Acceleration of multiple reflection physical optics scattering analysis with the MLFMM

Abstract

The physical optics (PO) approximation is commonly used for scattering analysis of electrically large, conducting objects. The standard PO approximation is purely local and does not take multi-bounce effects into account. The multiple reflection PO (MRPO) method takes multiple reflections into account in an iterative manner. In this paper the mesh-based MRPO with standard RWG basis functions on triangle elements is considered. In cases where shadowing can be pre-specified based on physical insight, the main computational bottleneck is the integration over the currents to obtain the next reflection's contribution to the surface current. It is shown that the multilevel, fast multipole method (MLFMM) can be used to accelerate these calculations significantly, while yielding essentially identical results as the MRPO with conventional integration.