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Antennas and Propagation, IEEE Transactions on

Issue 5 • Date September 1978

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Displaying Results 1 - 25 of 28
  • [Front cover and table of contents]

    Publication Year: 1978 , Page(s): 0
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  • Correction to "Application of the unimoment method to electromagnetic scattering of dielectric cylinders"

    Publication Year: 1978 , Page(s): 755
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  • Comments on "Influence of the earth in the HF transmission of LPD antennas"

    Publication Year: 1978 , Page(s): 755 - 756
    Cited by:  Papers (1)
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  • The effect of the outer scale of turbulence and wavelength on scintillation fading at millimeter wavelengths

    Publication Year: 1978 , Page(s): 712 - 715
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (416 KB)  

    Amplitude scintillation measurements made on two-millimeter microwave links at 36 GHz and 110 GHz along a common 4.1 km path across central London are deseribed. The variances of the logarithmic amplitude scintilliations at these two frequencies are compared for different ranges of the outer scale of turbulence. A comparison is made between the experimental results and the theoretical predictions of Tatarski. Good agreement has been found for the two cases when the outer scale of turbulence is greater than and smaller than the Fresnel zone size. View full abstract»

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  • Shielding effectiveness of corrugations in corrugated horns

    Publication Year: 1978 , Page(s): 654 - 658
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (528 KB)  

    A moment-method solution is used to obtain new design data for corrugated horns. The current density on the walls of corrugated dihedral horns is evaluated as a function of such corrugation parameters as the tooth density, and the ratio of the gap to the period (of the corrugations). The shielding effectiveness or the capability of the corrugations to prevent the edge of the horn from being illuminated is discussed, as is the question of the efficiency of corrugated horns. View full abstract»

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  • Remote sensing of sea state by analysis of backscattered microwave phase fluctuations

    Publication Year: 1978 , Page(s): 699 - 705
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (600 KB)  

    The relative phase of a normally incident microwave signal scattered off the sea surface is a random function of space and time. The statistics of these random phase fluctuations contain information about the wave-height statistics. This study demonstrates that the wave-height spectra can be deduced directly in terms of the spectra of the phase fluctuations without recourse to inversion techniques even when surface roughness exceeds many wavelengths of the incident signal. In the particular case of a nadir-directed satellite-mounted microwave source operating in the backscatter mode, the wave-height and phase spatial spectra are proportional with a constant proportionality of (2k_{0})^{2} , where k_{0} is the wavenumber of the scattered signal. View full abstract»

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  • Procedures for improving convergence of moment-method solutions in electromagnetics

    Publication Year: 1978 , Page(s): 743 - 748
    Cited by:  Papers (4)
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    Two new methods, termed "plane-wave correction" and "cylindrical-cell correction," are presented for improving the convergence of moment-method solutions in electromagnetics. Convergence is improved because the calculations include an approximation for the variation of the field within each cell. View full abstract»

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  • Volumetric pattern analysis of airborne antennas

    Publication Year: 1978 , Page(s): 636 - 641
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (600 KB)  

    By blending together the roll and elevation plane high-frequency solutions, a very efficient technique has been developed for the volumetric pattern analysis of antennas mounted on the fuselage of a generalized aircraft. The fuselage is simulated by an infinitely long, perfectly conducting, elliptic cylinder in cross section and a composite elliptic cylinder in profile. The wings, nose section, stabilizers, and landing-gear doors may be modeled by finite flat or bent plates. Good agreement with accurate scale model measurements has been obtained for a variety of aixborne antenna problems. View full abstract»

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  • Amplitude bias in the Fourier transforms of noisy signals

    Publication Year: 1978 , Page(s): 730 - 731
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (216 KB)  

    Fourier transforms are often useful in characterizing measured transient signals. It is shown that the amplitudes of such transforms are overestimated in the presence of normal zero-mean random noise. This bias is shown to be significant (greater than 5 percent) for signals with signal-to-noise ratios less than approximately 2.5:1. The result is independent of signal waveform. View full abstract»

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  • Multiple scattering by two conducting circular cylinders

    Publication Year: 1978 , Page(s): 748 - 751
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (408 KB)  

    Multiple scattering by two conducting circular cylinders is studied by applying three different methods: the method of Zitron and Karp (ZK), the method of Karp and Russek, and an iterative method which gives the exact solution. It is found from the numerical results for the total scattering cross section that the ZK method gives very precise results even for rather large ka and small kd , where a and d are the radius of the cylinder and the separation between the cylinders, respectively. View full abstract»

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  • Time domain integral equation approach for inhomogeneous and dispersive slab problems

    Publication Year: 1978 , Page(s): 658 - 667
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (680 KB)  

    A numerical approach is described, based on a rigorous integral formulation, to the problem of an inhomogeneous dispersive slab illuminated by incident TEM plane wave with arbitrary time dependence. The slab is assumed to be nonmagnetic and its complex permittivity only varies normally to its interfaces. The numerical process consists of a space-time discretization. The solution can be determined step by step from simple recurrence formulas. Some examples are given for normal incidence in order to illustrate the most interesting features of the method and its possible field of applications. View full abstract»

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  • Reflection and cross-polarization properties of grooved dielectric panels

    Publication Year: 1978 , Page(s): 741 - 743
    Cited by:  Papers (3)
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    The cross-polarization and reflection properties of grooved dielectric windows are calculated. Measurements on two windows in the range 8-12 GHz are found to be in good agreement with the theory. It is shown that cross-polarization is substantially reduced if the grooves on the front and back faces of the window are orthogonal to each other. View full abstract»

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  • The determination of sky-wave received signal level

    Publication Year: 1978 , Page(s): 731 - 736
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    HF sky wave signal strengths measured at a number of frequencies over short- and medium-range paths (100-2000 km) are compared with two prediction methods. The statistical behavior of the rapid fluctuations of the received signal level are analyzed, and the diurnal dependence of the fading depth is found qualitatively. View full abstract»

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  • An integral equation solution to the scattering of electromagnetic radiation by dielectric spheroids and ellipsoids

    Publication Year: 1978 , Page(s): 706 - 712
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (576 KB)  

    A new approach to the scattering of electromagnetic radiation by dielectric scatterers and application of it to the case of scattering by homogeneous spheroidal and ellipsoidal raindrops is presented. We transform the (singular) integral equation for the scattering into an integral equation for the Fourier transform of the internal field, which has a nonsingular kernel. This equation is solved by reducing it by quadrature into a set of algebraic equations. The scattering amplitude so obtained is shown to satisfy the Schwinger variational principle, and the method is thus both numerically stable and known to be convergent. We present sample calculations for spheres, for spheroids, and for ellipsoids. View full abstract»

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  • Strip antennas in a dielectric slab

    Publication Year: 1978 , Page(s): 647 - 653
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (576 KB)  

    A general technique for analyzing wire antennas in the presence of a dielectric inhomogeneity is described. The solution is a moment method technique and has the advantage that the dielectric inhomogeneity introduces no new unknowns into the solution. The technique is applied to strip antennas in an electrically thin dielectric slab. View full abstract»

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  • Role of controlled mode conversion in leaky feeder mine communication systems

    Publication Year: 1978 , Page(s): 690 - 694
    Cited by:  Papers (3)
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    Using an idealized model, we consider VHF wave transmission in a straight mine tunnel that contains a braided coaxial cable. The controlled interchange of energy between the propagation modes can be used to optimize the communication range and allow for coupling to and from portable hand-held antennas. In particular, we show that the optimum lengths for maximum transmission through the leaky cable sections or mode converters predicted here are compatible to those predicted by approximate coupled mode theory. View full abstract»

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  • Refraction of a uniform plane wave incident on a plane boundary between two lossy media

    Publication Year: 1978 , Page(s): 738 - 741
    Cited by:  Papers (3)
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    The expressions describing the modified propagation constants of the refracted nonuniform transmitted field, produced by a uniform plane wave incident on a plane boundary between two lossy media, are presented. Some examples under which the modified propagation constants must be used are illustrated to determine the limitations. View full abstract»

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  • Simple formula for current on a cylindrical receiving antenna

    Publication Year: 1978 , Page(s): 683 - 690
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (680 KB)  

    An approximate formula is presented for the induced current on a loaded (or unloaded) thin cylindrical receiving antenna which is illuminated by an incident plane wave from an arbitrary direction. This formula involves only elementary functions and therefore can be calculated easily. Its derivation is based on the multiple reflection approach originated by Weinstein, Shen, and others. Currents calculated by the present formula are found to be in good agreement with experimental data. View full abstract»

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  • An examination of the limited aperture problem of physical optics inverse scattering

    Publication Year: 1978 , Page(s): 695 - 699
    Cited by:  Papers (7)
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    The limited aperture problem of physical optics inverse scattering is examined via the method of multidimensional stationary phase. It is shown that target information is recoverable from bandlimited and aspect-limited scattering data. Numerical examples are presented for the case of a perfectly reflecting circular cylinder. View full abstract»

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  • Superdirective receiving arrays

    Publication Year: 1978 , Page(s): 629 - 635
    Cited by:  Papers (16)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (624 KB)  

    Some of the characteristics of arrays designed for maximum directive gain subject to a tolerance constraint are described. Numerical data are presented which illustrate trade-offs between array size, directive gain, SNR, efficiency, bandwidth, tolerances, and farfield patterns. The results of an experimental study are found to be in good agreement with theoretical predictions. View full abstract»

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  • Theory on small radiating apertures in the outer sheath of a coaxial cable

    Publication Year: 1978 , Page(s): 674 - 682
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    An analytical expression for the aperture field is obtained from an integral equation formulation and a subsequent use of a quasistatic approach in which the dominant part of the solution can be extracted from canonical problems. Unlike the conventional approach of replacing the aperture field by equivalent dipoles, our method retains the basic features of the propagating mode in the coaxial region, and the radiation characteristic of the coaxial cylinder. An equivalent network representation of a small aperture is then derived. The network equivalence of a symmetrical aperture with its axes oriented in the direction of the incident field is shown to consist of a lumped shunt capacitance C_{b} and a series impedance Z composed of an inductive element L_{b} , a capacitive element C_{T} and the input admittance Y_{b\infty } of the external antenna, all in parallel. View full abstract»

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  • Conformal microstrip phased array for aircraft tests with ATS-6

    Publication Year: 1978 , Page(s): 642 - 646
    Cited by:  Papers (15)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (560 KB)  

    The development of a novel L -band microstrip phased array for aircraft is described. The array is electronically steerable in elevation, conformal to the surface of an aircraft, 0.14-in thick, low cost in production quantities, installed without cutting large holes in the aircraft, and capable of 12-dB gain relative to right hand circular isotrope. The microstrip radiating element is described, and its operation is explained. The array design is considered in relation to ground plane curvature, grating lobes, sidelobes, beam shape and gain. A technique for obtaining 30\deg phase resolution from 3-bit phase shifters is presented. The design of simple loaded line and switched line phase shifters is reported. View full abstract»

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  • Measurements of atmospheric attenuation near 225 GHz: Correlation with surface water vapor density

    Publication Year: 1978 , Page(s): 737 - 738
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (248 KB)  

    The total attenuation through the earth's atmosphere for radio waves at frequencies near 225 GHz has been monitored for several weeks from a 1-km elevation site. The zenith attenuation at these frequencies was found to be correlated with the ground level water vapor content of the atmosphere; the correlation is consistent with the relation A (db)= 0.50 \rho ( g \cdot m-3of water) predicted for clear sky conditions by theory, assuming a 2-km scale height for water in the atmosphere. View full abstract»

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  • Fading at 9.6 GHz on an experimentally simulated aircraft-to-ground path

    Publication Year: 1978 , Page(s): 715 - 719
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    This report describes an experimental study of fading at 9.6 GHz on a fixed slanted line-of-sight path simulating aircraft-to-ground propagation conditions. Recordings of signal fading were made over about one year. The data were analyzed to provide a statistical description of the fading, and to compare some of these statistics with those obtained elsewhere under different climatic and terrain conditions. The results include the probabilities of occurrence of fading rates and fade durations at several signal levels below the hourly median level. The extent to which fading behavior depends on time-of-day and time-of-year was investigated, along with the correlation of hourly average fade duration and hourly fading rate. View full abstract»

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  • The use of complex monopulse techniques to detect scintillations produced by propagation through turbulence

    Publication Year: 1978 , Page(s): 727 - 730
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    Propagation of radar signals through turbulence produces an erroneous off-axis angle indication in a conventional monopulse radar. Such turbulent propagation also creates a phase-quadrature (imaginary) component of the indicated angle which can be used to detect the presence of these errors in the real angle indication. 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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Meet Our Editors

Editor-in-Chief                                                 Kwok W. Leung