Efficient Multilevel Approach for the Generation of Characteristic Basis Functions for Large Scatters

An efficient approach for deriving the characteristic basis functions (CBFs) for analyzing radiation and scattering problems is proposed. The spectrum of the incident plane waves is partitioned into several angular regions that are progressively enlarged in a multilevel procedure to generate orthogonal functions. The CBFs are obtained at the final orthogonalization level, so that they cover the entire angular range. This approach to generating the CBFs is better suited for electrically large objects than the conventional approach, which utilizes the entire angular range (visible) of the plane wave spectrum in a single level.