Showing papers on "Slot antenna published in 1978"
TL;DR: The radiation characteristics of an N -port antenna system can be controlled by impedance loading the ports and feeding only one or several of the ports, and the direction of maximum gain can becontrolled by varying the load reactances.
Abstract: The radiation characteristics of an N -port antenna system can be controlled by impedance loading the ports and feeding only one or several of the ports. Reactive loads can be used to resonate a real port current to give a radiation pattern of high directivity. The theory of resonance is extended to include complex port currents and impedance loads. The initial design of an array is obtained by resonating a desired port current vector, which is then improved by an optimum seeking univariate search method. The direction of maximum gain can be controlled by varying the load reactances. Several numerical examples are given for a circular array of seven dipole elements.
450 citations
TL;DR: In this article, a theory enlarges on Stevenson's method, and uses a modified form of Booker's relation based on Babinet's principle to treat nonresonant longitudinal shunt slots in the broad wall of a rectangular waveguide.
Abstract: The differences in mutual coupling for a central slot and a peripheral slot cannot be ignored in small arrays if good patterns and impedance are to be obtained. A theory has been developed whereby the length and offset of every slot in the array can be determined, in the presence of mutual coupling, for a specified aperture distribution and impedance match. The theory enlarges on Stevenson's method, and uses a modified form of Booker's relation based on Babinet's principle to treat nonresonant longitudinal shunt slots in the broad wall of a rectangular waveguide. A general relation between slot voltage and mode voltage is developed, and then formulas are derived for the active, self-, and mutual admittances among slots. These formulas result in a design procedure. Analogous treatments of inclined series slots in rectangular guide and of strip-line-fed slots are possible. Comparison between various experiments and the theory is presented. Tests of the theory include the resonant length of a zero offset slot, resonant conductance versus offset and resonant conductance versus frequency for a single slot, and self- and mutual admittances for two staggered slots. The design and performance of a two-by-four longitudinal shunt slot array is also described.
233 citations
TL;DR: In this paper, the effects of horn aperture size, slot width-to-pitch ratio and frequency on the cross-polarization of the radiation pattern are considered, as well as the range of slot parameters which can be used and the design of the slots near the throat of the horn to achieve a low VSWR for bandwidths of 1.5 to 1.
Abstract: Details of the design of circumferentially corrugated conical horns are presented. Radiation pattern and phase-center characteristics for both "wide-band" and "narrow-band" horns are considered, and a comparison is made between the relative sizes of the two types of horns. The effects of horn aperture size, slot width-to-pitch ratio and frequency on the cross-polarization of the radiation pattern are included. The range of slot parameters which can be used and the design of the slots near the throat of the horn to achieve a low VSWR for bandwidths of 1.5 to 1 are also considered. The results of measurements on horns with both narrow and wide included angles are given.
106 citations
Patent•
16 Jan 1978
TL;DR: In this article, a slot antenna capable of relatively broad bandwidth operation is disclosed that may be used for wide angle scanning in phased arrays, by shorting the feed element to the slot radiator at multiple points.
Abstract: A slot antenna capable of relatively broad bandwidth operation is disclosed that may be used for wide angle scanning in phased arrays. By shorting the feed element to the slot radiator at multiple points, the relatively broad bandwidth operation is achieved.
66 citations
TL;DR: In this paper, a planar antenna with a dielectric substrate and a superstrate was proposed for coupling to a primary mirror with a gain of about 15 dB, which was found to have a single-lobed pattern well-suited for coupling.
64 citations
TL;DR: In this paper, a single-sided microwave applicator has a section of a microwave waveguide with an open end for receiving microwave energy and an end which is electrically shorted.
Abstract: The single-sided microwave applicator has a section of a microwave waveguide with an open end for receiving microwave energy and an end which is electrically shorted. A slot is located in one of the wide sides of the waveguide extending along the center line from the shorted end. A conductive ridge is mounted within the waveguide extending upward from the other side through the slot. One end of the ridge is connected to the shorted end of the waveguide, while the other end of the ridge is tapered from a point within the slot. The slot is generally in the order of 3/4 to 1 inch and at least 21/2 inches long, when the operating frequency is 2450 MHz. Since one end of the waveguide is shorted, standing waves are produced resulting in a non-uniform field having at least one maximum along the length of the slot. The electric field produced is non-radiating and its strength diminishes exponentially above the slot.
27 citations
TL;DR: In this article, an inhomogeneous spherical model of a 3.3 cm radius cranial structure is assumed to be placed symmetically in the near field of a small loop antenna or an electrical dipole antenna at 3 GHz.
Abstract: An inhomogeneous spherical model of a 3.3-cm radius cranial structure is assumed to be placed symmetically in the near field of a small loop antenna or an electrical dipole antenna at 3 GHz. The transitions between the layers are taken to be sharp but sinusoidal. Calculations of the heat potential are performed using a spherical wave expansion technique in which linear differential equations are solved for the unknown multipole coefficients. The results are also compared with the plane-wave excitations. It is seen that a more uniform distribution of the heat potential occurs for the dipole antenna excitation which is also similar to the E-plane distribution in the case of plane-wave excitation. For the loop excitation, a significant hot spot occurs near the center of the structure.
19 citations
TL;DR: A survey of planar antenna design techniques can be found in this article, where the authors summarize the well-established methods using slotted waveguide arrays, the more recent stripline and cavity backed printed antennas are surveyed; finally the latest techniques using microstrip arrays are introduced and state-of-the-art designs discussed.
Abstract: The increasing compactness of modern microwave communication and radar equipment commonly demands that the associated antennas have flat profiles; this paper surveys the various planar antenna design techniques that are available. After summarizing the well-established methods using slotted waveguide arrays, the more recent stripline and cavity backed printed antennas are surveyed; finally the latest techniques using microstrip arrays are introduced and state-of-the-art designs discussed. Outline design and explanatory details are given for each antenna and any special characteristics, advantages and disadvantages are noted; ample references are given throughout the text. Several conclusions are reached about ways of improving the various individual designs but the need to improve the control of both mechanical and electrical tolerances and also more accurately predict the sidelobe behaviour of arrays are seen as important general requirements for further research.
15 citations
01 Nov 1978
TL;DR: In this paper, the I-shaped geometry for radiating slots entirely in the narrow wall of a waveguide is outlined. But the I2R losses in the metal of the waveguide wall are identified as an undesirable feature of impedance-loaded slots or slots of reduced height.
Abstract: The development of an I-shaped novel geometry for radiating slots entirely in the narrow wall of a waveguide is outlined. I2R losses in the metal of the waveguide wall are identified as an undesirable feature of impedance-loaded slots or slots of reduced height. The I-shaped geometry developed does not include these features, and is demonstrated to be a useful low-loss waveguide array element, offering a wide range of coupling values.
11 citations
TL;DR: In this paper, the effect of slotted flanges on the radiation pattern of a waveguide is investigated experimentally, and it is shown that considerable changes can be effected in the beamwidth of the pattern by changing the flange inclination.
Abstract: The effect of slotted flanges on the radiation pattern of a waveguide is investigated experimentally. The slotted flanges are mounted at the aperture of the waveguide. Both straight and inclined slotted flanges are used. It is seen that considerable changes can be effected in the beamwidth of the pattern by changing the flange inclination. Such a simple control on beamwidth thus makes it possible to use the slotted flange device as a feed to meet a variety of applications.
9 citations
Patent•
05 Sep 1978TL;DR: In this article, a low profile transmitting antenna consisting of a circular slot in a coal cavity that is folded several times is presented, and the last inner fold of the coaxial cavity is loaded with the tuning coil.
Abstract: A low profile transmitting antenna consisting of a circular slot in a coal cavity that is folded several times. The last inner fold of the coaxial cavity is loaded with the tuning coil. The tuning coil can in the alternative be connected in series with the transmitter leeds connected to the radiating slot. Concentric cylinders alternately attached to the top and bottom of the cavity are used to form the folded coaxial cavity that provides the equivalent of a tapered transmission line. Energy to be transmitted is fed across the circular slot of the antenna or in the alternative may be fed into the last inner fold in the center of the cavity. The antenna radiates energy out with the same radiation pattern as a vertical monopole antenna.
TL;DR: In this article, a flat Doppler module, only 18 mm thick, was fabricated based on a microwave integrated circuits (MIC) stabilized oscillator having a dipole antenna on a single substrate.
Abstract: A flat Doppler module, only 18 mm thick, was fabricated. The module is based on a microwave integrated circuits (MIC) stabilized oscillator having a dipole antenna on a single substrate. It emits a microwave beam normal to the substrate plane whose radiation pattern is nearly symmetrical around the normal axis with a half-power-angle of about 60/spl deg/.
TL;DR: In this paper, an exact solution was obtained for the problem of a radiating parallel plate waveguide when the inside walls are inductively loaded and the outside walls are capacitively loaded.
Abstract: An exact solution is obtained for the problem of a radiating parallel plate waveguide when the inside walls are inductively loaded and the outside walls are capacitively loaded. Also, an impedance boundary condition is assumed along the center line of the configuration. The structure serves as a canonical model for two important types of antennas: an inductively loaded horn and a horn-type surface wave launcher. Exact closed-form expressions are computed for quantities of physical interest: the reflection coeffieient at the waveguide mouth, the radiation power pattern, and the power in the radiated surface wave. Various graphs show how the antenna pattern and the launching efficiency vary with the different parameters.
Patent•
25 Mar 1978
TL;DR: In this article, a modification and contrivance to the conventional flat slot antenna in terms of the structure and the power supply circuit was proposed to secure an extremely good-quality vertical polarized wave non-directional property, with an enhanced mass productivity.
Abstract: PURPOSE:To secure an extremely good-quality vertical polarized wave non-directional property, with an enhanced mass productivity, by having a modification and contrivance to the conventional flat slot antenna in terms of the structure and the power supply circuit.
01 Oct 1978
TL;DR: In this article, the difference between the several modes, i.e., the guided modes, the radiation modes and the leaky waves are clarified, and computed results as well as experimental results of different mode characteristics are presented.
Abstract: Planar waveguides like microstrip and microslot have been used not only as waveguides but also for radiation purposes (microstrip antenna). Therefore, the paper tries to give a clear description of waveguide characteristics as well as radiation characteristics of planar waveguides. The difference between the several modes, i. e. the guided modes, the radiation modes and the leaky waves are clarified. Moreover, computed results as well as experimental results of different mode characteristics are presented.
Patent•
05 Sep 1978TL;DR: In this paper, a cuplike cavity backing a radiating annular slot antenna is used to communicate to submarines or surface ships or as a navigation transmitting antenna, which can be inflated with air or a liquid dielectric material.
Abstract: A transmitting antenna that can be inflated with air or a liquid dielectricnd floated in seawater. It consists of a cuplike cavity backing a radiating annular slot antenna. It can be used to communicate to submarines or surface ships or as a navigation transmitting antenna. It is small compared to the wavelength of the operating frequency.
TL;DR: The reciprocal theorem is used with the previously determined receiving properties of embedded bare and insulated dipoles and two-element arrays to obtain the ratio of the voltage across the load in a receiving dipole or Yagi array in air to the voltages driving various embedded transmitting antennas.
Abstract: Electromagnetic problems relating to biomedical telemetry are reviewed. The reciprocal theorem is used with the previously determined receiving properties of embedded bare and insulated dipoles and two-element arrays to obtain the ratio of the voltage across the load in a receiving dipole or Yagi array in air to the voltages driving various embedded transmitting antennas. The solution of the electro-magnetic problem of the transponder at vrious depths in a body of skin is thus completed.
TL;DR: In this article, the responses of aircraft antennas to a broad-band electromagnetic wave such as the nuclear electromagnetic pulse (EMP) are analyzed and the antennas are divided into five classes: blades, loops, slots, bowls, and long wires.
Abstract: The responses of aircraft antennas to a broad-band electromagnetic wave such as the nuclear electromagnetic pulse (EMP) are analyzed. For convenience of analysis the antennas are divided into five classes: blades, loops, slots, bowls, and long wires. From each class a few specific antennas are selected as examples for detailed discussion. For each exemplary antenna the detailed equivalent circuit, input impedance, and effective height at the antenna's connector are given. Measurements of input impedance on some antennas are compared with the corresponding calculated results.
TL;DR: In this paper, the radiation fields of small air-cored toroidal antennas carrying a uniform in-phase current have been evaluated and it is shown that according to whether the number of turns is one or more, different radiation patterns result.
Abstract: The radiation fields of small air-cored toroidal antennas carrying a uniform in-phase current have been evaluated. It is shown that according to whether the number of turns is one or more, different radiation patterns result. For the single turn toroid the position of its null axis can be adjusted by altering the ratio of its mean radius to the radius of its cross-section.
15 Mar 1978
TL;DR: The choked waveguide feed antenna, which exhibits E-and H-plane radiation pattern equality, good pattern symmetry and low cross polarisation, is an excellent feed for symmetrical reflector antennas with f/D ratios in the range of about 0.3 to 0.4 as discussed by the authors.
Abstract: The choked waveguide feed antenna, which exhibits E- and H-plane radiation pattern equality, good pattern symmetry and low cross polarisation, is an excellent feed for symmetrical reflector antennas with f/D ratios in the range of about 0.3 to 0.4. An experimental programme has been carried out to determine the variation of beamwidth with feed aperture diameter, and the results are presented here.
01 Sep 1978
TL;DR: In this article, the authors present an analysis model for the microstrip slot antenna excited by a non terminated microstripline, which is an extension of the well-known method for the analysis of the radiation by a slot in a waveguide.
Abstract: In this paper we present an analysis model for the microstrip slot antenna excited by a non terminated microstripline The model is an extension of the well-known method for the analysis of the radiation by a slot in a waveguide. By application of the Lorentz reciprocity theorem we find an equivalent circuit which parameters are determined with the aperture theory. This n ew model is simple and easy to use for analyzing a single as well as an array of radiating slots fed by the same microstripline.
TL;DR: This model gives an insight into the strip-slot-cavity coupling and hence the working of the structure and is useful for predicting the performance of such practical antennas.
Abstract: An equivalent network for the strip-fed cavity-backed slot antenna is derived. The model is based on some physical insight into the problem. The various parameters of the network are derived from the experimental data on the input reflection parameter of the antenna. This model gives an insight into the strip-slot-cavity coupling and hence the working of the structure. It is also useful for predicting the performance of such practical antennas.
Patent•
13 Apr 1978
TL;DR: In this article, the packing density of antennas is increased by insertion between each two wide band antennas for the full antenna system frequency range, of a similar antenna for a part of the total frequency range.
Abstract: Individual antennas are mounted in a plane and can be connected as required. In order to widen the antenna frequency range without increasing secondary lobes of its directional characteristic and without unwanted couplings between adjacent individual antennas, the packing density of antennas is increased by insertion between each two wide band antennas for the full antenna system frequency range, of a similar antenna for a part of the total frequency range. Alternatively two or more individual antennas of the same or similar type for the same or for different parts of the total frequency range may be inserted.
Patent•
21 Sep 1978
TL;DR: In this paper, a VHF transmitter aerial with omnidirectional characteristics and high vertical beam forming properties is mounted upon a self-supporting base body of non-metallic, non-conductive, material, e.g. glass-fibre-reinforced epoxy resin.
Abstract: VHF transmitter aerial with omnidirectional characteristics and high vertical beam forming properties esp. a cylindrical slot antenna, has >=1 metallic reflecting surface. The latter is mounted upon a self-supporting base body of non-metallic, non-conductive, material, e.g. glass-fibre-reinforced epoxy resin. The reflecting surface is embedded in the base body.
TL;DR: In this paper, the responses of aircraft antennas to a broad-band electromagnetic wave such as the nuclear electromagnetic pulse (EMP) are analyzed and the antennas are divided into five classes: blades, loops, slots, bowls, and long wires.
Abstract: The responses of aircraft antennas to a broad-band electromagnetic wave such as the nuclear electromagnetic pulse (EMP) are analyzed. For convenience of analysis the antennas are divided into five classes: blades, loops, slots, bowls, and long wires. From each class a few specific antennas are selected as examples for detailed discussion. For each exemplary antenna the detailed equivalent circuit, input impedance, and effective height at the antenna's connector are given. Measurements of input impedance on some antennas are compared with the corresponding calculated results.
TL;DR: In this article, the radiation characteristics of a narrow nonresonant slot close to, or straddling, the center line of a notched-wall dual-mode waveguide are compared with the behaviour of similar slots in the corresponding single-mode guide.
Abstract: Some radiation characteristics of a narrow nonresonant slot close to, or straddling, the centre line of a notched-wall dual-mode waveguide are presented, and compared with the behaviour of similar slots in the corresponding single-mode guide The theoretical results have been evolved using Bethe's small-hole diffraction theory They are supported by some experimental evidence
01 May 1978
TL;DR: In this paper, a theory for the inpurt reflection coeffecieint as a function of frequency for a basic Dlelectric-Filled Edge-slot (DFES) antenna was developed.
Abstract: A theory is developed for the inpurt reflection coeffecieint as a function of frequency for a basic Dlelectric-Filled Edge-Slot (DFES) antenna recently developed experimentally by the Harry Diamond Laboratories [1]. These antennas belong to a class of circumferential slot antennas that are suited for informal mounting on conducting bodies of revolution so that the radiating aperture coincides with the surface. The simplest form of the antenna consists of a disc of dielectric substrate that is copper-plated on both sides and mounted between the two halves of a conducting body of revolution. It is excited at the center by a single coaxial stub and can be tuned for proper operating frequency by using a number of passive inductive posts that connect the two conducting surfaces of the substrate. The input reflection coefficients of the antenna are found to be minimum at some discrete frequencies called the operating frequencies where the antennas radiates most efficiently.
01 Jan 1978
TL;DR: In this article, a large diameter (200 - 300 m) spaceborne antenna and microwave system operating at frequencies in the range from 20 GHz to at least 300 GHz are addressed.
Abstract: Problems associated with controlling a large diameter (200 - 300 m) spaceborne antenna and microwave system operating at frequencies in the range from 20 GHz to at least 300 GHz are addressed. Such large structures must point to any new target and settle in one hour, and have control surface accuracy to 50 microns rms. Critical technologies required to enable system development by 1990 to 2000 for radio/ radar astronomy, orbiting Deep Space rela satellite, SETI, very long base interferometry, and earth looking radiometry applications are discussed.