Attenuation in superconducting striplines

Measurements of the Q of stripline resonators yield values for the attenuation of Nb-Nb
2
O
5
-Pb striplines typical of those used in superconducting microcircuits. At 4 K the attenuation between 50 and 500 MHz is proportional to frequency and probably results from dielectric losses. Near the transition temperature of Pb, the attenuation begins to show the frequency-squared dependence associated with superconducting losses.