Metal Crack Detection Sensor Based on Microstrip Antenna

A metal crack detection sensor based on a microstrip antenna is presented in this article to detect cracks hidden under the coating. Since the frequency offset of the microstrip antenna is caused by the disturbance of the current path by the metal surface crack, the crack width, depth, and length can be characterized by the frequency offset of the microstrip antenna. First, a dual-band microstrip antenna based on a transmission line coupling feed is employed to detect metal cracks. The simulation and measurement results verify that the sensor can detect the crack width, length, and depth. Second, the sensor has good scalability and can detect multiple cracks. Taking the triple-band sensor as a sample, it is verified that the sensor can be easily expanded to multiband for crack detection. This feature significantly improves detection efficiency. Finally, experimental results confirm that the sensor can detect large-area metal surface cracks, broadening its application scope.