Estimation of cloud attenuation over some coastal cities for satellite space links in South Africa

Abstract

One of the vital constraints on satellite space link systems operating at higher frequencies is attenuation due to clouds. This paper presents a 5-year estimation of cloud attenuation in the millimeter-wave propagation over two coastal cities in the Republic of South Africa. The results show that some salient features of clouds observed were monthly and location dependent. The observed average cloud value ranges between 16% and 55.6%, the relative humidity recorded between 65.4% and 84.2%, while the rainfall amount is between 5.43 and 79.66 mm over the study locations. The specific attenuation coefficient and cloud attenuation increases as the frequency increases over the studied locations. Furthermore, about 1 dB and above was observed at frequencies from 60 GHz and above. The study reveals the impact of liquid water content (LWC) in the clouds, which has a more significant effect on radio signals. The differences in the attenuation observed may be due to the impact of LWC and other salient features observed over the locations.