MAGNETICALLY TUNABLE YBACUO MICROSTRIP RESONATORS AND BANDPASS-FILTERS

We report experimental results on frequency tuning in superconductive resonators and bandpass filters with controlling magnetic fields, The frequency shifts are attributed to the presence of vortices modifying the microwave penetration depth and therefore the kinetic inductance o f the circuit. 7-pole microstrip filters with a center frequency of 14 GHz and a bandwidth of 4% were fabricated using YBaCuO films deposite d on MgO substrate with Au ground plane, A negative frequency shift of - 12 MHz for fields lower than 0.1 mT was observed at 40 K. (C) 1996 American Institute of Physics.