Chipless RFID Sensor for Real‐Time Environment Monitoring

This chapter proposes a chipless radio‐frequency identification (RFID) sensor for environment monitoring. It integrates smart humidity sensing materials with radar cross‐section (RCS) scatterers to incorporate environment sensing in frequency spectral analysis. Chipless RFID sensor development is carried out into two phases. The aim of the first phase is to perform RF characterization of two humidity sensing polymers Kapton and polyvinyl alcohol (PVA) to compare their humidity sensitivity. In this phase, the chapter identifies a number of RF sensing parameters for calibrating humidity in real environments. In the second phase, a chipless RFID humidity sensor is developed based on RCS scatterer. Detailed experimentation is carried out to verify humidity sensor performance. The measured sensor response is analyzed to exploit calibration curve for unknown humidity measurement. Finally, the chapter discusses the effect of hysteresis, repeatability, and time response.