THE EFFECT OF COHERENCE FACTOR ON SLOW-WAVE PROPAGATION IN SUPERCONDUCTING PLANAR TRANSMISSION-LINES

The propagation characteristics of conventional and high-T-c thin-film superconducting strip transmission lines are investigated theoretical ly by using the London equation and modified two-fluid model incorpora ted with the microscopic coherence effect, The attenuation constant an d phase velocity are studied as functions of temperature and frequency . Special attention is paid to the propagation properties due to the c oherence effect. The usual dips observed in the temperature-dependent phase velocities predicted by the traditional two-fluid model are smea red out in our case. Also, the influence of the coherence factor on th e phase velocities is more pronounced at high frequencies and temperat ures near T-c. The dependence of the attenuation constants on frequenc y, however, is shown to bear a strong resemblance to the common surfac e resistance in the microwave region.