Padé-finite-difference time-domain analysis of electromagnetic scattering in magnetic anisotropic medium

Abstract

Based on the matrix Padé approximation theory, the complex relative permeability tensor of magnetized dispersive media is described by a matrix function expansion with respect to jω in frequency domain. By substituting the operator of /t into jω, the expansion is then transferred into the time-domain. In order to derive the formulation of the matrix expansion of complex relative permeability tensor in discretised time domain, a shifted operator in discretised time domain is introduced as a replacement of time differential operator /t. Therefore the dispersion relation between B and H in discretised time domain can be obtained, which is then implemented to the gyrotropic medium, yielding the time iterative formulation for finite-difference time-domain computation. To verify the feasibility of the presented scheme, we apply the above-mentioned method to the electromagnetic scattering by a magnetized ferrite sphere. The computed result is in good agreement with the one obtained by recursive convolution technique. The analysis and example show the feasibility of the proposed scheme.