Broadband calibration of long lossy microwave transmission lines at cryogenic temperatures using nichrome films

A one-port method to calibrate the S parameters of a long, lossy microwave transmission line in a cryogenic system is presented. This method exploits the relative temperature independence and frequency stability of nichrome thin films used as a known termination load. We have used the calibration on coaxial lines 1.2 m long from 0.5 to 12 GHz and at temperatures down to 100 mK. (C) 2000 American Institute of Physics. [S0034-6748(00)02712-X].