A Hybrid Symmetric FEM/MOM Formulation applied to Scattering by Inhomogeneous Bodies of Revolution

| A new symmetric formulation of the Hybrid Finite Element Method(HFEM) is described which combines elements of the Electric Field Integral Equation (EFIE) and the Magnetic Field Integral Equation (MFIE) for the exterior region along with the nite element solution for the interior problem. The formulation is applied to scattering by inhomogeneous bodies of revolution. To avoid spurious modes in the interior region a combination of vector and nodal based nite elements are used. Integral equations in the exterior region are used to enforce the Sommerreld radiation condition by matching both the tangential electric and magnetic elds between interior and exterior regions. Results from this symmetric formulation as well as formulations based soley on the EFIE or MFIE are compared to exact series solutions and integral equation solutions for a number of examples. The behavior of the symmetric, EFIE, and MFIE solutions is examined at potential resonant frequencies of the interior and exterior regions, demonstrating the advantage of this symmetric formulation.