Parallel extended-Born analysis of electromagnetic scattering from 3-dimensional sub-rough surface targets

The real 3-dimensional rough surface (RS) half space is treated as a perfect half-space with a special target which leads to a huge problem size if the integral equation (IE) based method of moments (MoM) is used, so a parallel algorithm is applied to speedup the EM scattering calculation from the RS. The message-passing interface (MPI) is the most widely used new standard for parallel calculation. It is not a new programming language, rather it is a library of subprograms that can be called from C++ and Fortran programs. In the paper, a powerful cluster with 33-CPU units connected by MPI network technique provides a good chance to investigate the real 3D RS half space EM scattering. Instead of rigorous MoM, a more efficient algorithm named extended-Born (E-Born) is used to model this 3D RS scattering problem. As E-Born is a very natural parallel algorithm, the complete parallel E-born code is almost P times fast as a series E-born code, where P is the CPU number in the cluster. When N is the problem size which is usually very large for real 3D-RS scattering, the LU-decomposition (LUD) solution of MoM is of the order of N³ complexity, while a series E-Born solution is of the order of 27N, and the parallel E-Born solution is of the order of 27N/P. With such a computational complexity of 27N/P, a problem with size N >10⁵ is no longer a prohibitive task. The accuracy and efficiency of the parallel E-Born method are validated by the MoM results.