Electromagnetic scattering from material coated PEC objects: a hybrid volume and surface integral equation approach

We propose a hybrid integral equation approach that combines the volume integral equation (VIE) and the surface integral equation to model the mixed dielectric and conducting structures. The volume integral equation is applied to the material region and the surface integral equation (SIE) is enforced over the conducting surface. This results in a very general model as all the volume and surface regions are modeled properly. The advantage of this approach is that in the coated object scattering problem, the coating material can be inhomogeneous, and in the printed circuit and microstrip antenna simulation problem the substrate can be of finite size. Another advantage of this approach is the simplicity of the Green´s function in both the VIE and SIE. However the additional cost here is the increase of the number of unknowns since the volume that is occupied by the dielectric material is meshed. This results in a larger memory requirement and longer solution time in solving the MoM matrix equation. But this deficiency can be overcome by applying fast integral equation solvers such as the multilevel fast multipole algorithm. We first give the formulation of the problem using the method of moments (MoM), and then show numerical simulation results to demonstrate the validity of the proposed method.