Showing papers on "Slot antenna published in 1974"
Patent•
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TL;DR: In this article, an improved antenna of a coaxial type utilizing Z-shaped slots disposed in the outer conductor to provide an omnidirectional antenna pattern was proposed, where current coupling to the slots is achieved by means of the transverse portion of the Z slot.
Abstract: An improved antenna of a coaxial type utilizing Z-shaped slots disposed in the outer conductor to provide an omnidirectional antenna pattern. Current coupling to the slots is achieved by means of the transverse portion of the Z slot. Detuning effects due to the presence of a transmission line are compensated for by dielectrically loading the slots with a dielectric cover over the coaxial line and/or by lengthening the longitudinal arms of the Z. The longitudinal spacing between each slot and the length of the transverse portion of each slot are chosen while considering all line effects to obtain the required phase and amplitude relationships. The antenna consequently requires no additional coupling, tuning or phasing devices mounted within or without the coaxial line.
123 citations
Journal Article•
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TL;DR: In this paper, a number of heuristic procedures are presented relating to the computation of transient radiation from elementary sources, coaxial apertures, infinitely long cylindrical antennas, finite cylindric antennas, and loop antennas.
Abstract: The problem of pulsed antennas has two complementary parts: i) analysis of the radiation field when the driving voltage is given and ii) synthesis of the driven voltage when the radiation field is given. In this paper a number of heuristic procedures are presented, relating to the computation of transient radiation from elementary sources, coaxial apertures, infinitely long cylindrical antennas, finite cylindrical antennas, and loop antennas. Comparison with available rigorous solutions and experiments is also provided.
75 citations
TL;DR: In this paper, a variational solution for computing the impedance of a radiating longitudinal shunt slot of rectangular shape in the broad face of a rectangular waveguide was derived, which yields the slot resonant length, accounting for the displacement of the slot from the center of the waveguide.
Abstract: A variational solution is derived for computing the impedance of a radiating longitudinal shunt slot of rectangular shape in the broad face of a rectangular waveguide. This solution, an extension of Oliner's deviation, yields the slot resonant length, accounting for the displacement of the slot from the center of the waveguide. Taking advantage of the results reported in the existent literature, the computation of impedance can be extended to that for a slot in a large array environment, with or without a dielectric sheath covering. Under some reasonable assumptions and comparing the experimental data with theoretical values, a semi-empirical equation is obtained for the resonant length of a slot with round ends in practical applications. The computational method presented in this paper is experimentally assessed to be valuable for the design of slotted waveguide arrays.
71 citations
TL;DR: In this article, the authors derived the mutual admittance between two slot antennas, either in the same or different planes, by assuming that the slots are small enough so that when short-circuited at their terminals the electric field scattered from the slot is negligible.
Abstract: The mutual admittance method is used to calculate the transmission through a two layer array of slots The slot arrays are thin and parallel The plane wave illumination is at an arbitrary angle in either the E -plane or H -plane The mutual admittance between two slot antennas, either in the same or different planes, is derived In this derivation it is assumed that the slots are small enough so that when short-circuited at their terminals the electric field scattered from the slot is negligible The evaluation of the mutual admittance sums is simplified by the extension to the slot case of certain impedance relationships established previously for a two-layer dipole array For many applications the two-layer slot array is more desirable than a single-layer array since a wider passband and sharper skirts can be obtained with proper design The analysis shows, however, that for high incidence angles the dip in the center of the passband may be deeper than for the similar two-layer dipole array
57 citations
TL;DR: Results of the measurements indicate that for vertically polarized antennas 100 ft above ground level, an antenna separation of 6-7 wavelengths in the horizontal plane provides sufficient signal decorrelation for satisfactory diversity operation.
Abstract: Base station spatial diversity measurements at 821 MHz have been performed in a New Jersey suburban area using directional antennas separated by 3.4, 6.6, and 10 wavelengths. The cross-correlation coefficients between the signals received by pairs of antennas have been computed as a function of antenna height, antenna separation, and signal polarization. Both vertical and horizontal antenna spacings have been investigated. The cross-correlation coefficients were obtained by measurements in ten different probe areas, ranging from 1 to 5 miles in distance from the base station. Results of the measurements indicate that for vertically polarized antennas 100 ft above ground level, an antenna separation of 6-7 wavelengths in the horizontal plane provides sufficient signal decorrelation for satisfactory diversity operation.
54 citations
10 Jun 1974
TL;DR: In this article, the roll and elevation plane patterns are computed for a monopole, axial slot, and circumferential slot mounted both over and forward of the wings of a KC-135 aircraft.
Abstract: Numerical solutions for the radiation patterns of aircraft antennas provide an excellent means of designing and locating antennas in order to achieve the desired performance. The high frequency solutions presented in this paper are based on fuselage antennas mounted on a general-type aircraft but applied specifically to the KC-135 aircraft. The roll and elevation plane patterns are computed for a monopole, axial slot, and circumferential slot mounted both over and forward of the wings. In each case the calculated patterns compare very favorably with the measured patterns. The precision pattern measurements were taken on a \frac{1}{25} scale model of the KC-135 aircraft at NASA (Hampton, Va.) with special emphasis on reducing the mount and background effects.
53 citations
10 Jun 1974
35 citations
Patent•
15 May 1974
TL;DR: In this paper, a broadband slot line non-reciprocal microwave device which comprises a matched load placed on the face of a ferrite plate which is located within the microwave magnetic field of the slot line, said face being opposite to said slot and designed so that its height is larger than 3 times the width of the slots and its length is at least equal to a half wavelength as propagated within the slot at the maximum operating frequency.
Abstract: A broadband slot line non reciprocal microwave device which comprises a matched load placed on the face of a ferrite plate which is located within the microwave magnetic field of the slot line, said face being opposite to said slot and designed so that its height is larger than 3 times the width of the slot and its length is at least equal to a half wavelength as propagated within the slot at the maximum operating frequency. Said matched load may be a second slot line or a lossy ferrite plate. The device operates as an isolator with more than 20 dB isolation. It can be designed as a four port circulator.
27 citations
TL;DR: In this paper, a planar log-periodic antenna structure with radiation characteristics similar to those of a half-wave dipole has been found, which can be easily fabricated by using printed circuit techniques.
Abstract: A planar log-periodic antenna structure that has radiation characteristics similar to those of a half-wave dipole has been found. The bandwidth can be as large as desired, and antennas can be easily fabricated by using printed circuit techniques. When fed with a suitable balun, VSWR's lower than 1.8:1 can be obtained over a wide-frequency band.
16 citations
TL;DR: In this article, the design of a K band frequency scanned array in an RG 96/U waveguide is presented, where the radiating elements consist of slots machined in the narrow wall of the guide.
Abstract: This paper presents the design of a K band frequency scanned array in an RG 96/U waveguide. The radiating elements consist of slots machined in the narrow wall of the guide. experiment-resluts of the measured slot conductances for the antenna elements and the feed system are given for slot spacings of 0.25 inches and various slot orientations and depths. Theoretical optimum efficiencies for uniform, Chebyshev, and Taylor distributions are also presented. Finally, the experimental results for a 400-element planar array are given.
TL;DR: In this paper, the concept of antenna beam steering by variable surface impedance loading is investigated and it is shown that if an electric dipole is mounted over a prolate spheroid with a variable SA, then the radiated beam can be scanned considerably.
Abstract: The concept of antenna beam steering by variable surface impedance loading is investigated. It is shown, as an example, that if an electric dipole is mounted over a prolate spheroid with a variable surface impedance, then the radiated beam can be scanned considerably. This is achieved provided that the real part of the surface impedance can obtain both negative and positive values. The possible realization of such a scheme is briefly discussed.
Patent•
16 Apr 1974
TL;DR: In this paper, a turnstile slot antenna for a spacecraft having a substantially cylindrical body portion is described. The antenna comprises a circumferential slot about the periphery of the spacecraft body portion with an annular wave guide cavity defining a radial transmission line.
Abstract: A novel turnstile slot antenna is disclosed, the antenna being for and integral with a spacecraft having a substantially cylindrical body portion The antenna comprises a circumferential slot about the periphery of the spacecraft body portion with an annular wave guide cavity defining a radial transmission line disposed within the spacecraft body portion behind and in communication with the circumferential slot Feed stubs and associated transmission apparatus are provided to excite the annular cavity in quadrature phase such that an omnidirectional, circularly polarized, rotating radiation pattern is generated The antenna of the instant invention has utility both as a transmitting and receiving device, and ensures continuous telemetry and command coverage with the spacecraft
TL;DR: In this article, the coupling between minimum scattering antennas (MSA's) is investigated by the coupling theory developed by Wasylkiwskyj and Kahn and graphs of relative mutual impedance are presented as a function of distance and pattern parameters.
Abstract: Coupling between minimum scattering antennas (MSA's) is investigated by the coupling theory developed by Wasylkiwskyj and Kahn. Only rotationally symmetric power patterns are considered, and graphs of relative mutual impedance are presented as a function of distance and pattern parameters. Crossed-dipoles and helices are considered in order to establish a correspondence with simple antenna structures.
Patent•
24 Jul 1974
TL;DR: In this paper, a corrugated horn antenna with V-shaped slots was proposed, which is more easily machined than previous slots and the resulting antenna is readily adaptable to unfurlable antennas for space applications.
Abstract: This invention is a corrugated horn antenna in which the corrugated surfaces of the antenna are formed by V-shaped slots. The depth of the slots is between 0.3125 and 0.625 wavelengths. For this range of depths the surface impedance is capacitive and operates in a cut-off mode. The V-shaped corrugated slots are more easily machined than previous slots and the resulting antenna is readily adaptable to unfurlable antennas for space applications.
TL;DR: In this paper, the transmitting and receiving patterns of a dipole antenna for an electron plasma wave have been measured by using the interference method, and the results agree fairly well with the theoretical patterns that were predicted from the fluid model analysis and also experimentally prove the reciprocity relationship between transmitting and the receiving patterns, which is theoretically found to be valid in the plasma wave approximation.
Abstract: The transmitting and the receiving patterns of a dipole antenna for an electron plasma wave have been measured by using the interference method The results agree fairly well with the theoretical patterns that were predicted from the fluid model analysis and also experimentally prove the reciprocity relationship between the transmitting and the receiving patterns, which is theoretically found to be valid in the plasma wave approximation The characteristics of the transmitting and the receiving efficiencies versus the dc bias voltage applied to the dipole antenna have been also experimentally investigated
Patent•
02 Jan 1974
TL;DR: In this paper, an elongate cylindrical tube is provided with a pair of longitudinally-spaced slots forming a slot antenna capable of producing a signal at each slot in response to the electromagnetic radiation component of a detonation wave travelling within the tube.
Abstract: An elongate cylindrical tube is provided with a pair of longitudinally-spaced slots forming a slot antenna capable of producing a signal at each slot in response to the electromagnetic radiation component of a detonation wave travelling within the tube. A polarizing and integrating circuit applies the signal of each slot to the ''time-base'' trace of an oscilloscope to provide a recording of the time required for a detonation wave produced in the tube to travel the distance between the spaced slots. Dielectric material can be used to adjust the slot size to the frequency of the electromagnetic radiation component.
TL;DR: In this article, the radiated power intensity decreases suddenly at the upper hybrid resonance, which depends upon the velocity and the constitutive parameters of the plasma due to the Doppler effect.
Abstract: Radiation from an aperture in a conducting cylinder surrounded by a magnetoplasma layer moving in the axial direction is treated theoretically. Numerical computations are carried out for axial and circumferential slot apertures. For the axial slot case, it is shown that in addition to the main-polarized fields, cross-polarized fields occur in the presence of motion of the plasma layer, and that the radiated power pattern of each polarized field depends on both the constitutive and the velocity parameters of the plasma. For the circumferential slot case, the radiation patterns for two polarized fields are obtained separately, and numerical results are presented. It is shown that the radiated power intensity decreases suddenly at the upper hybrid resonance, which depends upon the velocity and the constitutive parameters of the plasma due to the Doppler effect. In the vicinity of the resonance, rapid oscillations appear in the pattern, and hence the radiated power pattern is remarkably distorted in the resonance region.
TL;DR: In this paper, it was pointed out that Banos's formulas of the contribution from the pole in the evaluation of the Hertz vector for the radiation field of a dipole cannot be applied even when both the dipole and the observing point are in the lossy half-space due to the approximate method for the integration.
Abstract: It is pointed out that Banos's formulas of the contribution from the pole in the evaluation of the Hertz vector for the radiation field of a dipole cannot be applied even when both the dipole and the observing point are in the lossy half-space due to the approximate method for the integration.
01 Jun 1974
TL;DR: In this article, a general theory of thin-wire multiturn loop antennas is presented, where the windings of the loop are considered to form a circular helix and the antenna impedance, efficiency, and pattern are obtained.
Abstract: A general theory of thin-wire multiturn loop antennas is presented. For convenience the windings of the loop are considered to form a circular helix. An integral equation is derived and solved numerically for the current distribution on the antenna. The antenna impedance, efficiency, and pattern are obtained.
01 Oct 1974
TL;DR: In this article, the authors presented design datas for slot antennas backed by a homogeneous filled and optimized cavity where dimension restrictions have been considered, and several advantages have been obtained, for example, lower Q-factor, lower weight, better economy, and possibility for a more convenient feeding arrangement.
Abstract: The resonance frequency of a cavity-backed slot antenna and also the Q-factor are highly dependent of the dimensions of the cavity and of the dielectric filling of the cavity. A low Q-factor is desired for wideband frequency performance. Recently, the author published the values of the dimensions of the cavity which gave the lowest Q-factor of a slot antenna at prescribed resonance frequency, slot dimensions, and dielectric constant of the homogeneous cavity filling. However, the optimal cavity dimensions for the slot antenna are too big for using it in a wide scanning square lattice phased array. This paper presents design datas for slot antennas backed by a homogenous filled and optimized cavity where dimension restrictions have been considered. A new design with partially filled cavities will also be presented. Hereby several advantages have been obtained, for example, lower Q-factor, lower weight, better economy, and possibility for a more convenient feeding arrangement.
TL;DR: It is shown how the special geometry of a leg-periodic dipole antenna may be exploited within the general framework of matrix methods to permit multiple-frequency analysis without the need to repeat all computations for each frequency.
Abstract: Matrix methods for analysis of dipole antenna arrays have been applied to general computer programs but often require large amounts of computation time for multiple-frequency analysis of electrically long arrays, since most of the computations must be repeated for each frequency. It is shown how the special geometry of a leg-periodic dipole antenna may be exploited within the general framework of matrix methods to permit multiple-frequency analysis without the need to repeat all computations for each frequency. The computation of antenna currents at one frequency is made use of in solving for currents at a different frequency; the time consuming matrix inversion step is required only once.
10 Jun 1974
TL;DR: In this article, the development of a 5,5 λ λ diameter flat plate array antenna operating at X-band is described, including the theoretical design, including aperture excitation synthesis, mutual coupling consideration and tolerance analysis.
Abstract: The development of a 5,5\lambda . diameter flat plate array antenna operating at X-band is described. The antenna has 52 stripline fed slot elements with plated mode suppressors and a feed network integrated in a single-layer structure. The main interest has been in side lobe performance. As a goal specification an average side lobe level of -35 dB was required. This has also been achieved in practice but with the first side lobes peaking somewhat higher. In the paper the theoretical design, including aperture excitation synthesis, mutual coupling consideration and tolerance analysis, is discussed. The development of the radiating element and the feed network is also treated and a brief description is given of the manufacturing process and the measured performance of two prototypes.
TL;DR: In this article, the authors examined theoretically the influence of the slot depth on the reflection coefficient and coupling, and the useful bandwidth was shown to be of the order of 4% in the E plane coupling.
Abstract: A method of minimising the E plane coupling between two waveguides is to introduce a quarter-wave slot between them. This letter examines theoretically the influence of the slot depth on the reflection coefficient and coupling. The useful bandwidth is shown to be of the order of 4%.
10 Jun 1974
10 Jun 1974
TL;DR: In this article, a cavity-backed slot radiator operating at 2450 MHz is described, and the near field patterns and axial energy density are presented as a function of distance from the slot.
Abstract: A compact, light weight cavity-backed slot radiator operating at 2450 MHz is described. The near field patterns and the axial energy density are presented as a function of distance from the slot.
01 Nov 1974
TL;DR: In this article, the complex radiated power and the discontinuity in the modal voltage, as well as from the scattering coefficients, using the energy balance equation, have been calculated for an equivalent network of slots having any arbitrary orientation in the broad wall of a rectangular waveguide.
Abstract: The nature of an equivalent network of slots having any arbitrary orientation in the broad wall of a rectangular waveguide, for both even and odd distributions of the aperture field, has been investigated. The complex power radiated by the slot has been determined from the angular spectrum of plane waves. The impedance characteristics of the transverse slot and of the centred inclined slot have been obtained from the complex radiated power and the discontinuity in the modal voltage, as well as from the scattering coefficients, using the energy balance equation. The impedance characteristics calculated by the two methods are identical. The theoretical results are in good agreement with experimental results.
TL;DR: In this article, pitch and roll plane radiation patterns computed by use of an integral equation formulation are presented for a space shuttle annular slot communications antenna, and the excellent agreement between computed patterns and experimental patterns obtained from 1/35 scale models supports the use of this method as a design tool for similar spacecraft/aircraft antenna applications.
Abstract: Pitch and roll plane radiation patterns computed by use of an integral equation formulation are presented for a space shuttle annular slot communications antenna. The excellent agreement between computed patterns and experimental patterns obtained from 1/35 scale models supports the use of this method as a design tool for similar spacecraft/aircraft antenna applications.