A Review on the Effects of Radio Refractivity and Atmospheric Parameters on Signal Quality at Ultra High Frequency (UHF)

Refractivity is an important factor in predicting the performance of radio link. The structures of the refractive index of the troposphere are responsible for many complicated mechanisms such as, multipath effects, absorption, scattering of radio signals, etc. and these mechanisms can cause a lot of propagation impairment such as, loss of signal for mobile communication, the accuracy of tracking radio source (such as stars) with radio telescopes, radar system etc. Understanding the effects of the weather on radio wave propagation will help to improve the quality of radio signals, as the Weather variables are useful ingredients in the predictions of refractivity distributions and the anomalous radio wave propagation conditions of the atmosphere. This study contends that refractivity variations significantly affects received signal strength at Ultra High Frequency (UHF) and gave a brief theoretical background on Electromagnetic wave, Atmospheric effects on radio propagation anomalous propagation condition and the mathematical expression for refractive index and refractivity of the troposphere. Also, the paper review related articles in the following area; refractive index and refractivity of the troposphere, effects of weather variables and refractivity of troposphere. The analysis of the review articles summits that, refractivity reveals seasonal variations with high value in rainy season and low values in dry season. Also observed from the review articles, is that the diurnal variations are influenced by three atmospheric parameters; water vapour has the greatest effect on refractivity variations followed by temperature and pressure. Furthermore, the Refractivity is function of local meteorological parameters. Eventually, the study suggests that, the effect of Atmospheric parameters and consequently the Radio Refractivity should be compensated for when designing wireless communication links in an environment