Microwave propagation attenuation due to earths atmosphere at very high frequency (VHF) and ultra-high frequency (UHF) bands in Nsukka under a clear air condition

The microwave propagation attenuation due to earth’s atmosphere under a clear-air condition for fade depth of 10 dB was investigated using refractivity data calculated from weather vagaries measurement carried out between January and December 2008. The International Telecommunication Union-Radiocommunication Sector (ITU-R) model for multipath fading for small percentage of time with link distance of 100 km was used. The result showed that at this distance, the refractivity gradient has a strong correlation of 0.747 with percentage of time that the fade depth was exceeded. It was also observed that the percentage of time that the fade depth was exceeded increases with frequency until about 1.2GHz when the result becomes unreliable.   Key words: Attenuation, fade depth, microwave, multipath fading, refractivity gradient.