Airport surface area propagation path loss in the VHF band

The wireless channel in the very high frequency (VHF) band at airport surface areas has not been quantitatively characterized in several ways. As new communication services are introduced, and as the band's spectral efficiency must be increased, a quantitative characterization of this channel will become critical for advanced wireless networking [1]. This paper describes a first step in this direction: measurement and modeling of propagation path loss in the VHF band [2]. Narrowband measurements were made in the aeronautical VHF band at Detroit Metropolitan Airport (DTW). A continuous wave (sinusoidal) signal was transmitted from existing VHF radio transmitter-receiver (RTR) sites, and a mobile receiver moved about the airport surface area in a prescribed path. Propagation path loss was computed using basic link budget analyses. Results for both line-of-sight (LOS) and non-line-of-sight (NLOS) conditions are provided using the log-distance path loss model. The mean propagation path loss exponents are found to be approximately 5.6 and 4 for NLOS and LOS regions, respectively. Results for LOS regions also correspond to the well-known “2-ray,” or “plane-earth” model.