A microwave interferometer based contactless quasi-TEM waveguide position encoder with micrometer accuracy

Abstract

Position measurement plays an important role in industrial process technology. Hereby, a waveguide based position sensor system for industrial applications is described. The proposed system features a Phase Locked Loop controlled 24 GHz signal source, an interferometric Six-Port receiver structure, a radar coupler, and a terminated quasi-TEM parallel plate waveguide structure. Furthermore, the system concept comprises a target, which can be applied both touching and contactless in the waveguide's fringing field, reflecting a part of the transmitted wave. To obtain the target's position information, the reflected wave is compared to a reference signal with respect to the relative phase difference. Hence, this phase shift is directly related to the position information.