Performance of the progressive numerical method and its comparison with the modified spatial decomposition technique in solving large scattering problems

Techniques for solving electromagnetic scattering from electrically large structures are studied. Two techniques, the progressive numerical method (PNM) and the spatial decomposition technique (SDT), are applied to study the two-dimensional problems of perfectly conducting objects with TM and TE plane wave illuminations. Both PNM and SDT are based on the method of moments (MoM) and divide the objects into a number of small regions and hence reduce the matrix size and computer time. The PNM uses the concept of overlapping regions. Accurate solutions can be obtained for the TM case and good agreement with the full matrix MoM can be achieved for the TE case. It is found that the SDT needs modification, by not taking into account the virtual interface currents between the two adjacent regions and the iteration procedure is only useful for the TM case. It is also shown that, the modified SDT is a special case of PNM in which there is no overlapping region. Finally, it is found that the PNM is an efficient way to eliminate the internal resonances of scattering problems.