Long Array of Microwave Sensors for Real-Time Coating Defect Detection

A real-time, inexpensive, and easy-to-install resonator-based microwave sensor array for coating defect detection on metallic structures is presented. The sensor array is composed of 55 identical rectangular spiral resonators coupled to a 120-cm-long transmission line. The array was simulated, fabricated, and measured. A stopband was created at the fundamental resonant frequency of the resonators. The fabricated sensor array was implemented on the coating to monitor defects beneath the sensor. The proposed sensor array can be used to detect water ingress and coating delamination, which are causes for alarm in metallic structure corrosion and cracking. The proposed structure is a low-cost solution for real-time coating failure identification.