Wide-band superconducting microstrip delay line

This paper describes the design, fabrication, and testing of a novel microstrip superconducting delay line. The structure of the delay line is a double-spiral meander line. The device is patterned from a YBa₂Cu₃O_7-δ(YBCO) thin film deposited on both sides of a 2-in-diameter LaAlO₃ substrate with a thickness of 0.25 mm. It exhibits low insertion loss up to 20 GHz. At 10 GHz, the measured attenuation is 0.031 dB/ns at 30 K, 0.049 dB/ns at 60 K, and 0.118 dB/ns at 77 K. The magnitudes of the ripples are below 2 dB across the entire band. The total delay at low frequency is approximately 29 ns.