Very low noise differential radiometer at 30 GHz

The description of the design, implementation and test results of a differential radiometer at 30 GAz with a 20 per cent of effective bandwidth for the Planck mission is presented. This Elegant Breadboard (EBB) 30 GHz radiometer is composed of a Front-End Module (FEM) assembled at Jodrell Bank Observatory (UK) and a Back- End Module (BEM) assembled at the University of Cantabria and Technical University of Catalonia (Spain). The achieved system noise temperature was lower than 10 Kelvin using state-of-the-art InP HEMT devices. Several tests have been carried out with the FEM cooled at cryogenic temperature (20 K) and the BEM at room temperature demonstrating system noise temperature, gain, effective bandwidth and 1/f noise cancellation according to its requirements.