Adaptive Sampling of Physical Optics Currents Based on EFIE Error Prediction

Simple and efficient method for a numerical analysis of an electromagnetic scattering problem is developed by converting the electric field integral equation (EFIE) into a simple integral equation with known variables. Regarding electrically large conducting objects, the surface current density can be easily approximated by the physical equivalent principle. The combination of the equivalent surface current and the EFIE generates unexpected tangential field component right on the perfectly conducting surface, which is against the boundary condition for electric field. The unexpected tangential field component which is against the physical behavior of electric field can be used to define numerical error that represents abnormality of the object. Instead of taking more samples over the entire surface, focusing on the abnormal surfaces by subdividing adaptively according to predefined error can improve the computation efficiency. In this paper, an adaptive sampling of physical optics (PO) currents is performed based on the error prediction by EFIE. Furthermore, the proposed method is applied to the conventional iterative PO algorithm in order to increase the calculation efficiency by adaptively meshing the target domain. The resulting radar cross section is compared to the results from the method of moments as well as the general PO method.