Computations of Electromagnetic Wave Scattering From Penetrable Composite Targets Using a Surface Integral Equation Method With Multiple Traces

We present a surface integral equation domain decomposition method (SIE-DDM) for time harmonic electromagnetic wave scattering from bounded composite targets. The proposed SIE-DDM starts by partitioning the composite object into homogeneous sub-regions with constant material properties. Each of the sub-regions is comprised of two sub-domains (the interior of the penetrable object, and the exterior free space), separated on the material interface. The interior and the exterior boundary value problems are coupled to each other through the Robin transmission conditions, which are prescribed on the material/domain interface. A generalized combined field integral equation is employed for both the interior and the exterior sub-domains. Convergence studies of the proposed SIE-DDM are included for both single homogeneous objects and composite penetrable objects. Furthermore, a complex large-scale simulation is conducted to demonstrate the capability of the proposed method to model multi-scale electrically large targets.

I. Introduction

Numerical solutions of electromagnetic (EM) wave scattering from arbitrarily-shaped three-dimensional (3-D) general bounded composite metallic and dielectric structures have attained significant interests lately. In cases where the dielectric regions are homogeneous, or piecewise homogeneous, the surface integral equation (SIE) method [1], [2] is an appealing full wave approach for solving EM scattering from them efficiently and effectively. It is mainly due to the fact both the analysis and unknowns reside only on the boundary surfaces of the homogeneous dielectric regions. Nonetheless, the use of the SIE method to compute EM scattering from 3-D general composite objects does pose non-trivial challenges. The treatment of a general composite structure with multiple materials and metallic junctions is still an active research area [3]. Particularly, for electrically large and multi-scale electromagnetic wave problems, we shall need an effective and reliable preconditioning strategy to assure fast convergence in iterative matrix solutions.