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Digest on Antennas and Propagation Society International Symposium

26-30 June 1989

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  • AP-S International Symposium 1989. 1989 International Symposium Digest: Antennas and Propagation (Cat. No.CH2654-2/89)

    Publication Year: 1989
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    Freely Available from IEEE
  • Spherical wavefunction analysis of radiation from the pyramidal horn

    Publication Year: 1989, Page(s):3 - 6 vol.1
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (149 KB)

    The pyramidal horn may be approximated as a quasi-pyramidal horn if the flare angles that describe it are measured from the same point. The quasi-pyramidal horn model is analyzed using spherical wave functions. Only the dominant TE/sup r01/ mode is considered. To simplify the boundary condition it is useful to consider the horn enclosed by a perfectly conducting sphere concentric to the horn apex.... View full abstract»

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  • Treatment of vector potential in a three-dimensional lattice network of spatial network method

    Publication Year: 1989, Page(s):7 - 10 vol.1
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (169 KB)

    The authors assess the validity of applying the equivalent circuit for electromagnetic fields in the spatial network method to the vector potential fields in three-dimensional space and the time domain. The electric vector potential is introduced as the dual quantity of the magnetic vector potential to satisfy the property of the equivalent circuit for Bergeron's method. The validity of the treatm... View full abstract»

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  • Radiation by a modulated sheet electron beam propagating parallel to a reflection grating under a finite magnetic field

    Publication Year: 1989, Page(s):11 - 14 vol.1
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (178 KB)

    The authors investigate two-dimensional radiation from a modulated sheet electron beam propagating parallel to a reflection grating under the influence of an externally applied magnetic field. From the wave-theoretic viewpoint, the spontaneous emission can be interpreted as the radiative leakage of the space-charge waves associated with the electron beam. The analysis is reduced to the determinati... View full abstract»

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  • On matrix partitioning, the Sherman-Morrison-Woodbury technique and the add-on method

    Publication Year: 1989, Page(s):15 - 18 vol.1
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (155 KB)

    The moment method matrix is compared with the add-on technique for the analysis of scattering from large planar structures. It is shown that the two formulations yield the same results, provided that the physical model, the basis and testing functions, and the truncation and discretization criteria are the same. The differences lie in the numerical routes taken to arrive at those results. The nume... View full abstract»

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  • A uniformly valid insulated antenna theory

    Publication Year: 1989, Page(s):19 - 20 vol.1
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (69 KB)

    The authors describe a uniform insulated antenna theory, valid through transition to bare antennas. The transition of the insulated antenna solution to the bare antenna solution is characterized by two parameters: the equivalent bare antenna parameter and the Sommerfeld numerical distance. The error incurred in using WKG theory (Wu, King and Giri, 1973) is discussed.<> View full abstract»

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  • Error estimate of the Fourier-Bessel expansion in computation of field distributions

    Publication Year: 1989, Page(s):21 - 24 vol.1
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    Formulation, solution, and numerical results are presented for the error estimation of the Fourier-Bessel expansion in the computation of field distribution in coaxial regions. It is shown that there exists an optimal number of terms of the expansion which gives the minimum mean square error. This optimal number of terms is a function of the eigenvalue uncertainties.<> View full abstract»

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  • The dispersion characteristics of the FD-TD method

    Publication Year: 1989, Page(s):26 - 29 vol.1
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (145 KB)

    The numerical phase and group velocity characteristics of the three-dimensional FDTD (finite-difference time-domain) algorithm are derived from the dispersion relation for wave propagation in the TEM, TE, or TM mode. From these dispersion characteristics, numerical errors due to dispersion can be easily assessed and would be used in determining the mesh size and the stability factor in order to mi... View full abstract»

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  • Characterization of radiation boundary conditions used in the finite-difference time-domain method

    Publication Year: 1989, Page(s):30 - 33 vol.1
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (172 KB)

    When the finite-difference time-domain (FDTD) method is applied to open region scattering and coupling problems, some artificial mechanism must be used to simulate the infinite region on the necessarily finite spatial grid. The current method of choice is to use a radiation boundary condition (RBC) based on an approximate one-way wave equation. Typically, these RBCs are tested numerically. Unfortu... View full abstract»

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  • Time domain finite difference calculations using a variable step size

    Publication Year: 1989, Page(s):34 - 37 vol.1
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (167 KB)

    The authors describe a novel method of computational electromagnetics which uses a variable step size (calculation increment) in the finite-difference technique (VSSFDM). The step size is kept small around discontinuities and larger away from them, thereby using only about 1/3 of the memory required by a straight application of K.S. Yee's (1966) method. The results obtained by VSSFDM are very clos... View full abstract»

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  • On the use of conformal grids for propagation and scattering problems in finite-difference time-domain computations

    Publication Year: 1989, Page(s):38 - 41 vol.1
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (206 KB)

    The authors examine the use of grids that are conformal with the geometry of the material boundaries and, consequently, reduce the discretization errors introduced by the stair-stepped approximation. However, it is found that the introduction of the nonuniformity in the grid gives rise to at least two difficulties in the implementation of the finite-difference time-domain algorithm. The first is t... View full abstract»

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  • Accurate computation of the radiation from simple antennas using the finite-difference time-domain method

    Publication Year: 1989, Page(s):42 - 45 vol.1
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (124 KB)

    The analysis of a group of three simple antennas is used to illustrate the accuracy of the FDTD (finite-difference time-domain) method and to show that various geometrical features are handled correctly by the method. Each antenna is a well-posed electromagnetic boundary value problem that corresponds to a realizable experimental model. The three antennas considered are of increasing complexity: a... View full abstract»

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  • Absorbing boundary conditions for arbitrary outer boundary

    Publication Year: 1989, Page(s):46 - 49 vol.1
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (142 KB)

    The authors propose an absorbing boundary condition that can be applied to an outer boundary of arbitrary shape, even one that is conformal to the geometry of the scatterer. In order to investigate the application of the new boundary condition, several strip and wedge type geometries were considered, both for TE and TM incidence.<> View full abstract»

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  • FDTD formulation for frequency dependent permittivity

    Publication Year: 1989, Page(s):50 - 53 vol.1
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (135 KB)

    Current finite-difference time-domain (FDTD) formulations require the permittivity, permeability, and conductivity to be constant. However, for many real materials of interest these parameters vary significantly with frequency. The effects of constitutive parameters which vary with frequency are included in a frequency dependent FDTD formulation, (FD)/sup 2/TD, by extending the traditional Yee for... View full abstract»

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  • A simple absorbing boundary algorithm for the FDTD method with arbitrary incidence angle

    Publication Year: 1989, Page(s):54 - 57 vol.1
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (177 KB)

    An algorithm was developed by X. Zhang and K.K. Mei (1988) for simulating the propagation of the quasi-TEM wave in a microstrip structure with the wave impinging at normal incidence onto the absorbing boundary. The amount of reflection was reported to be on the order of 3 to 5%. For the present work, the authors rationalize the concept of the absorbing boundary for the finite-difference time-domai... View full abstract»

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  • The application of a simple absorbing boundary algorithm to cylindrical waveguide

    Publication Year: 1989, Page(s):58 - 61 vol.1
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (157 KB)

    The authors present the implementation of a very simple, yet very effective, plane absorbing boundary algorithm for a rectangular waveguide operated in the TE/sub 10/ mode analyzed with the FDTD (finite-difference time-domain) method. This absorbing boundary produces an amount of reflection smaller than 0.02% at the tuning frequency, works for arbitrary incidence angle, and is very local, meaning ... View full abstract»

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  • The phase retrieval by a reference source

    Publication Year: 1989, Page(s):64 - 67 vol.1
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (116 KB)

    Exploiting the knowledge of the amplitude of a reference element, the authors develop a novel numerical technique in the phase retrieval problem. An example is shown in the case of a discrete source distribution. Specifically, consideration is given, in a bidimensional geometry, to an array of 18 elements spaced lambda /2 apart plus a reference element spaced 10.5 lambda above the last element of ... View full abstract»

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  • Linear array diagnostic from near-field measurements

    Publication Year: 1989, Page(s):68 - 71 vol.1
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (113 KB)

    The authors present an inversion procedure to obtain the current distribution on a linear array from a near-field measurement. Numerical simulations were performed for a 50-element linear array. Single elements are half-wavelength dipoles spaced 0.75 lambda . The measuring distance is 5 lambda and the frequency 10 GHz. The current distribution is a Taylor (one parameter) of 35 dB, with a Gaussian ... View full abstract»

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  • Prediction of far-field patterns using synthesized steerable spatial filtering functions

    Publication Year: 1989, Page(s):72 - 74 vol.1
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (113 KB)

    An improved version of the integral equation formulation proposed earlier by Biraud (1971, 1976) for predicting the far-field patterns of aperture antennas from measured near-field data is presented. It is shown that the numerical computational work can be significantly reduced by performing the near-field measurements over a large surface so as to realize a band-pass spatial filtering function wh... View full abstract»

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  • Practical aspect of spherical near-field measurement

    Publication Year: 1989, Page(s):75 - 77 vol.1
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (89 KB)

    A special custom-tailored near-field range is described. The test range is a large radome (typically 68-foot diameter) and is used to host the antenna under test (AUT) and the circular track which carries the scanning probe. The scanned surface encloses the AUT completely, thereby distinguishing itself from other near-field techniques where only partial scan coverage is possible. Alignment of refl... View full abstract»

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  • Measurement of correction parameters for a dipole probe

    Publication Year: 1989, Page(s):78 - 81 vol.1
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (164 KB)

    A procedure for experimentally determining the correction coefficients for a dipole antenna was demonstrated. The resulting coefficients can be used to correct the measured tangential field in planar near-field measurements. The results also indicate the possibility of asymmetry in the dipole spectral response. The method described has been used to measure the far field of an isolated microstrip p... View full abstract»

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  • Microwave diversity imaging of perfectly conducting object in the close near-field region

    Publication Year: 1989, Page(s):82 - 85 vol.1
    Cited by:  Papers (9)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (158 KB)

    The use of frequency, angular, and polarization diversity approaches in a close near-field microwave imaging system is investigated theoretically. A two-dimensional close near-field microwave imaging system is used to illustrate the theoretical considerations. Numerical results for a perfectly conducting cylinder with a radius of 15 cm in a backward scattering arrangement using frequency and angul... View full abstract»

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  • Measurements of antenna radiation patterns with a computer controlled 108-220 GHz transmitter/receiver system

    Publication Year: 1989, Page(s):86 - 89 vol.1
    Cited by:  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (149 KB)

    Measurements of antenna radiation patterns in the D- and G-bands have been performed with a novel mm-wave transmitter/receiver system. With this system, measurements can be made at any frequency in the 108-220-GHz band. The cost of the system is considerably lower than that of systems which use separate mm-wave sources for each frequency. Measured radiation patterns of a broadband corrugated horn ... View full abstract»

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  • An alternative plane wave synthesis method for Fresnel-zone antenna measurements

    Publication Year: 1989, Page(s):90 - 93 vol.1
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (156 KB)

    It has been demonstrated that the method of successive projections applied to plane wave synthesis yields a fast and effective method for analyzing Fresnel-zone data. In particular, compact range performance can be simulated without the need for a large reflector, at the cost of an increased number of azimuth scans. As an example, for a range length of 320 lambda , 21 scans may be used to achieve ... View full abstract»

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  • Measurements of dipole, bow-tie, log-periodic and log-spiral antennas on a dielectric-filled parabola

    Publication Year: 1989, Page(s):94 - 97 vol.1
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (216 KB)

    The power patterns and input impedances of four types of planar antennas on a dielectric-filled parabola are presented. The measurements were made on a microwave scale model of a proposed submillimeter-wave receiver front end. The dipoles have the lowest input impedance (generally preferred for matching to most nonlinear elements used in low noise receivers), while the log spiral has the broadest ... View full abstract»

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