摘要:

The classical electromagnetic field problem of a perfectly conducting half plane and a two-dimensional line source parallel to the edge is formulated in terms of image sources in complex space. It is seen that the image currents can be expressed in terms of simple trigonometric functions in contrast to the more complicated functions characterizing the physical currents on the half plane. Also, in contrast to the nonphysical edge currents applied in the physical diffraction theory, the image currents are exact and do not depend on the point where the field is to be calculated. However, the field can be computed from a single converging image in a half space only, which can be chosen at will. Because of the exponential decay of the image, approximation by a finite source becomes effective. As a validity check of the theory, the diffraction coefficient of GTD is obtained in the high-frequency asymptotic limit, as a normalized value of the image current at a certain point. Also, diffraction patterns computed from the image source are seen to demonstrate the equivalence to the usually applied field integrals. The method is suggested for integral equation formulation of problems involving a conducting half plane and for extending the physical optics edge current method to field points where the physical optics is no longer valid.

ISSN:0920-5071    

DOI:10.1163/156939393X00282

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

In practical applications it is necessary to analyze radar scattering by a chaff cloud in a ground-based system rather than in the scattering plane-based system. By means of the Stokes-parameter method, a series of expressions of the bistatic radar scattering cross section (BRSCS) corresponding to arbitrarily polarized combinations of transmitters and receivers are derived in the ground-based system in the present study. The influence of chaff wires' orientation on the BRSCS is also studied based on the comparison between the cases of the spherically randomly oriented wires and the horizontally Gaussian-distribution-oriented wires, which may provide a valuable reference for designing various types of chaff as well as transmitter and receiver systems upon different demands.

ISSN:0920-5071    

DOI:10.1163/156939393X00291

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A numerical method is presented for the problems of transverse magnetic (TM) and transverse electric (TE) multiple scattered fields from homogeneous dielectric and imperfectly conducting parallel cylinders. The numerical solution uses fictitious filamentary sources to simulate the field scattered by and transmitted into the cylinders. The currents of the fictitious sources are solved for subject to the boundary conditions. Numerical results, for multiple scattering by two cylinders having different parameters, are given and compared with method of moments solutions.

ISSN:0920-5071    

DOI:10.1163/156939393X00309

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The theoretical behavior of TE-plane wave scattering from a dielectric-loaded semicircular trough in a conducting half-space is investigated. The dielectric loading is made of a circular cylinder which is partially buried in a semi-circular trough in a perfectly conducting plane. The scattered field is numerically evaluated to investigate the angular scattering pattern under the various dielectric loading conditions. The presence of the dielectric loading in the trough can substantially affect the angular scattering behavior. The difference between the TE and TM-scattering angular patterns is also observed. The field magnitude inside the trough is found to be much greater than the outside, thus indicating that the trough focuses the incident beam inside the trough.

ISSN:0920-5071    

DOI:10.1163/156939393X00318

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

This paper presents the analysis and evaluation of an indoor far-field chamber used for radar cross section (RCS) evaluation. The range has conductive walls on all sides except for the pyramidal absorber covered back wall. The chamber was designed such that wall/floor/ceiling interactions occur with a distance (time) delay allowing for their isolation from the test region. Software gating techniques were used to remove these unwanted signals. This paper presents an analysis of the conductive chamber using Geometrical Optics (GO). The objective was to analyze and evaluate the plane wave quality in the chamber test region. The evaluation of the plane wave was performed using the angle transform technique. This method involved measuring the complex RCS vs. aspect angle of a rotating cylinder. The measured results were compared to analytical results and measured antenna patterns.

ISSN:0920-5071    

DOI:10.1163/156939393X00327

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Shanks has developed a powerful nonlinear extrapolation method by assuming a partial series can be decomposed into a finite sum of exponential transients. The use of this extrapolation method is rarely justified, however. This paper presents a means for determining the transient order of a partial series as well as a justification for its use on Fourier series.

ISSN:0920-5071    

DOI:10.1163/156939393X00336

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A rigorous modeling of vertical coaxial probes embedded in thick (uniaxial) anisotropic multilayered structures is presented. An integral equation for the current along the isolated probe is derived and solved by the method of moments. Two types of testing are used: point-matching and Galerkin. The steepest-descent method with a modified saddle-point approximation is used to obtain the asymptotic electromagnetic far field. Results are discussed in terms of the surface and leaky waves locations in the steepest-descent complex plane. The effect of anisotropy is pointed out. Computed results are compared with measurements.

ISSN:0920-5071    

DOI:10.1163/156939393X00345

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A mixed boundary value problem is formulated for the surface currents that are induced by a time-harmonic plane wave incident upon an open-ended conducting tube of finite length. Scattered fields are represented by spatial Fourier transforms in the axial dimension for each of the uncoupled azimuthal Fourier modes of this body of revolution. Numerically efficient mathematical expressions having explicit physical significance are derived to solve the set of linear equations from a Galerkin expansion of the currents in terms of Chebyshev polynomials with edge-condition weighting. Resultant surface currents and axial fields are calculated for several combinations of scatterer geometry and frequency, and interpreted partially in terms of travelling waves external and internal to the conducting cylinder.

ISSN:0920-5071    

DOI:10.1163/156939393X00354

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

ISSN:0920-5071    

DOI:10.1163/156939393X00363

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

ISSN:0920-5071    

DOI:10.1163/156939393X00372

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor