【摘要】 该文探讨了一种基于介电原理的、可实时测量土壤水分剖面分布的套筒式结构土壤水分传感器.由于麦克思维尔方程对边缘电磁场分布求解的局限性,研究过程中采用了以下技术路线:①借助于超高频矢量网络分析仪与有机标定液体相结合的办法分析传感器的高频特征参数;②根据获取的高频特征参数优化电路结构设计;③实验室环境下应用不同容积含水率的土样进行相关检验;④进一步分析套筒壁厚的影响;⑤针对一个由三种不同含水率构成的土柱进行穿层试验.试验数据统计分析表明,该传感器归一化频偏指数与土壤容积含水率之间呈线性关系.更多还原

【Abstract】 A soil-moisture profile sensor with a sliding probe and an accessing tube was designed and tested based on the principle of the dielectric theory. Due to the limitation of Maxwell equations for modeling the electric-fringe distribution, this research was conducted as the following procedures: 1) to determine the sensor’s characterized parameters using a network analyzer and a variety of solvents with known relative electric constants; 2) to optimize the circuitry design with the identified electric parameters of the sensor; 3) to calibrate the sensor with different soil water contents under the laboratory conditions; 4) to validate the effect of the tube’s thickness on the measurement results; 5) to perform a multi_layer test with a prepared soil column including three volumetric water contents. The statistic results of the measured data demonstrated a linear relationship between the normalized frequency shift of the sensor and soil volumetric water contents with a correlation coefficient of 0.95.更多还原