Vibration Sensors Using Complementary Split-Ring Resonators Based on Pendulum Structure for Frequency Detection

In this paper, a method for measuring weak vibration is presented by using microwave sensors. A set of complementary split ring resonators (CSRRs) is utilized to detect a pendulum with metallic patch above the CSRR when any external vibration occurs. The whole system response of the pendulum structure and the CSRRs is analyzed to evaluate the vibration force. Furthermore, the material of the pendulum string could be changed to achieve different sensitivities and natural frequencies, which can be applied for interference cancellation and measurement of different axial orientation. The proposed test system was fabricated and tested to detect the vibration amplitude less than 0.19 mm and the vibration frequency can be detectable as low as 0.5 Hz.