A higher-order multilevel fast multipole algorithm for scattering from mixed conducting/dielectric bodies

Electromagnetic scattering from composite bodies that consist of both conducting and dielectric objects is an important and challenging problem in the field of computational electromagnetics. In this paper, we present a higher-order multilevel fast multipole algorithm (MLFMA) for computing electromagnetic scattering from 3-D bodies comprising both conducting and dielectric objects. We first formulate the surface integral equations using the Poggio-Miller-Chang-Harrington-Wu-Tsai (PMCHWT) approach for multiple homogeneous dielectric objects and the combined-field approach for conducting objects. This formulation is known to be accurate and free of interior resonance corruption. The resultant integral equations are discretized by the method of moments (MoM), in which the conducting and dielectric surfaces/interfaces are represented by curvilinear triangular patches and the unknown equivalent electric and magnetic currents are expanded using higher-order vector basis functions. MLFMA is then employed to speed up the matrix-vector multiplication in the iterative solution of the MoM matrix equation. Numerical examples are presented to demonstrate the performance of the proposed method.