Effects of the finite HTS film thickness on the resonant frequency of the axially symmetric TE/sub 01/spl delta// mode of a parallel plate dielectric resonator

An axially symmetric TE/sub 01/spl delta// mode of a parallel plate dielectric resonator is studied for investigating effects of the film thickness (t) of high-temperature superconductor (HTS) films on the mode resonant frequency (f/sub 0/). A sapphire-loaded cylindrical cavity resonator with YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) endplates and mode f/sub 0/ of about 19 GHz has been prepared and its unloaded Q (Q/sub 0/) and f/sub 0/ are investigated at temperatures below the critical temperature of YBCO. From theoretical analysis, it appears that f/sub 0/ changes by less than 0.4% for different t's when the ratio of t to the London penetration depth (/spl lambda/) is more than 10/sup -2/. Meanwhile, from experiments, significant dependence of f/sub 0/ on the gap distance (s) between the sapphire rod and the top endplate is observed with f/sub 0/ changing by about 1 GHz (/spl sim/5%) from 19.578 GHz to 18.648 GHz, as s increases from 0 to 1 mm at 77 K. The experimental values of f/sub 0/ are observed to agree well to the calculated f/sub 0/. Applicability for tunable high-Q resonators is described.