A Self-Calibrated Plant Water Estimation Sensor

In this paper, a self-calibrated plant water estimation sensor based on the concept of spectral dispersion is presented. The double reversal anomalous phase is exploited to determine the moisture content inside the leaf. The narrow spectral signature at resonance provides a high level of sensitivity, and the use of phase response makes the sensor less prone to environmental losses. Due to the self-calibration feature, no detailed profiling of the plant species is required. The concept is practically demonstrated, and a prototype tuned at 4.3-5.2 GHz is fabricated on the Rogers RO4003c board. The simulation results match well with the measurement results. The leaves of a White Rose were used for measurements. The moisture content of fresh and water-stressed leaves was measured to determine the water content inside the leaf sample. The sensor determines the difference in healthy and water-stressed leaves through dielectric sensing of the moisture inside the tissues of the leaves. The proposed sensor is self-powered, low cost, and can be implemented with minimum RF-sense electronics.