New analysis capabilities for electrically large antennas and platforms

We present recent advances in the RF modeling of electrically large antennas and platforms, with an emphasis on reflector antennas and satellite platforms. The Higher-Order Multilevel Fast Multipole Method (HO MLFMM) was introduced recently in the commercial software tool GRASP, and this algorithm is employed in this paper due to the very low memory requirements and the need for very high accuracy. We show that the memory distribution of HO MLFMM is different from the typical low-order MLFMM, thereby enabling a more efficient out-of-core solution which allows very large problems to be solved with modest memory requirements. We also investigate the challenging problem of MLFMM-based computation of waveguide scattering parameters when several horn feeds are mounted on large satellite platforms. We show that the use of a Block GMRES method provides a faster and/or more accurate solution than the standard GMRES solution method.