Fast multipole method for targets above or buried in lossy soil

We demonstrate the accuracy of the half-space fast multipole method (FMM) by considering two targets: a model unexploded ordnance (UXO) buried under soil and a rectangular box situated above the ground. In both examples, the bistatic radar cross sections (RCS) is computed via the FMM developed here, as well as with a rigorous method of moments (MoM), wherein the half-space Green´s function is evaluated rigorously via the method of complex images. The results show an excellent agreement between the FMM and MoM, for co- and cross-polarized RCS. The RAM and CPU requirements of the half-space FMM are about twice to three times compared to the free-space FMM (caused by the extra set of real images and the additional Fourier transforms), but the complexity of N/sup 3/2/ is unchanged.