摘要: The Johnson-Gierhart tropospheric propagation program of the Institute for Telecommunications Sciences is used to obtain predictions of excess propagation loss over that of free space for super-high frequency (SHF) air-to-ground p... 展开 The Johnson-Gierhart tropospheric propagation program of the Institute for Telecommunications Sciences is used to obtain predictions of excess propagation loss over that of free space for super-high frequency (SHF) air-to-ground paths within or on the radio horizon. The principal loss (gain) mechanisms considered are atmospheric absorption and refraction, surface multipath interference, smooth spherical Earth diffraction, and single knife-edge diffraction caused by terrain roughness and/or a site-specified obstacle. The program uses a semi-empirical database to statistically weigh the losses from these mechanisms. The excess propagation loss increases with increasing range and can exceed 3 decibels at distances as close as halfway to the radio horizon.... Probability of Prediction, Super-High Frequency, Propagation, Tropospheric. 收起