High-frequency asymptotic solution for scattered fields by a discontinuity of a planar impedance surface

In this paper, by applying the aperture field method and the saddle point technique, we shall derive a novel asymptotic solution with higher-order terms for the high-frequency scattered fields by an impedance discontinuity of a planar surface. We will assume that both the transmitting and receiving antennas are placed at arbitrary heights from the earth´s surface. In order to obtain the accurate solution, we will newly derive the higher order terms. The validity and the utility of the novel asymptotic solution are confirmed by comparing with the reference solution calculated from the numerical integration.