Investigation and development of VHF ground-air propagation computer modeling including the attenuating effects of forested areas for within-line-of-sight propagation paths

An investigation into short-distance (5-100 nm), air-ground, VHF propagation computer models is presented. An evaluation of existing propagation models is afforded by measured signal strength data, collected for this study, obtained for a variety of propagation paths; this evaluation shows existing models to be deficient due to their incapability to calculate attenuation caused by trees for within-line-of-sight propagation paths. The theory behind, and the development of, a computer model that does successfully account for tree attenuation is discussed and documented. A complete description of signal strength data collection is given detailing measurement equipment, site conditions and data reduction.