Efficient computation of the reaction terms to fill the interaction matrix in the Characteristic Basis Function Method (CBFM)

In this paper, an efficient method for the computation of the reduced matrix elements is presented. The paper begin by modeling the scatterer as a non-uniform rational B-spline (NURBS) surface. Since a NURBS representation is used in most of the CAD design softwares, this formulation allows us to directly connect the output of the CAD software with the EM solver. In order to decrease the number of low-level basis function needed to represent the CBFs in each block, a linear-phase model is considered in the integrand for the evaluation of the scattered field. Furthermore, to optimize the number of low-level basis functions defined on each block, an adaptive meshing algorithm is utilized to partition the domain of integration. These steps serve to lower both the memory requirements and the CPU time for computing the reduced matrix elements, as compared to the conventional methods.