Comparison between sets of synthetic basis functions based on different generating processes

The conventional method of the moment (MoM) formulations have well-known limits to the problem size, because they lead to large, dense and sometimes ill-conditioned matrices. In order to overcome these problems, different schemes have been presented in literature. Among these schemes, we mention the family of methods that employ an "iteration free" approach, where standard (e.g. RWG) basis functions are aggregated into larger functions. This notably includes the synthetic function expansion (SFX) and the characteristic basis function (CBF) methods. These aggregate basis functions are defined from the solution of smaller-size numerically-tractable problems, excited by appropriate sources, and then used in the MoM solution of the large problem. Thousand of wavelength structures can be treated with memory and CPU cost provided by a standard personal computer. In this paper we make a comparison between aggregated functions obtained for treat large portions of PEC planar objects containing edges (special cases include geometries with large polyhedral sub-surfaces) obtained by using different excitation sources.