RAY-OPTICAL PREDICTION OF RADIOWAVE PROPAGATION CHARACTERISTICS IN TUNNEL ENVIRONMENTS - PART 1 - THEORY

A tunnel is modeled as congregates of walls, with the wall being appro ximated by uniform impedance surface. The aim is to get a solution for a canonical problem of a wedge with uniform impedance surface. The di ffraction by a right-angle wedge with different impedance boundary con ditions at its two surfaces is first considered. A functional transfor mation is used to simplify the boundary conditions, The eigenfunction solutions for the transformed functions are replaced by integral repre sentations, which are then evaluated asymptotically by the modified Pa uli-Clemmow method of steepest descent. The asymptotic solution is int erpreted ray optically to obtain the diffraction coefficient for the u niform geometrical theory of diffraction (UTD). The obtained diffracti on coefficients are related directly to Keller diffraction coefficient s in uniform version. The total field is continuous across the shadow of the geometrical optics fields.