Research on a chipless RFID sensor and encoding reconfigurable method for humidity monitoring

In this paper, a chipless RFID sensor based on frequency domain code reconfigurability and humidity monitoring is designed. The sensor is composed of two and a half ELC resonators and two microstrip band-stop filter structures. A PIN diode is added to the 3-bit encoding unit to control the on or off state of the diode to realize the reconfigurability of the tag antenna. At the same time, Rogers RT 3003 was used as the substrate to make the real sensor, and the designed humidity monitoring unit was covered with polyimide (PI) film, and a sealed experimental detection box was built to monitor different humidity, and the vector network analyzer (VNA) for real-time data collection. The feasibility of the sensor for humidity monitoring was confirmed by observing the shift of the resonance frequency of the humidity sensing unit under different humidity conditions of 50%-85%.