Analysis of Scattering from Multiple Objects by the Finite-Difference Frequency-Domain Method With an Iteration-Free Multiregion Technique

An iteration-free multiregion (IFMR) technique was proposed and applied to finite-difference frequency-domain (FDFD) analysis of electromagnetic scattering from multiple objects in open space. The entire computational domain is divided into several small subdomains. The mutual coupling effect among subdomains is introduced through combining total-field/scattered-field (TF/SF) formulation and mode series of scattered field. The final matrix equation is a Schur complement system, so the computation for each subdomain is relatively independent. The numerical results obtained by the FDFD method with IFMR are in a good agreement with those by the full-domain FDFD method, but both the amount of unknowns and the computational time are reduced. Additionally, compared to the iterative process based on multiple scattering, the computational time is reduced, and the truncation error of the iteration is avoided, as IFMR is the limit of the iterative process.