Numerical study of SEM

The validity of the singular expansion method (SEM) for transient scattering from a perfectly conducting sphere is investigated under different excitations. One of the advantages of choosing a sphere to be the scatterer is that the conclusion obtained may be more general than that drawn from a one or two-dimensional scatterer. The following conclusions are drawn: (1) using an incomplete collection of poles in the SEM expansion together with time-independent coefficients to calculate scattering current and scattered field is valid when the first creeping wave reaches the observation point; (2) the speed of the convergence of Prony series in one-direction and n-direction is mainly dependent on observation time and the properties of the excitation, respectively; and (3) SEM expansion is efficient to describe creeping wave contribution but not valid to describe the reflect portion in the response.<>