A performance evaluation of an RF switching radiometer

The authors present a performance evaluation of an RF switching radiometer used as a noise comparator at X-band. The sensitivity, thermal stability, and noise source stability are examined. The temperature stability was improved by circulating water on the critical components. The system is sufficiently sensitive and stable for the calibration of noise sources. The precision of the noise temperature measurement is estimated within 0.01 dB using a gas-discharge standard noise source.<>