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Antennas and Propagation, IRE Transactions on

Issue 1 • Date Jan. 1956

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Displaying Results 1 - 22 of 22
  • Table of contents

    Publication Year: 1956 , Page(s): 1 - 2
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  • News and views

    Publication Year: 1956 , Page(s): 1 - 4
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  • Exterior electromagnetic boundary value problems for spheres and cones

    Publication Year: 1956 , Page(s): 5 - 16
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    The problem of determining a harmonic time-varying electromagnetic field where the electric vector assumes prescribed values for its tangential components over given spherical or conical boundaries and which has proper radiation characteristics at infinity is considered by a procedure very much like that used in the theory of slots in waveguide walls. The technique used in solving this type of boundary value problem is to establish, by an application of the Lorentz Reciprocity Theorem, a Green's function which represents the electric and magnetic fields of a point generator (infinitesimal dipole) applied at an arbitrary position on the conducting surface where the fields satisfy homogeneous boundary conditions. The total fields for an arbitrary source are then obtained by superposition; i.e., direct integration over the aperture. Since detailed results for the case of a sphere have been obtained by many authors, we confine the details of the technique to the infinite cone. It is assumed that in each case the tangential components of the electric vector are given functions over the entire boundary surface. The results apply directly to the theory of radiating apertures in a perfectly conducting spherical wall or a cone, since the tangential components of the electric vector are different from zero only in the area of the aperture, where it is presumed they are known. The results are also applicable to scattering by conducting spheres and cones, since the tangential electric field components over the boundary surfaces are the negative of those of the incident field. To illustrate the applicability and the limitations of the results, we shall present the formal solutions for arbitrarily shaped apertures on cones and apply them to the several types of delta slots which are usually discussed in connection with other radiating structures. View full abstract»

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  • Analysis of a terminated-waveguide slot antenna by an equivalent circuit method

    Publication Year: 1956 , Page(s): 16 - 26
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    The pattern in a half-space of a slot in the wall of a waveguide is a function of the terminating impedance. The description of the far fields in such a configuration is simplified considerably by the adoption of a network viewpoint, whereby the half-space is represented approximately by two (or more) spherical transmission lines, the feeding waveguide by a single uniform transmission line, and the slot by a coupling network which is directly analogous to that for a hybrid junction. For a given waveguide termination, the spherical mode voltages are computed by a simple network calculation, and the gain pattern is obtained by modal synthesis. The slot equivalent circuit parameters are obtained readily by simple measurements or from available theoretical formulas. Described in detail both theoretically and experimentally is a symmetric rectangular slot cut in either the broad or narrow face of a rectangular waveguide. View full abstract»

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  • An experimental study of the disk-loaded folded monopole

    Publication Year: 1956 , Page(s): 27 - 28
    Cited by:  Papers (1)
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    Data is presented to show the reduction in size and increase in radiation resistance and bandwidth of the disk-loaded folded monopole as compared with a disk-loaded monopole of the same electrical length. The ratio of diameters of the folded part to the diameter of the driven part was varied for one series of impedance measurements and the axial spacing between the driven part and folded part was varied for another series. The resonant radiation resistance and resonant length may be varied almost independently. The radiation resistance depends upon the ratio of diameter of the folded part to the diameter of the driven part, and the resonant length depends upon axial spacing. The radiation resistance multiplication factor relative to a disk-loaded monopole of the same electrical length is approximately the same as the multiplication factor of a folded dipole relative to a dipole. The disk-loaded folded monopole has a greater bandwidth than an unloaded monopole of the same wavelength-to-diameter ratio. Where the effective diameter1 of the folded antenna is ¿2DdS, its radiation pattern is essentially that of an unloaded monopole. View full abstract»

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  • Some data for the design of electromagnetic horns

    Publication Year: 1956 , Page(s): 29 - 31
    Cited by:  Papers (1)
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    Using an idea recently suggested by the author,1 a table is presented from which the gain of all electromagnetic horns may be calculated with substantially the same accuracy obtainable using the gain formula. The exact parameters of an optimum horn are given, and a simple procedure for the design of optimum horns with a specified gain and other desirable properties is described. View full abstract»

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  • Measured performance of matched dielectric lenses

    Publication Year: 1956 , Page(s): 31 - 33
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    Two microwave lenses whose surfaces have been matched respectively by embedded capacitive walls and by simulated quarter-wave transformers were built and compared experimentally to an unmatched lens of identical aperture and focal length. At the design frequency, the matched lenses exhibited reductions in side-lobe level of 14 and 10 db with respect to the unmatched lens, and increases in over-all gain of 0.35 and 0.1 db. The input vswr of the feed horn was reduced from 1.6 for the unmatched case to 1.02 and 1.05 for the matched cases. The bandwidth of good performance for the two lenses ranged from lö per cent to at least 44 per cent View full abstract»

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  • Microwave lens matching by simulated quarter-wave transformers

    Publication Year: 1956 , Page(s): 33 - 39
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    The reflections from the surface of a dielectric lens may be cancelled by a quarter-wavelength layer of refractive index intermediate between that of air and the lens medium. The possibility of simulating a quarter-wave matching section by perturbing the boundary of the lens is described in this paper. Some of the configurations considered are corrugated surfaces, arrays of dielectric cylinders, and arrays of holes in the dielectric surface. In each case, a match may be obtained at a given frequency and angle of incidence by the proper adjustment of the depth of the perturbation, and of one other parameter such as the width of a groove. View full abstract»

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  • A mechanically simple Foster scanner

    Publication Year: 1956 , Page(s): 40 - 46
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    This paper describes the design, construction, and testing of a Foster scanner that is much simpler to build than the conventional Foster scanner. The simplifications result from the use of a choke groove and a solid barrier to replace the conventional inter-leaving finger barriers. The choke groove and solid barrier are very simple to construct, give excellent electrical performance, and permit very high scan rates. A scanner has been built and tested at 35 kmc, where the tolerance problems are very severe, and found to perform extremely well over at least a 10 per cent frequency bandwidth. View full abstract»

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  • Surface currents excited by an infinite slot on half-planes and ribbons

    Publication Year: 1956 , Page(s): 47 - 50
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    The distribution of surface current density on a perfectly conducting half-plane excited by an infinite axial slot is determined. The slot is assumed to be of small width and it is excited throughout its length by a uniform transverse voltage. It is shown that the surface currents which flow toward the edge of the half-plane are somewhat smaller than they would be if they were on an infinite plane. For sake of comparison the surface currents of an infinite axial slot on a thin elliptic cylinder or ribbon are also examined View full abstract»

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  • Radar back-scattering cross sections for nonspherical targets

    Publication Year: 1956 , Page(s): 51 - 53
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    Studies were made of the scattering of electromagnetic waves from nonspherical targets by making exact determination of the nose-on radar back-scattering cross sections of conducting prolate spheroids of various sizes and shapes. Curves are given for the back-scattered cross sections as a function of dimensionless size and shape parameters for prolate spheroids. The results are compared with the Rayleigh-Gans first order approximation and Stevenson's third-order approximation, and the range of applicability of these approximations is evaluated. View full abstract»

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  • An experimental investigation of cavity-mounted helical antennas

    Publication Year: 1956 , Page(s): 53 - 58
    Cited by:  Papers (2)
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    This paper presents the results of an experimental investigation which led to the development of cavity-mounted helical antennas for airborne applications. The effects on patterns and impedance of various antenna parameters, such as number of turns, cavity size and shape, helix pitch, angle, and conductor size, were investigated. Methods of feeding the helix which produce an input impedance near 50 ohms, without external compensation, throughout the axial mode frequency range are discussed. Some of the types of cavity-mounted helices developed and typical performance data are described. View full abstract»

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  • Radiation patterns of unsymmetrically fed prolate spheroidal antennas

    Publication Year: 1956 , Page(s): 58 - 64
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    This paper describes the radiation pattern of the un-symmetrically-fed prolate spheroidal transmitting antenna. Maxwell's equations are solved in prolate spheroidal coordinates subject to the boundary conditions. The prolate spheroidal functions are expressed in the form of power series and Laurent series. Radiation patterns have been obtained for antennas of three different lengths up to about one wavelength long, for length/thickness ratios of about 5/1, 10/1,22/1, and 316/1, and for nine unsymmetrical gap locations as well as for the symmetrically-fed cases. It was found that the two most important factors affecting the radiation pattern of a fairly thin antenna were the location of the gap and the electrical length. For antennas less than a half wavelength long, the pattern was the usual symmetrical figure eight and was essentially independent of the location of the gap (except for magnitude changes due to the different gap impedances). For antennas two-thirds to three-quarters of a wavelength long the figure eight patterns could be "bent" in the direction of the longer element, and for antennas one wavelength long or longer minor lobes began to appear. View full abstract»

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  • Optical Fresnel-Zone gain of a rectangular aperture

    Publication Year: 1956 , Page(s): 65 - 69
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    An equation for the on-axis gain of a uniformly illuminated rectangular aperture is derived which is valid in the "Optical Fresnel Zone." This equation is formulated in terms of the ordinary radiation field gain multiplied by a correction factor which depends upon the aperture dimensions and the distance, R, from the aperture at which the gain is measured. A table of the function [C2(v)+S(v)]/v2 is given; C(v) and S(v) being the Fresnel integrals. The gain of a square aperture (LXL meters) in the Fresnel-zone region is compared with the gain of a circular aperture and it is shown that for apertures of equal Gsquare < Gcircle when (L2/¿) View full abstract»

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  • Some relationships between total scattered power and the scattered field in the shadow zone

    Publication Year: 1956 , Page(s): 69 - 71
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    Equations are derived which relate the far-zone scattered field, as measured in the shadow zone of an electromagnetic scatterer, to the total energy scattered and absorbed by the scatterer. In the case of a perfectly conducting scatterer, the energy stored in the fields about the scatterer is also related to the far-zone scattered field in the shadow zone. View full abstract»

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  • Long range meteoric echoes via F-layer reflections

    Publication Year: 1956 , Page(s): 72 - 76
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    This note reports HF observations of meteoric back-scatter echoes at ranges greatly exceeding radio line-of-sight. The observations were part of a program of measurements on backscatter using COZI equipment, Examples are given of observations at South Dartmouth, Massachusetts in 1949 on 16 mc and of more recent observations in 1954 on 12 and 16 mc using improved equipment. Short duration echoes are observed in advance at ranges shorter than those of the ground backscatter. No such meteoric echoes are observed when the ground backscatter disappears. The meteoric echo ranges move with time of day just as the range to the ground backscatter moves. A plausible explanation for the observed meteoric echo ranges exceeding 1,000 miles is that they are due to backscatter from the trail, ionospherically propagated to and fro via the F region, just as the ground backscatter. Other possible ionospheric propagation modes are discussed View full abstract»

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  • Correlation in VHF propagation over irregular terrain

    Publication Year: 1956 , Page(s): 77 - 85
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    A study has been made of the correlation in transmission loss observed over irregular-terrain paths. Simultaneous mobile measurements were made of two pairs of VHF broadcasting stations in the Washington, D. C-Baltimore, Maryland area. The correlation coefficients derived from sample sets of transmission loss data indicate that when reception is from opposite directions, no significant correlation is evident, and when the paths of propagation are the same even though the frequencies are separated considerably, the correlation appears to be significantly high. View full abstract»

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  • Control of surface currents by the use of channels

    Publication Year: 1956 , Page(s): 85 - 87
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    THE PRESENCE of radiation in the shadow zone of an antenna depends upon surface currents that flow away from the optically lighted region. Minimizing this shadow illumination requires control of these surface currents. For example, even with a large cylinder (circumference =40¿) excited by an infinite axial slot, the shadow zone of the theoretical pattern has maxima 90° from the slot which are down only 3 db, and others 180° away only 28 db below the power level at 0°. This paper is an experimental study of methods of controllino: shadow zone illumination. View full abstract»

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  • The impossibility of certain desirable luneberg lens modifications

    Publication Year: 1956 , Page(s): 87 - 88
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    THE DIFFICULTY of rapid scanning over the outer surface of a Luneberg lens has led Gutman1 to devise a lens in which the feed moves on a smaller radius. In Gutman's lens the feed horn points toward the center of the lens and the center section, which rotates during the scan, also serves as a focusing region. In some applications it would be desirable to point the feed horn outward and reserve this center section for rf components. The rotational torque required could also be reduced considerably thereby. We assume throughout that the lens must be radially symmetric to allow 360° of scan. View full abstract»

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  • ¿Fresnel antenna patterns¿

    Publication Year: 1956 , Page(s): 89 - 90
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    D. K. Cheng.:1 In a recent article, Lechtreck presented a number of radiation patterns for rectangular apertures with quadratic phase errors. I would like to make several comments about that article. View full abstract»

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  • Summary of normal mode theory symposium

    Publication Year: 1956 , Page(s): 90 - 94
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    A SYMPOSIUM on Normal Mode Theory was convened, under the chairmanship of Dr. S. A. Schelkunoff, at the Navy Electronics Laboratory on July 5, 6, and 7, 1955. This symposium consisted of an informal trip to Palomar Mountain on July 5 and a round-table discussion on July 6¿7 for the purpose of exchanging ideas about the present state of theoretical knowledge of wave propagation through stratified media, the known methods of attack, and the outstanding unanswered questions. Although the emphasis was on normal mode theory, the possibility of extending the ray theory of physical optics was explored. The following list of topics was on the agenda: View full abstract»

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  • Contributors

    Publication Year: 1956 , Page(s): 95 - 100
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Aims & Scope

The Transactions ceased publication in 1962. The current retitled publication is IEEE Transactions on Antennas and Propagation.

Full Aims & Scope