摘要:

The resonance properties of certain arrays consisting of the simplest possible Maxwell scatterer, the pseudodipole, are studied. T. T. Wu's analysis of the uniformly spaced infinite linear array of pseudodipoles is generalized to allow for certain classes of pseudodipole rotations; in all cases, it is shown that these arrays can admit zero-width resonances. It is then shown that the uniformly spaced circular array can admit resonances whose widths tend to zero exponentially as the number of pseudodipoles tends to infinity while the arc-length spacing remains constant-a property which has been studied by A. Grossmann and T. T. Wu for the quantum mechanical analogue of the pseudodipole. From the asymptotic analysis of the circular array of pseudodipoles, it is observed that instability can sometimes arise. It is conjectured that this stability problem can be eliminated by modifying the original pseudodipole definition to allow for a frequency-dependent pseudodipole parameter. With this generalization, the precise nature of the instability is investigated. Based on a recent result showing that the pseudodipole can be derived as the limit of a resonant cylindrical dipole, a formula for the frequency dependence of the pseudodipole parameter is proposed.

ISSN:0920-5071    

DOI:10.1163/156939394X00191

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The main propagation effect on interference between a satellite system and an adjacent terrestrial path is considered to be the differential rain attenuation. In the present paper, a predictive method for the differential rain attenuation statistics is presented based on a convective raincell model and the assumption that the point rainfall statistics follows a gamma form. This is valid for various climatic zones of the world, such as J, M, N, P, Q zones. The results of the predictive procedure are compared with the only available set of experimental data taken from Yokosuka, Japan. The sensitivity of various parameters affecting the differential attenuation statistics is also examined.

ISSN:0920-5071    

DOI:10.1163/156939394X00209

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Uniform asymptotic expressions for the doubly diffracted fields excited on the edges of a resistive strip located on a dielectric interface are obtained using a spectral iteration technique. The incident electric field is assumed to be parallel to the edges of the strip. The results also include the contribution of the surface wave fields to the secondary diffraction.

ISSN:0920-5071    

DOI:10.1163/156939394X00218

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

An adaptive collocation method using subdomain sinusoidal basis functions is presented. The method combines the computational efficiency of a conventional collocation method with the rapid convergence properties of a Galerkin method. The method uses a reaction integral equation formulation and is based on quadrature principles.

ISSN:0920-5071    

DOI:10.1163/156939394X00227

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Four efficient algorithms that have been recently developed provide a direct solution of certain canonical singular integral/integrodifferential equations formulating electromagnetic scattering by arbitrarily wide strips or slots either in free space or in the presence of separating boundaries. In this paper, two of these algorithms are used for investigating the scattering properties of a slot on an infinite ground plane loaded a) by a cavity with a perfectly conducting semi-cylindrical wall, or, b) by a dielectric semi-cylinder surrounded by air. Plotted results, which are presented either for E- or H-type plane wave/line-source excitations, bring to light the effect of varying several geometrical parameters on the response of the structures. The characteristic current problems for these same configurations are also investigated.

ISSN:0920-5071    

DOI:10.1163/156939394X00236

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

In practical calculations it is often essential to truncate the computational domain by introducing artificial boundaries. The manner in which boundary conditions are approximated has an important influence on the accuracy of the results. In this paper we present a time domain technique to quantify the spurious reflection of waves from an artificial boundary, obtained by using a nonreflecting boundary condition based on rational approximations.

ISSN:0920-5071    

DOI:10.1163/156939394X00245

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

ISSN:0920-5071    

DOI:10.1163/156939394X00254

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

ISSN:0920-5071    

DOI:10.1163/156939394X00263

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor