Self-Dual Integral Equations for Electromagnetic Scattering From IBC Objects

In this paper, a novel surface integral equation formulation is proposed to solve electromagnetic scattering from objects with impedance surfaces. Derived from a new implementation of the impedance boundary condition (IBC), the proposed surface integral equations are able to calculate scattering not only from objects with impedance surfaces, but also from perfect electric conductors (PEC) and perfect magnetic conductors (PMC) if the surface impedance is set to zero and infinity, respectively. By including both the surface electric and magnetic currents as unknown quantities, the proposed formulations are dual formulations of themselves, and are free of spurious interior resonance corruption. The condition numbers of the resulting system matrices with respect to different surface impedance and mesh densities, and applications to uniform and nonuniform cases are discussed. The multilevel fast multipole algorithm is employed for calculation of electromagnetic scattering from very large objects. Numerical examples are given to demonstrate the performance of the proposed formulations.