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基于石墨烯和金属网格的两种柔性透明天线及其应用

Two kinds of flexible transparent antennas based on graphene and metal mesh and their applications

作者:贾秀峰
  • 学号
    2018******
  • 学位
    硕士
  • 电子邮箱
    jia******com
  • 答辩日期
    2021.05.17
  • 导师
    杨轶
  • 学科名
    电子科学与技术
  • 页码
    84
  • 保密级别
    公开
  • 培养单位
    026 集成电路学院
  • 中文关键词
    石墨烯天线,金属网格,透明柔性,眼压传感器,屏上天线
  • 英文关键词
    Graphene antenna, Metal mesh, Transparent and flexible, Intraocular pressure sensor, Screen antenna

摘要

近年来,5G、物联网、可穿戴技术等领域发展迅速,作为通讯技术中重要的组成部分,对天线的需求也越来越高,朝着轻量化、柔性、隐蔽性、高性能和低功耗的方向发展。传统的金属与硬质PCB组合构成的天线渐渐无法满足应用需求,为此需要找寻具有透明和柔性的天线材料。本论文中提出了两种透明柔性天线的制作工艺,并进行了关于天线设计的研究,研究主要包括以下几个方面:第一,提出了石墨烯与银纳米线复合制作透明柔性天线的工艺方法。经测试得到的薄膜的厚度为100nm,同时具有75%的透光率以及6Ω/sq的方阻。基于该薄膜设计了一种具有超宽带、高柔性的蝶形天线,与之前研究工作中的石墨烯天线相比性能有了很大提升。第二,在金属网格天线的研究中,采用了蜂窝状的结构设计提高了金属网格的结构强度以及透光率,同时使用光刻与电沉积的制作工艺来制备金属网格以提高网格的精度,最后使用UV树脂将金属网格转移到PET衬底上得到导电薄膜,经测试金属网格的透光率达到90%以上,同时还有0.1Ω/sq的超低方阻。基于该导电薄膜设计了工作在5G n79(4.4~5GHz)频段的正交双端口天线,通过仿真与测试得到天线的最大增益为4.5Bi,效率达到84%,与近期的同类工作相比该天线具有最佳的透明度以及效率。以及对天线进行了柔性和可穿戴测试,该天线在不同弯曲角度下保持了稳定的工作频点。第三,基于金属网格天线表现出的优异的导电性能和透明度,进行了天线在应用方向的探索。首先是眼压传感器上的应用,在隐形眼镜上设计了叉指电容-蛇形电感以及谐振环两种的LC谐振电路,在眼压改变的情况下导致隐形眼镜的形变导致谐振电路中电容值的改变,进而使得LC谐振电路的谐振频率发生改变,通过测试谐振频点的改变来计算眼压。通过仿真验证了眼压传感器的可行性,同时设计了智能眼镜与隐形眼镜的眼压探测系统。另外设计了屏内天线的应用,通过将天线设计到屏幕正面,拓展了天线的应用场景,为了降低屏内导体的屏蔽作用以及增强辐射增益,选择了8阵列的毫米波天线,经测试天线在毫米波频段的反射系数符合指标要求。

In recent years, 5G, Internet of Things, wearable technology and other fields have developed rapidly. As an important part of communication technology, the demand for antennas is also getting higher and higher, which is developing towards the direction of lightweight, flexible, concealed, high performance and low power consumption. The traditional combination of metal and hard PCB antenna is gradually unable to meet the application requirements, so it is necessary to find a transparent and flexible antenna materials. In this paper, two kinds of transparent flexible antennas are proposed, and the antenna design is studied. The research mainly includes the following aspects:Firstly, a transparent flexible antenna fabricated by graphene and silver nanowires is proposed. Firstly, graphene was grown on copper foil, and then graphene was composite with PET/EVA/ silver nanowire thin film by hot pressing. Finally, graphene and copper were layered by electrochemical bubbling to obtain graphene-silver nanowire composite film. The measured thickness of the film is 100nm, with a transmittance of 75% and a square resistance of 6Ω/sq. Based on this film, a butterfly antenna with ultra-wideband and high flexibility is designed, which has a great improvement in performance compared with the graphene antenna in previous research work. At the same time, the application test of the RFID antenna was also carried out, and the communication distance of the antenna was verified to be up to 1.3m by practical application, which met the working requirements of the near field communication.Second, in the study of metal mesh antenna, using the honeycomb structure design improves the metal grid structure strength and light transmittance, at the same time use photolithography and electrodeposition process for the preparation of metal grid in order to improve the accuracy of the grid, finally using UV resin transfer the metal grid to PET substrate conductive films, the light transmittance of the metal mesh is more than 90% after testing, and the ultra-low square resistance is 0.1Ω/sq. Based on this conductive film, an orthogonal dual-port antenna working in 5G N79 (4.4~5GHz) frequency band is designed. Through simulation and test, the maximum gain of the antenna is 4.5Bi, and the efficiency is up to 84%. In the target frequency band, the gain and efficiency of the antenna maintain a stable value, showing excellent performance. The antenna has the best transparency and efficiency compared with the recent similar work. The antenna maintains a stable working frequency point under different bending angles, and the working frequency band of the antenna is almost unchanged under the influence of the arm being close to the antenna. Meanwhile, the radiation amount of the antenna calculated in the SAR simulation of human tissue radiation from the antenna is lower than IEEE C95.1-2019 standard. The results show that the antenna is safe to wear on the surface of clothing.Thirdly, based on the excellent conductivity and transparency of the metal mesh antenna, the application direction of the antenna is explored. First is the application of the pressure sensor on the lens design refers to the fork - coil inductance capacitance and resonant ring two LC resonance circuit, in the case of intraocular pressure changes cause the deformation of contact lenses lead to the change of capacitance value in a resonance circuit, which makes the resonant frequency of LC resonance circuit changes, through testing the change of the resonant frequency to calculate the intraocular pressure. The feasibility of the intraocular pressure sensor is verified by simulation. At the same time, the intraocular pressure detection system of smart glasses and contact lenses is designed. In addition, the application of the in-screen antenna is designed. The antenna is designed on the front of the screen to expand the application scenarios of the antenna. In order to reduce the shielding effect of the in-screen conductor and enhance the radiation gain, the millimeter wave antenna with 8 arrays is selected.