基于传输线理论的土壤水分传感器的性能试验

Research of Soil Moisture Sensor Based on Transmission Line Theory

介绍了一种根据土壤介电常数和传输线理论来测量土壤含水量的新型土壤水分传感器。传感器采用四针不等长结构 ,从探针结构、土壤种类、土壤容重和盐分等几个方面对该传感器的工作特性进行试验研究 ,结果表明该传感器输出稳定、线性度好 ,适应大多数土壤类型的测量。

Techniques based on the measurement of the dielectric constant of the soil,either capacity probes or time-domain reflectometry (TDR),are becoming increasingly popular now. In this paper,the soil water sensor designed on the transmission line theory was used in laboratory trials to determine what other soil factors influence capacitance measurement by the sensor. Trials demonstrated that there is a distinct influence as to the probe configuration. The sensor with 4 probes of unequal length had the advantage of that with equivalent length. Soil types and bulk density have limited impact on measurement result,and the sensor should be calibrated for specific soil in order to minimize the errors. The ionic conductivity of salts dissolved in the soil moisture has significant influence on soil water measurement,especially high salinity in soil.