PTD analysis of impedance structures

Based on an approximate dyadic diffraction coefficient, equivalent currents (ECs) are derived for computing the scattering by a finite-length impedance wedge of arbitrary angle. The derived equivalent currents are implemented in a standard general purpose physical theory of diffraction (PTD) code and results are presented demonstrating the accuracy of the formulation for a number of impedance and (dielectrically) coated structures. These include typical shapes such as plates, finite-length cones, and cylinders which have been partially or fully coated. The PTD implementation requires a dyadic physical optics diffraction coefficient which is presented in the appendix.