Low-loss microstrip delay line in Tl2Ba2CaCu2O8

We have fabricated and tested a 1 ns microstrip delay line using thin films of Tl2Ba2CaCu2O8. We determined the loss in the delay line by weakly coupling at the input and output and measuring the width of the fundamental resonance at 461 MHz. At 15 K, the loss was lower than that calculated for an equivalent cryogenic copper line by a factor of 300. Resonance peaks were observable up to 102.7 K. At 77 K and 3.29 GHz, the observed loss was lower than that calculated for an equivalent Cu line by a factor of 10. Power limiting due to film defects occurred at an effective power level in the line of −43 dBm at 15 K.