A Configurable Dielectric Resonator-Based Passive Wireless Sensor for Crack Monitoring

Since infrastructures are frequently exposed to atmosphere and stress, e.g., costal infrastructure, railway track, pipeline, service-induced cracks occur. Recently, passive wireless antenna sensors are emerging for early crack detection and life-long monitoring. However, the mode distribution challenges the direction stability in crack detection. Enabling by a cylindrical dielectric resonator (CDR), this communication proposes a passive wireless sensor for ubiquitous crack monitoring. The proposed CDR can excite a HE11 delta mode and its polarization can be configured through the change of the polarization of the incident wave. Due to the high dielectric substrate selected, the proposed CDR has a compact size of 24.0 mm (diameter) x 9.0 mm (height). By confining the near-field energy into a small magnetic wall, the CDR is naturally turned into a sensitive crack sensor. Crack growth causes a continuous shift in the resonant frequency of the radar cross section (RCS). This behavior can be wirelessly monitored in a distance of 0.25 m through a horn antenna. For a fixed crack width of 2.0 mm, the sensitivity in crack depth characterization is 25.4 MHz/mm. Due to the absence of electronic device and metal, the proposed sensor can work in extreme conditions, e.g., high-temperature environment.