Geo-spatial distribution of radio refractivity and the influence of fade depth on microwave propagation signals over Nigeria

Abstract

The need for more bandwidth for a broad range of purposes necessitates research into how radio refractivity, multipath fading, and geoclimatic variables affect terrestrial and satellite propagation links. In this study, a geographical distribution approach to radio refractivity and fade depth over five locations in Nigeria—Akure, Enugu, Jos, Minna, and Sokoto based on five-year (2017–2021) measured data of atmospheric pressure, relative humidity, and temperature—at two levels (ground surface and 100 m heights). The results demonstrated the percentage occurrence of the dry terms dominating the radio refractivity constituent at the surface level, with a minimum and maximum contributions of about 78 and 92%, while at heights of 100 m, the percentage occurrence of the dry terms dominated the radio respectively refractivity constituent, contributing a minimum of about 79% and a maximum of about 92%. The spatial distribution reveals that, regardless of height, the tropical rainforest (TRF) and freshwater swampy mangrove (FWSM) regions reported the highest values of radio refractivity. The statistical estimate shows that fading values can differ by as much as 1.5 dB, especially near the TRF and FWSM coastlines, even during clear air conditions. The current findings will be helpful for budgeting Earth-space microwave links, particularly for the rollout 5G and future-generation microcellular networks in Nigeria.