Clouds can cause radio signals to fade, especially clouds that contain
a great deal of liquid water. Signals that travel between the ground and
high altitude platforms such as satellites, balloons and aircraft must
sometimes penetrate thick layers of cloud en route. It is important for
systems planners to be able to predict what effect different types of
clouds are likely to have on their signals. The problem is particularly
key for high frequency signals, which are increasingly in demand for these
sorts of communications systems. The current push to use higher frequencies
stems from the growing demand on the lower frequencies, and the trend
towards high bandwidth applications, such as the Internet and video.
This project aims to investigate how different types of clouds affect
EHF frequency signals, including how long and how severe signal fading
really is. Researchers measured beacon signals from the Italian ITALSAT
F1 satellite for three years to try and identify which types of cloud
cause the signal to fade on its way to earth.
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