基于频率选择表面的太赫兹标签设计

Design of terahertz tags based on frequency-selective surfaces

摘要:

设计了一种基于频率选择表面(Frequency-selective Surface,FSS)的太赫兹超表面标签,整体结构由表面金属图案、中间介质和底面金属板组成。频率选择表面的结构单元是由对称八边形嵌套环构成,刻蚀在材料为聚酰亚胺(Polyimide)的中间介质上。标签采用频率编码规则,当一个嵌套环消失时,相对应的共振频率点的吸收峰消失,从而完成不同的编码,通过频率编码也实现有效的带宽利用。仿真结果表明,所提出的结构实现了4bit的编码容量,其工作频率范围0.1~0.5THz范围内,标签面积仅为0.25mm2,具有较高的编码密度,角度稳定性大于等于45度,具有偏振不敏感的特性,满足标签识别准确性的要求,具有良好的编码性能。此外,提出了一种频移编码规则,通过改变谐振结构参数来引入频移,从而实现了在不改变标签体积的基础上增加了编码容量、提高标签编码密度,能够更灵活的满足实际应用需求。本文所提出的基于超表面的柔性太赫兹标签区别于流行的射频标签,在医疗和工业部件、汽车零件和硅芯片等微小物体上有很好的应用前景。

Abstract:

A terahertz metasurface labelbased on frequency-selective surface (FSS) was designed, and the overall structure was composed of a surface metal pattern, an intermediate medium and a bottom metal plate. The structural unit of the frequency-selective surface consists of symmetrical octagonal nesting rings etched on an intermediate medium made of polyimide. When a nested ring disappears, the absorption peak of the corresponding resonant frequency point disappears, so as to complete different coding, and the effective bandwidth utilization is also achieved through frequency coding. The simulation results show that the proposed structure achieves a 4-bit coding capacity, its working frequency range is 0.1~0.5THz, the label area is only 0.25mm2, it has a high coding density, the angular stability is greater than or equal to 45 degrees, it has the characteristics of polarization insensitivity, meets the requirements of label recognition accuracy, and has good coding performance. In addition, a frequency shift coding rule is proposed, which introduces frequency shift by changing the resonant structure parameters, so as to increase the coding capacity and label coding density without changing the label volume, which can meet the practical application requirements more flexibly. The metasurface-based flexible terahertz tag proposed in this paper is different from the popular RF tag and has a good application prospect for tiny objects such as medical and industrial components, automotive parts, and silicon chips.