Investigation of the Effect of Ground and Air Temperature on Very High Frequency Radio Signals

Abstract

This paper presents the results of the investigation of the effect of ground surface temperature and air temperature on the Very High Frequency (VHF) radio wave propagation by experimental method. The experimental measured data obtained were analyzed by regression technique. The results based on the best trendline shown that as the ground surface temperature increases, the loss (Path Loss) in the VHF radio signal reduces with gradient coefficient of 21.8dB/⁰C. Also, the results shown that as the air temperature increases, the loss in the VHF radio signal reduces, however with very smaller gradient coefficient of 7.5dB/⁰C than the ground surface temperature. The observation of Path Loss against increase in temperature is based on the weather condition when relative humidity (RH) is low. However, when the RH is high and the temperature is also high, the observation is relatively different. This is evident from another results which shown that as the RH increases, there is little increase in  loss of the VHF radio signal, with gradient coefficient of about 2.32dB/⁰C. This can be due to the effects of refraction, diffraction and scattering of the radio wave by the presence of the water vapor in the air when RH is high. Significantly, the results have shown that the VHF radio wave propagates through the ground surface more than the space (air) during the period under consideration.

Keywords: Ground surface, Air, Temperature, Path Loss, Very High Frequency radio