Variability of sector averaged signals for UHF propagation in cities

The theoretical model proposed by D.O. Reudink (1974) for the range dependence of UHF propagation over cities so as to predict the statistical properties of the sector-averaged signal is extended. It is shown that the observed distribution of sector averages can be explained by two features of the urban environment, the first of which is the presence of variations of building height. The second feature consists of differences in building construction and design, and the presence of foliage. These sources of variation are independent and act in cascade, so that the received signal is a product of the corresponding coefficients. The cascading of these two randomly distributed coefficients leads to a distribution of signal levels that is close to log-normal and that has a 5 to 95% variability near to measured values