Numerical determination of diffraction, slope-, and multiple-diffraction coefficients of impedance wedges by the method of parabolic equation: Space waves

By generalizing the results of Malyuzhinets (1959), Ufimtsev (1965), and Popov (1969), the method of the parabolic equation (PE) can be applied to study the space wave diffraction of a line source by an impedance wedge. The respective diffraction as well as the slope-diffraction coefficients are numerically determined. Contrary to conventional methods, which usually first solve the scattering by a finite body containing the desired diffraction center and then extract the corresponding diffraction coefficient, the PE studies a semi-infinite scattering body and the diffracted field directly. A comparison of PE results with exact ones, as far as available, and uniform geometrical theory of diffraction (UTD) results confirm the accuracy of this method. In addition, a straightforward application of the PE for calculating multiple wedge diffraction eliminates the discontinuities which are typical of the "mechanical" application of the UTD to the same problem. A possible way for combining the PE and the UTD is pointed out. The latter should be of special interest to dealing with wave propagation problems.