VARIABILITY OF SECTOR AVERAGED SIGNALS FOR UHF PROPAGATION IN CITIES

When the UHF signal received by an antenna at street level is averaged over a distance on the order of ten wavelengths, the result is referred to as the sector average. Measurements in city and suburban environments, but away from high-rise buildings, have typically found that these sector averages vary randomly with approximately log-normal distribution. In this study we show that the observed distribution of sector averages can be explained by two features of the urban environment, the first of which is 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 5–95% variability near to measured values. © 1990, IEEE