Fast Physical Optics Method Based on Adaptive Mesh Technique

The fast physical optics (FPO) method based on adaptive mesh technique is proposed for analyzing scattered fields from electrically large scatterers. In this work, an adaptive mesh technique is introduced to realize the nonuniform distribution of mesh size, and the FPO method is adopted to obtain the scattered field from every element. The technique is adopted for two reasons. Firstly, the physical optics (PO) scattered fields mainly originate from high-frequency critical points, resulting in a nonuniform distribution of the PO integral on scatterers’ surfaces. Secondly, the fast variation of the PO integral depends on the gradient of the phase term, which is nonuniform on the surface. Therefore, the proposed adaptive mesh technique has the potential to use fewer patches than the standard Nyquist sampling rate in certain regions. The technique is based on a posteriori error estimation, which allows for adaptive refinement of the mesh. Finally, advantages of the technique in computational accuracy and efficiency are verified through several numerical examples. The proposed method satisfies accuracy requirements at all scattered angles and reduces the number of sampling points by one order of magnitude compared with a uniform mesh algorithm.