Electromagnetic Scattering From Multiple Moving Targets Above a Rough Surface

Aimed at solving composite scattering from multiple moving targets above a rough surface, a hybrid method combining the multilevel fast multipole algorithm (MLFMA) and the Kirchhoff approximation (KA) is presented. The technology combining the MLFMA with the ray-propagation fast multipole algorithm (RPFMA) with the fast far-field approximation (FAFFA) is applied to accelerate coupling matrix filling. There are two main bottlenecks in this problem. The first is that, with moving targets, specifically, we need to refill the impedance matrix and recompute composite scattering, and the second is solving the tremendous coupling matrix between multiple targets and a rough surface. To solve the first bottleneck, the hybrid MLFMA-KA based on the domain decomposition method (DDM) is used, with the target region solved by the MLFMA and the surface region solved by the KA. In addition, the impedance matrix on each target is divided into the near-field matrix and the far-field matrix on the same target and the far-field matrix between different targets and between targets with a rough surface. With moving targets, the impedance matrix on the same target remains unchanged and only needs to be solved once, and the far-field matrix between different targets and between targets with a rough surface needs to be recomputed. To solve the second bottleneck, the MLFMA-RPFMA-FAFFA is used to accelerate matrix-vector multiplication between the targets and rough surfaces. Compared with the MLFMA, the proposed method is proven to be efficient and accurate. In addition, electromagnetic scattering from multiple moving targets above the surface is analyzed.