HTSC INVERTED AND CONVENTIONAL GEOMETRY MICROSTRIP RESONATOR FOR UHF FREQUENCIES

HTSC planar resonators may be used to replace voluminous normal conductivity high Q resonators by miniaturized ones at UHF frequencies (0.3 ... 3 GHz). Therefore an inverted microsrip resonator has been investigated. Both electrodes of the resonator are made of epitaxial films of YBa2Cu3O7-delta, one of them is structured into a meander type stripline. The distance between stripline and ground plane is hold by a 50 mu-m thick spacer foil which is also carrying the resonator feeding lines in conventional microstrip design. The small distance between both electrodes ensures that only a small amount of electrical energy is located in the LaAlO3 substrates and that the effective dielectric loss factor is low. At 77 K and at a resonant frequency of 700 MHz the measured unloaded Q was 2800. During improving the structuring process and reoptimizing the resonator design the unloaded Q of the conventional geometry microstrip resonator has been increased to Q0 = 25000. The use of the inverted microstrip resonator design will improve the Q values beyond that.