Study On Measurement Of Soil Water Content Based On The Principle Of Standing-Wave Ratio

摘要

The relationship between apparent dielectric constant of an unsaturated porous medium and volumetric water content was presented. The unsaturated soil was considered as a three-dimensional (solid, water and air components) network of capacitors. A new device based on the principle of standing-wave ratio of transmission line has been designed and a series of theoretical treatments have been developed. Compared with other ways of measurement of soil water content, for example, time domain reflecomtry (TDR), it is cheaper and more convenient. Especially, we got the ideal linear relationship between the output voltage (it matches to impedance of transmission line) and soil water content. Furthermore, we have found a new form of soil probe in order to expend to measuring range.