IEEE Transactions on Antennas and Propagation

Issue 6 • November 1977

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Displaying Results 1 - 25 of 44
  • [Front cover and table of contents]

    Publication Year: 1977, Page(s): 0
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    Freely Available from IEEE
  • Mutual coupling coefficients in collector arrays on circular cylindrical concave surfaces

    Publication Year: 1977, Page(s):741 - 747
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (645 KB)

    An analysis is presented of mutual coupling in collector arrays on a concave side of a large conducting circular cylindrical surface. The collector elements are uniformly spaced narrow axial slits which are parallel-plate-guide-fed in the TEM mode. Each element is equipped with a matching network appropriate to broadside scan in the corresponding planar slit array. The properties of coupling coeff... View full abstract»

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  • Impedance-match and element-pattern constraints for finite arrays

    Publication Year: 1977, Page(s):747 - 755
    Cited by:  Papers (14)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (697 KB)

    It is shown how anN-element antenna array may in principle be impedance matched by means of a specially designed interconnecting feed network toNreal generators (for arbitrary excitation of these generators). The resulting element patterns for a single excited element (a single generator) in the terminated-array environment are then calculated. It is shown that for closely sp... View full abstract»

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  • Currents induced in a wire cross by a plane wave incident at an angle

    Publication Year: 1977, Page(s):775 - 781
    Cited by:  Papers (12)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (548 KB)

    The currents induced in a thin-wire cross with equal mutually perpendicular arms by an incident plane electromagnetic wave are determined when the normal to the wave front is perpendicular to the horizontal wire and is at an anglethetawith respect to the vertical wire; the direction of the electric vector in the wave front is arbitrary. The analysis is formulated in general terms but ex... View full abstract»

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  • An approach to high-frequency scattering from smooth convex surfaces

    Publication Year: 1977, Page(s):781 - 788
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (756 KB)

    A method based on the Galerkin procedure in the transform domain that not only allows accurate solutions for both the farfield and the induced surface current be derived but also provides a convenient accuracy check for the solutions thus obtained is introduced. The total solution is constructed using only the geometrical optics method and a newly introduced synthetic aperture technique well suite... View full abstract»

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  • Plane wave pulse propagation through random media

    Publication Year: 1977, Page(s):822 - 828
    Cited by:  Papers (26)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (623 KB)

    The theory of plane wave pulse propagation through a random medium, under the forward-scattering assumption is presented. Since pulse propagation characteristics are determined by two-frequency mutual coherence functionGamma, a set of normalized curves is given forGammafor different propagation parameters (operating frequency, propagation distance, turbulence strength or dens... View full abstract»

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  • A short horn with high E-plane directivity

    Publication Year: 1977, Page(s):854 - 859
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (502 KB)

    TheE-plane beamwidth of a small pyramidal horn can be substantially reduced by the addition of paxabolic cylinder flanges of the proper focal length. Analysis of this antenna involves both geometrical diffraction theory and conventional aperture techniques. In the numerical and experimental examples chosen the flanges halve the half-power beamwidth without severe bandwidth reduction. Co... View full abstract»

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  • Comments on "Calculation of the radiation resistance of loop antennas with sinusoidal current distribution"

    Publication Year: 1977, Page(s):900 - 901
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (167 KB)

    Richtscheid's paper (see ibid., vol.24, p.889-891, Nov. 1976) used the far zone Poynting power to determine the radiation resistance. The same calculation has been carried out using the conventional induced EMF method (see Sci. Rep. RITU B, vol.9, p.9-10 (1957) and p.79-103, similarly Electrons and Communications in Japan, vol.52-B, p.73-80 (1969)) View full abstract»

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  • A practical method for the numerical evaluation of Sommerfeld integrals

    Publication Year: 1977, Page(s):904 - 906
    Cited by:  Papers (21)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (307 KB)

    Sommerfeld integrals, which appear frequently in dipole radiation problems, often must be evaluated numerically. Gauss-Laguerre quadrature is an effective integration method, provided the horizontal distancerhofrom the source to the receiver is less than their vertical separationzeta. A complementary method is to use Romberg adaptive quadrature to integrate over the positive ... View full abstract»

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  • Comments on "Electromagnetic excitation of a wire through an aperture-perforated conducting screen"

    Publication Year: 1977, Page(s):907 - 908
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (210 KB)

    Comments on paper (see ibid., vol.24, p.456-462 July (1976)) and authors' reply View full abstract»

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  • Comments on "New plane wave spectrum formulations for the near-fields of circular and strip apertures"

    Publication Year: 1977, Page(s):908 - 912
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (478 KB)

    The above paper (see ibid., vol.24, p.438-449, July (1976)) applies a plane wave spectrum (PWS) formulation to diffraction problems involving circular and strip apertures and gives new results in terms of Fresnel integrals for the electric field near the aperture. In this note, a discussion of those new results is presented; conclusions are: As a technique for solving electromagnetic aperture diff... View full abstract»

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  • [Back cover]

    Publication Year: 1977, Page(s): c4
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    Freely Available from IEEE
  • Scattering of a surface wave from a curvature discontinuity on a convex impedance surface

    Publication Year: 1977, Page(s):796 - 801
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (520 KB)

    An asymptotic "boundary-layer" set of quasimodes is constructed for the representation of fields in the vicinity of a convex reactive surface, whose formal structure is the same as that of the exact modes for the corresponding straight surface. These quasimodes are then used to solve for the scattering of a surface wave at a curvature discontinuity in a reactive surface. The present approach is a ... View full abstract»

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  • A 50-ohm input impedance for helical beam antennas

    Publication Year: 1977, Page(s): 913
    Cited by:  Papers (18)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (91 KB)

    A helical beam antenna with uniform conductor size has a nominal impedance of 140 ohms. This may not be convenient for some applications. The purpose of this note is to call attention to the fact that the impedance can be adjusted to 50 ohms by increasing the conductor size close to the feed point at the ground plane. This lowers the characteristic impedance of the conductor-ground plane combinati... View full abstract»

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  • Transmission of horizontally polarized waves and trapped waveguide modes in inhomogeneous media

    Publication Year: 1977, Page(s):807 - 813
    Cited by:  Papers (10)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (608 KB)

    A generalized Wentzel-Kramer-Brillouin (WKB) approach is used to obtain full wave solutions for horizontally polarized waves in inhomogeneous media when no closed form analytic solutions are known. This approach is suitable for complex permittivity profiles with critical coupling regions even when the permittivity gradient approaches zero. The transmission and reflection coefficients and the chara... View full abstract»

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  • Bandwidth of a Yagi array with optimum directivity

    Publication Year: 1977, Page(s):913 - 914
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (184 KB)

    The frequency bandwidth of a Yagi array is studied. It is found that when the array is optimized for maximum forward gain by adjusting the interelement spacings, the frequency bandwidth is reduced only slightly. View full abstract»

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  • A mathematical model for the impedance of the cavity-backed slot antenna

    Publication Year: 1977, Page(s):829 - 833
    Cited by:  Papers (14)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (504 KB)

    A mathematical model is derived that relates the impedance of a cavity-backed slot antenna to that of an identical slot which is free to radiate on both sides of a large ground plane. The model, which utilizes empirical constants from a previous experimental investigation, provides a continuously variable function of frequency and cavity depth for the impedance of a cavity-backed slot of fixed len... View full abstract»

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  • Superconducting superdirectional antenna arrays

    Publication Year: 1977, Page(s):885 - 887
    Cited by:  Papers (19)  |  Patents (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (288 KB)

    Electrically and physically small antenna arrays in a superconducting state can be used to obtain a radiation pattern of moderate directivity with high radiation efficiency. The loss resistance is reduced by several orders of magnitude, and superdirectivity is achieved with a loop antenna array. Radiation beamwidth depends upon only the number and relative phase of the loops and is independent of ... View full abstract»

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  • A surface formulation for characteristic modes of material bodies

    Publication Year: 1977, Page(s):789 - 795
    Cited by:  Papers (141)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (440 KB)

    A theory of characteristic modes for material bodies is developed using equivalent surface currents. This is in contrast to the alternative approach using induced volume currents. The mode currents form a weighted orthogonal set over the material body surface, and the mode fields form an orthogonal set over the sphere at infinity. The characteristic modes of material bodies have most of the proper... View full abstract»

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  • On the use of active coupling networks with electrically small receiving antennas

    Publication Year: 1977, Page(s):841 - 845
    Cited by:  Papers (13)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (488 KB)

    An analysis of the noise performance of an active receiving antenna system consisting of an antenna, active coupling network, and high-gain preamplifier is described. It is shown how this noise performance can be described by circular loci in the output-impedance plane of the coupling network. These loci are not restricted to the right-half plane. A coupling network having an output impedance in t... View full abstract»

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  • A model for microwave intensity propagation in an inhomogeneous medium

    Publication Year: 1977, Page(s):876 - 882
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (656 KB)

    A combined analytic and phenomenological approach, utilizing Maxwell's equations in the Born approximation with radiative transfer theory, is used to describe the propagation of microwave intensity in a scattering medium characterized by three-dimensional random fluctuations in refractive index, as well as nonrandom variations in permittivity, temperature, and loss. This approach yields microwave ... View full abstract»

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  • Scattering by periodic metal surfaces with sinusoidal height profiles--A theoretical approach

    Publication Year: 1977, Page(s):869 - 876
    Cited by:  Papers (25)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (768 KB)

    A theory of scattering by periodic metal surfaces is presented that utilizes the physical optics approximation to determine the current distribution in the metal surface to first order, but modifies this approximate distribution by multiplication with a Fourier series whose fundamental period is that of the surface profile (Floquet's theorem). The coefficients of the Fourier series are determined ... View full abstract»

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  • Propagation of VHF and UHF electromagnetic waves over a grove of trees in full leaf

    Publication Year: 1977, Page(s):866 - 869
    Cited by:  Papers (12)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (400 KB)

    Results are reported of horizontally polarized signal strength measurements at frequencies of 82,210,633, 1280, and 2950 MHz. Measurements of signal strength versus height were made at various distances behind a grove of live oak and hackberry trees in full leaf. Propagation took place over approximately the same path neat the receiver terminal at all frequencies. Ideal knife edge diffraction curv... View full abstract»

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  • Coupled Yagi arrays

    Publication Year: 1977, Page(s):889 - 891
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (304 KB)

    The purpose of this study is to obtain the optimum design of a three-row Yagi array antenna under constraints on bandwidth, directivity, or the length of the array. It is shown that the array configuration is determined if any two of these contraints are specified. It is also shown that a properly designed coupled Yagi array can be operated at certain frequency band with higher directivity and wid... View full abstract»

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  • Aberration of a microwave holographic imaging system over a line-of-sight propagation path

    Publication Year: 1977, Page(s):860 - 863
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (344 KB)

    The spherical aberration inherent in a microwave holographic imaging system proposed in previous papers [1], [2] for application over a line-of-sight propagation path is described. The relation between the spherical aberration and various parameters, such as the effective earth-radius factor, the path length, etc., is calculated and plotted. The limitations and the applicability of this holographi... View full abstract»

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IEEE Transactions on Antennas and Propagation includes theoretical and experimental advances in antennas.

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Editor-in-Chief                                             Danilo Erricolo