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Antennas and Propagation, IEEE Transactions on

Issue 3 • Date May 1982

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Displaying Results 1 - 25 of 38
  • [Front cover and table of contents]

    Publication Year: 1982 , Page(s): 0
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  • Correction to "Radiation properties of microstrip dipoles"

    Publication Year: 1982 , Page(s): 526
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  • Correction to "Boresight-gain loss and gore-related sidelobes of an umbrella reflecter"

    Publication Year: 1982 , Page(s): 526
    Cited by:  Papers (2)
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  • Correction to "A statistical raindrop canting angle model"

    Publication Year: 1982 , Page(s): 526
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  • [Back cover]

    Publication Year: 1982 , Page(s): c4
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  • Wave transmission through a spherical dielectric shell

    Publication Year: 1982 , Page(s): 373 - 380
    Cited by:  Papers (4)
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    The transmission of a spherical electromagnetic wave through a dielectric shell is considered. The two surfaces of the shell are spherical (either concave or convex), and their centers are arbitrarily located in relation to the source point. The field solution determined by the geometrical optics (GO) theory is given in a simple closed form. Special attention is given to the lens effect of the dielectric shell which converts the incoming spherical pencil into a focusing pencil. View full abstract»

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  • On wave modulation by a rotating object

    Publication Year: 1982 , Page(s): 486 - 489
    Cited by:  Papers (4)
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    When a time harmonic electromagnetic wave is incident upon a rotating object which is not rotationally symmetric about the axis of rotation, modulation in the secondary waves generally will occur. Two scattering and reflection problems where, under certain conditions, no modulation occurs, are discussed. In the first case, a transverse electric (TE) or transverse magnetic (TM) wave is incident upon an object inside a circular waveguide. The object is rotating about the axis of the waveguide and has periodic characterisitcs in the azimuthal direction with period 2\pi/N ( N : an integer). In the second case, the waveguide is removed, and a linearly polarized plane wave is incident upon the object along its axis of rotation. View full abstract»

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  • A unified and consistent view on the singularities of the electric dyadic Green's function in the source region

    Publication Year: 1982 , Page(s): 463 - 468
    Cited by:  Papers (12)
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    Ambiguities associated with the singularity of the electric dyadic Green's function are clarified. The numerical advantages of finite and infinitesimal principal volumes are dependent on the particular problem being treated. It is shown that apparent discrepancies are nonexistent and that either the method of potential or the theory of distribution can be used in this problem and a unified and consistent view can be formed. View full abstract»

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  • Tropospheric wet path-delay measurements

    Publication Year: 1982 , Page(s): 502 - 505
    Cited by:  Papers (2)
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    A dual-channel microwave radiometer measuring the sky brightness temperature at the frequencies 21.0 and 31.4 GHz, an infrared spectral hygrometer (IRSH) measuring the ratio of the radiation from the sun at the wavelengths 931 and 880 nm, and radiosondes have been used simultaneously to determine the excess path length due to water vapor (wet path delay) of radio waves propagating through the troposphere. By a least squares fit of the measured parameters from the microwave radiometer and the infrared spectral hygrometer, respectively, to the wet path delay calculated from the radiosonde profiles, the following root mean square (rms) differences of the wet path delay in the zenith direction were obtained: infrared spectral hygrometer-radiosondes, 1.1 cm; microwave radiometer-radiosondes, 0.7 cm; and 0.5 cm for a selected group of "good weather" data. The wet path delay was also calculated from surface meteorological measurements alone and the rms difference compared with corresponding radiosonde data was 2.0 cm in the zenith direction. View full abstract»

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  • Radiating elements for hemispherically scanned arrays

    Publication Year: 1982 , Page(s): 457 - 462
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    The problem of obtaining hemispherical coverage using an electronically steered antenna beam is considered. Radiating elements consisting of combinations of slots, parasitic dipoles, and surface wave structures were investigated for this application. Both planar and cylindrical supporting structures were used. It was found that such elements showed enhanced radiation near the horizon in both the E -plane and the H -plane. Patterns were measured on an eight-element linear array of slots covered by a surface wave structure. When the beam was scanned electronically to endfire, the pattern was enhanced by several dB over that obtained from the array without the surface wave structure. View full abstract»

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  • A transform technique for computing the radiation pattern of prime-focal and Cassegrainian reflector antennas

    Publication Year: 1982 , Page(s): 520 - 524
    Cited by:  Papers (11)
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    An efficient numerical method based on the use of the fast Fourier transform (FFT) algorithm is developed for computing radiation patterns of aperture antennas with given aperture distributions. The method is also readily applicable to the problem of computing the radiation pattern of paraboloidal reflector antennas when the induced surface currents on the surface of the reflector are known. Using an efficient launching and scanning scheme for subreflector analysis, the method is extended to a Cassegrainian reflector antenna system. View full abstract»

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  • Discrete energy conservation law and reciprocity relationship for one-dimensional wave propagation problems

    Publication Year: 1982 , Page(s): 483 - 486
    Cited by:  Papers (1)
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    A mathematical derivation is presentcd to establish the discrete energy conservation law and reciprocity relationship for explaining the insensitive phenomenon round in the previous investigations of a one-dimensional wave propagation problem. It is shown that there do exist certain discretized differential and variational systems which can preserve the energy conservation and reciprocity relationships. This then excludes the use of these relationships in error estimation. View full abstract»

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  • EM scattering from bodies of revolution with attached wires

    Publication Year: 1982 , Page(s): 426 - 431
    Cited by:  Papers (11)
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    The scattering of an arbitrary plane wave by a body of revolution with multiple attached wires is calculated by the method of moments (MM). Predicted and measured results are presented for sphere/wire, cylinder/wire, and spherical end-capped cylinder/wire-loop geometries for resonant region body sizes. View full abstract»

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  • Analysis of a monopole mounted near an edge or a vertex

    Publication Year: 1982 , Page(s): 401 - 408
    Cited by:  Papers (20)
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    The problem of a monopole mounted near the edge of a wedge or a vertex is considered. Three types of solutions-surface patch modeling, moment method/geometrical theory of diffraction (MM/GTD), and MM/eigenfunction-are presented, discussed, and compared with measurements. Results are in the form of input impedance and radiation patterns. View full abstract»

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  • A first-order treatment of aberrations in Cassegrainian and Gregorian antennas

    Publication Year: 1982 , Page(s): 331 - 339
    Cited by:  Papers (16)  |  Patents (1)
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    The decrease in aperture efficiency caused by small aberrations in a reflector antenna is determined. The important case of a Cassegrainian (or Gregorian) antenna with a feed placed in the vicinity of the focal point is treated in detail. For this case the various aberration components due to astigmatism, coma, etc., are derived explicitly, their effect on aperture efficiency is shown, and the conditions that optimize performance are given. The results are useful for the design of multibeam antennas in ground stations and satellites. View full abstract»

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  • New expressions of dyadic Green's functions in uniform waveguides with perfectly conducting walls

    Publication Year: 1982 , Page(s): 497 - 499
    Cited by:  Papers (3)
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    New expressions of the dyadic Green's functions in uniform waveguides with perfectly conducting walls are obtained. Significant features of these expressions are an explicit modal evaluation of their singular part. The same forms as in the free space appear; moreover the use of the divergence theorem allow to apply the \bigtriangledown operator on the currents in the integral representations of the electromagnetic fields. Consequently the involved kernels are less singular, and this procedure can be conveniently used in some applications. View full abstract»

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  • On the accuracy of physical optics

    Publication Year: 1982 , Page(s): 509 - 512
    Cited by:  Papers (1)
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    The first-order correction to the physical optics (PO) solution for the axial radiation field from parabolic reflector antennas is found. The correction is of order k^{-1} and is in quadrature with the PO solution. By means of the correction term the accuracy of the PO surface integral is round to be better than 0.22(\lambda /D)^{2} dB on axis, where D is the diameter of the reflector. Thus, the PO solution for the directivity is extremely accurate for commun reflector sizes of several wavelengths \lambda . View full abstract»

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  • Electromagnetic diffraction by a slot in a ground screen covered by a dielectric slab

    Publication Year: 1982 , Page(s): 390 - 395
    Cited by:  Papers (2)
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    An integral equation is formulated for the problem of transverse electric (TE) illumination of an infinite slot in a conducting screen situated between two dielectric slabs having different electromagnetic properties. Numerical results are given for the slot magnetic current for selected cases where a slab exists only on the shadow side of the screen. Far-zone magnetic fields are presented. View full abstract»

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  • Admittance analysis of nonuniformly spaced phased arrays of waveguide apertures in a ground plane

    Publication Year: 1982 , Page(s): 432 - 437
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    A general formulation for the analysis of a phased array of waveguide apertures in a common ground plane has been given for finite number of elements and nonuniform spacings based on network representation of the system. The analysis yields the radiation pattern, reflection coefficient, and aperture field in each waveguide. The pattern of an array of physically identical elements is expressed as superposition of patterns of infinite number of arrays. The formulation, when applied to single and two aperture cases, confirms the known results. It is then applied to investigate the properties of the element position modulated phased array of 15 rectangular waveguide apertures excited by uniform incident waves. Uniformly spaced arrays are also analyzed for comparison. The dominant mode and one higher order evanescent mode are included in the computations. The results show that the overall power reflection coefficient of the nonuniform array does not undergo any peaks over a wide scan range. It is concluded that the advantages of nonuniformly spaced arrays in suppressing grating lobes and eliminating blind spots are physically realizable. View full abstract»

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  • Characterization of rain profiles in a second-order approximation and application to attenuation beyond 10 GHz

    Publication Year: 1982 , Page(s): 396 - 400
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    A new approach to characterizing the rain profile for applications involving attenuation beyond 10 GHz is presented. It is based on the use of three functionals of the rain intensity profile (referred to as "intrinsic profile parameters" because of their peculiarity of being independent of frequency) which encompasses all the relevant information contained in the profile itself with respect to the attenuation. The attenuation can then be evaluated without the need for any profile model, as happens when starting from the more usual "average rain intensity" or other similar meteorological parameters. The intrinsic parameters therefore allow for the separate accounting of the profile and the other factors affecting attenuation such as frequency, raindrop size distribution, etc. Moreover, they can be easily related to the various kinds of "effective rain intensity" and "rainy path length" defined in the literature, thus offering a tool to clean out the inherent dependence of these latter on frequency and to obtain results that are comparable among each other even though they are collected under different circumstances. View full abstract»

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  • A modified hyperplane method for null synthesis in an array pattern

    Publication Year: 1982 , Page(s): 512 - 516
    Cited by:  Papers (1)
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    It has recently been shown by Prasad that the problem of synthesizing nulls in an array pattern admits a geometrical formulation for which the alternative orthogonal projection (AOP) algorithm (previously used in image restoration applications) is a useful solution. We apply a modification to the original AOP suggested by Ramakrishnam et al. for image restoration purposes and show that it results in a computational savings in array pattern synthesis problems. A numerical example is presented to illustrate the computational advantages of this modification. View full abstract»

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  • Signal level distributions and fading for a long over-water link at 5 GHz

    Publication Year: 1982 , Page(s): 479 - 483
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    Measurement results are presented for an 88-km multiple-diversity line-of-sight microwave link across the English Channel operating in the 4 to 5 GHz frequency range. Signal level and fade duration statistics derived from the measurements are compared with the applicable International Radio Consultative Committee (CCIR) models. Although signal level distributions are in fair agreement with CCIR predictions, the median fade duration tends to be shorter than values estimated from the CCIR model. View full abstract»

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  • Measured bounds on rain-scatter coupling between space-earth radio paths

    Publication Year: 1982 , Page(s): 493 - 497
    Cited by:  Papers (3)
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    Attempts were made to measure rain-scatter coupling for two satellite paths displaced in angle by 0.85\deg . For rain attenuation up to 15 dB, upper bounds on coupling were -40 dB at 19 GHz and -45 dB at 28 GHz. These experimental bounds are limited by antenna sidelobe levels which are on the order of 20 dB greater than theoretical rain-scatter predictions. View full abstract»

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  • Accurate evaluation of a millimeter wave compact range using planar near-field scanning

    Publication Year: 1982 , Page(s): 419 - 425
    Cited by:  Papers (12)
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    Significant progress has been made in recent years on planar near-field measurements for antenna calibrations. Such measurements are also useful in the alignment and evalnation of compact ranges because they provide more information than a limited number of analogue plots in one dimension. Contour plots of amplitude and phase data obtained from more complete two-dimensional measurements precisely and accurately locate sources of problems in the range reflector, with phase contour plots being more useful as diagnostic tools. View full abstract»

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  • A corrugated corner reflector system

    Publication Year: 1982 , Page(s): 524 - 526
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    A new type of corner reflector (CR) system with corrugated reflector elements has been realized, and experimental results are presented. This system gives better performance than conventional corner reflectors with plane elements. Experimental data regarding hall-power beamwidth (HPBW), on-axis power, and voltage standing-wave ratio (VSWR) are presented for a direct comparison with corresponding plane CR systems. View full abstract»

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Aims & Scope

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

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Editor-in-Chief                                                 Kwok W. Leung