Snow on Polar Radomes and Performance Deterioration at 26 GHz for a Receiving Ground Station: the SNOWBEAR Project

In the near future, many forthcoming Earth Observation missions operating in a Polar orbit, will rely on a new high data-rate downlink channel, defined in the frequency band from 25.5 to 27 GHZ. This band was made available to download the ever growing amount of scientific data, collected during satellite operations and stored on-board, throughout the short time in which it is visible from a ground station. For Earth Observation missions, the receiving station on Earth is naturally placed at Polar latitudes, to maximise the number of visible passes. However, the use of such frequencies for this kind of communication link is still on an early development stage. In particular, the precise link budget modelling and experimental performance validation are still open points of discussion and research. This is especially true for the effects caused by the presence of the snow on the radome, mandatory to protect the antenna from strong wind gusts. This paper presents a general overview of a dedicated project (SNOWBEAR), developed under European Space Agency coordination, for which the performance degradation due to the accumulation of snow on the radome top is addressed. AS a preliminary result, two major effects on the signal disruption have been identified, snow absorption and de-pointing.