A closed form physical theory of diffraction solution for electromagnetic scattering by strips and 90° dihedrals

The physical theory of diffraction is applied to the high-frequency scattering of a plane electromagnetic wave by a perfectly conducting strip. Closed form expressions are obtained for the farscattered field in the TE and TM cases. These expressions are continuous at grazing incidence and uniform in the overlapping transition regions. They extend the closed form results of Tiberio and Kouyoumjian from strictly grazing to nearly grazing incidence. The comparison with numerical results based on the moment method shows that these expressions furnish an excellent high-frequency approximation to the exact solution of the strip problem. The results for a strip are then used in a ray tracing analysis of the backscattering from a 90° dihedral.