Time-domain electromagnetic field analysis based on discrete time signal expansion and its relation to frequency domain banded signals

In this paper we presents a novel time-domain (TD) electromagnetic (EM) field signal process by using discrete-time signal expansion. In particular, the TD signals are first expanded by a set of orthogonal basis functions which may be used to represent frequency-domain (FD) banded signals. As a result, the coefficients of TD field expansion form a matrix field in a form analogous to the EM field quantity. Thus, the conventional FD solutions for the scattering and diffraction problems can be used to predict the TD wave propagation problems. The characteristics of these TD basis functions will be investigated and presented. Examples demonstrating the applications of this technique of discrete-time signal expansion will be presented.