Full-Range CSRR-Based Angular Displacement Sensing With Multiport Interferometric Platform
Pedro Cheong, Ke Wu
Abstract
This article presents a compact, low-power, yet efficient wireless sensing platform to detect the angular displacement of an object with a reoriented complementary split-ring resonator (RCSRR). This RCSRR sensor belongs to the CSRR family, consisting of a 90° feedline on the stator and slots on the rotor. The reflected signal of the sensor experiences a monolithic phase response to the angular displacement because of its asymmetricity. In the platform, the sensor acts as a variable load of the multiport interferometer. The multiport converts the reflected signal into dc voltage readouts representing the real and imaginary parts of the phase of the reflection coefficient. Moreover, this platform operates at a fixed frequency (i.e., 2.4 GHz), and it requires only a biasing power as low as −30 dBm. This platform prevents ponderous system architecture and power consumption. This innovative wireless sensing platform has been designed, implemented, and tested. The experimental results show good agreement with their theoretical counterparts, and the standard deviation of angular displacement uncertainty is only <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^\prime $ </tex-math></inline-formula> .