Dalian Zheng

Electromagnetic scattering and radiation by surfaces of arbitrary shape in layered media. I. Theory

An accurate and general procedure for the analysis of electromagnetic radiation and scattering by perfectly conducting objects of arbitrary shape embedded in a medium consisting of an arbitrary number of planar dielectric layers is developed. The key step in this procedure is a formulation of the so-called mixed-potential electric field integral equation (MPIE) that is amenable to an existing advanced solution technique developed for objects in free space and that employs the method of moments in conjunction with a triangular-patch model of the arbitrary surface. Hence, the goal is to immediately increase analysis capabilities in electromagnetics, yet remain compatible with the large existing base of knowledge concerning the solution of surface integral equations. Three alternative forms of the MPIE in plane-stratified media are developed, and their properties are discussed. One of the developed MPIEs is used to analyze scatterers and antennas of arbitrary shape that penetrate the interface between contiguous dielectric half-spaces. >

Electromagnetic scattering and radiation by surfaces of arbitrary shape in layered media. II. Implementation and results for contiguous half-spaces

For pt.I see ibid., vol.38, no.3, p.335-44 (1990). In pt.I, three mixed-potential electric field integral equations (MPIEs) for conducting surfaces of arbitrary shape residing in plane-stratified dielectric media with an arbitrary number of layers were formulated. One of the MPIEs (formulation C) was found to be particularly well suited for the application of the method of moments (MM). In pt.II, formulation C is specialized to the important case of a scatterer or antenna of arbitrary shape residing in contiguous half-spaces. This MPIE is solved by the MM employing a triangle-patch model of the surface of the object. Sample numerical results for several cases of interest are presented. >

Rigorous analysis of open microstrip lines, of arbitrary cross section in bound and leaky regimes

The problem of an open microstrip line of arbitrary cross section is solved by an integral equation technique in conjunction with the method of moments. The approach is general and can handle, as special cases, multiple strips and strips of finite or infinitesimal thickness. It applies to both the fundamental and higher order modes, whether in the bound or the leaky regime. Computed dispersion curves and modal current distributions are presented for several cases of interest and, where possible, are compared with published data. >

Analysis of microstrip resonators of arbitrary shape

A space-domain approach based on a mixed-potential integral equation formulation is developed for efficient computation of complex resonant frequencies of laterally open microstrip-pitch resonators of arbitrary shape. The effects of the substrate-which may consist of any number of planar, possibly uniaxially anisotropic, dielectric layers-are rigorously incorporated in the formulation by means of the vector and scalar potential Greens functions. The current distribution on the conducting patch is approximated in terms of vector basis functions defined over triangular elements. Computed resonant frequencies, quality factors, modal currents, and far-field radiation patterns are presented for several microstrip resonators. For patches of simple, regular shapes, the results are in agreement with published data obtained by specialized techniques, which, unlike the method presented here, are not easily extendible to arbitrary shapes. >

Analysis of multiconductor transmission lines of arbitrary cross section in multilayered uniaxial media

A mixed-potential electric field integral equation is formulated and applied in conjunction with the method of moments to analyze a transmission-line system consisting of multiple conducting strips of arbitrary cross section embedded in a stratified medium with or without top and/or bottom ground planes. Each layer of the medium is possibly uniaxially anisotropic, with its optical axis perpendicular to the dielectric interfaces. Computed dispersion curves and modal currents are presented and, when possible, are compared with data available in the literature. >

Rigorous analysis of open microstrip lines of arbitrary cross-section in bound and leaky regimes

The problem of a microstrip line of arbitrary cross-section is solved by an integral equation technique in conjunction with the method of moments. The approach is general and can handle as special cases multiple strips and strips of finite or infinitesimal thickness. It applies to both the fundamental and the higher-order modes, whether in the bound or leaky regime. Computed dispersion curves and modal current distributions are presented for several cases of interest and, where possible, are compared with published data.<<ETX>>

Comparison of Lorentz and Coulomb gauge formulations for transverse-electric wave scattering by two-dimensional surfaces of arbitrary shape in the presence of a circular cylinder

Two forms of the so-called mixed-potential electric field integral equation (MPIE) are developed for two-dimensional perfectly conducting (PC) surfaces of arbitrary shape in the presence of an infinite PC cylinder of circular cross section subject to transverse-electric (TE) excitation. One of the MPIEs is based on the Coulomb gauge; the other uses the Lorentz gauge. In either case, the effect of the cylinder is incorporated in the integral equation by means of the appropriate Greens functions, leaving the current distribution on the arbitrary surface as the only unknown. The Greens functions are derived by the eigenfunction expansion technique. An existing well-established moment method procedure is adapted to solve both forms of the MPIE numerically. Computed results are presented for several cases of interest, and the relative merits of the Coulomb and Lorentz gauge MPIEs are discussed. >