Calderon multiplicative preconditioner for acceleration of fast direction multilevel algorithm for scattering problem

In this paper, a new method called fast directional multilevel algorithm is preconditioned by an efficient Calderon multiplicative preconditioner (CMP) for three-dimensional (3-D) electromagnetic problems. The new algorithm does not require the implementation of multipole expansions of the Green´s function but based only on kernel evaluations. Combined with the Caldron identities of the CMP, the new algorithm has a fast convergence rate of iterative solvers and is stable at low frequency for the electrical field integral equation (EFIE) solutions. The numerical results demonstrate that the CMP preconditioned FDMA leads to significant reduction of both the iteration number and the CPU time for RCS calculation.