A dual sensor combining dielectric and mechanic principles wasdeveloped. The geometric structure of this sensor has been designedaccording to the ASAE-standard for penetrometer cones, and the sensorcan provide a pair of output signals when inserted into soil. By analyzingboth signals, one can determine the correlation among cone index, soilbulk density, and moisture content. Some preliminary experiments wereperformed in a laboratory environment, and the sensor will be ready foruse in the field in the near future.

在基于TDR、FD和SWR等不同方法的土壤水分测量仪器中多针土壤探头作为采样传感器的一个重要组成部分，深入研究它的阻抗计算方法对于改进这些仪器的测量精确度具有很高的理论与应用价值。由于描述多针土壤探头电磁特性的麦克斯韦尔方程的边界条件很难确定，所以试图利用麦氏方程的解析解分析其阻抗特性从理论上说是“可望而不可及”的。本文依据高频传输线阻抗变换理论与数学分析中夹逼定理的思想提出了一种土壤探针阻抗计算模型。进一步通过对该模型的计算机仿真与实验研究，发现土壤探针的阻抗特性可随着测试频率与针长等相关参数的改变在感性负载与容性负载间相互转化。此外，当这些相关参数改变时，土壤探针的阻抗计算模型还存在着周期性的间断点。

A soil moisture sensor with low-cost, reliability and sufficient accuracy has been desired for many years. This paper presented an improved measurement method based on FD principle for determining soil water content. Unlike other measurement principles, a new measurable index, which is independent of the output impedance and the amplitude of the oscillator but relies on the electric impedance of the multi-pin probe, was proposed. Moreover, a model for treating the impedance of the multi-pin soil probe was also discussed and several important electric properties were approached. In order to confirm the theoretical analysis, the necessary experiments were conducted. Finally, using obtained modeling, the relationship between the proposed index and soil volumetric water content was linearly corrected.

土壤含水量的快速、准确测量问题由于其特有的复杂性至今尚未得到圆满的解决。将微波传输线阻抗变换理论应用于土壤水分测量，据此理论提出的测量方案从数学上证明其可行，所设计出的便携式土壤水分测量仪不仅成本低，而且测量精度满足使用要求。

根据羊毛毡类多孔材料的结构特点，建立了2种计算毛细管水分吸附高度的数理模型。其中3维正交模型的计算值与实验值吻合较好，模型的计算精度可以满足工程应用的需要。这种建模思想对于分析其他类型多孔介质材料水分吸附与保持问题时也有参考价值。