Propagation measurements on a transalpine over-the-horizon path

Results of propagation measurements on a transhorizon UHF path are presented. The path was a 287 km forward scatter link between southern Germany and northern Italy, traversing the Swiss Alps. Measurements were carried out during the period January to June 1977. The results illustrate the large variation in propagation characteristics, caused by a diurnally fluctuating mixture of troposcatter and diffraction propagation. Received signal level predictions, based on a detailed topographic analysis of the test link, and measured data were shown to be in reasonable agreement. Frequent periods of rapid fading attributed to aircraft passage through the scatter volume were noted, and data were presented which characterizes aircraft passage events, according to their signal level and differential delay profiles.