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Antennas and Propagation, IEEE Transactions on

Issue 5 • Date September 1973

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Displaying Results 1 - 25 of 45
  • [Front cover and table of contents]

    Publication Year: 1973 , Page(s): 0
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    Freely Available from IEEE
  • Correction to "The radiation efficiency of a dipole antenna located above an imperfectly conducting ground"

    Publication Year: 1973 , Page(s): 755 - 756
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    First Page of the Article
    View full abstract»

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  • Comments on "The influence of chordal paths on signals propagating to the near antipode of an HF radio transmitter"

    Publication Year: 1973 , Page(s): 755
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    For reference see abstract B40050 of 1972 View full abstract»

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  • Comments on "Reflector antenna radiation pattern analysis by equivalent edge currents"

    Publication Year: 1973 , Page(s): 756
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    For ref. see abstract B5328 of 1973 View full abstract»

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  • [Back cover]

    Publication Year: 1973 , Page(s): c4
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    Freely Available from IEEE
  • Pulse scattering from a sphere coated with an inhomogeneous sheath

    Publication Year: 1973 , Page(s): 727 - 728
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    The backscattered waveform produced by a short electromagnetic pulse incident upon a metallic sphere clad with a radially stratified dielectric is considered. Typical results are presented which demonstrate the dependence of the specular and creeping wave returns on the permittivity gradient and thickness of the sheath. View full abstract»

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  • Scattering of electromagnetic waves from rough oscillating surfaces using spectral Fourier method

    Publication Year: 1973 , Page(s): 734 - 736
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (328 KB)  

    The generalized spectral Fourier method is applied to the investigation of scattering of plane electromagnetic waves from rough oscillating surfaces. The surface is characterised in terms of surface impedance formulation. The relationships between radar cross section and the spatial and temporal spectrum of the surface are obtained. The backscatter radar cross section is determined using phillips ocean scatter. View full abstract»

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  • Impedance properties of a longitudinal slot antenna in the broad face of a rectangular waveguide

    Publication Year: 1973 , Page(s): 708 - 710
    Cited by:  Papers (32)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (296 KB)  

    The impedance properties of a waveguide longitudinal slot antenna of arbitrary length and offset in guide walls of finite thickness are investigated. These properties are obtained by treating the slot discontinuity as an electromagnetic boundary value problem and the resulting pair of coupled integral equations are solved by numerical techniques. Results are given for slots having lengths from 0.35\lambda to 1.7\lambda and are in good agreement with experimental results. View full abstract»

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  • Angle and Doppler measurements of the quasi-coherent and incoherent components of microwave transhorizon signals

    Publication Year: 1973 , Page(s): 746 - 750
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (616 KB)  

    This communication compares the differences between the quasi-coherent and incoherent components of microwave transhorizon signals where the differences are exhibited in the received-signal characteristics in several respects: the distribution of the signal level, the shape of the antenna response patterns, and the width of the RF Doppler spectrum. These differences are also accompanied by corresponding differences in the meterological profiles. There is a clear implication that the atmospheric structure giving rise to the transhorizon scatter of the propagated radio wave is markedly different for each case. The important point of this work is that the distinctions between the quasi-coherent and incoherent components of the signal are revealed in independently measured quantities. View full abstract»

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  • Propagation of electromagnetic waves through turbulent plasma using transport theory

    Publication Year: 1973 , Page(s): 750 - 755
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (712 KB)  

    Transport methods have been employed to study the propagation of a narrow-angle electromagnetic beam through a turbulent plasma. Results are presented for the mean-square angular divergence of the beam, the beam cross section, and the power received by a planar aperture in the medium and the mutual coherence function. The problem of backscattered radiation is also considered and results are obtained which reduce, in the limit of zero true absorption, to previous results. View full abstract»

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  • Broad-band antenna array with application to radio astronomy

    Publication Year: 1973 , Page(s): 697 - 700
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    A broad-band antenna element and beam-forming matrix have been developed for reception of signals at 25-100 MHz. The element is a zig-zag log-periodic antenna with a nominal impedance of 430\Omega and a VSWR of less than 1.9. The matrix utilizes time-delay gradients to obtain frequency-independent beam positions and also allows several different beam positions to be monitored simultaneously. Observations of natural radio sources using a 16-element array have verified its usefulness. View full abstract»

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  • Modification of antenna radiating characteristics with multi-impedance loading

    Publication Year: 1973 , Page(s): 715 - 721
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (536 KB)  

    For a radiating linear antenna, the loading of M + N appropriate impedances at M + N specified locations can lead to: 1) producing M + N desired currents at M + N specified points along the antenna, 2) producing M + N desired radiation fields in M + N specified directions, 3) maintaining desired input impedances at M + N different frequencies, or 4) any linear combination of cases 1), 2), and 3). With M + N pure reactive loadings, only (M + N)/2 values of antenna characteristics can be specified. A method was developed to solve the nonlinear equations in the analysis. View full abstract»

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  • Evanescent fields produced by totally reflected beams

    Publication Year: 1973 , Page(s): 730 - 732
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (392 KB)  

    When the coordinates of a line source are assigned complex values in the free-space Green's function, the resulting field represents a bounded beam. This property is employed to formulate an integral expression for the field transmitted across a plane dielectric interface. Asymptotic evaluation of the integral requires detailed study of the saddle point and steepest descent path configurations, especially when the incident beam is totally reflected. The asymptotic results in that case are employed to chart the power flow lines and to deduce the lateral shift of the reflected beam. View full abstract»

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  • Babinet's principle for a perfectly conducting screen with aperture covered by resistive sheet

    Publication Year: 1973 , Page(s): 738 - 740
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (320 KB)  

    In this paper, a more general form of Babinet's principle for electromagnetic waves and perfectly conducting screens with apertures covered by resistive sheets is presented. It shows that the field components parallel to the screens are now further related to one another by the resistance of the resistive sheets whereas the field components normal to the screens retain the same relationship as in the absence of the resistive sheets. View full abstract»

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  • Improved point-matching method with application to scattering from a periodic surface

    Publication Year: 1973 , Page(s): 657 - 662
    Cited by:  Papers (21)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (528 KB)  

    The method of modal expansions is a fundamental technique for solving the electromagnetic boundary value problems. As its practical alogrithm, the point-matching method has been used but frequently failed. A new computer-aided procedure based on the method of modal expansions is presented and applied to the scattering from a periodic structure composed of a perfectly conducting surface. As an example, the scattering from the grating with a sinusoidal height profile is calculated. It is demonstrated numerically that the new procedure leads to desirable results, while the point-matching method does not. Several physical characteristics on the reflection grating including the diffraction anomalies are explored. View full abstract»

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  • Short axial length broad-band horns

    Publication Year: 1973 , Page(s): 710 - 714
    Cited by:  Papers (24)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (792 KB)  

    Ever-increasing antenna frequency bandwidth requirements for countermeasures applications and electromagnetic compatibility measurements have provided the impetus for the development of a series of very broad-band horns. In addition to the broad bandwidth, a substantial reduction in axial length over that of earlier models has been achieved for the two designs discussed in this communication. The first horn described covers the frequency range from 1.0-12.0 GHz with the flared portion of the horn having an axial length of 6 in as compared with 12 in for an earlier model. Although horn antennas are not commonly considered for use at frequencies as low as 0.2 GHz, the short axial length design appeared to be an attractive approach in developing a very reasonably sized antenna operating in the 0.2-2.0 GHz range. The technique of fabricating the H plane walls in the form of a grid was used in both designs as a means of maintaining the required H -plane half-power beamwidths. The grid for the 1.0-12.0 GHz horn is of printed circuit form while the grid elements of the lower frequency horn are made of aluminum tubing. Electrical characteristics of both designs are presented, as well as some additional data for recent advances which indicate that a further reduction in axial length or an increase in bandwidth can be achieved with only a moderate rise in VSWR in the lower portion of the frequency range. View full abstract»

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  • Simple expressions for the electric and magnetic field strengths between the elements of an infinite array

    Publication Year: 1973 , Page(s): 721 - 722
    Cited by:  Papers (3)
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    Suitable engineering expressions for the electric- and magnetic-field strengths between the elements of an infinite array are derived by employing finitely conducting earth image-theory techniques. View full abstract»

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  • Equivalent currents for a ring discontinuity

    Publication Year: 1973 , Page(s): 693 - 695
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (312 KB)  

    Based on the geometrical theory of diffraction, equivalent filamentary currents are derived for a linear element of a surface singularity for general incidence and polarization. The currents are used to obtain an analytical expression for the bistatic field diffracted by a ring singularity, valid within the caustic region as well as at wide angles. View full abstract»

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  • Projective analysis of log-periodic dipole antennas

    Publication Year: 1973 , Page(s): 756 - 757
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (208 KB)  

    Using a Fortran IV program the authors analyse log-periodic dipole antennas of any given structural bandwidth operating in the half-wavelength mode View full abstract»

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  • Beamwidth of phased arrays

    Publication Year: 1973 , Page(s): 695 - 697
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (272 KB)  

    A formula is developed for estimating the far-field beamwidth of an arbitrary narrow-beam phased array of identical isotropic elements at a single frequency. Equations are developed for the effects of errors in the estimated positions of the array elements. View full abstract»

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  • Circularly polarized linear waveguide array

    Publication Year: 1973 , Page(s): 704 - 705
    Cited by:  Papers (1)
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    For the particular case of a circularly polarized linear waveguide array using crossed-slot radiators, in addition to solving the grating lobe problem, it is shown that the use of corrugated guide offers appreciable bandwidth advantages. View full abstract»

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  • An array technique with grating-lobe suppression for limited-scan applications

    Publication Year: 1973 , Page(s): 597 - 602
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (672 KB)  

    A new technique called "odd-mode scanning" is introduced and shown to function by suppressing grating lobes and hence allowing large elements to be used in a phased array for limited-scanning applications. Analytical and experimental results are included to show the E -plane-scan behavior of the technique, while H -plane- and intercardinal-plane-scan conditions are discussed to give a basis for predicting the two-dimensional-scan characteristics. View full abstract»

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  • Diffraction coefficient of a conducting wedge loaded with a dielectric slab on the illuminated surface

    Publication Year: 1973 , Page(s): 728 - 729
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (208 KB)  

    The asymptotic solution for the diffraction of an E -polarized plane incident electromagnetic wave by a conducting wedge, whose illuminated surface is loaded with a dielectric slab of small thickness and relative permittivity, is employed to derive a ray optical diffraction coefficient for the edge. View full abstract»

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  • Two frequency radar interferometry applied to the measurement of ocean wave height

    Publication Year: 1973 , Page(s): 649 - 656
    Cited by:  Papers (16)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (888 KB)  

    A technique is developed for measuring the rms wave height averaged over an area of the sea that is much greater than any horizontal scale of the surface waves. The method involves a nadir looking radar which transmits and receives two monochromatic signals simultaneously. Signal processing at the receiver involves the computation of the correlation between the two returning signals as a function of theft variable frequency separation. The cross correlation between the amplitude and phase functions of the individual returning carriers depends on the distribution of discrete scatterers along the direction of propagation. This information can be used to determine the rms surface elevation (about the mean); it does not depend on the temporal or spatial frequency spectrum of the wave height or slope. Under conditions which are typical for a microwave signal being normally incident and reflected by the sea, the two frequency correlation function R(\Delta k) is seen to be equal to the characteristic function of the surface elevation of specular points. Laboratory measurements have been conducted on wind driven waves, and the measured correlation function compares favorably with the theory developed here. View full abstract»

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  • A cavity-backed dipole antenna with wide-bandwidth characteristics

    Publication Year: 1973 , Page(s): 725 - 727
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (416 KB)  

    This communication describes a cavity-backed dipole antenna that has a broad-band VSWR response, unidirectional radiation patterns, and almost constant gain ( 10.5 \pm 1 dB) over an operating bandwidth of 1.8: 1. Measured pertinent electrical characteristics are presented. 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