Propagation characteristics of ground based urban communications in the military UHF band

A series of experiments were conducted to characterize the propagation characteristics in an urban canyon setting between ground-based communicators operating within the military ultrahigh frequency band (225 to 450 MHz). The experiments were 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, RF 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. The results are compared with similar measurements by other investigators operating at higher frequencies in an attempt to identify the impact of RF frequency on urban propagation. This study addresses an important but largely overlooked propagation environment