Passive Accelerometer Using Unstressed Patch Antenna Interrogated by FMCW Radar

Conventional accelerometers rely on cables or batteries to transmit power and data, which has raised the possibility of failure and maintenance complications. However, antenna-based acceleration sensors can achieve wireless and passive sensing, while the cycling stress inside the vibration member will significantly influence the durability of the sensor in practical utilization. Based on the patch antenna with an overlapping subpatch, this study proposes an unstressed passive wireless accelerometer with a frequency-modulated-continuous-wave dynamic access. The sensing antenna of the proposed accelerometer is not affected by inertial forces, which effectively improves its usability and endurance for structural monitoring. A COMSOL-based simulation is conducted to verify the workability of the accelerometer’s sensing node. The practical viability of the sensing node and wireless interrogation system is investigated via experiments. Furthermore, the shifts of the resonant frequency of the antenna sensor triggered by the change in total radiation length due to inertial forces are collected to obtain acceleration. Subsequently, the obtained results are compared to the theoretical value, with an average testing range error of 4.3%. Accordingly, this design provides a promising alternative for engineering requirements such as modal parameter identification due to its simple construction, optimal accuracy, and durability.