Diffraction by a planar junction between a perfectly conducting and a periodically loaded impedance surface

By using a perturbative method, an integral representation for the field scattered by a planar junction between a perfectly conducting and a periodically loaded impedance surface is determined, when the junction is illuminated by a plane wave perpendicularly incident on its edge. Both a uniform, asymptotic expression and a series representation are presented for the first-order perturbative correction to the field scattered by the junction. The series representation is expressed in terms of Bessel functions of integer order and is suitable for field calculations at small distances from the edge. Several numerical results are presented to demonstrate the applicability of the proposed technique