Microwave characterisation of superconducting materials: what accuracy can be achieved in surface resistance measurements using the Hakki-Coleman dielectric resonators?

This paper discusses accuracy of loss measurements of High Temperature Superconductors (HTS) using the Hakki-Coleman sapphire resonator. Possible sources of errors in Rs measurements are presented and evaluated. It has been shown that in order to minimise ΔRs/Rs errors the fractional power ratios should be below 0.1. This can be achieved by appropriate aspect ratio of the sapphire and the cavity to sapphire diameter ratio. For optimised designs errors in Rs measurements can be as small as 1.5 times the measurement error in the Q0-factor even for 100% uncertainty in tan