UTD ray tracing for building imaging studies

Abstract

Radar imaging studies of full-scale buildings present serious electromagnetic modeling challenges. The large electrical size makes numerical methods impractical, and the complexity makes ray methods difficult to apply. In this paper we adapt the NEC-basic scattering code (NEC-BSC) [1] to generate simulated radar scattering data for building imaging purposes. The NEC-BSC is based on the uniform geometrical theory of diffraction (UTD) ray tracing method [2,3]. The NEC-BSC combines geometrical optics (GO) ray tracing with the edge and corner diffraction contributions of UTD by constructing models build up of basic canonical shapes, such as plates, cylinders, ellipsoids, cone frustums and wires. For buildings we are primarily interested in models made from multi-layered dielectric plates which represent walls, floors and ceilings. The code traces rays through multiple reflections and diffractions to include the dominant building scattering mechanisms shown in Figure 1, such as dihedrals, trihedrals, direct reflection, and edge and corner diffraction. Higher order combinations of reflections and diffractions are also included, as well as transmission through dielectric plates.