中圖分類號：TP212.9 文獻標志碼：A DOI: 10.16157/j.issn.0258-7998.244893 中文引用格式： 邰正一,，馬潤波. 用于土壤濕度監(jiān)測的無芯片RFID傳感器設(shè)計[J]. 電子技術(shù)應用,，2024,，50(5)：84-89. 英文引用格式： Tai Zhengyi，Ma Runbo. Design of a chipless RFID sensor for soil moisture monitoring[J]. Application of Electronic Technique,，2024,，50(5)：84-89.
Design of a chipless RFID sensor for soil moisture monitoring
Tai Zhengyi，Ma Runbo
School of Physics and Electronic Engineering,， Shanxi University
Abstract： To improve the flexibility and reliability of soil moisture sensors, a low-cost chipless RFID sensor is designed for wireless monitoring of soil moisture. The sensor consists of three Complementary Split Ring Resonators (CSRR) and two orthogonal broadband circular microstrip patch antennas. Two CSRRs of the same size are closely spaced, which can easily cause coupling between resonators, resulting in more significant changes in resonant frequency in high moisture soil. In addition, the CSRR as a reference resonator is used to eliminate the influence of environmental conditions and improve the reliability of measurement. Two microstrip patch antennas are used for transmitting and receiving signals, achieving wireless sensing function. The Radar Cross Section (RCS) of the sensor with single and double CSRR structures is studied, establishing a linear relationship between soil moisture and the difference in resonance frequency. This relationship has been further confirmed through actual measurements. The experimental results show that the sensor has a sensitivity of 18.2 MHz/%θ at soil moisture ranging from 0% to 12%.
Key words : chipless RFID sensor,；soil moisture；CSRR,；microstrip patch antenna
由于土壤的介電特性受土壤濕度影響顯著，介電方法得到了廣泛發(fā)展,。文獻[1]和文獻[2]利用時域反射儀(TDR)技術(shù),，通過測量反射信號的傳播時間可以得到土壤濕度的變化。頻域反射儀(FDR)技術(shù)則根據(jù)輸出波和反射回波之間的差異來確定土壤濕度[3-4],。上述兩種介電方法雖然精確可靠,，但也需要復雜的電子設(shè)備，這限制了它們在大規(guī)模部署情況下的使用,。因此,，結(jié)構(gòu)簡單、制作方便的諧振器更適合用于監(jiān)測土壤濕度,。開口環(huán)諧振器(Split Ring Resonator, SRR)及其互補結(jié)構(gòu)CSRR對介電常數(shù)變化敏感,，被廣泛用于環(huán)境監(jiān)測中。文獻[5]和文獻[6]通過SRR來監(jiān)測土壤濕度,，濕度變化使得介電常數(shù)變化,，進而使諧振器的諧振頻率發(fā)生改變。文獻[7],、文獻[8]和文獻[9]利用CSRR對土壤濕度進行監(jiān)測，結(jié)果表明CSRR結(jié)構(gòu)具有相當高的靈敏度,，但是在高土壤濕度下諧振峰值過低,，實測時難以確定其諧振頻率。文獻[10]通過在基板頂部采用微帶線耦合三角形螺旋諧振器,，以及底部蝕刻矩形螺旋諧振器的方法,，實現(xiàn)差分傳感，可去除土壤成分,、溫度等環(huán)境因素產(chǎn)生的影響,，提高傳感器的準確度,，然而這種結(jié)構(gòu)將參考諧振器放置在土壤之下，導致參考諧振頻率仍受土壤濕度的影響,。
