Performance of microstrip bandpass filters using highhyphen;Tcsuperconducting YBa2Cu3O7minus;dgr;thin films on LaAlO3

摘要

We have fabricated a microstrip threehyphen;pole bandpass filter with a fractional bandwidth of 5percnt; at a center frequency of 10.5 GHz utilizing laser ablated highhyphen;thinsp;Tcsuperconducting YBa2Cu3O7minus;dgr;thin films on LaAlO3substrates. Microwave performance of the filter was carried out as a function of temperature. The filter exhibited low insertion losses of about 0.077 and 0.304 dB at 20 and 77 K, respectively. More than 15 dB in return losses was obtained at the same temperatures. Intermodulation distortion measurements were performed to evaluate powerhyphen;handling capacity of the filter, which results from the nonlinear effects of surface resistance. Thirdhyphen;order intercept points were 68 dBm at 20 K and 58 dBm at 77 K. The nonlinear performance in the passband was also measured using a group delay method. The superconducting filter was compared with an equivalent gold filter which showed the insertion loss of more than 3.5 dB at 77 K. copy;1996 American Institute of Physics.