Estimation of Radio Climatic Variables for the Design of Radio Links in South western Nigeria

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Abstract

Point refractivity gradient, effective earth radius and geoclimatic factor were calculated from atmospheric data obtained from National Aeronautics and Space Administration (NASA) in urban, suburban and rural environments of some states of South-western Nigeria. The measured atmospheric conditions are: temperature (T), atmospheric pressure (P) and relative humidity (H). Monthly data obtained at 1000 and 950 hPa with equivalent height based on pressure level of 111 and 540 m for the one-year period (2017-2018) of field investigation of this research work. The worst month value of point refractivity gradients are - 88 N-unit/km, - 78 N-unit/km and - 67Nunit/km in Akure, Ore and Omifon in Ondo State. In Ekiti State, the worst month value of point refractivity gradient are -74.23 N-unit/km in Ado-Ekiti, -58.37 N-unit/km in Oye-Ekiti and -66.46 N-unit/km in Ilupeju while in Osun State, the worst month vale of point refractivity gradient are -59.87 N-unit/km in Ilesa, -85.08 N-unit/km in Osu and -86 N-unit/km in Olode. The k-factor and geoclimatic factor values calculated from the point refractivity values vary with months and season, with the wet season exhibiting the highest values. The geoclimatic factor values estimated in the study are applicable in fade depth calculations while the values of k-factor obtained can be applied in radio link design to estimate the height of antenna requirement and diffraction fade estimation in South-western Nigeria

Keywords: Effective earth radius, link budget, Fade depth, Geoclimatic factor, Refractivity gradi

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