Comparison of diffraction over mountain ridges-experimental results with diffraction loss calculation by different theoretical methods

For diffraction loss calculation of real mountain obstacles it is proposed usually to use the results of the method of diffraction over smooth rounded obstacles, such as a sphere and a cylinder, with application of boundary conditions on the surface of these geometrical bodies. Optical diffraction methods are also proposed. Such methods is recommended for rough surface obstacles. There is a large difference between the results of calculation by the different methods. However, there is not an alternative criterion for application of the first or second method.