Investigation of the efficiency of Moment Method solutions based on expansion functions defined in an infinite domain

The efficiency of the moment method (MM) when the expansion functions are defined in an infinite domain is checked. It is shown that efficient solution is obtained when the expansion functions obey the known physical behavior of the fields. The age-old problem of the thin, charged disk is solved by the MM for which an electric field component is expanded outside the body. This solution is compared to the known analytic solution and to the MM solution for which the surface charge density is expanded on the finite disk. Excellent agreement between the analytical solution and the MM solution based on expansion functions defined in the infinite domain was achieved. Moreover, it is shown that the efficiencies of the MM solution based on the expansion functions defined in the infinite domain and of the MM solution based on the expansion functions defined in the finite domain are similar.