Approximate diffraction coefficients for an anisotropic impedance wedge

Two approaches are proposed to determine the diffraction coefficients for a nonpenetrable wedge with the faces characterized by anisotropic impedance boundary conditions when it is illuminated at oblique incidence by an electromagnetic plane wave. In the more general case the anisotropic impedance tensors associated with the faces have their principal axes not coincident with the edge of the wedge. The first solution is obtained by using a physical optics approximation for the surface current densities on the wedge and by performing a uniform asymptotic evaluation of the radiation integral (uniform asymptotic physical optics solution). The second solution is derived by following a heuristic approach. The effectiveness of both solutions is demonstrated by comparing them with analytical solutions available for particular cases.