摘要:

The radiation patterns of a three-element array of staggered parallel-plate waveguides is calculated by ray-optical methods. Experiments with a long H-plane sectoral horn at about 12 GHz show good agreement with the theory.

ISSN:0272-6343    

DOI:10.1080/02726348908915231

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Given the natural frequencies of an object (electromagnetic scatterer) in free space, one can consider how they are changed by the presence of another object in its proximity. This paper considers the case that the second object is symmetrical with respect to the first with a plane of symmetry between them. A perturbation of the natural frequencies is found which is applicable to an intermediate range of spacing between them.

ISSN:0272-6343    

DOI:10.1080/02726348908915232

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A thin semi-infinite layer of a non-magnetic dielectric material is modelled using a combination of resistive and (modified) conductive sheets, and for the problem of a plane wave at skew incidence on the resulting half-plane, the exact solution is determined by the Wiener-Hopf technique. The far zone diffracted field is then derived and expressed in the form of an edge diffraction tensor.

ISSN:0272-6343    

DOI:10.1080/02726348908915233

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A numerical technique is presented for computing transverse magnetic (TM) scattering by perfectly conducting wedges and half-planes coated with dielectric and/or magnetic materials. The technique combines finite element method with surface integral equation and physical optics formulations. Example results are presented for surface fields from which the corresponding surface impedances are calculated.

ISSN:0272-6343    

DOI:10.1080/02726348908915234

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

An analysis of electromagnetic scattering by an arbitrarily shaped anisotropic, but homogeneous material structure utilizing combined field surface integral equation formulation is presented. Derivation of the appropriate electromagnetic potentials for the time harmonic Maxwell's equations is also undertaken. The medium in this study is characterized by its permittivity and permeability tensors, and the mathematical formulation is specialized to the two-dimensional anisotropic scatterer of arbitrary shape excited by a plane wave at normal incidence. The derived potentials along with their appropriate gauges are used to represent the fields in the medium. Subsequently, these field representations are utilized in the derivation of a set of coupled integral equations with the help of the equivalence principle. Rigorous analysis approach is developed for the two-dimensional objects, both for the TM and the TE polarizations.

ISSN:0272-6343    

DOI:10.1080/02726348908915235

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The Singularity Expansion Method (SEM) parameters (natural frequencies, natural modes, and coupling coefficients) are presented for several different geometries each composed of four arbitrarily-oriented, thin, straight wire scatterers with one end of each of the four straight members connected at a common intersection point. Various choices of the orientations (and lengths) of these four members result In specific configurations which have been investigated previously (perpendicular crossed wires, planar symmetric tri-arm, L-shaped wire, and straight wire) as well as several other configurations which have not (nonplanar symmetric and nonsyrametrlc tetra-arms, nonplanar symmetric and nonsymmetrlc trl-arms, and arbitrarily bent wire). The SEM parameters for the general tetra-arm structure are calculated for a wide range of geometrical configurations. Commonalities which exist between the SEM parameters of the general tetra-arm scatterer and the previously analyzed “dipoles”, “tripoles” and “crossed dipoles” are presented and discussed. These data suggest that the SEM parameters of some of the more complicated scattering structures may be expressed partially as (or decomposed Into) combinations of the SEM parameters of several simpler geometrical configurations.

ISSN:0272-6343    

DOI:10.1080/02726348908915236

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

In this paper. Lie algebra techniques are used to generate new nonseparable exact solutions to the two-dimensional Helmholtz equation. While certain classes of nonseparable solutions have been found previously, no systematic method of generating them has been formulated. The symmetry group of the Helmholtz equation allows us to generate many new solutions, which include the previously known solutions as special cases. The possible use of these solutions for analysis of electromagnetic waveguides/cavities with e γzlongitudinal dependence and nonseparable cross-sectional geometry is considered.

ISSN:0272-6343    

DOI:10.1080/02726348908915237

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor