Scheduled System Maintenance:
On Monday, April 27th, IEEE Xplore will undergo scheduled maintenance from 1:00 PM - 3:00 PM ET (17:00 - 19:00 UTC). No interruption in service is anticipated.
By Topic

Antennas and Propagation, IEEE Transactions on

Issue 6 • Date November 1968

Filter Results

Displaying Results 1 - 25 of 40
  • [Front cover and table of contents]

    Publication Year: 1968 , Page(s): 0
    Save to Project icon | Request Permissions | PDF file iconPDF (538 KB)  
    Freely Available from IEEE
  • Contributors and back cover

    Publication Year: 1968 , Page(s): c4
    Save to Project icon | Request Permissions | PDF file iconPDF (2320 KB)  
    Freely Available from IEEE
  • Effective boundary conditions for reflection and transmission by an absorbing shell of arbitrary shape

    Publication Year: 1968 , Page(s): 706 - 712
    Cited by:  Papers (44)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (640 KB)  

    The reflection and transmission properties of an absorbing shell of arbitrary shape can be described by two algebraic boundary conditions relating the four tangential fields E_{+}, H_{+}, E_{-}, H_{-} at corresponding points on the outer surface S_{+} and inner surface S_{-} , respectively. The boundary conditions contain first-order curvature correction terms, but it is still necessary that the shell curvature be reasonably small compared to the attenuation per unit distance in the shell material. Especially simple conditions are obtained for shells thin compared to the attenuation length. The shell boundary conditions can also be used to determine an effective surface impedance for a conducting body coated by multiple layers of absorbing material. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Displacement of rays in a turbulent medium

    Publication Year: 1968 , Page(s): 678 - 683
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (496 KB)  

    The Fokker-Planck equation associated with the fluctuation (ray) equation is derived. The resulting equation for an isotropic turbulence is in the form of a diffusion equation. It has been found that the diffusion coefficient is more naturally defined in terms of the logarithmic refractive index. In the limit of weak turbulence, the present definition reduces to the conventional one. For a general and arbitrary "initial" condition, certain moments of the diffusion equation have been obtained. These moments give 1) the probability of finding a ray with a given ray direction and given path length, and 2) the mean and mean-square position of the ray in a given direction and given path length. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Scattering of a beam wave by a spherical object

    Publication Year: 1968 , Page(s): 724 - 727
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (344 KB)  

    The theoretical analysis of the scattering of a beam wave by a small spherical object, which exists at the neighborhood of the beam waist on the propagation axis, is treated. In this analysis, the property of a spherical object is generalized so as to have an r -dependent dielectric constant. Through numerical calculations for the case of the conducting sphere, the difference between the scattering of a beam wave and that of a plane wave are discussed. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Pattern synthesis of circular arrays with many directive elements

    Publication Year: 1968 , Page(s): 758 - 759
    Cited by:  Papers (5)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (240 KB)  

    A method for synthesizing the radiation pattern of a circular array with directive elements is presented. The required excitations are determined from an explicit formula which requires no reduction or inversion of matrices. It is particularly useful for designing large circular arrays with many elements. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Studies of the focal region of a spherical reflector: Stationary phase evaluation

    Publication Year: 1968 , Page(s): 646 - 656
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (784 KB)  

    The geometric optics and polarization properties of a spherical reflector are used to develop an integral representation of its focal region fields. These integrals are evaluated by the extended method of stationary phase for field points off the caustics, on the axial caustic, on the caustic surface, and at the paraxial focus. The contributions to the field at a field point are shown to arise respectively from three ordinary stationary points: a stationary ring and a stationary point at the vertex; an ordinary stationary point and a caustic type stationary point; and a fourth-order stationary point. The resulting formulas are used to compute the value of the focal region fields. The computed results are then compared to measured data. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Analysis of mode conversion in waveguide transition sections with surface impedance boundaries applied to VLF radio propagation

    Publication Year: 1968 , Page(s): 673 - 678
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (528 KB)  

    First- and second-order correction terms are derived for the reflection and transmission scattering coefficients for a step-type transition between two uniform waveguides with surface impedance boundaries. This analysis yields rigorous expressions for the differential transmission and reflection coefficients defined for an infinitesimal step transition. These coefficients are essential in the derivation of the coupled differential equations for the wave amplitudes in a transition section of gradually varying height. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Diffraction by thick conducting half-plane and dielectric-loaded waveguide

    Publication Year: 1968 , Page(s): 778
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (80 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.
  • A Poynting vector approach to creeping-wave analysis of the sphere

    Publication Year: 1968 , Page(s): 774 - 776
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (360 KB)  

    A ray path geometry is derived using the Poynting vector to calculate the surface fields due to creeping waves in both the E - and H -planes of the sphere. The geodesics (great circles) are determined by assuming that at each point on the shadow boundary the initial direction of the ray is specified by the direction of real power flow calculated from the exact Poynting vector. The resulting ray geometry allows calculation of the creeping-wave surface field in both the E - and H -planes. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • On antenna impedances in a cold plasma with a perpendicular static magnetic field

    Publication Year: 1968 , Page(s): 728 - 736
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (808 KB)  

    A flat strip antenna is embedded in a magnetoionic medium with its longitudinal axis perpendicular to the static magnetic field. The antenna characteristics differ for antennas oriented with their surfaces parallel and perpendicular to the static magnetic field. In the former case there are no resistance peaks for frequencies near the plasma frequency and the reactance of a short antenna is capacitive for low frequencies. For frequencies near the gyrofrequency the antennas are electrically longer for the parallel orientation of their surfaces. The accuracy of the solutions is illustrated by computing the tangential electric surface fields that are excited by the approximate current distributions used in the impedance computations. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Theoretical and experimental studies on the long dipole antenna

    Publication Year: 1968 , Page(s): 664 - 673
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (832 KB)  

    The long transmitting dipole antenna is studied theoretically and experimentally. The Wiener-Hopf technique is used to obtain explicit expressions for the current and charge distributions along the antenna. These quantities are also measured. The theoretical and experimental results are in good agreement. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The influence of the scattered field on the reradiation pattern of reflector arrays

    Publication Year: 1968 , Page(s): 751 - 752
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (304 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.
  • Radio propagation over a cylindrical hill including the effect of a surmounted obstacle

    Publication Year: 1968 , Page(s): 700 - 705
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (464 KB)  

    An analysis is presented for wave propagation over a smooth cylindrical surface of constant curvature when the boundary impedance is specified. High-frequency approximations are introduced which permit a universal plot of the diffraction loss as a function of a hill-height parameter. The results are extended to allow for the presence of a knife-edge obstacle located on the crest of the rounded hill. For the conditions considered, the latter produces a substantial gain which, to some extent, overcomes the diffraction loss associated with the hill. The results have direct application to HF and VHF radio propagation over heavily vegetated and forested terrain. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Conjugate echoes in Alouette-2 topside-sounder data

    Publication Year: 1968 , Page(s): 771 - 774
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (504 KB)  

    Three types of ionograms containing symmetric conjugate echo traces which appear frequently in the Alouette-2 satellite topside-sounder data are presented and explained in terms of multiple reflections between conjugate points of the field line passing through the satellite. Such symmetric traces have not been previously reported in the literature. The high intensity of these traces gives credence to the existence of magnetospheric waveguides along which signals can propagate with very little attenuation. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Log-periodic antennas with modulated impedance feeders

    Publication Year: 1968 , Page(s): 633 - 642
    Cited by:  Papers (10)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (744 KB)  

    The proper phasing of the active region of a log-periodic array can be obtained by means of a feeder without the conventional transposition of the wires. This is of practical importance for arrays of monopoles and slots where the transposition is not possible. However, the input impedance of such structures, when fed from a line with constant impedance, varies greatly with frequency. The impedance variation has been traced to reflections from a stop region between the antenna feedpoint and the active region. By introducing a step modulation of the characteristic impedance of the feedline, the reflections can be reduced and a stable impedance obtained. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The theory of braodside arrays; the theory of endfire arrays

    Publication Year: 1968 , Page(s): 778
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (80 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.
  • Pressure-formed parabolic reflectors for millimeter wavelengths

    Publication Year: 1968 , Page(s): 762 - 764
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (312 KB)  

    An empirical investigation of metallic diaphragms deformed by uniform normal pressure to produce accurate parabolic reflectors is discussed. 30-cm diameter ( f/D =0.4 ) reflectors produced by this technique were measured mechanically and found to have maximum deviations of only 0.5 mm or \lambda /20 at 30 GHz from a true paraboloid within a circle of 14-cm radius. Electrical measurements at 30 GHz are discussed. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Scattering by a finite perfectly conducting wedge

    Publication Year: 1968 , Page(s): 776 - 777
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (240 KB)  

    Some numerical results are presented for the radar cross section of finite wedges for the case of symmetric illumination by a plane wave polarized in the direction of the wedge axis. Some preliminary results are given comparing calculations based on satisfying boundary conditions at discrete points with the exact approach. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Nonlinear interaction of electromagnetic waves in bounded plasmas

    Publication Year: 1968 , Page(s): 737 - 741
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (384 KB)  

    A method is presented for the solution of second-order electromagnetic fields in a bounded plasma which is excited by two high-frequency electromagnetic waves. Due to nonlinearities inherent in any plasma, incoming waves are mixed, creating sum and difference frequencies. The signal from the difference frequency \omega _{1}-\omega _{2} , where \omega _{1} and \omega _{2} are source frequencies, can be of considerable consequence when \omega _{1}-\omega _{2} is sufficiently low to cause a significant reaction in a plasma as resonant conditions develop. In particular, the problem considered in this paper is the optimization of second-order fields in a uniform plasma confined to a circular waveguide including reference to diagnostic applications. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Determination of resonance conditions in dielectric- sheathed or plug-loaded phase arrays

    Publication Year: 1968 , Page(s): 753 - 755
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (312 KB)  

    Formulas are derived for the conditions of resonance in phased arrays either covered by dielectric slabs or loaded with dielectric plugs. Numerical results are obtained to show the effects on these resonances due to the waveguide wall thickness, dielectric constant, and the thickness of the slab or plug. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • ELF and VLF fields of a horizontal electric dipole

    Publication Year: 1968 , Page(s): 689 - 700
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (952 KB)  

    The waves in the spherical guide between the earth and ionosphere are excited by a horizontal electric dipole. The guide boundaries are characterized by surface impedances and the resulting waves are expressed as a superposition of TM and TE modes. The wavenumbers, excitation factors, height-gain functions, and height-dependent impedances are examined for both types of modes. A thin-shell approximation of the radial wave functions is shown to be adequate for phase velocity estimates; but other propagation parameters are of restricted validity in the VLF range where Airy integral approximations provide more reliable data. A horizontal electric dipole is shown to provide a nearly omnidirectional coverage of horizontal field components in the frequency range of the lower Schumann resonances. For an elevated source the horizontal fields are essentially omnidirectional also in the VLF range. Near fields are expressed as a summation of waveguide modes. The vertical field components vanish at the antipode, but the horizontal components remain of finite magnitude. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Surface tolerance of a radar calibration sphere

    Publication Year: 1968 , Page(s): 718 - 724
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (736 KB)  

    The effect of small-amplitude surface irregularities on the backscattering properties of a metal sphere is examined using a full-wave boundary perturbation method. When the irregularities are resolved into their various spherical harmonics, it is shown that their total effect can be expressed as a weighted sum of their individual spectral amplitudes. The behavior of the weight coefficients as a function of both spectral order and frequency is described using graphs and various approximate formulas. This gives the complete description necessary for computing the effect of an arbitrary (small) surface variation for all frequencies from the Rayleigh region through the resonance region to the short wavelength region. The magnitude of the cross-polarized reflected power is included among the effects that can be computed. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The field pattern of a long antenna with multiple excitations

    Publication Year: 1968 , Page(s): 643 - 646
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (360 KB)  

    The field pattern of an asymmetrically driven long antenna is obtained by the Wiener-Hopf procedure. The formula is algebraic in form and involves no numerical integration. Comparison with experiment is made and the agreement is found to be satisfactory. Application of the result to field pattern synthesis is discussed and two examples are given. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A log-periodic cavity-backed slot array

    Publication Year: 1968 , Page(s): 756 - 758
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (304 KB)  

    This communication describes the element investigation, design, and testing of a backfire log-periodic cavity-backed slot array operating from 2.8 to 5.9 GHz in a frequency-independent fashion. The gain of the antenna is approximately 10 dB, and the VSWR is below 2.5 to 1. The H -plane power patterns are given with nearfield plots along file array. The advantages of the antenna are a simple stripline feeding system and the fact that the structure protrudes a little because shallow cavities are used. 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