Wireless Sensing with Enhanced Interrogation Range by Passive Ultrasensitive NSRR Sensors

Wireless sensing with an extended interrogation range is demonstrated using coupling-based passive sensors designed in nested split-ring resonator (NSRR) geometry. Contrary to previous utilization of the NSRR as a sensor placed within the near-field region of the transceiver antenna, the proposed sensing system uses separate antennas for TX and RX so that the signal reflected from the NSRR sensor is not affected by the dominating effect of the clutter, which limits the interrogation distance dramatically. The separation of the communication channels into TX and RX enables the extension of the interrogation distance to far field, which is critical for applications such as Structural Health Monitoring. The proposed sensing method is validated by experiments where NSRR sensor is used to detect displacement. However, the system can be exploited for measurement of different quantities such as strain and moisture content, as well.