No abstract

The transient excitation of a straight thin wire segment parallel to a plane interface between two homogeneous dielectric half spaces is analyzed by the continuous‐time, discretized‐space approach. The analysis is carried out in three steps. First, the subproblem of a single wire embedded in a homogeneous dielectric medium, excited by a voltage source and an incident electric field, is studied with the aid of a time domain integral equation. This equation is discretized in space and transformed to the frequency domain. This procedure results in a system of linear equations of a fixed dimension which is solved by marching on in frequency. Second, the subproblem of a horizontal, pulsed dipole over the interface between two homogeneous dielectric half spaces is considered. The reflected field in the upper medium is computed by spectral techniques. With the aid of a time domain Weyl representation, a fixed, composite Gaussian quadrature rule is derived for the semi‐infinite integral involved. The angular integral is evaluated in closed form. Third, for the complete problem, the reflected field in the upper medium is expressed as a superposition of contributions from dipole sources on the wire axis, and subsequently treated as a secondary incident field in the integral equation for the current on the wire. This integral equation is then solved by combining the techniques developed for the two subproblems. Representative numerical results are presented and discussed.

A computer program named DOTIG1 was developed for the study, in the time domain, of the interaction of transient electromagnetic pulses (EMP) with structures modelled by thin wires. The numerical procedure used is described and the results obtained with DOTIG1 are compared with those obtained, in the frequency domain, by other authors, using the Fourier transform. The comparison is specifically applied to the scattering cases from a simple stick model of an aircraft, from a wire cross in front of an infinite perfect conductor and from a junction of two wires with different radii.

This letter presents a new hybrid method that efficiently combines two versatile numerical techniques, viz., the finite difference time domain (FDTD) and the method of moments in the time domain (MoMTD). The hybrid method is applicable to complex geometries comprising arbitrary thin-wire and inhomogeneous dielectric structures. It employs the equivalence theorem to separate the original problem into two subproblems: 1) the region containing the wires, which is analyzed by using the MoMTD, and 2) the dielectric zone that is modeled with the FDTD. The application of the method is illustrated by analyzing two canonical problems involving thin wires and inhomogeneous media.Index Terms-FDTD, hybrid methods, method of moments, thin wires, time domain.

Abstract-This paper describes a hybrid technique directly operating in time domain