RF transmission line for cryogenic applications

摘要

We have fabricated a miniature coaxial transmission line with characteristics suitable for cryogenic applications. The materials were chosen for reduced thermal conduction and improved high-frequency signal transmission, and for mechanical properties allowing easy connector assembly and forming into complicated cryogenic structures. Comparing with the best commercial line, made with stainless steel outer conductor of twice larger diameter, the heat conduction integral of our line at 100 K temperature is slightly lower, while the signal attenuation is reduced by an factor of 1.34. Defining the figure of merit as a product of the signal attenuation per unit length and the heat conduction integral, our line is superior to all commercial cryogenic lines above 80 K by a factor varying from 1 to more than 20, and allows much easier soldering and bending. Further improvements of the line are also briefly discussed. (C) 1998 Elsevier Science Ltd. All rights reserved. [References: 4]