Determination of Material and Circuit Properties Using Superconducting and Normal Metal Ring Resonators

摘要

The microwave properties of both substrates and superconducting materials have been determined from relatively large area microstrip resonator circuits mounted in an automated measurement system over the temperature range 10-290K and frequency range 0.5-l0GHz. Properties such as dielectric constant and surface resistance are presented for a variety of materials, such as YBa_2Cu_3O_(7-x), Tl_2Ba_2Ca_2Cu_3O_x, Cu and Ag on either YSZ, MgO or LaAlO_3 substrates. Estimates of the loss tangent from normal metal resonator circuits suggest that in practice substrate materials may differ from their ideal properties. The surface resistance of thick film YBa_2Cu_3O_(7-x) ring resonators on YSZ substrates were found to be limited by the loss tangent of the substrate while the surface resistance of similarly-sized Tl_2Ba_2Ca_2Cu_3O_x thin film ring resonators on MgO substrates showed a marked power dependence. At 3 GHz the surface resistance of thick film YBa_2Cu_3O_(7-x) on YSZ at -l0dBm was found to be superior to thin film Tl_2Ba_2Ca_2Cu_3O_x on MgO below T_c/2 as a result of better power handling.