Measurements of the propagation characteristics of VHF/UHF radiowaves over two over-sea paths in the Channel Islands

In order to test the current understanding of the propagation mechanisms and to gather statistical information about ducting/super-refraction and signal fading effects, an experimental investigation has been undertaken with a transmitter and two receivers deployed in the Channel Islands. The main objectives of this investigation were to: 1) Measure the propagation characteristics at antenna heights appropriate to inter-ship communications at VHF. and UHF at ranges beyond the direct line of sight. 2) Test current understanding of over-sea VHF/UHF propagation. 3) Identify any propagation effects that are not attributable to currently understood phenomena. 4) Gather statistics of the various effects, in particular the occurrence of ducting and fading. 5) Relate the above to prevailing weather conditions. Rather than discuss the observations in detail a summary of the more important aspects is given.