Urban propagation measurements for ground based communication in the military UHF band

Results are presented from an experimental investigation to characterize path loss in urban terrain within the military ultrahigh frequency band (225 to 450 MHz) between ground-based communicators. Testing was conducted over a two-day period in downtown Philadelphia. Profiles of received power versus distance were generated along a variety of straight and L-shaped paths for different radio frequencies and antenna heights. The results were analyzed to determine the dependency of the received power on street width, frequency, antenna height, and corner distance (the distance between the transmitter and the corner on an L-shaped path). The results showed well-defined dependencies on all of the parameters except antenna height, which did not appear to affect the results over the range of values considered in this study. An empirical model for predicting received power was developed by fitting regression curves to the data. The model was found to be accurate to within approximately ±10 dB when compared against the data collected in this investigation. This study addresses an important but heretofore largely overlooked propagation environment.