Fully Coupled Multi-Hybrid FEM-PO/PTD-UTD Method for the Analysis of Scattering and Radiation Problems

A hybrid method combining the finite element method (FEM) and several high frequency techniques (HFTs) for the efficient analysis of the radiation and scattering of electromagnetic waves on complex three-dimensional environments is presented. It makes use of FEM for the regions with small and complex features and one or more HFTs for the analysis of the electrically large objects of the structure. The hybridization is done in a full coupling way taking into account mutual interactions between the FEM domains and the objects analyzed with HFTs. Two main HFTs are used: physical optics (PO) and the uniform theory of diffraction (UTD) in order to take advantage of the use of distributed and point sources. Physical theory of diffraction (PTD) is also used when needed in order to improve the accuracy of PO. The UTD modeling is based on NURBS (non-uniform rational B-spline) surfaces. Ray acceleration techniques and simple clustering strategies are used to speed up the computation time of the UTD