Analysis of transient electromagnetic scattering from dielectric objects using a combined-field integral equation

In this paper, we analyze the transient electromagnetic response from three-dimensional (3D) dielectric bodies using a time-domain combined-field integral equation. The solution method in this paper is based on the method of moments (MoM), which involves separate spatial and temporal testing procedures, Triangular-patch basis functions are used for spatial expansion and testing functions for arbitrarily shaped 3D dielectric structures. The time-domain unknown coefficients of the equivalent electric and magnetic currents are approximated by a set of orthonormal basis functions derived from the Laguerre polynomials and exponential functions. These functions are also used as temporal testing. In addition to use of the Laguerre polynomials as expansion functions for the transient portion of the response, two new source vectors related to the equivalent currents enables one to handle the time derivative terms of the vector potential in the integral equation in an analytic fashion. Numerical results computed by the proposed method are presented and compared.