A new 20/30/50 GHz radiometer has been developed for use in a propagation experiment to characterise atmospheric attenuation up to 50 GHz. The radiometer is being used with the ITALSAT propagation payload and beacon receivers at the CSTS experiment station of the Italian Research Council sited at Spino d'Adda, 30 km east of Milan. Details of the radiometer and experimental results obtained since the radiomter was commissioned in July 1993 are presented.