A Microwave Sensor for Leaf Moisture Detection Based on Split-Ring Resonator

A microwave split-ring resonator (SRR) is presented for leaf moisture detection in this paper. The proposed sensor is based on a split-ring resonator with a single port. The sensor operates at a resonant frequency of 2.8-3.4GHz in order to detect varying degrees of moisture. The dielectric characteristic of the leaf is detected by shifting resonant peaks. Relationship between the resonance characteristics and the moisture content of the leaf is established by experimental data. A change in leaf moisture content from 0% to 45% corresponds to a decrease in resonant frequency from 3.4 to 3.0GHz. This work presents a miniaturized, environmentally friendly, and non-destructive microwave device and provides a practical method of leaf moisture sensing.