Calculation of the Physical Optics Scattering by Trimmed NURBS Surfaces

Physical optics (PO) is a commonly used technique in solving electromagnetics (EM) scattering problems. The trimmed non-uniform rational B-spline (NURBS) is widely used in computer-aided design (CAD) systems as the standard representation of surfaces. To evaluate the PO integral on the target surfaces modeled by trimmed NURBS, one of the greatest challenges arises in the nonrectangular parameter domain of the trimmed NURBS surface (TNS) enclosed by the trimming contours. An effective trimmed region classification technique is introduced to solve the integral domain for the PO integration on the TNS, which is able to classify the parameter domain of the TNS into regions of fully trimmed, not trimmed, and partially trimmed. On the resulted not trimmed and partially region, Gaussian-type quadratures are adopted for the evaluation of the PO integral. Numerical results demonstrate effectiveness and the capability of the proposed method.