Multilevel fast multipole algorithm for mixed combined-field integral equations

In solving the magnetic-field integral equation (MFIE) with the method of moments (MoM), the Buffa-Christiansen (BC) function is shown to be a better testing function than the Rao-Wilton-Glisson (RWG) function, since it produces a numerical solution with a much better accuracy while maintaining the same iterative convergence. As a result, the numerical accuracy and efficiency of the mixed discretization of the combined-field integral equation (CFIE) are also better than that of the Galerkin discretization. In this paper, the solution of the mixed CFIE is accelerated by employing the multilevel fast multipole algorithm (MLFMA). In order to preserve the similar accuracy as MoM, special care needs to be taken in the implementation of MLFMA.