The Use of Cryogenic HEMT Amplifiers in Wide Band Radiometers

摘要

Advances in device fabrication, modelling and design techniques have made wide band, low noise cryogenic amplifiers available at frequencies up to 106 GHz. Microwave radiometry applications as used in radio astronomy capitalize on the low noise and large bandwidths of these amplifiers. Radiometers must be carefully designed so as to preclude sensitivity degradations caused by small, low frequency gain fluctuations inherent in these amplifiers.