a Finite Difference Maxwell Equation Solver for Harmonic Wave Scattering.

A method is presented for computing time harmonic plane wave scattering by general two dimensional bodies within the resonance frequency regime. The governing equations are derived from the Maxwell equations by casting the equations in terms of scattered field variables, and then applying a time harmonic transformation. Material interface conditions are derived by direct evaluation of the integral form of the governing equations. The governing equations are discretized using a globally fourth order accurate compact operator for spatial derivatives and a multistage Runge-Kutta operator for a fictitious pseudotemporal derivative. Stiffness resulting from lossy media is alleviated by a point implicit treatment of the real time source term. Fourier analysis of differential, semidiscrete and fully discrete forms of model governing equations is employed to establish the solution space, the spatial stability and the temporal stability; and to derive a unique material interface boundary condition and a highly effective radiation boundary condition. Electromagnetic field solutions are computed for two-dimensional scattering bodies composed of perfectly conducting, lossless and lossy media for both transverse electric and transverse magnetic polarizations of the incident field. The accuracy of the numerical methods is determined through the comparison of bistatic radar cross sections computed from analytic and integral equation solutions.