Design of Microwave-Based Angular Displacement Sensor

This letter presents a novel microwave-based rotation sensor having a wide dynamic range to detect and measure the angular displacement in terms of the change in resonant frequency. The proposed sensor is based on the microstrip technology, where a rotor comprised of a complementary splitring resonator (CSRR) placed on the ground plane of the microstrip line is free to rotate around its axis. The mechanical rotation of CSRR determines a change in the cross coupling between the microstrip line and the CSRR, thus changing the overall inductance. The proposed planar unloaded microwave sensor, working around ISM band of 5.8 GHz, is quite sensitive to detect angular rotation in the wide dynamic range of 0 degrees-90 degrees. The linearity in dynamic range is achieved in the range of 30 degrees-60 degrees. Operating frequency and bandwidth can be adjusted by loading the rotor with dielectric. Depending on the type of dielectric loading of CSRR, it is possible to select the center frequency from a wide range of 4.67-5.94 GHz, with the bandwidth ranging from 116 to 250 MHz. Due to its features, the proposed sensor can be useful for various industrial applications.