Refractivity Variation Effect on Radio Wave Propagation

Adegboyega Gabriel Adisa

Abstract: The study of the vertical variation of refractivity in the troposphere is required for radio systems planning. Atmospheric refractivity variation in troposphere is one of the aspects that influence electromagnetic wave propagation and consequently performance of communication links and systems. This work makes use of meteorological data (atmospheric pressure, temperature, humidity) of Akure, South Western Nigeria to compute radio refractivity and gradient in Akure while also making use of UHF band signal measurements for both days and nights in the month of March, 2013 with respect to the location in Akure. The results of refractivity for both periods were compared and so also were the field strength profiles. This was being used to deduce the relationship between the refractivity and UHF band signal strength. Results obtained ascertained that each atmospheric parameter has a role to play in refractivity with humidity as the major factor that is having more influence than other factors. In addition, the surface refractivity is also being influenced by the latitudinal and seasonal variations. Generally, radio refractivity and broadcast signal strength are inversely related with correlation factors of -0.81 and -0.97 for day and night respectively.

Keywords: Refractivity, Troposphere, Akure, UHF broadcast signal strength