An Efficient Implementation of the Combined Wideband MLFMA/LF-FIPWA

An efficient implementation of the low frequency fast inhomogeneous plane wave algorithm (LF-FIPWA) combined with the multilevel fast multipole algorithm (MLFMA) is presented. The seamless combination of the LF-FIPWA with the MLFMA renders a powerful method applicable for a wide frequency range. As the MLFMA is already well established we will describe possibilities for an efficient formulation of the LF-FIPWA: an implicit filtering reduces the bandwidth of the integrand. An interpolation of the excitation vectors is introduced which avoids dealing with the in general complex angles. An adaptive quadrature rule on the path in the complex plane further increases the efficiency. We present a simple but accurate interpolation and interpolation method on this path. In addition, for symmetric objects or for perfectly conducting ground the incorporation of a symmetry wall is described.