A Rotational Speed Measurement System Based on Floating Complementary Split-Ring Resonator

The floating complementary split-ring resonator (FCSRR) is presented in this letter. Because of its unique resonant mode, the FCSRR is suitable for the perception of rotational motion. The amplitude of the resonant signal changes as the motor rotor drives the rotation of the FCSRR at 3.34 GHz, which produces an amplitude-modulated signal. Then, the rotation period is double of envelope period. A rotational speed measurement system with FCSRR is investigated based on the above principle. The signal processing circuit of the system converts the microwave envelope signal into digital pulses to sense rotational speed. The test results indicate that the measurement resolution of this system is 0.5 r/s with an average error of 0.44% compared to a commercial speedometer. This system can be used as an alternative to a laser tachometer when ambient visibility is low.