Observations of beyond line-of-sight radio propagation at 40-50 MHz and correlation with meteorological conditions

摘要

Several studies of beyond line-of-sight radio propagation in the low VHF band have been undertaken at the University of Hull. In previously reported work it was shown that the pilot signals from a meteor burst system operated at a frequency of around 47 MHz could often, and at times predictably, propagate over the 265 km path from the transmitter to a receiver at Hull. Various experiments were carried out to characterise the type of propagation involved, including the use, over several months, of three receivers at ranges of 100, 265 and 400 km from the transmitter as well as the use of a mobile receiver at various ranges in between these limits. At that time it was hypothesised that the observed propagation may be due to a form of reflection from small-scale stratification in the troposphere. This view was supported by work carried out at the University of Rennes. The results presented in the article pertain to an analysis of the signal strength received over the same 265 km path at 49.952 MHz during the period from December 1994 to July 1995.