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Showing papers on "Dipole antenna published in 1974"


Book
01 Jan 1974
TL;DR: In this article, the authors proposed a new definition of mutual impedance for application in array phase shifters, based on the idea of the butler matrix, which is used in the analysis of microstrip antenna arrays.
Abstract: theory and application of antenna arrays ouaps theory and application of antenna arrays theory and application of antenna arrays zaraa basic antenna theory and application theory and application of antenna arrays satcar antenna arrays antenna theory fractal antenna engineering: the theory and design of antenna theory and design john wiley & sons applications of antenna arrays to mobile communications 5. antenna types ncjrs robust synchronization of di erent coupled oscillators design of microstrip patch antenna array for wlan application session 3p3 antenna array synthesis | theory, algorithms eece 174 antenna theory and design opus college of theory and application of array coils in mr spectroscopy application of butler matrix to a tree structure of design and analysis of microstrip patch antenna arrays a study of loaded microstrip antennas and their compwnent part notice defense technical information center leaky cpw-based slot antenna arrays for millimeter-wave antenna array synthesis for suppressed side lobe level antenna theory tutorialspoint application of the neural network to the synthesis of a power wave theory of antennas e-fermat synthesis of thinned linear and planar antenna arrays fractal antenna elements and arrays university of maryland the application of the fdtd method to aperturecoupled a new definition of mutual impedance for application in array phase shifters: theory and technology origins of the digital antenna array theory slyusarev eel 4461 antenna systems eel 3472 university of florida double application of superconductor and photonic material session 2p7 antenna and array: theory and design piers course syllabus eel 4935/5462 antenna theory academics antenna array optimization using evolutionary approaches design of dielectric resonator antenna arrays for wireless planar antenna arrays for correlation direction finding design, simulation and tests of a low-cost microstrip design of microstrip antennas arrays for applications in design of antennas and antenna arrays [ d12 eth zürich design and performance analysis of microstrip array koch fractal antenna application in monopulse antenna array

148 citations


Patent
24 Dec 1974
TL;DR: In this paper, the authors developed a complete mathematical theory for the characteristics of a multi-turn, series-connected loop antenna formed of planar turns that are closely spaced and exhibit strong mutual coupling effects.
Abstract: A miniaturized thin-wire multi-turn series-connected helical loop antenna, the volutes of which are concentric turns, closely spaced so as to exhibit strong mutual coupling effects. A lumped impedance, fixed or variable, is disposed electrically in series with one of the turns, and a selectively actuable multi-position switch interconnects the turns and the lumped impedance to maximize efficiency. BACKGROUND OF THE INVENTION 1. Field of the Invention The subject invention relates to miniaturized multi-turn series-connected loop antennas. 2. Description of the Prior Art The theoretical solution for multi-turn loop antennas, whether transmitting or receiving, is initially based on the solution for a single-turn loop. The single-turn solution can be obtained by considering the antenna to be a transducer which converts concentrated or distributed voltages into distributed fields and vice-versa. The phenomenon which accomplishes this is the flow of current on the antenna conductor. Thus, if one can postulate the true form of the current and the resulting fields in space in response to timevarying driving forces, the solution for the single-turn loop, whether transmitting or receiving, can be obtained. A previous patent issued to me on Feb. 19, 1963, U.S. Pat. No. 3,078,462, was titled "One-Turn Loop Antenna". This patent discloses the basic solution for a thinwire, one-turn loop antenna in air, without and with inserted impedances. Although the one turn loop antenna described in the aforesaid patent was a distinct advance over available loop antennas, its limitation to a single loop design subjects it to several limitations. The extension of the theoretical analysis of the operational characteristics to multi-turn loop antennas had not been accomplished, probably because of the difficulty in developing a solution which takes into account the interconnection discontinuity between turns of a multi-turn series connected loop antenna having concentric planar turns. Without such a usable theoretical analysis, prediction of the operation of a multi-turn loop, or the effects of various modifications thereof are well-nigh impossible. As a result, the development of loop antennas today has not progressed much beyond the level of my aforesaid patent. I have now developed a complete mathematical theory for the characteristics of a multi-turn, series-connected loop antenna formed of planar turns that are closely spaced and exhibit strong mutual coupling effects. The theory from which the multi-turn loop has been developed is applicable not only to miniaturized antennas, but to any electrical size. Hence, the ability to control radiation coverage and antenna impedance of a transmitting antenna, and the ability to control response to incident fields and the antenna impedance of a receiving antenna, apply also to an antenna of any electrical size constructed in accordance with the principles and teachings of the present invention. SUMMARY OF THE INVENTION The present invention relates to a multi-turn thin-wire series-connected loop antenna formed of, planar concentric turns, cylindrical turns, or any three-dimensional geometric configuration, having turns that are closely spaced so as to exhibit strong mutual coupling effects. A lumped impedance, fixed or variable, is disposed at a selected point in the periphery of one or more turns, and a multi-position switch is interconnected between the turns and the lumped impedance to maximize efficiency. In accordance with the present invention, there is provided a miniaturized antenna capable of achieving high radiation efficiency such as 50% or more for a miniaturized antenna whose maximum dimension is less than 0.07λ over a 10 to 1 frequency range and having an impedance that can be easily adjusted to almost any desired value. The radiation pattern can be selected to conform to many desired coverages. When utilized for reception, the miniaturized receiving antenna converts incident fields into a maximal signal voltage at the input of a receiver over a frequency range of as much as 16 to 1 by utilizing the ability to control the antenna impedance. Being miniaturized, the receiving antenna can act as a probe in space so as to finely select and respond to a particular incident field in the presence of a number of simultaneous incident fields. In essence, it can reduce the undesirable "ghost" effect. Such a receiving antenna responds to both horizontally and vertically polarized fields. Hence, its physical attitude can be easily adjusted to provide polarization sensitivity. Accordingly, it is an object of my invention to provide a miniaturized transmitting antenna in a concentric multi-turn series-connected loop configuration, planar and non-planar, smaller than any other transmitting antenna presently known, where the radiation efficiency is an appreciable fraction of 100%. Another object of my invention is to provide a miniaturized transmitting antenna in a multi-turn series-connected loop configuration capable of covering frequency bands of as much as 16 to 1: (a) by the use of a single tuning condenser inserted in a single turn of the multi-turn loop; (b) by the use of switches to switch opens to shorts and vice-versa in one or more turns. A further object of my invention is to provide a transmitting antenna in which, regardless of size, a prescribed and desired field pattern and a desired impedance level can be easily adjusted by using inserted impedances, fixed and/or variable, in one or more turns of a multi-turn loop to select and/or repress particular current modes. Still another object of my invention is to provide a multi-turn series-connected loop antenna configuration for radiation and/or reception of electromagnetic waves in which turns can be connected in single spiral form, in double spiral form, in reversed turn form, and in partial turn form, so as to achieve characteristics such as broad-banding, field pattern control, impedance level control. Another object of my invention is to provide a miniaturized passive probe antenna in a concentric multi-turn series-connected loop configuration, planar and non-planar, for reception of VHF black and white and color TV and FM, with maximum loop antenna diameter being less than five inches. A further object of my invention is to provide a miniaturized passive probe antenna for VHF black and white and color TV and FM, capable of minimizing "ghosts" by universal adjustment of the plane of the multi-turn series-connected loop. Another object of the invention is to provide a miniaturized passive probe antenna for VHF black and white and color TV and FM which uses internal antenna tuning in the form of a single miniature tuning condenser inserted in one turn of a multi-turn series-connected loop to maximize the signal voltage developed across the input impedance of the TV or FM receiving set. A further object of my invention is to provide a miniaturized passive probe receiving antenna capable of covering frequency bands of as much as 16 to 1 by the use of switching configurations which change opens to shorts and vice-versa in one or more turns of a multi-turn series-connected loop antenna. A distinct and important advantage of the present invention is that the foregoing objects can be achieved through a frequency spectrum from a few hertz up to the point where physical limitations preclude practical embodiment which is about 5000 MHZ.

132 citations


Journal ArticleDOI
TL;DR: The gain of centrally obscured optical transmitting antennas is analyzed in detail and a number of auxiliary design curves are drawn that display the losses in antenna gain due to pointing errors and the cone angle of the beam in the far field as a function of antenna aperture size and its central obscuration.
Abstract: The gain of centrally obscured optical transmitting antennas is analyzed in detail. The calculations, resulting in near- and far-field antenna gain patterns, assume a circular antenna illuminated by a laser operating in the TEM(00) mode. A simple polynomial equation is derived for matching the incident source distribution to a general antenna configuration for maximum on-axis gain. An interpretation of the resultant gain curves allows a number of auxiliary design curves to be drawn that display the losses in antenna gain due to pointing errors and the cone angle of the beam in the far field as a function of antenna aperture size and its central obscuration. The results are presented in a series of graphs that allow the rapid and accurate evaluation of the antenna gain which may then be substituted into the conventional range equation.

127 citations


Journal ArticleDOI
01 Dec 1974
TL;DR: In this paper, a review of the microwave theory of phased array antennas is presented, emphasizing large planar arrays suitable for phased-array radar, and a necessary and sufficient condition for array blindness has been derived which removes a major uncertainty about the blindness effect.
Abstract: The microwave theory of phased-array antennas is reviewed, emphasizing large planar arrays suitable for phased-array radar. The review looks in detail at the three major parts of the antenna, namely, the element array, the phase shifters, and the feed system. The element array is studied by first modeling it as being infinite in extent and the concept of the per element absorption cross section and gain versus angle is developed. The technique of modal analysis using plane waves is explained and used to calculate the aforementioned quantities for waveguide and dipole elements. The review proceeds first through an analysis which applies to small elements, using a single element mode, and then to a more accurate solution containing the first higher mode in addition. The author has added new research to the review which explains the blindness effect for waveguide arrays. A necessary and sufficient condition for array blindness has been derived which removes a major uncertainty about the blindness effect. A result is that a blindness angle will always occur in E and H plane scanning of rectangular waveguide elements for any waveguide size, provided the array lattice is such as to permit a grating-lobe singularity by the simple one-element-mode theory. Elements large than some critical size are not required to produce blindness but the large size has the effect of producing greater shift of the blindness angle towards broadside from the grating lobe angle. The singularity in element admittance right at the grating lobe angle, which is a well-known milestone in the analysis of elements which have been modeled to support only one mode, is in reality a fiction. When higher modes are added to the solution, as is necessary for any physical element, the grating-lobe singularity is found to disappear. Thus for any real physical element, there is no grating lobe blindness, but the blindness angle is shifted inside of this angle by an amount which depends upon the element size. A review of element design calculations using many higher element modes is presented, and element configurations are shown which produce a good impedance match over a wide scan angle as well as a wide-frequency band. The application of the aforementioned results obtained from the infinite-array model to a practical, finite array are discussed. The theory of the most useful phase-shifter types for phased arrays is discussed, including those using both ferrite and semiconductor diodes. The ferrite toroid in a waveguide is a very effective design and the results of an optimization analysis for this configuration are presented. Choices of ferrite material parameters for low loss at both small and large signal levels are discussed. A method of reducing the temperature sensitivity of phase shift by means of the driver circuit is also reviewed. Semiconductor diode phase shifters have a greatly increased potential due to an improvement in diode reliability that has produced an expected mean life of 109h. The theory of phase-shifter operation using diodes in a balanced hybrid circuit is discussed and relations are given for bandwidth, loss, and power capability. The high-power limitation of the phase shifters is due to a nonlinear loss effect in the reverse biased state and is caused by the large RF voltages. The loss can be reduced by circuit techniques and by employing the new diodes of improved design, which are discussed. Feed systems for phased arrays are synthesized from a number of basic techniques according to the antenna applications. A few of the important techniques are reviewed here. Feed systems are required to produce an optimum aperture distribution for two types of patterns simultaneously, the sum pattern (Taylor distribution) and the difference pattern (Bayliss distribution). For the constrained feed, which uses transmission line throughout, two alternatives are presented for accomplishing the aforesaid. It is shown that the feed network can prevent reflections from the element array, which are always present to some degree, from adding an error component to the desired aperture distribution by employing 4-port power dividers which are provided with a reflection absorbing termination. An approximate method of wide-band beam steering is discussed in which a small number of time delay devices are used to feed subarrays of elements steered by conventional phase shifters. The subarray feeding technique is also employed in another application with the Butler beam forming matrix to form simultaneous multiple beams in an approximate manner that reduces the size of the beam forming matrix required. The space feed is an alternative to the constrained feed and distributes energy to the elements by free-space propagation. This method possesses great flexibility and may approach the capability of the constrained feed in secondary aperture performance by using a large number of feed elements. A design method of accounting for the near-field diffraction produced by the large feed is given.

99 citations


Journal Article
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


Journal ArticleDOI
TL;DR: In this paper, the reception theory for quasi-monochromatic partially polarized emissions is employed to describe the antenna temperature when observing a flat scene from within or above an absorbing/emitting atmosphere.
Abstract: The reception theory for quasi-monochromatic partially polarized emissions is employed to describe the antenna temperature when observing a flat scene from within or above an absorbing/ emitting atmosphere When the polarization aspects of the antenna and scene are carefully observed, the resulting integral expression for the antenna temperature differs significantly from that reported for polarization invariant temperature distributions It is observed that the antenna couples to both emitted surface polarizations, and the phase character of the antenna introduces a term involving the product of the polarized and cross-polarized antenna patterns A matrix approximation of the integral expression is suggested and developed as a means for inverting polarized antenna temperature observations for the underlying partially polarized apparent temperature distributions The resulting matrix formulation is interpreted and special cases are treated By means of sample cases, the cross-coupling effect between the antenna and the emitted field polarization vectors is illustrated When the polarization aspects of the radiometer and the scene are ignored, inversions for the apparent temperature are shown to suffer appreciably even for a highly efficient antenna The sensitivity of the matrix inversion technique to errors in the measurement vector is also examined

51 citations


Patent
17 Jan 1974
TL;DR: In this article, a selectively rotatably extendable sensitivity pattern provided by an array of three or more dipole antenna units, each of substantially equal mechanical length and located at the corners of a substantially regular polygon having the same number of sides as the number of units in the array, is described.
Abstract: Antenna having a selectively rotatably extendable sensitivity pattern provided by an array of three or more dipole antenna units, each of substantially equal mechanical length and located at the corners of a substantially regular polygon having the same number of sides as the number of units in the array and switching means having connections to each dipole unit to selectively energize at least one of said units and interpose an electrically-lengthening inductive reactance in at least two other units located, with respect to the direction in which the sensitivity is to be extended, behind and on either side of an energized unit to serve as parasitic reflectors extending the lobe of sensitivity of an energized unit in the selected direction.

36 citations


Book
01 Jan 1974

36 citations


Journal ArticleDOI
TL;DR: In this paper, a 21-km horizontal very-low frequency (VLF) antenna was constructed at Siple Station, Antarctica and the electrical properties of the ice layer beneath the antenna were modeled.
Abstract: A 21-km horizontal very-low frequency (VLF) antenna has been constructed at Siple Station, Antarctica. This antenna is to be used to inject VLF waves into the magnetosphere in order to perform wave particle interaction experiments. In the present paper, the properties of this antenna are analyzed and its impedance and efficiency calculated. The electrical properties of the ice layer beneath the antenna are modeled. The ice is represented by several layers, each with a different dielectric constant and conductivity. A variational method due to Galejs [2] for an antenna in a stratified dielectric is used. In this method the cylindrical antenna is replaced by an equivalent strip antenna so that the entire geometry is planar. The efficiency is calculated as a function of frequency for different lengths of the antenna. It is found that the antenna is most efficient near its antiresonant frequency. The optimum length for efficient operation at a given frequency is discussed. It is shown that the antenna has an efficiency greater than 2 percent over more than a 2 to 1 frequency range. Some advantages of the Siple antenna, as compared with other horizontal and vertical antennas, are pointed out.

35 citations


Patent
27 Aug 1974
TL;DR: An omnidirectional wideband antenna which operates with simultaneous horizontal and vertical polarisation consists of two truncated conductive cones which operate as a bi-conical antenna and each truncated cone is associated with a conductor array perpendicular to the axis of the cones.
Abstract: An omnidirectional wide-band antenna which operates with simultaneous horizontal and vertical polarisation consists of two truncated conductive cones which operate as a bi-conical antenna and each truncated cone is associated with a conductor array perpendicular to the axis of the cones. The conductors are in the form of logarithmic spirals.

32 citations


Patent
24 Jul 1974
TL;DR: In this article, a series resonant circuit with a transmission line connected in series with the circuit and having such a length that impedance matching may be obtained is presented. But the line length is not specified.
Abstract: In a receiving loop antenna especially adapted for use as a built-in antenna of a portable wireless set and of the type wherein the antenna output terminals are so tapped that power matching impedance of the wireless set may be attained, a circuit having series resonant circuit characteristics and a transmission line connected in series with the circuit and having such a length that impedance matching may be obtained, which may minimize the noise at or in the proximity of the center frequency of the frequency band of the series resonant circuit, are inserted between the antenna output terminals and the input terminals of the wireless set.

Journal ArticleDOI
TL;DR: In this paper, it was demonstrated theoretically and experimentally that a log-periodic monopole array with a meander-line feeder may be expected to exhibit high values of voltage standing-wave ratio.
Abstract: It is demonstrated theoretically and experimentally that a log-periodic monopole array with a meander-line feeder may be expected to exhibit high values of voltage standing-wave ratio. Improved match can be obtained by allowing the impedance of the feeder to go to a higher value near each monopole. A good match to 50 \Omega is achieved in this way.

Patent
04 Mar 1974
TL;DR: In this paper, an opto-electronic antenna system includes a plurality of transmitting/receiving antennas disposed over a prescribed geometrical surface such as a sphere, and an evaluation circuit is associated with each unit for determining the azimuth and elevation directions of received radiation.
Abstract: An opto-electronic antenna system includes a plurality of transmitting/receiving antennas disposed over a prescribed geometrical surface such as a sphere. To the antennas are optically coupled transmitter/receiver units such as photo-detectors or laser transmitters. The antenna units are scanned electronically according to their position on the geometrical surface by supplying to the individual units, signals differing in phase in accordance with the position of the antenna with which the units are associated both in the vertical and horizontal directions. An evaluation circuit is associated with each unit for determining the azimuth and elevation directions of received radiation.

Journal ArticleDOI
TL;DR: In this article, the mutual impedance method for determining the reflection from a loaded dipole array is extended to the case of two parallel planar dipole arrays, and the criteria for the validity of a simple transmission line solution are given.
Abstract: The mutual impedance method for determining the reflection from a loaded dipole array is extended to the case of two parallel planar dipole arrays. The dipole arrays are illuminated by a plane wave with arbitrary incidence angle in either the E - or H -plane. The specular reflection coefficient obtained is shown, with proper design, to have a more narrow stop band with steeper skirts and a flatter top than that for a single array. The near-field coupling is included in the analysis, and the criteria for the validity of a simple transmission line solution are given. For close spacings the near fields may cause the reflection coefficient curve to: 1) not reach unity reflection; 2) attain unity reflection at one frequency; or 3) attain unity reflection at two frequencies, with a shallow dip between. The type of resonance curve obtained depends on the spatial arrangement of the two arrays. The evaluation of the mutual impedance sums is greatly simplified by certain impedance relationships that are presented. Calculated and measured reflection curves for various array separations are included.

Journal ArticleDOI
01 Sep 1974
TL;DR: In this paper, an orthogonal solution of the general non-uniformly spaced antenna array by the orthogonality method was given, when the array factor f(ϕ, ϑ) is given.
Abstract: An effort is made to give a solution of the general non-unifomly spaced antenna array by the orthogonal method when the array factor f(ϕ, ϑ) is given.

Journal ArticleDOI
TL;DR: In this article, a method to determine accurately the strength of magnetic fields produced by a transmitting small loop antenna for the RF field standards is presented, which can be determined by the magnetic dipole moment of the loop.
Abstract: A method to determine accurately the strength of magnetic fields produced by a transmitting small loop antenna for the RF field standards is presented. The field strength can be determined by the magnetic dipole moment of the loop. A loop antenna factor is introduced to express the magnetic dipole moment of a transmitting small loop antenna in terms of the incident power to the antenna input port. The emergent power from the output port of a receiving small loop antenna can also be expressed in terms of the magnetic field to be detected and of the loop antenna factor. The insertion loss method (or the three antenna method) is applied to measuring the loop antenna factor. Small loop antennas with diameters 10 cm were designed, and loop antenna factors were measured by the insertion loss method over frequencies up to 30 MHz with a systematic error of 0.08 dB.

Patent
04 Feb 1974
TL;DR: In this article, a single length of insulated, stranded steel cable extends vertically through a bin or other material container and functions as a radiating antenna for an electrical signal transmitter, which is inductively linked to an oscillator circuit in the transmitter.
Abstract: A single length of insulated, stranded steel cable extends vertically through a bin or other material container and functions as a radiating antenna for an electrical signal transmitter. The reactance of the antenna, which varies as a function of the level of material in the container adjacent the antenna, is inductively linked to an oscillator circuit in the transmitter. The transmitter's signal which is altered in frequency with changes in the antenna's reactance is combined with that of a constant frequency reference signal. The frequency of the resulting difference signal is employed to form a remote indication of the material level and to provide control information for automatically maintaining or varying material levels.

Journal ArticleDOI
01 Oct 1974
TL;DR: In this paper, a rigorous derivation of the power-reciprocity theorem in antenna theory is presented, which relates the absorption cross-section of the load in the receiving situation to the power gain of the antenna in the transmitting situation.
Abstract: A rigorous derivation of the power-reciprocity theorem in antenna theory is presented. It relates the absorption cross-section of the load in the receiving situation to the power gain of the antenna in the transmitting situation. The most general case is considered, namely (a) the materialof which the antenna is made may be lossy, anisotropic and inhomogeneous, if only linear in its electromagnetic behaviour, (b) the vectorial amplitude radiation characteristic of the antenna in the transmitting situation and the incident plane wave in the receiving situation may be arbitrarily elliptically polarised, and (c) the impedance of the load in the receiving situation may be arbitrarily mismatched to the input impedance of the antenna in the transmitting situation. Therefore the known, restricted form of the theorem is generalised; also some notions are made more precise. As a corollary, a generalised theorem is presented as to the average value of the absorption cross-section of the load taken over all directions of incidence.

Patent
29 Jul 1974
TL;DR: In this article, a short dipole antenna array with a switch between each two segments is used to control the directivity, reflectivity, transparency and tuning of R.F. antennas.
Abstract: Control of the directivity, reflectivity, transparency and tuning of R.F. antenna array is accomplished by building antenna with short dipole segments with a switch between each two segments. The elements are properly connected to exhibit these electrical characteristics by remotely controlling the closing and opening of selected switches. The means for controlling the switches is isolated from the R.F. working frequencies of the antenna.STATEMENT OF GOVERNMENT INTEREST

Patent
24 Apr 1974
TL;DR: In this article, a cylindrical array antenna is described, where rows of antenna elements disposed about the periphery of the antenna each include a feed network coupled to a monopulse arithmetic unit through a radial line power divider and a hemispherical sector selector switching network.
Abstract: A cylindrical array antenna is disclosed wherein rows of antenna elements disposed about the periphery of the antenna each include a feed network coupled to a monopulse arithmetic unit through a radial line power divider and a hemispherical sector selector switching network. Monopulse "sum" and circumferential "difference" patterns are obtained by dividing a selected hemispherical sector into four adjacent antenna aperture segments. The antenna elements associated with alternate antenna aperture segments are coupled to the arithmetic unit in like polarity and the antenna elements associated with adjacent antenna aperture segments are coupled to such arithmetic unit in opposite polarity. With such arrangement cross-polarization or "null filling" effects associated with the cylindrical array antenna are reduced.

Journal ArticleDOI
TL;DR: In this paper, the design procedure for the log-periodic dipole (LPD) antenna is discussed, by extending the results presented in a previous paper by the authors The results of gain calculations, already published, are summarized and extended to cases of very thick dipoles The gain analysis is completed with a discussion of the optimum antenna input feed line, the achievable VSWR, the voltage gradient, and the effects of the presence of the ground.
Abstract: The design procedure for the log-periodic dipole (LPD) antenna is discussed, by extending the results presented in a previous paper by the authors The results of gain calculations, already published, are summarized and extended to cases of very thick dipoles The gain analysis is completed with a discussion of the optimum antenna input feed line Z_{0}' the achievable VSWR, the voltage gradient, and the effects of the presence of the ground All the results of calculations given here are presented as a function of Z_{0} (the characteristic impedance of the transmission line feeder), h/a (the ratio between the half-length and the radius of the dipoles), \tau (the logarithmic decrement of the geometrical configuration), and \sigma (the spacing ratio of dipoles), ie, the parameters, which usually describe the geometry of an LPD array The results of calculations are presented in many diagrams, for different values of \tau,\sigma, Z_{0} and h/a , which can be useful for accurate design of LPD antennas including those for high-power applications Measurements of VSWR performed on antenna models have confirmed the computed results

Journal ArticleDOI
TL;DR: The most common antenna pattern observed at the fixed operating frequency, 300 kHz, was a dominantly biconic pattern with major axis parallel to the geomagnetic field as discussed by the authors.
Abstract: Near-field patterns of a short electric dipole antenna were measured in the magnetospheric plasma by an instrument aboard the polar orbiting satellite OV1-20S. The most common antenna pattern observed at the fixed operating frequency, 300 kHz, was a dominantly biconic pattern with major axis parallel to the geomagnetic field. The measured cone angles are in reasonable agreement with those predicted by warm plasma theory. There was no discernible systematic asymmetry in these angles such as could be attributed to field-aligned currents in the plasma or to the motion of the satellite through it.

Patent
23 Oct 1974
TL;DR: In this paper, a double omni-directional antenna for use with a transponder is disclosed allowing simultaneous operation within two different frequency bands, and a double coaxial line is provided having outer, central, and inner concentric conductors.
Abstract: A double omni-directional antenna for use with a transponder is disclosed allowing simultaneous operation within two different frequency bands. A double coaxial line is provided having outer, central, and inner concentric conductors. The outer and central conductors form a coaxial feed for a lower frequency antenna and the central and inner connectors form a coaxial feed for a high frequency antenna. The higher frequency antenna is located directly above the lower frequency antenna and each is either a unipole for vertically polarized radiation or a slot radiator for horizontally polarized radiation.

Patent
22 May 1974
TL;DR: In this paper, a dipole array consisting of at least two dipole antennas mounted one above the other in a generally vertical plane, having respective pairs of radiating elements substantially aligned on a common generally vertical axis and being fed from respective radio signal sources by the respective feed lines directed along the common vertical axis through the various radiating element.
Abstract: A dipole array consisting of at least two dipole antennas mounted one above the other in a generally vertical plane, having respective pairs of radiating elements substantially aligned on a common generally vertical axis and being fed from respective radio signal sources by the respective feed lines directed along the common vertical axis through the various radiating elements and being configured to also include a cable choke section on either side of the lower antenna as well as a cable choke section below the upper antenna An isolator section comprised of a plurality of series connected cable choke sections are located intermediate each dipole antenna Additionally, an impedance characteristic compensating network consisting of a predetermined length of transmission line is connected to each dipole feed line within one of the radiating elements of each dipole antenna



Journal ArticleDOI
TL;DR: In this paper, the impedance of a short dipole antenna has been computed using the quasistatic approximation, a triangular current distribution, and the full adiabatic hydrodynamic description of the plasma.
Abstract: The impedance of a short dipole antenna has been computed using the quasistatic approximation, a triangular current distribution, and the full adiabatic hydrodynamic description of the plasma. Some typical results are presented which show that for parameters typical of the ionosphere the temperature affects mainly the radiation resistance.


Proceedings Article
01 Jan 1974
TL;DR: The chain antenna as mentioned in this paper is a traveling wave antenna, which consists of a ground plane close to which is a chainshaped conductor along which propagates a TEM wave, and the loops of the chain are rectangular with typical dimensions of 0.4 wavelength times one wavelength.
Abstract: A novel traveling wave antenna, the chain antenna, is described. It consists of a ground plane close to which is a chainshaped conductor along which propagates a TEM wave. The loops of the chain are rectangular with typical dimensions of 0.4 wavelength times one wavelength. Several chain antennas can be connected in parallel giving a grid antenna. The grid antenna has a linearly polarized frequency scannable pencil beam and only one feed point per hundreds of radiating elements which makes it especially suitable for HF, VHF and UHF frequencies when high gain antennas are needed.

Proceedings ArticleDOI
J. Howell1
10 Jun 1974