Applicability of local-MoM and frequency dependence of computational cost in scattering analysis of a rectangular plate from a dipole

The method of moments (MoM) is the electromagnetic computation method where an integral equation is constructed for unknown currents assumed over the whole surface of scatterer and is solved by matrix inversion. The number of unknown currents N therefore becomes longer in proportion to the electrical size of scatterer. When the direct method is adopted as matrix inversion, computational times for matrix filling and matrix inversion are proportional to N² and N³, respectively. A required capacity of computer memory is proportional to N² as well. Since the electrical size of scatterer is proportional to square of frequency f when the physical size of scatter is unchanged, frequency dependencies of computational times and a memory capacity amount to O(f⁴), O(f⁶) and O(f⁴) respectively. Various techniques to suppress these dependencies have been proposed. The authors have also proposed a different type of the MoM computation with the smaller matrix size named “Local-MoM” (K. Ito, et al., IEICE Trans. Electron., vol.E94-C, no.1, pp72–79, Jan. 2011) as one of these techniques.