A Folded Monopole Shaped Novel Soil Moisture and Salinity Sensor for Precision Agriculture Based Chipless RFID Applications

This paper focuses on the design and analysis of an inexpensive novel chipless RFID sensing scheme for soil moisture and salinity content detection. The sensor is designed at the UHF RFID band so that it can be tweaked easily to a chip-based RFID sensor. Alongside the designed sensor, a theoretical soil model with different moisture and salinity levels is simulated here. A fabricated prototype is used to measure the variation of moisture and salinity levels in sandy soil. Both the simulated and measured results exhibit frequency shift of sensor resonance with moisture content variation at non-saline conditions. However, if the soil is saline, the resonance amplitude gets reduced with increased salinity levels and exhibits moisture content independence and hence no frequency variation.