To design an innovative X-Band cryogenic feed to be installed in the future in the Deep Space antennas . G/T in X-Band will be maximised by an integrated design of the feed (receive and transmit in X band) and the cryo- cooled LNA sub- systems

The reception performances of the Deep Space Ground Stations is limited by the noise generated in the front end. Any reduction of this noise will allow to increase the data transmitted or to reduce the required mass and power on the spacecraft transmitter.X band is presently used for the telemetry of all deep space missions and will still be the preferred frequency band for future Mars exploration missions. The existing feed and LNA systems have been designed separately. Therefore, the feed system is operated at room temperature while the LNA is operated at 12 K. The overall system noise temperature is therefore suboptimal due to the insertion loss of the waveguide connection and passive elements at room temperature. In order to increase the mission data return, it would be extremely beneficial improving the present G/T by more than 1 dB. This will be achieved by reducing the loss of the feed system and trying to cryo-cool as much as possible the passive components of the receiver front end (diplexer, polarizer, waveguides, tracking coupler...). The interconnection of the feed and LNA subsystems will be optimised and the cryo-cooler subsystem will be designed to guarantee a maximum availability and redundancy. The same feed is going to be used for the uplink at 20 kW. A proper study will be conducted to minimise the effect of the high power uplink on the cryogenic subsystem.