Refined Near Field Calculations in Method of Moments Solution of Multiple-Domain Problems

In electromagnetic analysis based on the solution of Surface Integral Equations (SIEs) equivalent electric and magnetic currents at the boundary surfaces of the domains are determined. Near field in each point is calculated using equivalent models for all domains. Since numerical solution for equivalent currents has finite accuracy, error is introduced by an equivalent problem for each domain. In some applications, e.g., microwave imaging (MWI), the accuracy of near field evaluation can be critical. We propose refined approach to improve the accuracy of near field. The domain to which a point belongs is determined, then near field in the point is calculated using the equivalent model for that domain only. Numerical results for a realistic model of human head show significant improvement in accuracy of near field compared to regular approach.