A quasi-optical reflectometer

There is an increasing need for accurate scattering parameter measurements at frequencies above 100 GHz owing to advances in millimeter-wave system technology. This paper describes the layout and workings of a novel multistate reflectometer implemented using passive quasi-optical components. The system as presently configured is capable of making one-port S-parameter measurements of components and devices up to 600 GHz; however, the measurement technique is applicable over a much larger frequency range. The paper presents a general analysis of a multistate reflectometer, together with a detailed look at the current circuit operation and the rationale for using quasi-optics. Methods of calibrating the reflectometer are discussed and preliminary results are presented. The paper concludes by outlining the future work plan for the project.