Incorporation of a symmetry wall in the combined wideband MLFMA/LF-FIPWA

The combination of the multilevel fast multipole algorithm (MLFMA) with the low-frequency fast inhomogeneous plane wave algorithm (LF-FIPWA) facilitates to solve integral equations for a wide frequency range. The different algorithms merge seamlessly for a group size of about one quarter of wavelength. If a symmetric object or an object above a perfectly conducting ground plane is considered the incorporation of a symmetry wall halves the number of unknowns. We present how to introduce a symmetry wall in the combined wideband MLFMA/LF-FIPWA. A coordinate transformation is derived which provides the opportunity of reusing the data already computed for the image.