VARIABILITY OF EFFECTIVE-EARTH RADIUS FACTOR OVER AKURE, SOUTH WESTERN, NIGERIA

Abstract

For proper radio link design and for any location where propagation is intended, a accurate prediction of the distribution of effective earth radius factor (k-factor) is required. Traditionally, a median value of 4/3 is assumed for communication design purposes, but in reality the true kfactor values differ for different locations globally. In this study, the mean diurnal, seasonal and annual variation of effective earth radius factor (k-factor) are investigated over Akure, South Western Nigeria, for a period of five years, January 2007 to December 2011. Data from the ongoing measurement of some meteorological parameters of the troposphere at the location were used for the study. The measurements were carried out using facilities of the Communication/Atmospheric Physics Research Group of the Department of Physics, the Federal University of Technology, Akure. The results indicate that the diurnal variation of k - factor over Akure during rainy season is majorly as a result of the contribution of the dry term of the refractivity, while the diurnal variation of k – factor in the dry season showed strong dependence on the wet term of the refractivity. k-factor values were generally high during the rainy season compared to dry season where k-factor values were lower.The median value of k-factor for the five calendar years in the height range (50, 100, 150 and 200) m are: 1.49, 1.46, 1.50 and 1.47 respectively, and the propagation condition in this geographical zone is mostly super refractive