Broadband cryogenic calibration two-port superconducting resonators

Superconducting resonators are useful for precision electromagnetic measurements, so broadband cryogenic calibration of these resonators are important. We found that a traditional three standards calibration, the Thru-Reflection-Line calibration, fails to calibrate the transmission lines between a vector network analyzer and a cryogenic two-port resonator. Here we introduce a modified calibration method that replaces the Reflection standard by a pseudo-Open standard. Experimental measurements show the new method significantly improves the calibrated results.