Coaxial Lines Containing Ceramic High‐ T c Superconducting‐Center Conductors

A superconducting line should be essentially lossless and dispersionless and have a purely resistive impedance up to at least 10 GHz. In fact we expect that a long (>1 km) line could carry nanosecond rise time pulses with zero distortion and low loss (<1 dB/km). We have measured the losses in some short sections of coaxial line containing ceramic high‐T c superconducting‐center conductors over the frequency range from 5 to 50 MHz. There is only a slight improvement over a completely copper coaxial line.