A Fast Iterative Physical Optics Method With Quadratic Amplitude and Phase Integral Terms

The iterative physical optics (IPO) method is a valuable technique for analyzing coupled scattering problems. In contrast to the fast physical optics (FPO) method, this article proposes an iterative physical optics method based on quadratic quadrilateral patches (QIPO). Specifically, quadratic patches in the QIPO method offer higher-order accuracy in calculating normal vectors which greatly benefits the accuracy of the iterative induction current. Then, a lit-shadow judgment criterion is introduced, and a general iteration formulation for proposed method is presented. Additionally, new amplitude and phase function expressions suitable for the QIPO method are proposed to accurately compute the far-field results. It is also verified for the case of discretization with quadratic triangular patches (QTIPO). To address numerical singularities, the QIPO method considers a linear phase function, where closed-form solution are provided. The results demonstrate the effectiveness of the treatment in handling singular cases. The accuracy of the QIPO method is validated through comparisons with existing results. Finally, numerical examples confirm that the proposed method reduces the number of patches, minimizes the computational cost of induced current iteration, and accurately calculates far-field results.