摘要
通过详细介绍传输线的高频率响应原理及其推导方程,以此为基础设计了基于频域反射的土壤水分探测传感器。传感器采用合适长度的传输线以及参数匹配的谐振电路,利用驻波的原理,使用简单的比较电路确定信号频率与土壤介电常数的关系,再利用介电常数和土壤成分结构之间的关系计算土壤水分含量。设计了传感器结构模块及给出了部分的试验对比结果。结果显示传感器测量数据与烘干法测量数据相吻合,最大误差不超过2%,满足农业气象探测的要求。
A new design of soil moisture sensor using frequency domain reflectometry technology is introduced by derivation of equation of high frequency response of transmission line.With proper length of transmission line and appropriate resonance circuit,a simple comparator circuit connected in parallel to the resonance circuit with standing wave can determine the relationship between signal frequency and relative permittivity of soil.Thus soil moisture can be calculated in theory of permittivity and ingredient of soil.The structure of new sensor is presented and data measured is shown.Results show that data from the new sensor matches that from oven drying method,and the maximum error is less than 2%,which can meet the need of agrometeorological monitor.
出处
《传感技术学报》
CAS
CSCD
北大核心
2011年第9期1367-1370,共4页
Chinese Journal of Sensors and Actuators
关键词
土壤水分传感器
频域反射
传输线
介电常数
soil moisture sensor
frequency domain reflectometry
transmission line
relative permittivity
