Apparatus for determining microwave characteristics of superconductive

Abstract

Apparatus for determining the electrical characteristics of a superconductive material in a range of microwave frequencies and in a range of cryogenic temperatures has the material incorporated within a resonant cavity mounted on a cold finger for maintaining the material at a predetermined temperature. A pair of test waveguides extend oppositely of the cavity and terminate in separable waveguide junctions for passage of microwave energy to measure the microwave characteristics of the cavity as affected by the superconductive material. The cavity and test waveguides are enclosed in a vacuum chamber from which the cold finger extends for connection to controlled temperature cryogenic cooling equipment. The chamber also contains a plurality of calibration waveguides which extend parallel to the test waveguides, each calibration waveguide terminating oppositely in separable junctions. The chamber has plates disposed oppositely of the waveguides and moveable transversely in relation to the waveguides without loss of vacuum. Each plate bears a connector waveguide having an outer portion connectable to a microwave network analyzer and having an inner portion extending through the plate and terminating in a separable junction alignable, by movement of the plate, with the junctions of the test of calibration wave guides so that the network analyzer is selectively connectable to the cavity or to a calibration waveguide without loss of vacuum or change in temperature of the superconductive material.