Diffraction by a wedge with variable-impedance faces

The scattering from a wedge with nonuniform impedance faces illuminated by a plane wave, perpendicularly incident on its edge, is analyzed. The solution technique is in the framework of perturbative methods; it applies to surface impedances of the wedge faces having the form of a constant plus a small amplitude perturbation which exhibits an exponential dependence on the distance from the edge in a plane transverse to the edge. This is of remarkable importance for applications as it allows the modeling of the actual behavior of the equivalent surface impedance in the special case of wedges coated with dielectric slabs. Uniform asymptotic expressions for the fields are obtained in the context of the uniform geometrical theory of diffraction (UTD).