Vibration Sensing Using Doppler-Modulated Chipless RFID Tags

The paper describes how chipless tags attached to non-metal vibrating objects can be utilized to sense the frequency and amplitude of mm-vibration without any calibration process, and to identify the tag from large distances in low microwave frequency band. It is demonstrated that micro-Doppler harmonics induced by vibrating high-resonant scatterers are more detectable than those induced by the vibrating object itself while the scatterers provide great area efficiency. Presented methods for vibration sensing and identification are experimentally validated for sub-millimeter vibrations at distances up to 8 meters.