The Study of diurnal and seasonal refractivity variations and its influence on VHF and UHF signal field strength profile of lapai

Abstract

The study of diurnal and seasonal variation of surface radio refractivity Ns over Lapai (9.625N/6.570E) Niger State, Nigeria was carried out using 3-years meteorological data collected with Integrated sensor Suite (Is-Vantage Pro2) weather instrument installed at surface level in Ibrahim Badamasi Babangida University, Lapai, Niger State. The data used were collected from 2010-2012. The seasonal variations were calculated using the data obtained at 5-minutes interval and the result showed that the mean value of radio refractivity during the rainy season months (April to October) is greater than the mean Ns value of the dry season months (November to March) for the location and years of the Study. The computed mean diurnal Ns over Lapai in the first 1 Km of height is 342 N-units, which gives the refractivity gradient (dN/dh) of – 46 N/Km; this shows that the station is on average characterised by low scale super-refraction, which was used to calculate both the K-factor and the mean field strength variability (FSV) over Lapai in the first 1Km of height as 1.38 and 5.52dB respectively. The mean reduce to sea-level refractivity (No) over Lapai is 357 N-units. The radio horizon distance within 1 Km at height for a transmitter height of 100m over Lapai is 41.93 Km. The seasonal Ns variation with respect to atmospheric parameters of temperature, pressure, humidity and time in Lapai were shown using 2-D contouring. These results gives broader insight into how Ns values directly affec VHF/UHF signal field strength profile in Lapai