An effective preconditioner for the IE-NDDM-MLFMA method for analyzing EM scattering from electrically large PEC objects

In this paper, an effective preconditioner is built for the integral equation-based nonoverlapping domain decomposition method (IE-NDDM) for analyzing electromagnetic (EM) scattering from electrically large PEC objects. The multilevel fast multipole algorithm (MLFMA) can be conveniently introduced into the IE-NDDM to accelerate matrix-vector products. However, for analyzing EM scattering from electrically large PEC objects, an effective preconditioner for each local model equation is imperative. In order to improve the convergence properties of each local model equation, the proposed preconditioner is based on the block-diagonal, incomplete lower and upper triangular matrices (DILU) and the matrix elements associated with the half-RWG (Rao-Wilton-Glisson) basis functions are also included in the near-field part. In numerical examples, the efficiency of the proposed scheme is shown.