A new broadband calibration method for cryogenic temperatures

In this paper a new calibration technique working at cryogenic temperatures over the broad frequency range from 0.16 to 20 GHz for the measurement of the complex input impedance of a one-port device is presented. The impedance is extracted from complex reflection coefficient measurements of the a thin film performed by a vector network analyser. The method has been validated by measuring metallic samples with a known temperature behaviour. Its broadband nature makes it particularly powerful when exploring a region of the magnetic field-temperature-frequency parameter space of superconductors that was previously inaccessible with a comparable precision.