3-D FEM BEM-HYBRID APPROACH BASED ON A GENERAL FORMULATION OF HUYGENSPRINCIPLE FOR PLANAR LAYERED MEDIA/

Huygens' principle is used to exclude inhomogeneous regions and ideal conducting regions from planar layered structures, The fields in the i nhomogeneous regions are modeled by the finite-element method (FEM) wi th tetrahedral edge elements in terms of the electric-field strength ( E) over right arrow. The fields in the layered structure are described by an integral representation of the electric-field strength (E) over right arrow in terms of equivalent electric and magnetic Huygens' sur face current densities for the inhomogeneous regions, and in terms of electric Huygens' surface current densities for ideal conducting regio ns, It is formulated with the help of electromagnetic (Ehl) potentials resulting in low-order singular integral kernels to facilitate the nu merical handling of the integral representation, A general formulation of the integral representation is given for observation points lying in the Huygens' surface, As compared to the homogeneous-space case, ad ditional terms in the integral representation have to be considered if parts of the Huygens' surface lie in an interface of layers with diff erent material properties, An integral equation is formulated and disc retized by a Galerkin testing procedure [boundary-element method (BEM) ], together with the finite-element (FE) system resulting in an unequi vocal discretized description of the entire field problem, The method is validated with the help of a canonical test problem, Further numeri cal results are presented for dielectric resonators coupled to microst rip circuits.