Uniform Surface Integral Equation Formulation for Mixed Impedance Boundary Conditions

A numerical approach based on the surface integral equation (SIE) method is developed for the analysis of time-harmonic electromagnetic scattering by impenetrable objects equipped with mixed impedance boundary conditions (MIBCs). MIBC is an axially anisotropic generalization of the conventional isotropic (Leontovich) impedance boundary condition. The developed SIE formulation utilizes surface Helmholtz decomposition, the self-dual formulation of Yan and Jin, and loop and star RWG functions. A combined field formulation is applied to avoid internal resonances.