Performance assessment of lower VHF band for short-range communication and geolocation applications

The focus of this paper is to characterize near-ground wave propagation in the lower very high frequency (VHF) band and to assess advantages that this frequency band offers for reliable short-range low-data rate communications and geolocation applications in highly cluttered environments as compared to conventional systems in the microwave range. With the advent of palm-sized miniaturized VHF antennas, interest in low-power and low-frequency communication links is increasing because (1) channel complexity is far less in this frequency band compared to higher frequencies and (2) significant signal penetration through/over obstacles is possible at this frequency. In this paper, we quantify the excess path loss and small-scale fading at the lower VHF and the 2.4 GHz bands based on short-range measurements in various environments. We consider indoor-to-indoor, outdoor-to-indoor, and non-line-of-sight outdoor measurements and compare the results with measurements at higher frequencies which are used in conventional systems (i.e., 2.4 GHz). Propagation measurements at the lower VHF band are carried out by using an electrically small antenna to assess the possibility of achieving a miniaturized, mobile system for near-ground communication. For each measurement scenario considered, path loss and small-scale fading are characterized after calibrating the differences in the systems used for measurements at different frequencies, including variations in antenna performance.