By Topic

Antennas and Propagation, IEEE Transactions on

Issue 1 • Date January 1973

Filter Results

Displaying Results 1 - 25 of 37
  • [Front cover and table of contents]

    Publication Year: 1973 , Page(s): 0
    Save to Project icon | Request Permissions | PDF file iconPDF (169 KB)  
    Freely Available from IEEE
  • Iterative least-squares synthesis of nonuniformly spaced linear arrays

    Publication Year: 1973 , Page(s): 106 - 108
    Cited by:  Papers (19)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (286 KB)  

    First Page of the Article
    View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Comments on "Difference pattern null depth and angular accuracy"

    Publication Year: 1973 , Page(s): 132 - 133
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (236 KB)  

    First Page of the Article
    View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Comments on "A transform solution for the fields from a current element"

    Publication Year: 1973 , Page(s): 132
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (145 KB)  

    First Page of the Article
    View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Comments on "Optimum pulse transmission through an exponential plasma inhomogeneity"

    Publication Year: 1973 , Page(s): 133
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (107 KB)  

    First Page of the Article
    View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • [Back cover]

    Publication Year: 1973 , Page(s): c4
    Save to Project icon | Request Permissions | PDF file iconPDF (685 KB)  
    Freely Available from IEEE
  • Line-of-sight PCM performance at 15.3 GHz

    Publication Year: 1973 , Page(s): 78 - 83
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (624 KB)  

    The effects of certain atmospheric conditions upon pulse-code modulation (PCM) data transmission at a carrier frequency of 15.3 GHz are discussed in this paper. Using an amplitude-shift keying (ASK) modulation to transmit 1300000 bit/s across a 9.5 mi line-of-sight path, the performance characteristics of the system, relating to conditions in the channel, were measured and are presented in this study. Theoretical curves of probability of error versus predetection signal-to-noise ratio (SNR), are compared to measured error probabilities; these are obtained at different received signal levels, and under various clear weather conditions ranging from humid to dry. Above 15 dB predetection SNR, the system operates more efficiently than theoretically predicted for ASK modulation over a Rayleigh fading channel. The detected envelope probability distributions are computed for different values of SNR. Results show that drier weather, which causes amplitude fluctuations of a shallow nature, results in greater error probabilities than those for more humid conditions; the term shallow fading is used to describe short term (5-10 min) received signal envelope variations of less than 1 dB. For example, error probabilities for a predetection SNR of 14 dB, ranged from 0.005 to 0.078, from humid to dry conditions respectively. These values fall between the theoretical values of 0.0005 for the nonfading case, and 0.0740 for Rayleigh fading. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Monte Carlo computer technique for one-dimensional random media

    Publication Year: 1973 , Page(s): 83 - 88
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (640 KB)  

    Hochstim and Martens were the first to use Monte Carlo computations to study scattering characteristics of scalar waves from randomly fluctuating slabs with an exponential spatial correlation. This paper describes an alternative procedure which overcomes some of the difficiencies in their treatment and extends the study to physical circumstances which their treatment excludes (e.g., background inhomogeneity, crossover into cutoff regions, etc.). The two-point correlation function characterizing the medium fluctuations (more directly the spectral density) may be arbitrarily selected and is no longer restricted to an exponential. The correlation properties of the medium are virtually independent of the length of the elementary slabs comprising the overall slab region, whence the medium may be structured by equal sized slab realizations-a major advantage whenever a background profile is superimposed. Furthermore, the statistics associated with the reflection and transmission of both the coherent as well as the incoherent waves are calculated separately. The results so obtained yield solutions with which appropriate analytical theories can be conveniently compared and they provide information additional to that found in previous studies. As examples, the syntheses of Gaussian and exponential correlation functions are shown. For the exponential, propagation calculations for a homogeneous random slab were made using the new technique and compared with results using Hochstim and Martens' approach. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Space wave field produced by a vertical electric dipole above a perfectly conducting sinusoidal ocean surface

    Publication Year: 1973 , Page(s): 32 - 37
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (544 KB)  

    Investigations of electromagnetic scattering from rough surfaces have been oriented toward radar surveillance or remote sensing applications. An important problem that has been relatively unexplored is that of a dipole antenna close to and illuminating an ocean surface with spherical waves; for example, communication antennas on submarines or surface ships. This work is concerned primarily with the fluctuations in the space wave field intensity caused by reinforcement and cancellation of the direct wave by the wave reflected from a moving sinusoidal ocean surface. Certain situations arise so that the sinusoidal model is a good approximation of an actual ocean surface. For this case, the amplitude of the sine curve is small compared with a free-space wavelength; therefore, a Fourier integral-perturbation series approach can be used to solve the boundary value problem. Two primary conclusions are drawn from this model of the ocean surface. First, the widest field variation occurs in the direction broadside to the direction of wave motion. Second, a depolarized field term is introduced, and it is directly proportional to the maximum slope of the surface. Finally some practical aspects of RF communications are discussed. For example, it is noted that the RF fading rate is related to sea state. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Dipole antenna coaxially mounted on a conducting cylinder

    Publication Year: 1973 , Page(s): 89 - 94
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (664 KB)  

    The problem of a cylindrical dipole antenna symmetrically mounted on a conducting coaxial cylinder is analyzed both theoretically and experimentally. The theoretical approach is based on the Fourier transform solution for thin wire antennas, equivalence and image principles, point matching, and numerical optimization. The basic idea is that the modified dipole structure can be replaced by an equivalent system (as far as exterior fields are concerned) consisting of a simple perfectly conducting rod excited by an array of magnetic ring sources. The coefficients of these sources are then adjusted to match boundary conditions on the cylindrical modification surface. For the locations of the match points and sources, three gauges involving weighted integrals of the tangential electric fields are used to optimize the solution. Good agreements between measurement and theory have been obtained for the input admittances, resonance properties, and radiation patterns. Results are also presented for a dipole on a sphere to contrast effects due to change in modification shape. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Errors in the predicted gain of pyramidal horns

    Publication Year: 1973 , Page(s): 25 - 31
    Cited by:  Papers (23)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (640 KB)  

    The concepts of the geometrical theory of diffraction are used to derive the on-axis gain of two-dimensional E plane sectoral horns. Geometrical optics and single (noninteraction) diffraction by the aperture edges yield essentially the Kirchhoff result-a monotonic gain versus wavelength curve. Reflection of diffracted fields from the horn interior and double diffraction at the aperture add an oscillation to this curve which is not significantly altered by further diffraction for moderate to large horns. Including these results approximately in Schelkunoff's equation for the pyramidal horn explains the gain variations observed in microwave gain standards and provides an error estimate in their predicted gain. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Impedance and radiation pattern of antennas above flat discs

    Publication Year: 1973 , Page(s): 97 - 100
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (456 KB)  

    Antenna imaging by a perfectly conducting finite flat disc is investigated analytically and numerically as a function of the radius of the disc. A conical monopole of variable length is considered above the screen and the normalized terminal admittance of the antenna is plotted versus the disc radius. The radiation pattern is also plotted and the current distribution above and below the screen is evaluated. The results provide a quantitative measure of the effectiveness of finite screens in imaging antennas and bring to light the persistent distortion of the pattern caused by the finite size of the screen in contrast to the behavior of the impedance. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Experimental investigations on the impedance behavior of a cylindrical antenna in a collisional magnetoplasma

    Publication Year: 1973 , Page(s): 70 - 77
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (792 KB)  

    An experimental study of the input impedance of a short cylindrical antenna immersed in a laboratory magnetoplasma is reported. The antenna is fixed in length and is aligned with its axis parallel to the dc magnetic field. Of particular interest is its impedance behavior in the vicinity of the resonance and cut-off conditions of the magnetoionic medium. Independent measurements are made to determine the electron density from the ion-current characteristics of a spherical Langmuir probe and the strength of the applied magnetic field with a Hall-effect probe. Measured impedances are compared with Balmain's theory. Essential features observed experimentally are a peak in the antenna input resistance near the upper hybrid resonance frequency and a peak in the antenna conductance near the cyclotron frequency. An additional small increase in the input resistance is observed near the plasma frequency when the plasma frequency is not close to either the upper hybrid resonance frequency or the cyclotron frequency. These results suggest the possibility of using a short cylindrical antenna as a diagnostic probe for measuring properties of a magnetoplasma such as the electron density and collision frequency. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The "Paradisc" antenna--A novel technique to improve the axial ratio of a circularly polarized high gain antenna system

    Publication Year: 1973 , Page(s): 108 - 110
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (280 KB)  

    A circularly polarized feed for an S -band high gain antenna system is designed to have a minimum axial ratio when radiating into free space. However, when the feed is located at the focal point of a 2-ft diameter parabolic reflector, the axial ratio "blows up." An experimental technique, which overcomes this difficulty without any change in the basic feed structure, is described. In addition, other RF test results are presented. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Scattering by nonconcentric circular plasma cylinders with axial magnetic fields

    Publication Year: 1973 , Page(s): 128 - 131
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (376 KB)  

    Matrix equations are given for solving the problem of scattering by a plasma cylinder surrounded by another plasma layer with an axial static magnetic field. The cylinders are assumed to be normally illuminated by an H wave. The numerical calculations were performed for nonconcentric circular plasma cylinders and the scattering properties of interest are also shown. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A new approach to the problem of wave fluctuations in localized smoothly varying turbulence

    Publication Year: 1973 , Page(s): 47 - 53
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (536 KB)  

    In the past, smoothly varying turbulence has been studied by changing the structure constant to the function C_{n}^{2}(\bar{r} ). The purpose of this paper is to show that this approach is insufficient, and that a random process developed by Silverman can be used to describe the wave fluctuations in localized smoothly varying turbulence. The localized turbulence is characterized by a correlation function which is a product of a function of the average coordinate and a function of the difference coordinate. The corresponding spectrum is also given by a product of a function of the difference wavenumber and a function of the average wavenumber. They are related to each other through two Fourier transform pairs. Making use of the preceding representations, the fluctuations of a wave propagating through such a turbulence can be given either by the integrals with respect to the two wavenumbers or by a convolution integral of the structure constant C_{n}^{2}(\bar{r} ) and a function involving the outer scale of the turbulence L_{0} . It is shown that for a plane wave case, if the distance L is within ( L_{0}^{2}/\lambda ), then the usual formula given by Tatarski is valid. But if the distance is between L_{0}^{2}/\lambda and (bL_{0})/\lambda where b is the total transverse size of the turbulence, the variance of the wave is nearly constant, and if L \gg (bL_{0})/\lambda , the variance decays as L^{-2} . Similar conclusions are shown for a spherical wave case. Some examples are shown illustrating the effectiveness of this method. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Radiation from a paraboloid with an axially defocused feed

    Publication Year: 1973 , Page(s): 104 - 106
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (296 KB)  

    The radiation characteristics of a paraboloid with an axially defocused idealized point-source feed are derived using numerical integration of the physical-optics currents. Results from the standard "linearized" analysis are compared with results obtained without approximating various factors in the integrand. In particular, the more complete analysis reveals that the defocusing curves are not symmetrical about the focus. At values of defocusing which cause deep nulls in the defocusing curves of less-tapered feeds, the angular beam exhibits bifurcation. Consequently, these less-tapered feeds are not generally suited to beam broadening applications. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Surface fields on the source-excited dielectric wedge

    Publication Year: 1973 , Page(s): 113 - 115
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (320 KB)  

    Approximate surface fields due to a plane-wave solution and a local-mode solution are compared. The plane-wave solution, which is new, is shown to agree well with experiment. The local-mode solution, which often has been applied to tapered waveguides and antennas, fails near the cutoffs of the surface waves. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Rayleigh scattering

    Publication Year: 1973 , Page(s): 134
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (144 KB)  

    By using a computer program, the authors intend to compute quantities specifying the low frequency scattering behavior of rotationally symmetric bodies which are metallic (electromagnetic scattering), soft, or hard (acoustic scattering) View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Shadow-zone diffraction patterns for triangular obstacles

    Publication Year: 1973 , Page(s): 121 - 124
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (480 KB)  

    A simplified ray-optics (scalar) theory is presented which can be used to calculate interference patterns in the shadow of a diffracting obstacle whose transverse profile consists of two or more straight line segments. The theory is applicable when the pathlength-to-wavelength ratio is large and the diffraction angle is small, conditions typical of terrestrial microwave diffraction links over conical mountain peaks. Scale-model test results show that the theory quite accurately predicts the pattern structure. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Line sources above lossy media for low-frequency underground communication

    Publication Year: 1973 , Page(s): 127 - 128
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (208 KB)  

    In this communication the equations for the radiation of a line source above a lossy medium (earth) are presented. Numerous data on the variation of the field as a function of distance and direction from the source, operating frequency, and conductivity are included. Changes as a function of source position are also investigated. The results can be used in the design of mine rescue communication systems. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Current distribution on a cylindrical antenna in a plasma

    Publication Year: 1973 , Page(s): 102 - 104
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (320 KB)  

    A general solution for the current distribution on a cylinder in a cold magnetoplasma has been obtained. It is complicated, but for practical applications several simplifications occur. We present an outline of this solution and a sample of results. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A comparison of mode match, geometrical theory of diffraction, and Kirchhoff radiation

    Publication Year: 1973 , Page(s): 100 - 102
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (344 KB)  

    Using as a model a parallel-plate flanged waveguide excited by a uniform magnetic line source, the techniques of mode match, geometrical theory of diffraction, and Kirchhoff radiation are compared. In all cases the aperture fields are analyzed in terms of waveguide modes; the far-field results are Fourier transforms of the aperture fields. To within normalization, the Kirchhoff results compare surprisingly well with the two other methods except near resonance and in the low observation angle regions where the diffracted components of the field are dominant. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Applications of conformal mappings to the diffraction of electromagnetic waves by a grating

    Publication Year: 1973 , Page(s): 37 - 46
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (832 KB)  

    The method previously proposed to investigate the diffraction of electromagnetic waves by gratings, in the case of an infinite conductivity is developed. This method, based on the properties of the analytic functions, allows the solution of theoretical problems and reduces the determination of the efficiencies to the study of differential systems. Some examples show its utility for numerical computation. Good agreement is observed in comparing with the results obtained from other techniques (integral equations). View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Eigenvalues of a class of spherical wave functions

    Publication Year: 1973 , Page(s): 8 - 14
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (584 KB)  

    An analytically simple and sufficiently accurate solution for the eigenvalues of a class of spherical wave functions is presented. The class of spherical wave functions considered are modes in conical and quasipyramidal waveguides with perfectly conducting walls and hybrid modes in corrugated conical and quasipyramidal horns with an impedance boundary. The indicated solution has been first used to obtain in closed form eigenvalues of the class of spherical wave functions considered which are subsequently used as the starting values for evaluating the exact eigenvalues with a simple digital-computer based iterative algorithm. The digital-computer evaluation of the eigenvalues has been found to be very fast, since the starting values are close to the exact solution, irrespective of the flare angle of the radial waveguides considered. Further, some mathematical insight has been provided in order to explain why the asymptotic solution, which appears to be valid only for small flare angles, yields eigenvalues close to the exact one even for wide flare angle(s) of the radial waveguides. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

Aims & Scope

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

Full Aims & Scope

Meet Our Editors

Editor-in-Chief                                                 Kwok W. Leung