Efficient method of moments formulation for large PEC scattering problems using asymptotic phasefront extraction (APE)

A method is introduced for reducing the exorbitant dependence on computer s torage and solution time in the Method of Moments (MoM) for electrically la rge electromagnetic (EM) scattering problems. The unknown surface currents on large, smooth parts of a perfect electrical conducter (PEC) scatterer ar e expressed by an efficient set of Linearly phased surface current basis fu nctions. The phasefront characteristics of the surface currents are numeric ally extracted from known current samples obtained from a lower-frequency s olution of the same configuration, The use of such basis functions for effi ciently representing the surface currents that are constructed in terms of linearly phased currents at higher frequencies is justified by considering the form of the surface currents predicted by high-frequency asymptotic ray methods. The procedure for extracting the current phasefronts is purely nu merical, obviating computationally expensive and nonrobust operations such as ray-tracing, and thus, is amenable to general purpose scattering codes. The nem MoM with linearly phased basis functions is shown to greatly reliev e the storage and solution time of the conventional MoM while accurately re producing the induced surface currents and scattered fields of some chosen targets.