Small Displacement Sensor for Bridge Structure using UWB Textile Antenna

Small displacement on a millimetre scale becomes a vital observation object in several fields, thus motivating the development of relevant sensor concepts for detecting small displacements. An antenna-as-a-sensor offers opportunities to integrate sensing and communication. The small displacement level is used as indicator in estimating the structure health. The need appeared in monitoring the bridge or large civil structure condition. Proposed sensor system consists of two textile ultrawideband antennas that connect to S 21 measurement devices and time domain processing unit. Small displacement monitoring on a bridge structure model is used as a case study in the experiment. The textile UWB antenna is fabricated on a flexible denim substrate, allows surface adaptive placement and stable performance under mechanical deformation. The changes in the transfer function between two antennas in response to the small displacement that occurred were studied. The experimental results show a clear linear correlation between structural displacement and the time-delay shift of the reconstructed main pulse peak. The proposed UWB textile antenna achieves a 1 mm resolution in detecting small structural displacements.