From a radio frequency propagation perspective, the general focus of the commercial wireless communications community has been primarily on frequencies above 800 MHz. Therefore, there is a limited number of available empirical data and validated prediction methods indicating what type of path loss or signal degradation one should expect in various urban settings at a very high frequency (VHF) range, which is the range of operation for numerous military tactical communications systems. Furthermore, the extensive literature survey revealed that indoor propagation models are particularly lacking in either availability and/or proven fidelity. This paper presents a new general urban path loss model derived from a log-distance path loss model, floor attenuation factor model and path loss measurements taken on campus of The Johns Hopkins University Applied Physics Laboratory (JHU/ APL), Laurel, MD, with a measurement hardware suite in 30-88 MHz frequency range. The authors felt that there is a void in the open literature on simple, empirically-verified large-scale path loss models that implicitly address the lower VHF range, more than one urban setting, short communications ranges ( 1 km) and low transmitting and receiving antenna heights as well as offer reasonably high fidelity without requiring a lot of information about the site.Index Terms-Ground-to-ground communications, indoor propagation, land mobile, land mobile to land mobile communications, low antenna height, military tactical communications, military operations on urban terrain (MOUT), path loss, peer to peer communications, radio frequency (RF) propagation prediction, short range communications, single channel ground and airborne radio system (SINCGARS), squad radio, urban canyon, very high frequency (VHF) , wireless communications.

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 Lshaped 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 Lshaped 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.

No abstract

No abstract