The fast physical optics method based on the adaptive mesh technique

The physical optics (PO) method is generally used to simulate the high-frequency EM scattered fields from the large-scale scatterers. This method requires the target to be dissected using a triangular mesh with the size of 1/8 wavelength. Nevertheless, the number of meshes increases exponentially with the operating frequency. In this work, the fast physical optics method with the amplitude approximated by the linear polynomial (L-FPO) based on one-wavelength quadric mesh is proposed. The new method can effectively reduce the number of meshes. Compared with the fast physical optics method with the amplitude approximated by the quadratic polynomial (Q-FPO), L-FPO method avoids Fresnel integral calculation, and the calculation speed is 1.22 times faster than Q-FPO method. In order to further reduce the number of mesh, the fast physical optics method based on the adaptive mesh technique (AFPO) is proposed, which allows less meshes than standard Nyquist sampling theorem. The accuracy and speed of the proposed algorithm are verified by posteriori error estimation and numerical examples. Compared with the method using uniform mesh generation, the number of meshes required by AFPO method is reduced by 89.58%.