Abstract
The diffraction of high-frequency waves by the edges of curved sheets is an important topic which finds several applications in the reflector antennas theory as well as in radar scattering investigations. The most effective methods to analyse such phenomena are the Geometrical Theory of Diffraction (GTD) and the Physical Theory of Diffraction (PTD) For the application of the former some coefficients (diffraction coefficients of different kinds, attenuation constants, divergence factors, etc) play basic role while the use of PTD requires the knowledge of explicit expressions for the induced surface currents. According to Ufimtsev's PTD [1] the total induced surface current J can be represented as the sum of two components, one the physical optics current J 0 and the other J 1 , a correction to J 0 due to all other effects not included in physical optics: J = J 0 + J 1 The correction term J 1 is due to perturbations created by the departure of the surface from an infinite plane and may arise, for example, from the curvature of the surface at a shadow boundary or from geometrical discontinuities such as edges.