LF Radio Wave Prediction at Short Ranges With High Propagation Angles Over Irregular Terrain

Propagation characteristics of low-frequency radio waves at short ranges and with high propagation angles are analyzed by the finite-difference time-domain and one-way/two-way parabolic equation (PE) methods. Both narrow-angle (NA) and wide-angle (WA) PE expressions are considered. It is observed that the NAPE method is hard to be applied in the region where the propagation angle is above 15°, whereas the WAPE method can obtain a higher accuracy so long as the earth surface slope is not very big. If the terrain slope changes dramatically, results of the two-way WAPE are more reliable with an interference pattern. However, diffraction effects of the waves over the mountain are not given full consideration.