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

We report the properties of disk resonators and end-coupled disk filte rs. High quality factors of 60,000 at 3 GHz and 27,000 at 7 GHz, respe ctively corresponding to TM11 and TM31 modes, were confirmed in a Nb d isk resonator with a diameter of 18 mm on a sapphire substrate. End-co upled three-pole disk filters were also fabricated using the 7-mm-diam eter 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 t he current concentration at the edges of each resonators.