HAPS to Ground Propagation Model Considering General Terrestrial Path

ITU-R ground-to-ground propagation model adaptable to any terrain was extended to predict basic transmission loss of high altitude platform station (HAPS)-to-ground path by considering the reduction of ray bending due to stratosphere. Using the proposed method, an example coverage map of a mobile base station on HAPS was produced highlighting the effects of terrain as well as spherical earth diffraction and troposcattering.