SI Traceable RF and Microwave Power Measurements at Cryogenic Temperatures

This work demonstrates SI traceable RF and microwave power measurements at cryogenic temperatures down to 3 K using a commercial balance thermoelectric type power sensor. This is the first time, to the best of our knowledge, a commercial RF power sensor has been tested at such cryogenic temperatures. To obtain SI traceability, a power sensor’s thermopile response was characterized over RF power levels from -35 dBm to 0 dBm in a frequency range from 100 kHz to 10 GHz using known DC power. The thermopile response was then utilized to calculate absolute RF power around 3 K. The results demonstrated suitability of the power sensor to operate at temperatures down to 3 K and RF and microwave power levels down to -35 dBm.