Propagation modeling for the design of data-downlink of non-GEO satellite systems (earth observation / space exploration) and DRS

In recent years the demand for high data rate satellite links in Earth Observation (EO) missions has increased because of the adoption of instruments with higher resolution. The high data rate systems envisaged require then very large bandwidth and for this reason the use of the Ka band for the Earth Observation Satellites has been planned. In the case of Space Exploration Systems (SES), the continuous development of payload and ground segment technologies enables the exploitation of the higher frequency bands with respect to the standard X-band baseline used in the last 30 years. The use of frequencies at the Ka band and above poses some constrains because of the high atmospheric attenuation (marginal at X band frequencies) and needs an accurate estimate of the propagation channel. In this contribution the main propagation issues related to EO and SES/DRS systems will be reviewed with a particular focus on attenuation and sky noise temperature.