Frequency-selective surface-based chipless passive RFID sensor for detecting damage location

Various types of wireless sensor systems are used for structural health monitoring. Especially, chipless wireless sensors are useful in harsh environmental conditions of high temperature and toxic chemicals. This paper reports a chipless passive structural health monitoring sensor made with frequency-selective surface (FSS) array for detecting damage location. FSS is a kind of microwave meta-material antenna that is selective by its electromagnetic characteristics associated with geometrical shape and electrical impedance. An FSS-array-based wireless sensor was made on a flexible substrate that can be easily attached to arbitrary structures. When microwaves are applied to the FSS via a single horn antenna, the sensor senses its reflection changes, and by scanning the horn antenna, the location of damage is detected. Design, fabrication, and characterization of cross-type FSS array are carried out, and a computer simulation is performed for comparison.