ANALYSIS OF INSTANTANEOUS RAIN RATE OVER A TROPICAL LOCATION: IMPLICATION ON RADIO WAVE PROPAGATION SIGNALS

Abstract

Rainfall is a vital factor that must be considered in the design of telecommunication systems. The challenges posed by rainfall at frequencies above 10 GHz on microwave terrestrial and space communication systems, especially in tropical and equatorial zones, is a major problem for the telecommunication engineer. In recent times, it has been observed that rain that fall within a very short period has more effect on radio signals than rain that occur at a longer period of time. However, instantaneous rain occur more in the tropical climate zone due to the convective rain occurrence in this region. Rain events can last for an extended period of time, but the most significant attenuation due to rain occurs during relatively short periods of very intense rainfall. In this work, 2 –year (January 2014 to December 2015) data collected using vertically-pointing Micro Rain Radar were used to characterize the vertical profile of instantaneous rain rate over a tropical location Akure; the characterization was carried out to deduce the implications on propagation signals especially at millimeter and microwave frequencies. The effect of integration times on cumulative distribution of rainfall rate was also compared with the results obtained at Ile-Ife, Ogbomoso and other part of the world. The value of conversion factor CR and CE obtained for Akure are 0.23 (70) and 0.67 (120) respectively. These results show that the conversion factors CR and CE obtained at Akure, Nigeria are generally lower than values derived at other locations in Europe. The results also revealed that different conversion factor is required for different location even within the same climatic region. Further results revealed that the level of attenuation at lower integration times is more than the one that occur at higher integration times.