A novel hybrid technique for mutual coupling modeling of antennas with strongly overlapped minimum-spheres

A novel technique to calculate the mutual coupling between antennas whose minimum spheres are strongly overlapped is presented in this paper. For this purpose, we obtain a Generalized Scattering Matrix (GSM) in terms of equivalent infinitesimal dipoles from a 3-D Finite Element /Modal Analysis method by making use of Singular Value Decomposition (SVD) and rotation and translation of spherical modes. Since infinitesimal dipoles correspond with the lower order of spherical modes whose minimum spheres have a vanishing radius, the overlapping of higher-order spherical modes is avoided. Several examples will be given, showing that the efficiency of the method to analyze arrays is improved, and the results will be compared with those provided by purely numerical full-wave methods.