An accurate approach for the calculation of MoM matrix elements

The method of moments solution on integral equations for electromagnetic scattering and radiation problems with Rao-Wilton-Glisson (RWG) and n×RWG basis functions requires the calculation of singular double surface integrals over triangular subdomains. In this paper, an approach is presented to deal with the singularity and almost singularity in which the triangle subdomain is divided into several subtriangles and then the singular or almost singular integral is calculated over each of the subtriangles. This approach is mainly based on the projection process and the local polar frame. It can be used to deal with the singular double surface integrals of order 1/R and 1/R², in which vector functions may be of zeroth-order and higher order. Numerical examples are provided to verify the validity of the method presented in this paper for dealing with the singularity and almost singularity.