“…The numerical simulation of the scattering problem (1)-(4) at a heterogeneous domain typically combines a boundary element method (BEM) [38,41,51], with unknown current densities in a finite-dimensional subspace of H − 1 2 (div Γ , Γ), with a finite element method [44,45], with an unknown electric field in a finitedimensional subspace of H(curl, Ω − ), resulting in a hybrid FEM-BEM method, sometimes called FE-BI (finite element, boundary integral) method [39,52,53]. In this way, the advantages of both methods, i.e., the natural incorporation of heterogeneous material parameters in FEM and the inherent validity of the radiation condition of the scattered fields in BEM, are combined.…”