Improved Hybrid Algorithm for Composite Scattering From Multiple 3D Objects Above a 2D Random Dielectric Rough Surface

In this paper, an improved hybrid scheme combining the method of moment (MoM) and physical optic (PO) is proposed to analyze composite scattering from multiple 3D conductingobjects above a 2D random rough dielectric surface. In the calculation scheme, rough surface scattering is calculated using the PO method and target scattering is calculated by the MoM. The coupling interactions between the multiple targets are considered using the domain distribution method (DDM), where the matrix equations are constructed upon each individual target and are then presented and solved as a whole. The contribution from rough surface scattering, which is calculated by the PO method, is coupled with the impedance matrix, and the unknowns must be considered only in the MoM region. Most of the composite scattering problems are computing interactions between objects and rough surface, and solving the complex impedance matrix equation in the MoM part. To solve these two problems, first, the combined multilevel fast multipole algorithm (MLFMA) and the fast far field approximation (FaFFA) are introduced to accelerate interactions between objects and rough surface, where the near area on the rough surface is computed by MLFMA, while the far area is computed by FaFFA. In addition, to further improve the efficiency, the adaptive integral method (AIM) is employed to solve the impedance matrix equation of the MoM part in the scheme. The results are compared to those obtained with the traditional MoM-PO method, showing that the hybrid method proposed in this paper can maintain a high accuracy with a much smaller computational time and fewer resource requirements. The numerical results obtained under several different conditions are presented and discussed in this paper.