ITD formulation for the currents on a plane angular sector

The electromagnetic scattering of a corner at the interconnection of two straight edges joined by a plane angular sector is important in the framework of the geometrical theory of diffraction (GTD) and of its uniform extension (UTD). The same canonical problem is also useful in order to obtain fringe currents, namely the currents that are induced on the face by the total diffraction mechanism; their radiation provides the improvement of the field in the framework of the physical theory of diffraction (PTD). In this paper, asymptotic, closed form expressions of the fringe currents of the plane angular sector are derived by using the incremental theory of diffraction (ITD). The application of this theory in deriving currents has been found particularly attractive for the case of circular ground plane illuminated by a vertical dipole. This is due to the fact that the ITD diffraction coefficients satisfy the boundary conditions of their relevant canonical problem, so that they warrant a reasonably accurate prediction of the currents.