LAUSR

A fast shadowing algorithm based on Levin method is proposed for physical optics (PO) integrals from the targets modeled with a B-spline surface. The CPU time of the proposed algorithm is independent of incident frequency. In the proposed shadowing algorithm, a scatterer is assumed to be fully illuminated by the incident plane wave, and shadowing computation is performed only on the endpoints of subintegrals, which are obtained by subdividing the PO integrals according to the location of critical points. To compute these critical points, including the stationary and resonant points of the PO integrals, we also propose a fast localization technique based on the new expression of phase function. The localization of the stationary and resonant points can be, respectively, reduced to a one-dimensional solution and an analytic solution by using the proposed technique. Several numerical examples are presented to demonstrate the accuracy and efficiency of the proposed methods.