A crack monitoring method based on microstrip patch antenna

Monitoring for cracks has been studied for decades as an important objective of the structural health monitoring system. But there is still no suitable sensor of convenience, low-cost, and wireless with high sensitivity for crack monitoring coming into practice. This paper will introduce a newly developed crack monitoring sensor based on the microstrip patch antenna. This is important as a resonant frequency shift will occur when a crack is introduced on the antenna patch. As a result, measuring the resonant frequency shift of the microstrip patch antenna can be utilized to monitor the crack length and orientation. This method was validated through both simulation and experiments. As a result, it was shown that the experiment results are in good agreement with the simulation results for crack detection and the patch antenna sensors can sufficiently detect the sub-millimeter crack with a pretty high resolution. Therefore this research can provide a preliminary theoretical basis for the application of this method in the area of wireless structural health monitoring.