High-Temperature Superconducting Coplanar Left-Handed Transmission Lines and Resonators

This paper implements wideband, low-loss, and via-free left-handed transmission lines (LH-TLs) using superconductor thin films. Introducing superconductors greatly reduces the loss inherited in the constituent series capacitors and shunt inductors of such planar LH-TLs. The measured results agree very well with design expectations. The bandwidth of left-handed characteristics is 4.9–10.9 GHz, with a minimum insertion loss of 0.03 dB at 30 K. Open-ended LH-TL resonators are also characterized at the different harmonics; of special interest are those with zero or negative phase constants, which are not possible when using any conventional transmission lines. Temperature-dependence measurements of the LH-TLs reveal the effect of the superconductor kinetic inductance.