Electromagnetic scattering computation using a hybrid surface and volume integral equation formulation

This paper presents a hybrid integral equation formulation for computation of electromagnetic scattering by composite conducting and dielectric materials. In the hybrid formulation, multiple material regions in a scatterer are classified into two categories, one is the surface integral equation (SIE) region, and the other is the volume integral equation (VIE) region. For the SIE region, the boundary conditions for tangential E-field and tangential H-field are applied to formulate the surface integral equation for the equivalent surface currents. For the VIE region, the equivalent principle is applied to formulate the volume integral equation for the induced volume currents. The hybrid formulation takes the advantageous of both the SIE and VIE. The integral equations are cast into a set of linear equations using the method of moments. For regions that are electrically large, the multilevel fast multipole algorithm is applied to accelerate the matrix-vector multiplication needed by iterative solvers. Numerical results are provided to verify the accuracy and the application of the program developed from the hybrid formulation.