of antennas having orthogonal dipole radiating elements. The antenna system utilizes microwave hybrids and phase shifters in a coaxial cable feed circuit that divides the power between horizontal and vertical dipole radiating elements. The circuit provides a variable antenna polarization that can be controlled to discriminate against interfering signals having any given polarization characteristics. Coaxial double folded baluns connect feed circuits to the dipole radiating elements and provide proper phasing and impedance transformation for efficient dipole operation.
Patent•
27 May 1975TL;DR: In this paper, a conformal electronically scanned antenna array system utilizing an inve Butler matrix in combination with directive antenna elements was proposed for simple and inexpensive device for scanning an elemental array without the problems of output frequency shift or mutual coupling between antenna elements.
Abstract: A conformal electronically scanned antenna array system utilizing an inve Butler matrix in combination with directive antenna elements. The system provides a simple and inexpensive device for scanning an elemental array without the problems of output frequency shift or mutual coupling between antenna elements.
Patent•
24 Apr 1975TL;DR: In this paper, a notch fed electric microstrip dipole antenna consisting of a thin electally conducting, rectangular-shaped element formed on one surface of a dielectric substrate, the ground plane being on the opposite surface.
Abstract: A notch fed electric microstrip dipole antenna consisting of a thin electally conducting, rectangular-shaped element formed on one surface of a dielectric substrate, the ground plane being on the opposite surface. The length of the element determines the resonant frequency. The feed point is located in a notch along the centerline of the antenna length and the input impedance can be varied by moving the feed point along the centerline of the antenna without affecting the radiation pattern. Of all the many types of microstrip antennas built to date, this antenna offers the best advantages as far as arraying of the elements are concerned. The notched antenna can be arrayed using microstrip interconnecting transmission lines. The corner losses in the clad material and the width of the notch determines how narrow the element can be made. The purpose of the notch feed system is to interconnect any array of elements at the elements' optimum feed point using microstrip transmission lines.
TL;DR: In this paper, the authors reviewed theoretical and experimental studies of the insulated linear antenna in a relatively dense ambient medium, and then directed to a description of the admittance and impedance of air-insulated monopoles as determined by theory and by measurements when two quite different junctions between the antenna and the feeding coaxial line are used.
Abstract: Recent theoretical and experimental studies of the insulated linear antenna in a relatively dense ambient medium are reviewed briefly. Attention is then directed to a description of the admittance and impedance of air-insulated monopoles as determined by theory and by measurements when two quite different junctions between the antenna and the feeding coaxial line are used. Graphs of the admittances of antennas with three different thicknesses of the insulation and lengths up to a wavelength are shown. No theory of the junction effects or simple corrective network is provided, but it is shown that with proper design of the junction region, the uncorrected (ideal) theoretical admittances are satisfactory approximations of measured values.
TL;DR: In this paper, a log-periodic V-dipole antenna (LPVA) operating in the 3-lambda/2 mode is analyzed numerically using the projective technique.
Abstract: The log-periodic V-dipole antenna (LPVA) operating in the 3\lambda/2 mode is analyzed numerically using the projective technique. The antenna is treated as a parallel connection of an array of V-dipoles and a feeder transmission line. This decoupling of the circuits enables one to obtain the dipole currents simply by considering the array of V-dipoles as a boundary value problem and solving the necessary integral equations. The currents can then be used to give the various properties of the antenna. Effects on the antenna behavior obtained by changing its parameters are illustrated, and general characteristic curves presented.
Patent•
10 Sep 1975
TL;DR: In this article, a yagi antenna having a director element, a half-wave active dipole element, and a reflector element mounted on an antenna boom is described. All antenna elements are rods that are adjustable in length from a collapsible position to an operating length for a predetermined frequency of operation.
Abstract: A yagi antenna having a director element, a half-wave active dipole element, and a reflector element mounted on an antenna boom. All antenna elements are rods that are telescopically adjustable in length from a collapsible position to an operating length for a predetermined frequency of operation, and removable from threaded mounting for storage. The director element and reflector element are slidably adjustable on the antenna boom for independent spacing with respect to the half-wave active dipole element. The antenna boom has two mast support holes; one for horizontal polarization and the other for vertical polarization. A ferrite core member surrounds a coaxial cable connecting the half-wave active dipole element to a coaxial connector, and provides balun action between the coaxial cable and a balanced antenna feed point.
TL;DR: In this paper, the singularity expansion method is used to compute the transient radiation pattern for a step-excited center-fed linear antenna, and the far-field natural modes for the linear antenna are defined.
Abstract: Previous investigation of the use of the singularity expansion method (SEM) for analyzing antennas or scatterers has concentrated on the behavior of currents and charges on a conducting body. In this paper the previous work is extended by defining the far-field natural modes for the linear antenna. The transient radiation pattern is then computed for a step-excited center-fed linear antenna.
Patent•
08 Sep 1975
TL;DR: In this article, a broad-band antenna device comprising a variable aperture element which radiates or receives signals in the high frequency portion of the band and a pair of fixed aperture elements which radiate or receive signals in low frequency portion, is described.
Abstract: A broad-band antenna device comprising a variable aperture element which radiates or receives signals in the high frequency portion of the band and a pair of fixed aperture elements which radiate or receive signals in the low frequency portion, the variable aperture element comprising a planar spiral antenna element with a double winding which is electrically coupled to the fixed aperture elements comprising a pair of oppositely positioned center fed slot antenna elements.
Patent•
24 Apr 1975
TL;DR: In this article, a diagonally fed electric microstrip dipole antenna consisting of a thin ctrically conducting, rectangular-shaped element formed on one surface of a dielectric substrate, the ground plane being on the opposite surface.
Abstract: A diagonally fed electric microstrip dipole antenna consisting of a thin ctrically conducting, rectangular-shaped element formed on one surface of a dielectric substrate, the ground plane being on the opposite surface. The length of the element determines the resonant frequency. The feed point is located along the diagonal with respect to the antenna length and width, and the input impedance can be varied to match any source impedance by moving the feed point along the diagonal line of the antenna without affecting the radiation pattern. The antenna bandwidth increases with the width of the element and spacing between the element and ground plane. Singularly fed circular polarization is easily obtained with this antenna.
Patent•
16 Dec 1975
TL;DR: An antenna combiner 2 n antenna element system with switchable variable delay line length broadband beam and null steering through 360° in azimuth is described in this paper, where the authors describe a two-antenna combiner system with two antenna elements.
Abstract: An antenna combiner 2 n antenna element system with switchable variable delay line length broadband beam and null steering through 360° in azimuth.
Patent•
17 Nov 1975
TL;DR: In this paper, a broadband antenna system of small dimensions and composed of at least one antenna having an associated design operating frequency, and a plurality of reflectors operatively associated with the antenna and disposed at respectively different distances therefrom, each reflector being spaced from the antenna with a reflection characteristic to be optimally matched to the antenna for operation at a respective partial frequency band, each reflecting node associated with a different partial band such that the total operating frequency range of the system is divided into a plurality.
Abstract: A broadband antenna system of small dimensions and composed of at least one antenna having an associated design operating frequency, and a plurality of reflectors operatively associated with the antenna and disposed at respectively different distances therefrom, each reflector being spaced from the antenna and having a reflection characteristic to be optimally matched with the antenna for operation at a respective partial frequency band, each reflector being associated with a different partial band such that the total operating frequency range of the system is divided into a plurality of partial bands equal in number to the number of reflectors and covering the design operating frequency range and a further frequency range below the lower limit of the design range, whereby the antenna characteristics are improved, and in particular the operative bandwidth of the system is increased in the low frequency direction.
02 Jun 1975
Patent•
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08 May 1975
TL;DR: In this article, an antenna system improvement for a conventional AM/FM radio having a ferrite coil antenna for AM and other antenna such as a telescoping whip for FM feeding an FM antenna input, includes a pair of terminals adapted to be connected to an external antenna lead in wire, an auxiliary coil wrapped around the ferrite antenna and a single pole double throw switch for connecting either the auxiliary coil or the FM antenna inputs to the terminals.
Abstract: An antenna system improvement for a conventional AM/FM radio having a ferrite coil antenna for AM and other antenna such as a telescoping whip for FM feeding an FM antenna input, includes a pair of terminals adapted to be connected to an external antenna lead in wire, an auxiliary coil wrapped around the ferrite antenna and a single pole double throw switch for connecting either the auxiliary coil or the FM antenna input to the terminals.
Patent•
20 Nov 1975TL;DR: A cavity-backed spiral antenna has a plurality of resistively loaded monopole radiators disposed in the cavity in orthogonal relation to the spiral windings to maximize the frequency range of the antenna without increasing the physical size thereof.
Abstract: A cavity-backed spiral antenna has a plurality of resistively loaded monopole radiators disposed in the cavity in orthogonal relation to the spiral windings to maximize the frequency range of the antenna without increasing the physical size thereof.
TL;DR: In this article, the effects of parallel resistive and inductive loading on the far-field radiated waveform and waveform pattern from a thin dipole antenna in the transmission line approximation were considered.
Abstract: The far-field radiated waveform and field pattern from a thin dipole antenna in the transmission line approximation are considered when the antenna is driven by a voltage generator of waveform V_{0}u(t) , where u(t) is the unit step function. The antenna is loaded with a tapered form of loading and is permitted to include reactance as well as resistance. Analytical and numerical solutions for the far-field pattern and waveform are discussed. In particular, the effects of parallel resistive and inductive loading are presented.
TL;DR: In this paper, the authors derived an expression for the antenna temperature for a scanning Earth-viewing satellite-borne microwave radiometer, in the form of an integral that includes the antenna gain function and brightness temperature.
Abstract: Expressions for the antenna temperature are derived for a scanning Earth-viewing satellite-borne microwave radiometer. The result is in the form of an integral that includes the antenna gain function and brightness temperature. A composite emissivity term appears in the brightness temperature equation that contains the horizontal and vertical components of surface emissivity weighted by their respective antenna gains. Analysis is performed to obtain the antenna temperature components corresponding to the emission of horizontally and vertically polarized radiation. Calculations are performed showing the effects of beam width and scan angle on the two components of antenna temperature for a linearly polarized antenna. Effects resulting from antenna cross polarization are also analyzed.
Patent•
20 Aug 1975
TL;DR: In this paper, a simple-structured circular polarized radiator with excellent radiation characteristics is proposed for the primary radiator of a circular polarized papabolic antenna, which can be used for a single-antenna single-input single-out (SISO) system.
Abstract: PURPOSE:To provide a small simple-structured circular polarized radiator featuring excellent radiation characteristics that can be used for the primary radiator of a circular polarized papabolic antenna.
TL;DR: In this article, an alternative procedure based on a simplified scattering model is presented, which is capable of yielding satisfactory results without the necessity of making empirical corrections, without the need of making any empirical corrections.
Abstract: The shortcomings of both the surface integration and the two-aperture approach to the prediction of dielectric rod antenna patterns are well known. An alternative procedure based on a simplified scattering model is presented which is capable of yielding satisfactory results without the necessity of making empirical corrections.
01 May 1975
TL;DR: In this paper, a new antenna-synthesis method is described that allows the antenna surface geometry to be arbitrarily specified and the radiating current distributions to be computed directly from the radiation patterns, which can be quite general and have any type of polarisation.
Abstract: A new antenna-synthesis method is described that allows the antenna surface geometry to be arbitrarily specified and the radiating current distributions to be computed directly from the radiation patterns, which can be quite general and have any type of polarisation: this latter process makes the synthesis procedure nonunique, but is of great practical value since phase information is not required. Illustrative examples based on rotational symmetry are given to show the effect of all the various sources of controllable error, and useful information is also extracted about the formulation of active conformal arrays of small closely spaced noninteracting radiating elements; in particular, a means of optimising a conformal beacon antenna and creating a wide bandwidth supergain system by utilising the closely spaced driven array principle is discussed.