土壤剖面水分传感器的边缘电磁场分析  

Edge electromagnetic field analysis of soil profile moisture sensors

作　　者：赵燕东[1,2,3] 李博 刘卫平 宋润泽[4] 米雪 Zhao Yandong;Li Bo;Liu Weiping;Song Runze;Mi Xue(The school of Technology,Beijing Forestry University,Beijing 100083,China;Beijing Laboratory of Urban and Rural Ecological Environment,Beijing 100083,China;Forestry and Grass Ecological Carbon Neutral Wisdom Sensing Research Institute,Beijing 100083,China;College of Information and Electrical Engineering,China Agricultural University,Beijing 100091,China;Dingzhou Lvgu Agricultural Science and Technology Development Co.,Ltd.,Dingzhou 073006,China)

机构地区：[1]北京林业大学工学院,北京100083 [2]城乡生态环境北京试验室,北京100083 [3]林草生态碳中和智慧感知研究院,北京100083 [4]中国农业大学信息与电气工程学院,北京100091 [5]定州市绿谷农业科技发展有限公司,定州073006

出　　处：《农业工程学报》2021年第24期177-188,共12页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国家重点研发计划项目(2020YFD1000500);北京市共建项目;河北省产业创新创业团队项目(205A7603D)。

摘　　要：为了提高基于驻波比原理(Standing Wave Ratio,SWR)的土壤剖面水分传感器非接触式测量精度及传感器在田间土壤水分测量中的实用性,该研究基于电磁仿真软件和印刷电路板工艺设计了一种基于边缘电磁场理论的小型定向测量探头,并进行了探头阻抗变换电路的设计,最后借助矢量网络分析仪探究了探头阻抗与介质、电导率的关系。在论证检测原理有效性的基础上,首先采用High Frequency Structure Simulator电磁场仿真验证探头结构的合理性。并配置不同介电常数的介质溶液进行试验,确定了剖面土壤水分传感器的阻抗特性及测量范围。同时,为了分析土壤电导率对测量结果的影响,配置不同水分、电导率梯度的土壤样本,利用矢量网络分析仪分析了探头阻抗与水分及电导率的关系。结果表明,在土壤含水率3%~56%、土壤电导率0~6 300μS/cm时,测量最大绝对误差6.33%。与ET-5、5TE两种商用传感器受土壤电导率影响精度性能进行对比,传感器在非盐碱土壤(电导率在0~6 300μS/cm内)土壤体积含水率相对误差相比其他两款传感器减少了0.17~5.27个百分点,受电导率影响在非盐碱土壤测量时更小,基本满足非盐碱地土壤田间实际检测需求。研究成果可为土壤剖面水分测量提供理论基础与技术参考。A soil moisture sensor has been widely used to measure the volumetric water content in soil at present. However,the detection of soil profile moisture sensors is often affected by the air and wiring in the pipeline, due to the inconsistent production and measurement direction of the probes. In this study, a small directional measuring probe was designed for the soil profile moisture non-contact sensor using the principle of Standing Wave Rate(SWR), electromagnetic simulation, and printed circuit board technology. Then, the impedance conversion circuit of the probe was designed to meet the requirements of SWR measurement. A vector network analyzer was utilized to determine the relationship among the probe measurement,medium, and conductivity. In detail, firstly, the impedance characteristics of the probe structure were verified to simulate the High-Frequency Structure Simulator(HFSS) electromagnetic field. The optimal probe size was then determined as the radius 15 mm and height 20 mm, according to the impedance and standing wave ratio of the probe at different heights and radii. The impedance of the probe was transformed in the impedance circuit, further to determine the relationship between the probe impedance and the object to be measured under different conductivity, as well as the dielectric constant. Secondly, the appropriate impedance conversion circuit of the probe was designed to verify in the range suitable for SWR to detect soil moisture using a vector network analyzer. Thirdly, a series of tests were performed on the different dielectric constants to evaluate the measurement accuracy of the probe. The measuring range of the probe was an approximate cylinder with a height of 15 mm and a radius of 37 mm, according to the impedance characteristics of the soil moisture sensor in the profile. Finally,the soil samples with multiple moisture and conductivity gradients were configured to evaluate the probe impedance. The results showed that, when the soil conductivity was less than 6 300 μS/cm in the range of

关 键 词：土壤 传感器 含水率 电导率 阻抗变换 电磁仿真 

分 类 号：S126[农业科学—农业基础科学]