IEEE Transactions on Antennas and Propagation

Volume 25 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 (25)
    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
  • Transient and time-harmonic diffraction by a semi-infinite cone

    Publication Year: 1977, Page(s):802 - 806
    Cited by:  Papers (12)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (328 KB)

    New representations for the time-dependent scalar Green's functions for a perfectly conducting semi-infinite cone are derived. When the cone angle is small and the source is located on the cone axis, the solutions for all observation times can be expressed in remarkably simple closed forms involving only elementary functions. New elementary time-harmonic Green's function approximations, valid for ... View full abstract»

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  • Incorporation of edge conditions in moment method solutions

    Publication Year: 1977, Page(s):845 - 850
    Cited by:  Papers (55)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (536 KB)

    The use of an edge condition in moment method solutions is investigated. Using as an example TM scattering by a strip, various numerical schemes for treating the edge behavior are examined for low frequencies where an analytical solution of the quasi-static integral equation is available for comparison. The same numerical techniques are then applied in the general dynamic case. It is found that fa... 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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  • Sidelobe reduction of circular arrays with a constant excitation amplitude

    Publication Year: 1977, Page(s):896 - 898
    Cited by:  Papers (27)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (280 KB)

    It is shown that the sidelobe level of circular arrays with a constant excitation amplitude can be reduced by adjusting the excitation phases of array elements. The resulting radiation pattern has equal-ripple sidelobes similar to a Chebyshev pattern. Examples are given. View full abstract»

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  • Geophysical subsurface probing of a two-layered uniaxial medium with a horizontal magnetic dipole

    Publication Year: 1977, Page(s):766 - 769
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (264 KB)

    The use of a horizontal magnetic dipole antenna with the electromagnetic interference fringes method is investigated. The radiation patterns due to the dipole placed on the surface of a uniaxial medium are plotted in both the broadside and the endfire directions. In the broadside direction there are very sharp peaks which can give rise to distinctive features in the interference plot. The interfer... View full abstract»

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  • Network parameter measurements of antenna arrays

    Publication Year: 1977, Page(s):760 - 766
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (520 KB)

    A new method is developed for determining the admittance or the scattering parameters of an antenna array considered as a multiport network. The technique requires the use of a hybrid junction to provide two different modes of excitation at the antenna ports taken in pairs. It is shown that by measuring the reflection coefficients at each port, for both modes of excitation, the desired parameters ... View full abstract»

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  • Influence of the Earth in the HF transmission of LPD antennas

    Publication Year: 1977, Page(s):891 - 896
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (680 KB)

    Log-periodic dipole (LPD) arrays have important applications in HF transmission for their large bandwidths and rather high gain. The nonideal terrain around the antenna gives a strong degradation of the radiation pattern at low elevation angles where the antenna is used in HF in order to utilize the ionospheric refraction. The problem is discussed, and the possible means for improving such situati... 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 (4)
    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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  • Scattering of electromagnetic plane waves by a circular cylinder

    Publication Year: 1977, Page(s):898 - 900
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (232 KB)

    Numerical investigation of scattering electromagnetic plane waves by a circular conducting cylinder is considered. The results presented are 1) validity of asymptotic far-field expressions when it is applied to calculate near-field around the cylinder and 2) equicontours of amplitude and phase of total field around the cylinder. View full abstract»

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  • An analysis technique for microstrip antennas

    Publication Year: 1977, Page(s):756 - 759
    Cited by:  Papers (43)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (304 KB)

    A method to analyze a microstrip antenna is presented. It involves representing the antenna by a fine wire grid immersed in a dielectric medium and then using Richmond's reaction formulation to evaluate the piecewise sinusoidal currents on the wire grid segments. The calculated results are then modified to account for the finite dielectric discontinuity. A comparison of calculated and measured res... View full abstract»

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  • The pseudo-Brewster angle

    Publication Year: 1977, Page(s):903 - 904
    Cited by:  Papers (9)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (168 KB)

    An exact expression for the pseudo-Brewster angle, and also some relatively easy-to-use formulas giving an approximate value for this angle and for the minimum value of the vertical polarization reflection coefficient are presented. 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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  • 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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IEEE Transactions on Antennas and Propagation includes theoretical and experimental advances in antennas.

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Editor-in-Chief                                             Danilo Erricolo