V.V. Akhiyarov

In this work the numerical methods for field strength prediction above terrestrial surface are considered. The complicated scattering problem is reduced to easier problem: scattering from a large-scale cylindrical surface that is supposed a perfect magnetic conductor. Such assumption is quite justified for vertical polarization and small heights above the surface, and it allows to consider this problem using the boundary conditions for a perfect magnetic conductor. Taking into account the considered simplifications, the initial problem has been produced to scalar one that has allowed calculating the surface currents along the terrain profile. The physical optics approach and Fredholm integral equations (IE) of the 1st and 2nd kind were used for the surface currents calculations. Further the scattering field calculated using this surface current distribution. The model diffraction problems solution for a wedge and a cylindrical segment are presented. It is shown, that the usage of Fredholm IE of the 1st kind provides the best results. The numerical solution for a spherical surface for perfect magnetic conductor and Fock-s diffraction formula calculation for the earth with real electric parameters is compared and good accordance of numerical and analytical solution is received. So the considered numerical technique for the field strength prediction is suitable for the earth terrain. The field strength calculations over a real profile are executed.