Extension of analytic physical optics to calculate bistatic 3D scattering from obtuse dihedral

As a canonical shape, dihedral’s scattering mechanism can be found in a variety of scenes and has been intensively studied in the past. The state-of-the-art analytic physical optics (APO), as a typical analytic solution, utilizes few physically relevant parameters to calculate the bistatic 3D scattering of dihedral accurately and efficiently. However, the original APO solution is only for right-angle dihedral case, in this paper, the APO is extended to calculate the bistatic 3D scattering of obtuse dihedral by introducing a parameter α (α ≥ 90°) which corresponding to the interior angle of dihedral. Then, with the general term α taking into account, like the right-angle dihedral case (i.e. α = 90°), the first- and second-order scatterings of obtuse dihedral are derived. Especially, for the computation of second-order scattering, the incident field and illuminated area of each plate are analyzed and derived in depth for the more complex and general obtuse dihedral geometry. Then, the total scattering solutions of obtuse dihedral composed of first- and second-order scatterings are presented. From the extension process, it is obvious that right-angle dihedral and rectangular plate are only the specific cases of the extended model. The experiments by comparing the extended model with shooting and bouncing rays and method of moments validate the effectiveness of the extension.