A hybridization technique for MLFMM utilizing generalized admittance matrices for a large class of cavity backed aperture scattering problems

An efficient technique for the analysis of electromagnetic problems involving large metallic bodies with arbitrary complex interior and a number of apertures is proposed. Typical applications for this technique are the computation of EMC related transfer-functions of the electromagnetic field, describing the coupling of energy into complex systems as well as the computation of the RCS of complex cavities in large metallic scatterers. The proposed method is based on the combination of generalized admittance matrices (GAMs) for the apertures with MLFMM (multilevel fast multipole method) for the outer problem. The GAMs are first computed by the most appropriate technique for the complex interior problem (e.g. FDTD). In the second step of this technique, the admittance matrices are incorporated into the MLFMM-accelerated iterative MoM solution process. This technique is especially suited for coupling studies of complex systems requiring many different field incident angles, since the GAMs are computed only once.