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30 March 2006 Development of the RF soil moisture sensors
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Accurate measurements of soil water content are important to land activities, especially those involving agriculture, forestry, hydrology, and engineering. In this paper, a theoretical and experimental study of the microwave moisture measurement sensors is conducted. A phase-based moisture sensor system using a transmission line sensor is designed. The amplitude of the transmission measurement is a strong function of the conductivity (loss of the media) and the imaginary part of the dielectric constant, and the phase is mainly a strong function of the real part of the dielectric constant. One can obtain the soil moisture information from measuring the phase shift of the transmitted waves. Microstrip resonator sensors are also studied and fabricated. The effective permittivity will change if a dielectric material is present near the substrate of the resonator, which causes the shift of the resonant frequency. The measured data show that both sensors are sensitive and accurate.
© (2006) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Jingheng Cheng, Xuemin Chen, Jing Li, and Richard Liu "Development of the RF soil moisture sensors", Proc. SPIE 6167, Smart Structures and Materials 2006: Smart Sensor Monitoring Systems and Applications, 61671Q (30 March 2006);


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