Development of RFID Humidity Sensor and Radar Cross Section Stability

Design and development of a novel smart chipless humidity sensor tag has been proposed. A key approach introduced in this article for the first time is to utilize ground plane chipless radio frequency identification (RFID) tags for effective data communication having an incremental radar cross section (RCS) with 50% tag’s footprint reduction. We opted for this approach to provide high performance in real-time identification tags with increased RCS values for stable threshold-level detection. We have composed a novel compact tag that can encode 18 bits in a $14\times 12.5$ mm footprint. The data is represented using 18 individual binary digits (0 or 1 s) generated via 18 resonators and slots on the top electrode layer of the tag. This study identifies an innovative solution to offset the decrease in RCS magnitude. The most significant finding from the experiments is the correlation between the ground plane and RCS parameters. The proposed tags are designed, fabricated, tested, and evaluated via experimentation. This research finds viable innovative alternatives to compensate for the loss of RCS magnitude as the most striking result emerged from the experiments in the relation between the ground plane and RCS parameters. The expected accurate measured results make the wireless smart tag as the ideal solution for humidity sensing applications. The proposed RFID sensor tag is designed for large-scale applications, utilizing an RFID reader and supporting multiple tags within the system.