PROPERTIES OF DISK RESONATORS AND END-COUPLED DISK FILTERS WITH SUPERCONDUCTING FILMS

We report the properties of disk resonators and end-coupled disk filters. High quality factors of 60,000 at 3 GHz and 27,000 at 7 GHz, respectively corresponding to TM11 and TM31 modes, were confirmed in a Nb disk resonator with a diameter of 18 mm on a sapphire substrate. End-coupled three-pole disk filters were also fabricated using the 7-mm-diameter Nb disks (TM11 mode). The disk filter with frequency of 7.5 GHz, fractional bandwidth of less than 1%, and insertion loss of less than 0.7 dB exhibited higher power handling capability of up to 22.5 dB(m) (180 mW). This high capability is thought to be achieved by reducing the current concentration at the edges of each resonators.