STUDY ON TUBE TYPE SOIL MOISTURE PROFILE SENSOR

摘要

A tube sensor is studied and used to measure the soil moisture profile. It measures not only soil water content but also soil depth. Essentially, this sensor is based on the fringe effect of the capacitance, so it is a kind of FD (Frequency Domain) sensor. The operating frequencies of the sensor circuit range from 60MHZ to 150MHZ. Among these frequencies the output of sensor is closely related to the soil water content and affected little by soil salt content. Unlike TDR with time-lapse, it is Real-time. This sensor fixed with depth sensors can measure the soil moisture profile. The laboratory experiment shows Frequency value of both the sensor in the soil that the water content is different and the circuit of sensor connected directly with known capacitance. We do the comparison of the two groups' values and find their correlation, and put forward a way of estimating the capacitance value of the tube and the medium.