An Angular Displacement Sensor-Based Active Feedback Open Complementary Split-Ring Resonator

This letter presents an active feedback microwave sensor with a wide dynamic range and high sensitivity for detecting angular displacement. The sensor comprises two types of movable ring resonators (the rotor), split-ring resonator (SRR) and complement SRR (CSRR), and a modified convex-shaped open complementary split-ring resonator (the stator). The stator is designed with an active circuitry to enhance the quality factor over 4.7 K, and the feedback loop surrounds the sensing zone to enhance the mutual coupling for tracking a finite rotation of rotors in a wide dynamic range. The stator uses the separation between two reflection coefficients or the decibel magnitude variation at a fixed frequency, which is generated from its resonance frequency shift and whose values vary as a function of the rotation angle to be measured. After rotor loading, the average decibel sensitivity in terms of variation in reflection was calculated as 0.32 and 0.13 dB/degree for the SRR and CSRR, respectively, within a dynamic range of 0°–90°.