Article Published In Vol.5 (March-April-2017)

Statistical Estimation of Effective Earth Radius Factor over Lagos using Radiosonde Data

Author : Lawal Yusuf B. and Ashidi Ayodeji G.

The path followed by tropospheric radio waves between any two points on earth is largely influenced by atmospheric parameters which vary temporally and spatially. The effective earth radius factor (k-factor) is a function of these atmospheric parameters and it plays an important role in the design of wireless communication links operating in the Very High Frequency (VHF) and Ultra High Frequency (UHF) range. It defines a curved earth’s surface without atmosphere, for which propagation pathis rectilinear. This study uses 2012-2014 radiosonde data of Relative humidity, Temperature and Pressure at first kilometer altitude in Oshodi (6o 32’N, 3o 21’E), Lagos, to estimate the effective earth radius factor for Lagos, a coastal region in southwestern Nigeria. An overall average value of 1.60±0.02 was obtained which is greater than the 4/3 recommended by ITU-R for this region.

Keywords: Tropospheric radio waves, Refractivity gradient, k-factor, VHF, UHF, Rectilinear, ITU-R, Radiosonde