The channel losses of a Very High Frequency (VHF) base station operating on 91.9 MHz in a Suburban City of Akure, South West Nigeria, were explored in this study. A BC1173 DBC field strength meter was used to measure the received signal strength at every 1km interval along four different paths from the base station. A Global Positioning System (GPS) receiver was utilized to log the coordinates and altitude of the data points and to monitor the line of sight with the station as a reference. The surface meteorological parameters such as temperature, atmospheric pressure, and relative humidity of data locations were measured using a portable weather monitoring device, and the associated surface radio refractivity values along the routes were computed from the atmospheric parameters obtained. For comparison, data was collected during the dry and wet seasons of 2021. The Okumura-Hata model was compared with the path loss obtained from the measured data and gave a mean value of about 108.2 dB and root mean square value of 1.25 dB which is within an acceptable range and best fit for the prediction of the study area. The results for all the routes and seasons showed that path losses increase with distance in all routes and over the seasons. However, path losses were higher during the wet seasons than the dry seasons. Furthermore, the result was used to modify an existing path loss model to suite the studied location. Radio engineers will benefit from the result of this study in terms of channel optimization and very high frequency system design.
Keywords: VHF, path loss model, atmospheric parameters, refractivity, RSS