A design of probe for measurement of moisture content using time domain reflectometry

TDR (Time Domain Reflectometry, TDR) is an important method for measuring soil parameters, e.g., soil water content. In this work, a new TDR probe has been developed and a criterion for designing the probe proposed. Also, the structure of TDR probe and signal detection circuit is addressed in detail. Test results showed that there is a strong positive linear relationship between the reference measuring instrument and TDR instrument in a watering experiment. However, measurement accuracy of soil moisture was easily influenced by heterogeneity of soil.