High-Sensitivity and Wide-Range Antenna Sensor Based on EBG and SiO<sub>2</sub> for Soil Water Content Monitoring
Huifeng Zhai, Xiuwei Xuan, Zheng Chen, Mingji Li, Hongji Li
Abstract
There are many problems with agricultural technology around the world, such as extensive irrigation which causes the waste of water. To significantly improve the efficiency of irrigation water, an antenna sensor, with high sensitivity and wide range, is proposed to measure the soil water content wirelessly. When the soil water content changes, the resonant frequency of the antenna will shift. By reading the resonant frequency of the antenna sensor, the soil water content can be measured and transmitted wirelessly. The antenna sensor has a wider detection range of soil water content, ranging from 10% to 44%, and a novel metamaterial structure (electromagnetic bandgap, EBG) is designed and its function in improving sensitivity is verified. Furthermore, by sputtering 60 nm thick SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> film on the surface of the antenna patch, its sensitivity has also been greatly improved. When the SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> film is sputtered on the antenna sensor, its sensitivity is 7.2 MHz/% and 7.6 MHz/% when the soil water content is 10%~29% and 30%~44%, respectively. In summary, this work contributes to methods and instruments for wireless measurement of the soil water content.