Ground Reflection Effect on Antenna Gain for Nap of the Earth Radio Communication by Nearly Vertical Incidence Skywave High Frequency Propagation.

摘要

The effects of ground reflection on horizontally polarized fixed station antennas are investigated for nearly vertical incidence skywave (NVIS) high frequency (HF) propagation. NVIS HF propagation can be used if beyond line-of-sight two-way radio communication without relaying to or between aircraft in low-level flight is required. Twenty-four plots were produced relating antenna height and ground reflection parameters to HF frequency and raypath elevation angle. The plots demonstrate that ground reflection reinforcement gain changes little with raypath elevation angles between 65to 90degrees. Calculations of raypath elevation angles for NVIS HF propagation up to flight distances of 150miles between radio terminals indicate a minimum elevation angle of 65degrees to distances of 60miles by E-layer reflection and of 150miles by 275-km high F-layer reflection. (Modified author abstract)