High-Q LaAlO3 dielectric resonator shielded by YBCO-films

• Published in: IEEE transactions on applied superconductivity Vol. 4; no. 3; pp. 143 - 148
• Main Authors: Tellmann, N, Klein, N, Dahne, U, Scholen, A, Schulz, H, Chaloupka, H
• Format: Journal Article
• Language: English
• Published: 01-09-1994
• ISSN: 1051-8223
• DOI: 10.1109/77.317829

A dielectric resonator consisting of a single crystalline LaAlO3-cylinder shielded by a cylindrically shaped Cu cavity with endplates made from epitaxial films of YBa2Cu307 or Nb is studied. For YBa2Cu3O7 films, unloaded quality factors of 4.5 x 10 exp 5 at 10 K and 1.3 x 10 exp 5 at 77 K were achieved at 11.6 GHz, using a compact shielding cavity with a diameter of 15 mm and a height of 3.8 mm. The loss contributions of the dielectric resonator, the normal conducting cylinder wall, and the superconducting endplates, with one of them being separated by a small distance h from the dielectric cylinder, were calculated by modeling the EM fields of the TE modes. The dielectric loss tangent of the LaAlO3 cylinders was found to be 10 exp -6 at 4.3 K and f = 11.6 GHz, and to increase slightly with temperature. These resonators are considered to be useful devices for stable oscillators and narrowband filters. (Author)