Solution of Electrically Large Problems With Multilevel Characteristic Basis Functions

We present a multilevel version to the characteristic basis function method (CBFM). This technique extends the range of applicability of the conventional CBFM and allows a direct solution of problems even when they exceed 250,000 degrees of freedom. In this paper, it is shown how we can use the multilevel CBFM, which is a natural extension of the conventional approach and which saves both time and memory, and yet retains excellent accuracy in the computed far fields. Also, the adaptive cross algorithm is used for fast calculation of the interaction between the blocks in the process of generating the reduced matrix.