Generation of Characteristic Basis Functions Defined Over Large Surfaces by Using a Multilevel Approach

An efficient procedure for the generation of characteristic basis functions (CBFs) over large arbitrary surfaces is presented in this work. The first step is to partition the original object into subdomains and then derive the CBFs for these domains by solving for the currents induced by a set of components of the planewave spectrum (PWS). Next, we aggregate the adjacent domains to obtain enlarged CBFs by expanding the original ones in terms of the weighted planewaves used to compute them. This process can be performed iteratively and involves fast, non-expensive matrix manipulation. We obtain a progressive decrease of the number of unknowns, as we increase the domain size, by following the procedure described above.