Rain Attenuation Studies in Tropics-A Critical Review

摘要

The exploitation of satellites for communication purposes has increased considerably during the last decades. The performance of satellite systems operating above 10 GHz essentially depends on the propagation characteristics of the transmission medium. A major hurdle in our efforts to go to higher frequencies in communications is the rain factor; this is especially true in satellite communications and for tropical latitudes where the rain rates are high. Presently in India an overwhelming segment of satellite telecommunications is through the 4GHz down link frequency from Indian geostationary satellites. There is compulsion to move up in frequencies beyond 10 GHz to take larger bandwidth and also much lower scintillation problem in the Ionosphere. However, this move to higher frequencies has to be constrained because of the tropospheric effects at higher frequencies caused primarily by rain attenuation and also to some extent by tropospheric scintillations and water varpour attenuation.