Study of Seasonal Surface Refractivity over North-Central Nigeria

Tropospheric radio wave signals experience loss due to multipath effect, scattering and other forms of attenuation through the atmospheric medium, primarily variations in weather conditions with time. The knowledge surface refractivity profile is important for optimal planning Very High Frequency/Ultra Frequency (VHF/UHF) terrestrial links a region. study (Ns) over North-Central Nigeria was carried out using meteorological data from seven locations zone Nigeria. seasonal Ns were also derived monthly summaries obtained Nigerian Meteorological Agency (NIMET) stations Abuja, Lafia, Lokoja, Makurdi, Jos, Minna Ilorin between 2005 2010.The results indicated that averages during rainy season months (April October) are greater than values dry (November March) all throughout years study. computed mean first 1 km above ground level 348 N-units, which gives gradient (dN/dh) -49 N/k, these shows region characterised by low scale super-refraction. k-factor entire 1.4; Field Strength Variability (FSV) height calculated be 14 dB. Radio Horizon distance within transmitter 100 m 42 km. provide useful information needed engineers set up new propagation or improve on existing ones especially at VHF, UHF Nigeria, as recommended International Telecommunication Union Recommendations (ITU-R P.453, 2013), observed need local reference gradients world.