用于包装物管理的无源声表面波标签设计

Design of Passive SAW Tag for Packaging Management

目的针对声表面波相位编码标签中不同位置反射栅的回波能量不一致,易受噪声干扰、误解调等问题,设计一种回波脉冲能量一致性高的声表面波标签模型,以降低误码率。方法基于耦合模理论并利用COMSOL有限元仿真软件建立反射栅膜厚、膜宽与反射栅反射率之间的关系;根据最优原则优化设计反射栅的结构参数,降低插入损耗,提高声表面波回波信号能量的一致性。结果通过仿真分析得出,当反射栅的厚度为530 nm、宽度为0.23λ时,反射栅的反射率达到最大值;优化反射栅结构得到回波一致性较好的标签,其4条反射栅的厚度均为640 nm;当宽度分别为0.245p、0.27p、0.32p、0.46p时,回波的最大幅值误差为2.02%。通过数字正交解调方法提取了回波脉冲幅值一致性调整前后的标签相位信息,结果证明经过回波脉冲幅值一致性调整后,可以正确地恢复标签的相位信息。结论设计的SAW标签模型可提高标签的抗干扰性和编码容量。

The work aims to design a SAW tag model with high consistency of echo energy to solve the problems that the echo energy of the reflectors at different positions in the SAW phase code tags is inconsistent, vulnerable to noise interference and incorrect in demodulation, thus reducing the error coding rate. Based on the coupled-mode theory and COMSOL finite element simulation software, the relationship between the thickness and width of the reflector film and the reflectivity was established. According to the optimal principle, the structure parameters of the reflectors were designed to reduce the insertion loss and improve the energy consistency of the SAW echo signal. The simulation results showed that when the thickness of the reflectors was 530 nm and the width was 0.23λ, the reflectivity of the reflectors was largest. For the tag with great consistency of echo energy obtained after optimization of reflector structure, the thickness of the four reflectors were 640 nm and the width were 0.245 p, 0.27 p, 0.32 p and 0.46 p respectively. The maximum error of echo was 2.02%. The phase information of the tag before and after the amplitude consistency adjustment of echo pulse was extracted by digital quadrature demodulation method. According to the results, the phase information of the tag could be correctly recovered after the amplitude consistency adjustment of echo pulse. The proposed SAW tag model can improve the anti-interference and coding capacity of the tag.