Effect of coupling state on power handling capability of HTS transmit filters with stripline structure

The effect of the coupling state on the power handling capability of a superconducting transmit filters with a stripline (SL) structure was investigated by comparing the performances of such a filter with combline configuration with that of one with an interdigital configuration. The coupling states between the resonators used with these filters are inherently different. The filters had three-pole half-wavelength straight-line resonators, a 5.0-GHz center frequency, and a 100-MHz bandwidth. They were fabricated using YBa2Cu3O7 thin films on an r-Al2O3 substrate. Measurement of their responses and maximum current densities using electromagnetic simulator showed that their power levels were 33.6 and 36.5 dBm, respectively. This indicates that the power handling capability depends on the coupling state, and that an interdigital filter has higher power handling capability than a combline filter.