A hybrid method for the calculation of transient EM scattering

Analytical and numerical studies have made clear that singularity expansion methods (SEMs) for scattering responses are inadequate in early scattering time. However, it is efficient to use SEM in later scattering time, especially after creeping waves reach the observation point. A combination of a discrete Fourier transformation (DFT-SEM) and an SEM expansion is reported that gives good results in the entire time domain. The method avoids the difficulties of SEM in calculation of early time responses and is more efficient and exact than the DFT method alone. Because contributions to the response are considered over all the frequency domain, there is no restriction on the excitation, it can be an impulse that has a white spectrum. The solutions given by the DFT-SEM method have high precision and are insensitive to frequency-response errors.<>