基于准静态同轴探头模型的土壤复介电测量方法  

Dielectric Measurement Method of Soil Moisture Content Based on Quasi-static Coaxial Probe Model

作　　者：许景辉[1] 邵明烨 李晓斌 林磊 XU Jinghui;SHAO Mingye;LI Xiaobin;LIN Lei(College of Mechanical and Electronic Engineering,Northwest A&F University,Yangling,Shaanxi 712100,China;College of Water Resources and Architectural Engineering,Northwest A&F University,Yangling,Shaanxi 712100,China)

机构地区：[1]西北农林科技大学机械与电子工程学院,陕西杨凌712100 [2]西北农林科技大学水利与建筑工程学院,陕西杨凌712100

出　　处：《农业机械学报》2021年第11期271-277,共7页Transactions of the Chinese Society for Agricultural Machinery

基　　金：陕西水利科技计划项目(2014slkj-18);“一带一路”创新人才交流外国专家项目(DL20200027006)。

摘　　要：末端开路同轴探头法测量土壤复介电值用于表征土壤含水率具有准确、快捷的优点。针对目前土壤介电同轴探头集总测量模型没有充分考虑探头的参数以及土壤体积对测量结果影响等问题,基于电磁场理论,对末端开路同轴探头建立了准静态数学模型,适用于土壤的复介电常数准确测量。通过全波软件仿真和模型计算结果对比,以无水乙醇介电实测值和理论值对比,验证模型的准确性。采用本文介电测量模型对不同含水率的黄绵土进行测量计算,复介电常数实部与实测土壤含水率二阶多项式拟合决定系数大于0.965,表明本文所提土壤介电测量方法适用于土壤复介电常数和含水率的测量。The determination of soil moisture content is of great significance for agricultural irrigation decision-making,crop yield improvement,effective management of water resources,and the study of soil mechanical properties.The open-ended coaxial probe method measuring the dielectric of soil was used to characterize the moisture content of soil,which is simple and accurate.Based on the open-end coaxial probe method,a quasi-static mathematical model was established for the measurement system with a short-circuit board.The appropriate thickness to be measured was selected to make the model suitable for the dielectric measurement of semi-infinite soil.Through the comparison of the full-wave simulation and model calculation results,the average absolute error of the real and imaginary parts were 0.001 and 0.022 respectively.Comparing the measured and theoretical values of the absolute ethanol dielectric,the average absolute errors of the real and imaginary parts were 0.375 and 0.279 respectively to verify the accuracy of the model.The model was used to measure and calculate loess soils with different moisture contents.The second-order polynomial fitting determination coefficient of real part of the obtained complex permittivity and the measured soil moisture content was greater than 0.965,indicating that the soil dielectric measurement model proposed was suitable for soil dielectric measurement of electrical value and moisture content.

关 键 词：介电测量 土壤含水率 微波测量 同轴探头模型 

分 类 号：S24[农业科学—农业电气化与自动化] P161.4[农业科学—农业工程]