Accurate mathematical models of microwave propagation over Earth-space paths are essential for successful design of satellite communications schemes. Whilst reliable models exist for temperate climates, little data are available to validate prediction procedures for the tropics. As satcomms terminals are rapidly proliferating in these regions, there is an urgent requirement to test current ITU-R recommendations against actual measurements. The most significant propagation impairments are attenuation, depolarisation and scattering, causing reduced circuit availability, and potentially resulting in cochannel interference. Though these effects are experienced at temperate latitudes, they are particularly severe in the tropics, due to the intensity of precipitation. We present design considerations for, and initial observations from, a polarimetric-Doppler radar deployed in Papua New Guinea for research on propagation effects caused by intense tropical precipitation.
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