An improved hybrid FEM/MOM combining MLFMA for composite electromagnetic scattering

A generalized hybrid scheme combining finite element method (FEM) and the method of moments (MoM) accelerated by multilevel fast multipole algorithm (MLFMA) is first presented to investigate scattering from a 3-D dielectric object above a 2-D electrically large dielectric rough surface. The hybrid FEM/ MoM scheme is divided into the FEM region for the object based on Helmholtz's equation and the MOM region for the rough surface based on coupled integral function, which can greatly reduce the computed region. MLFMA is employed to reduce computation complexity of MOM region itself and coupling interaction matrices between MOM region and FEM region. Consequently the iterative solving process can be greatly accelerated. This genralized hybrid FEM/MOM is very suitable for investigating scattering characteristics of composite model composed of a complex material object and electrically large dielectric rough surface. Some examples verify this generalized hybrid FEM/MOM features high efficiency, low storage requirement, high accuracy and generality.