Advances in hybrid finite element – boundary integral – multilevel fast multipole – uniform geometrical theory of diffraction method

[摘要] Numerical modeling of problems including composite metallic/dielectric objects with arbitraryshapes and electrically large conducting objects within a common environment is performed in anoptimum way with the recently developed powerful hybrid numerical method, which combines theFinite Element Boundary Integral (FEBI) method and the Multilevel Fast Multipole Method (MLFMM)with the Uniform Geometrical Theory of Diffraction (UTD), giving full electromagnetic couplingbetween all involved objects. In this contribution, the hybrid FEBI-MLFMM-UTD method is extendedto double diffracted fields on pairs of straight metallic edges, formulated with the hard and softscalar diffraction coefficients of UTD. The diffraction points on each pair of edges are determinedby an iterative three-dimensional parametric realization of the generalized Fermat'sprinciple. The divergence factor of the double diffracted field is computed by multiplying theappropriate divergence factors of the single diffracted UTD fields on each edge for the particularcase. Thereby, the ray caustic distance of the diffracted field at the second edge is determinedby linear interpolation between the radii of curvature in the two principal planes of the incidentastigmatic ray tube. Further, fast near-field computation in the postprocessing stage of the hybridmethod is extended in each translation domain to ray optical contributions due to the presence ofelectrically large objects, according to the hybridization of MLFMM with UTD. Formulations andnumerical results will be presented.

[学科分类] 电子、光学、磁材料