A cross-polarized antenna sensor based on U-shaped resonator for crack sensing

Abstract

To address the insufficient strain transfer ratio of monolithic antenna sensors and signal self-jamming in wireless interrogation, this paper presents a cross-polarized antenna sensor based on a U-shaped resonator for crack sensing. The sensor comprises an Rx antenna, a Tx antenna, and a sensing element. Employing cross polarization between Rx and Tx antennas mitigates ambient reflection, and the channel model of the sensing system based on cross polarization technique is demonstrated to reveal the working mechanism. Within the sensing element, a U-shaped resonator and movable shorted unit form an unstressed resonator, encoding the crack width in both the amplitude and phase in the retransmission signal, which are utilized to extract the sensor’s resonant frequency. The equivalent circuit model is established to analyze the monitoring mechanism comprehensively. The operational performance of the sensor is simulated in CST and validated by experiment. Results demonstrate a good linear relationship between the sensor’s resonant frequency and the crack width.