On the Edge Element Boundary Element Method/finite Element Method Coupling for Time Harmonic Electromagnetic Scattering Problems

Over recent decades coupled MoM/FEM formulation emerged as dominant method for solving EM scattering problems over inhomogeneous domains. Initial efforts on coupling of edge element BEM with edge element FEM have lost momentum and somehow disappeared from recent literature, possibly because of mathematical and other issues. This article, however, presents correct coupling of edge element BEM with edge element FEM. Such coupling is convenient because edge basis functions are used for modeling both the surface and the interior of the problem. We show that singularity extraction is simpler when compared with singularity extraction in MoM/FEM. Because BEM part of edge element BEM/FEM formulation uses simpler Green's function, the method is easier to implement than MoM/FEM which uses Dyadic Green's functions. The accuracy of the method is demonstrated by comparison with Mie series and with MoM/FEM and MoM/VSIE methods. Convergence of the method with respect to number of surface and interior edges was investigated by comparing 20 computational models with Mie series. Computational results suggest that edge-element BEM/FEM performs well for scattering problems involving objects with sharp corners. Finally, the ability of the method to cope with relatively large number of elements was demonstrated on the example of human head illuminated by 3.5 GHz EM plane wave.