Radiation and scattering from curvilinear 3D composite geometries using the hybrid finite element-method of moments SWITCH code

The SWITCH code is a fully curvilinear hybrid finite element-method of moments code. The hybrid formulation solves a coupled system of equations involving the finite element method (FEM) in interior dielectric regions along with the integral equation method of moments (MOM) on the exterior boundary surface. The formulation of SWITCH is fully curvilinear which eliminates geometry modeling errors associated with faceted approaches, such as the Rao-Wilton-Glisson (RWG) based MOM codes. A built in growth path for arbitrary order polynomial field approximations has been encoded to take advantage of the efficiency of higher order basis functions. The use of curvilinear geometry has resulted in efficiencies for even the first order field approximations (curvilinear roof top currents) as will be shown. The use of the finite element method in the dielectric regions of a geometry allows the characterization of fully anisotropic and highly inhomogeneous materials. This FEM approach also allows the efficient modeling of very thin layers of material over metal without the near singularity problems posed by the MOM formulations. The use of FEM in the layer eliminates the Green's function, which experiences this near-singularity problem. The hybrid approach has been able to handle thin layers with modeling the layer with only one element in the thickness direction.<>