Comparison between the OSRC approach and the PO approximation for solving EM scattering

Recently, a technique referred to as the on-surface radiation boundary condition (OSRC) approach was introduced and applied to a class of perfectly conducting cylinders for computing their scattering. The OSRC method is applied here to a variety of two-dimensional imperfectly conducting geometries. Specifically, analytical solutions and numerical data are presented for the scattering by elliptical and rectangular impedance cylinders and resistive strips. Of primary interest in this investigation is to compare the OSRC approach with the physical optics (PO) approximation in predicting the scattering by the aforementioned structures. It is concluded that in general the OSRC approach predicts more accurate results than the PO approximation for scatterers formed by smooth curved surfaces that do not deviate substantially from a circular one. In addition, for such geometries the applicability of the OSRC approach is not limited to the high-frequency regime but extends in the low frequency region as well. The OSRC approach, however, is not appreciably better when considering polygonal cylinders or more general structures with first-order surface discontinuities.