Millimeter-wave scanning surface resistance analyzer using a confocal resonator

Millimeter-wave confocal resonators are used in a new, commercially available instrument to map the surface resistance of large area (2 - 4 inch diameter) superconducting thin films. Q-factors are measured from the reflection coefficient of the cavity formed by a spherical aluminum mirror and a planar conductor sitting at half the radius of curvature of the mirror. The surface resistance of the superconducting film is extracted from the measured Q values. Typical Rs values of 20 - 40 m(Omega) are measured for high-quality 2' high-Tc superconducting thin films at 94 GHz and 77 K.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.