Rotation Sensor Based on the Cross-Polarized Excitation of Split Ring Resonators (SRRs)

This paper presents a novel rotation sensor based on the concept of cross-polarized excitation of split ring resonators (SRRs). The structure of the proposed sensor which is quite simple and as a result is low cost, involves a slotline loaded with a rotatable SRR. In this configuration, when the symmetry plane of the loading SRR is orthogonal to the orientation of the slotline, the reflection coefficients from the two ports of the slotline are in phase. However, if the symmetry of the structure is broken by the rotation of the loading SRR, a phase difference between the two reflection coefficients is observed. Therefore, a rotation angle up to 180° can be sensed by measuring the phase difference between the reflection coefficients. Furthermore, it is demonstrated that introducing a flag resonator with the same principle of operation can extend the dynamic range of the proposed sensor to full 360°. A prototype of the proposed sensor is designed and fabricated and its principle of operation and wide dynamic range are validated numerically and experimentally.