HIGH-TEMPERATURE SUPERCONDUCTING SLOW-WAVE COPLANAR TRANSMISSION-LINES WITH NORMAL-METAL CROSSBARS

A novel super-conducting slow-wave transmission line has been prepared by overlaying a superconducting coplanar waveguide with normal metal crossbars. The crossbars increase the energy storage along the transmi ssion line, reducing the line's group velocity allowing for shorter de lay lines. Additionally, the cross-sectional dimensions of the line ar e smaller than typical transmission line structures, allowing for a fu rther reduction of delay line size. Measurements show a group velocity of about 0.12 the speed of light with low dispersion, a 25 OMEGA char acteristic impedance, and moderate transmission loss. Because the grou p velocity is largely independent of any properties of the superconduc tor, these transmission lines exhibit excellent temperature stability and delay reproducibility.