By Topic

Antennas and Propagation, IEEE Transactions on

Issue 2 • Date March 1972

Filter Results

Displaying Results 1 - 25 of 30
  • [Front cover and table of contents]

    Page(s): 0
    Save to Project icon | Request Permissions | PDF file iconPDF (157 KB)  
    Freely Available from IEEE
  • G-AP best paper award for 1970

    Page(s): 121
    Save to Project icon | Request Permissions | PDF file iconPDF (94 KB)  
    Freely Available from IEEE
  • Full text access may be available. Click article title to sign in or learn about subscription options.
  • [Back cover]

    Page(s): c4
    Save to Project icon | Request Permissions | PDF file iconPDF (421 KB)  
    Freely Available from IEEE
  • An experimental study of a balun-fed open-sleeve dipole in front of a metallic reflector

    Page(s): 201 - 204
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (448 KB)  

    The characteristics of a balun-fed open-sleeve dipole mounted in front of a metallic reflector for operation in the 225 to 409 MHz band are investigated. A parametric study is made of the VSWR response as a function of dipole and sleeve diameter, sleeve length, and sleeve-to-dipole spacing. It is shown that an open-sleeve dipole can be operated over a bandwidth of 1.8:1 as compared with an operating bandwidth of approximately 1.25:1 for a conventional cylindrical dipole with the same diameter. Pattern and gain data are presented for an open-sleeve dipole mounted in front of a flat metallic reflector. Preliminary results on mutual coupling effects are also discussed. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • High resolution measurement of microwave refraction on short tropospheric paths

    Page(s): 176 - 181
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (616 KB)  

    A method of measuring angle of arrival, or angle of fire, of a microwave signal transmitted over a short line-of-sight path is described. The method used is similar to that employed in conical scan, or simultaneous lobing, radars. Accuracy in angular measurement is achieved by utilizing the portion of the antenna pattern in which the gain function varies rapidly with angle. Using 4-ft aperture antennas operating at 35 GHz on a6frac{1}{2}-mi path, angle of fire is detected linearly with an accuracy ofpm 0.010deg, and the resolution may be as good aspm 0.002deg. The effects of random atmospheric turbulence on the results is investigated. Many examples of layered structure have been observed, but the most dramatic records come when the atmosphere is unstable and large changes in refraction occur, e.g., at the onset of land and sea breezes. View full abstract»

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

    Page(s): 223 - 224
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (272 KB)  

    The cross polarized radar cross section of simple axially symmetric objects is shown to be related to transverse body dimensions and the severity of any edges. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The Toeplitz matrix: Its occurrence in antenna problems and a rapid inversion algorithm

    Page(s): 204 - 206
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (360 KB)  

    A special form of the Toeplitz matrix which frequently occurs in the numerical solution of antenna analysis and synthesis problems is discussed. Specific examples are presented illustrating its occurrence in the solution of the integral equation for a thin cylindrical antenna and in the theory of arrays. A matrix inversion algorithm is presented which, by exploiting the unique symmetry properties of the Toeplitz matrix, specifies the inverse matrix elements in terms of recurrence relationships. In this way computational time is proportional to the square of the matrix order rather than the cube as is the case with a general algorithm. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Plane wave pulse backscattering from a low-density dielectric sphere

    Page(s): 214 - 216
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (280 KB)  

    The solution to the scattering problem of a pulse incident on a low-density dielectric sphere is presented. Pulse modulated harmonic carriers and dc pulses are considered. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Solution near the wavefront of transient fields in inhomogeneous dispersive media

    Page(s): 219 - 221
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (352 KB)  

    Uniform asymptotic representations, valid in the vicinity of the wavefront, are derived for transient fields propagating in an inhomogeneous dispersive medium. When the space-time ray equations for these fields can be solved explicitly, the uniform representations yield explicit expressions in the space-time variables; otherwise, the representations involve a parameter which can, however, be eliminated under more restrictive conditions. The results are applied to plane pulse propagation in a plane stratified plasma with exponential variation of electron density, for which the space-time ray equations can be solved in closed form; in this case, the asymptotic representation is found to yield the known exact solution. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Characteristic modes for dielectric and magnetic bodies

    Page(s): 194 - 198
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (464 KB)  

    A theory of characteristic modes for material bodies, both with and without losses, is developed. For loss-free bodies, the modes consist of a set of real characteristic sources which diagonalize the generalized network matrix for the body, and a set of characteristic fields which diagonalize the scattering matrix. Most of the properties of these modes remain the same as those of the corresponding modes for perfectly conducting bodies. For lossy bodies, the corresponding modes have complex characteristic sources. However, in the lossy case there also exists a set of real characteristic sources which diagonalize the generalized network matrix, but their fields do not diagonalize the scattering matrix. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A modal analysis of the dielectric rod antenna excited by the HE11mode

    Page(s): 122 - 128
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (704 KB)  

    A hybrid modal solution is developed for the circular semi-infinite dielectric rod antenna excited in theHE_{11}hybrid mode. Numerical results for the near-zone and far-zone fields, as well as the gain, beamwidth, and percentage of power radiated, are determined for three rods of different diameter and dielectric constant by enclosing the rods with a concentric metal pipe and allowing the radius of the pipe to become large. Comparison is made between these results and previous approximate methods of solution that have been applied to the dielectric rod antenna. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The effects of a moving anisotropic grounded layer on radiation from a line source

    Page(s): 224 - 226
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (272 KB)  

    The radiation from a magnetic or an electric current line source embedded in an uniaxially anisotropic grounded dielectric or plasma layer moving perpendicular to the line source is described. The radiation pattern is obtained, and the effects of the motion of the layer on the radiated power distribution are examined with several numerical examples. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Effect of ground plane absorption coefficient on the admittance of a slot antenna radiating into a warm lossy plasma

    Page(s): 208 - 210
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (256 KB)  

    The effects of the ground plane electron absorption coefficient on the admittance of a half-wavelength slot antenna radiating into a warm lossy plasma are examined for a range of plasma conditions and slot widths. The ground plane absorption coefficient is observed to have significant effects on the admittance of a thin slot when the plasma is greatly overdense, even when the plasma is only mildly warm (T_{e} leq 1 eV). View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • On the Taylor distribution

    Page(s): 143 - 145
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (288 KB)  

    The original Taylor distribution was designed to terminate abruptly in a pedestal (alpha = 0) at its edges. It has been found recently, however, that a pedestal cannot be realized exactly in either theEorHplanes, nor even approximately in theHplane. A new distribution is derived here that produces a Taylor pattern of orderalpha = 1and, hence, that vanishes linearly at the edges. This edge behavior can be realized exactly in theEplane and can be approximated as closely as desired in theHplane. All practical differences in operating performance between the two distributions have been found to be negligible. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Conical-reflector antennas

    Page(s): 146 - 152
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (752 KB)  

    The mechanical advantages of a singly curved conical reflector are demonstrated by the experimental test of a furlable 1.83 m conical-Gregorian antenna at 16.33 GHz. The measured gain of 47.5 dB corresponds to a net efficiency of over 57 percent. A ray-optics analysis of conical-reflector antennas is presented, and data useful in the design of conical antennas is given. The conical-Gregorian antenna, in which a subreflector is used in conjunction with a conventional horn feed, is considered in detail. A physical-optics analysis of the conical-Gregorian antenna is used to investigate diffraction and other effects, and to analytically confirm the high performance of the antenna. It is concluded that conical antennas are a valuable addition to available antenna-design concepts. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Gain measurements of standard electromagnetic horns in the K and Kabands

    Page(s): 136 - 142
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (760 KB)  

    Measurements are described in which the gains of standardhorns in theKandK_{a}bands were determined at a number of wavelengths. The two-antenna method was used. It is believed, after a detailed error analysis, that the gain is known within a limiting error of about 0.05 dB at each wavelength measured. A method is described for measuring the ohmic losses in the horn, So that the measured gains may be compared with theoretical estimates. Gain values calculated from the formula of Schelkunoff and Friis and corrected for ohmic losses agree within about 0.1 dB on the average with the measured gains. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Uncoupled cylindrical wave modes for a radially inhomogeneous medium

    Page(s): 217 - 219
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (296 KB)  

    The equations for the transformation of the tangential electric and magnetic fields through a series of uniform cylindrical layers of arbitrary properties are transformed from their generally coupled form to an uncoupled set of two equations. The complexity of the transformation matrices is thereby greatly reduced. The decoupling operation amounts to a coordinate transformation which has a direct correspondence with the rotation of axes to the plane of propagation in the case of rectangular coordinates. The immediate usefulness of this approach for impedance transformation is shown. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Statistical performance of a magnetic energy-density antenna

    Page(s): 221 - 223
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (336 KB)  

    In mobile communication a three-element energy-density antenna responding to the total electromagnetic energy density offers a way for combatting fading in a standing-wave environment caused by multiple reflections from surrounding objects. Statistical analyses show that in certain respects the performance of a magnetic energy-density antenna consisting of two crossed slots can be expected to compare favorably with that of the three-element unit. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The peak sidelobe of the phased array having randomly located elements

    Page(s): 129 - 136
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (840 KB)  

    A formula is derived for the peak sidelobe level of a phased array in which the elements are randomly located. The parameters of the formula are the number and size of the array elements, size of the array, wavelength, beamsteering angle, and signal bandwidth. The theory is tested by measurement of the peak sidelobe of several hundred computer-simulated random arrays. Unlike the case for the conventional array the effect of spatial taper (nonuniform density of element location) upon the peak sidelobe level is minor. The peak sidelobe of the two-dimensional planar array is approximately 3 dB higher than that of the linear array of the same length and same number of elements. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Measured surface spectrum dependence of backscattering from rough surface

    Page(s): 211 - 214
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (480 KB)  

    The wavelength dependence of backscatter from a smoothly undulating randomly rough surface was measured over a broad continuous range of wavelengths using acoustic waves in water. The experiment resulted in discovering a transition region in which the wavelength dependence changed abruptly fromlambda^{0}tolambda^{+3}, apparently due to change in the surface height spectrum. The wavelength dependence corresponded to the measured surface height spectrum through the transition region in the manner predicted by the composite surface model formulated by Wright and others. A similar spectrum-dependent effect has been found in broad-spectrum electromagnetic measurements of natural surfaces. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Rain attenuation at 15 and 35 GHz

    Page(s): 181 - 187
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (680 KB)  

    In order to satisfy future earth-to-space communications needs, new regions of the electromagnetic spectrum must be exploited. A program to determine the feasibility of using millimeter waves for this application has been conducted at Air Force Cambridge Research Laboratories (AFCRL) for approximately 6 years and it has been shown that at frequencies of 15 GHz (lambda = 2.0cm) and 35 GHz (lambda = 8.6mm) atmospheric attenuation is relatively low except for conditions of heavy clouds and precipitation. A portable radiometric system designed to measure attenuation at 15 and 35 GHz under conditions of precipitation was constructed and located in Hilo, Hawaii, a region where it rains frequently thus making it possible to conduct many attenuation measurements for varying rainfall rates. Attenuation was determined from both extinction and emission measurements as a function of zenith angle and rain rate. On the basis of the results that were obtained, it is concluded that for orographic rain up to rates of 50 mm/h in Hawaii: 1) attenuations up to approximately 10 dB can be calculated quite accurately from an emission measurement; 2) zenith attenuations are well correlated with rain rate and can be estimated from the regression lines which have been obtained; 3) attenuations at angles off zenith are not as well correlated with rain rate and thus the values obtained from the regression lines are only approximate; 4) attenuations at 15 and 35 GHz are well correlated. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Waveguide excited dielectric spheres as feeds

    Page(s): 206 - 208
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (352 KB)  

    The results of experiments with dielectric obstacles of various geometries placed directly upon the apertures of circular and rectangular waveguides are presented. It is found that dielectric spheres, and in some instances dielectric cubes, two to four wavelengths in dimension produce directive patterns with low sidelobe levels. For some cross sections, the measured gain of these antennas is greater (6 dB in some cases) than that produced by optimum horns having apertures of identical cross section. The linearity of the polarization of these antennas is essentially the same as that of an open-end waveguide antenna. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Radar mapping: Prolate spheroidal wave functions versus truncated inverse fourier transform

    Page(s): 188 - 193
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (504 KB)  

    Prolate spheroidal wave functions may be used to obtain an estimate of a distributed source that has been observed from an aperture of finite size. An estimate of the source distribution can also be obtained by the use of the truncated inverse Fourier transform. A quantitative measure is obtained of the reductions in the mean-squared error in the estimates which are produced by the data processing techniques. The relative merits of the two processing techniques depend upon the aperture size and the signal-to-noise ratio. The processing of data by means of the wave functions is found to be more advantageous for small apertures and for large signal-to-noise ratios. The processing techniques are also compared as to the ability to reconstruct the detail in an isolated target or source distribution of limited size. The wave functions are shown to be useful for the processing of data obtained from a large aperture that is used to observe a small target. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Scattering of waves with normal amplitude distribution from cylinders

    Page(s): 216 - 217
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (192 KB)  

    The scattering of waves with a Gaussian amplitude distribution from perfectly conducting and radially inhomogeneous dielectric cylinders is presented. The plane wave scattering solution is obtained as the limiting case when the radius of the scatterer is much smaller than the size of the wave. The scattering of beam waves from spherically symmetric particles was considered recently by Morita et al. [1]. In this communication the case of scattering of waves with a Gaussian amplitude distribution from cylindrically symmetric and infinitely long targets is considered. In a future contribution the scattering of beam waves at normal and oblique incidence from cylindrically symmetric fibers will be reported. 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