Complex multipole-beam approach to three-dimensional electromagnetic scattering problems

A novel approach to reducing the matrix size associated with the method-of-moments solution of the problem of electromagnetic scattering from arbitrarily shaped closed bodies is presented. The key step in this approach is to represent the scattered field in terms of a series of beams that are produced by multipole sources located in a complex space. On the scatterer boundary the fields that are generated by these multipole sources resemble the Gabor basis functions. By utilizing the properties of the Gabor series, guidelines for selecting the orders as well as the locations of the multipole sources are developed. The present approach not only reduces the number of unknowns but also generates a generalized impedance matrix with a banded structure. We verify the accuracy of the proposed method by using internal accuracy checks and by comparing the numerical results with the analytic solution for a spherical scatterer.