Microwave Alignment and Displacement Sensors in Groove Gap Waveguide Technology

This paper is aimed at presenting highly sensitive microwave displacement and alignment sensors. With this goal, the method of realizing mechanically tunable cavity resonators in groove gap waveguides technology is presented. The resonance frequency of the cavity is then used for displacement sensing. It is also demonstrated that the symmetry properties of a pair of groove gap waveguide cavities can be used to improve the robustness of the sensor to variations in ambient conditions. The proposed sensor also benefits from a reference zero, thus can be used as an alignment sensor. A very good sensitivity of $S=1.25$ GHz/mm is achieved, which can be easily improved by scaling the operating frequency.