Estimation of Clear-air Fades Depth Due to Radio Climatological Parameters for Microwave Link Applications in Akure, Nigeria

In this paper, clear-air fade depth and outage probability occurrence of microwave signals is estimated based on the effect of tropical geoclimatic factor derived from atmospheric refractivity gradient computed for three years (January 2011-December 2013) of measurement of air temperature, pressure and relative humidity for terrestrial line of sight (LOS) link design application in Akure, Nigeria. The outage probability of fade depth exceeded at a given time over a single frequency is therefore estimated at a given path length. Furthermore, the parameter needed for clear-air propagation and interference, expressed as percentage of the time with refractivity gradient below -100 N-Units/km, are also presented. The results show that geoclimatic factor which cater for geographical and climatic conditions in multipath fading distribution exhibits monthly, seasonal and yearly variation. Finally, based on the link geometrical parameters used, the fade depth exceeded in 0.01% of time can be estimated by logarithmic fits with a very high coefficient of determination.