Radiofrequency and Microwave Noise Metrology

The radiofrequency interferometer, as compared to other methods for the measurement of amplitude noise and phase noise, shows higher sensitivity. In favorble onditions the background noise can be as low as—180 dB[rad2]/Hz at f= 1Hz off the carrier, up to microwaves (10 GHz) for real-time measurements. Exploiting correlation and averaging, a white noise floor of—204 dB[rad2]/Hz has been observed, not limited by the thermal energy k _B T₀ referred to the carroer power P₀. This article reports on the method, on the recent developments, and on the measurement of low-noise hard-to-measure devices.