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关键词： Antenna systems   joint design   microfluidic   radio frequency identification   self-tuning antennas   wireless sensing  

摘要： Microfluidic has been an enabling technology for over a decade, particularly in the field of medical and wearable devices, allowing for the manipulation of small amounts of fluid in confined spaces. Micro-channels can also be used for wireless sensing thanks to the variations in antenna properties when the fluid flows near it. However, up to now, microfluidic channels and sensing antennas have always been designed separately;instead, since the liquid flow and the antenna geometry both contribute to the overall performance, they should be considered simultaneously when optimizing the antenna-microfluidic system. In this paper, the joint design of the antenna and microfluidic channels is investigated for liquid quantification. Self-tuning RFID microchips are exploited to minimize communication degradation due to the increase of lossy liquid amount over the sensing antenna while digitalizing the impedance mismatch itself. To experimentally corroborate the joint design technique, two different geometries are obtained and prototyped starting from a given antenna-microfluidic layout by setting different goals for an optimization function. The two flexible RFID prototypes returned performance in agreement with the simulated ones, achieving a maximum sensitivity of about 20 units of the digital metric per milligram increase of water.

关键词： Axial ratio   biomedical   biomedical   circularly polarized   circularly polarized   IoT   IoT   RFID   RFID   5G   5G   5G  

摘要： This article presents a comprehensive discussion of different types of circularly polarized (CP) planar antennas used for various contemporary wireless applications including biomedical, RFID, 5G, IoT, etc. The analysis gives a distinct idea related to the use of CP antennas with pertinent factors to overcome various communication challenges like multipath loss, managing interference and coexistence, integration into new platforms, and cost-effectiveness. A sound understanding of the implementations as well as design considerations has been inferred by classifying and comparing several CP antenna types based on their usage. From a variety of application perspectives, the methods utilized to improve these antenna's crucial properties like axial ratio bandwidth and beam width are addressed and compared. The article is expected to provide essential recommendations to the antenna designers in terms of the selection of suitable patch configuration (like the inclusion of defects/slot, parasitic elements with main radiator, shorting pins), feeding mechanisms and substrate for their implementation in GPS, GNSS, Wi-Fi, satellite along with the above-mentioned applications.

关键词： RFID标签   氧化锌   薄膜晶体管   器件工艺   集成电路  

摘要： 射频识别(Radio Frequency Identification:RFID)是生活中广泛使用的无线通信技术之一,它可实现非接触式的自动识别和追踪。传统的RFID标签都是由硅基芯片与天线电连接封装而成,存在高温易脱落、成本较高等问题,难以在工业生产、生活中大规模使用。近些年金属氧化物薄膜晶体管因其高迁移率、低成本、低制备温度等诸多优点而广受业内关注,本文提出基于宽禁带氧化物薄膜晶体管实现芯片和天线一体化集成的超高频RFID标签设计和制备,从仿真设计和工艺实验两方面系统研究了其可行性,此方案成本低、耐高温,有望解决硅基RFID在物联网领域所遇到的问题。 本文以Zn O TFT(Thin Film Transistor)为基础,设计近场和远场两种标签,即860MHz超高频无源小尺寸RFID标签和925MHz超高频远距离通信RFID标签,并使用两种耗尽型负载反相器工艺制备RFID标签芯片,相比较之前高频RFID标签芯片,我们的标签芯片具有较高的输入信号频率、较低的电路功耗和较快的工作速率,且是低成本的一体化超高频RFID标签。这种低成本、小尺寸且光学透明的一体化超高频RFID标签电路将有助于物联网的进一步发展。 本文首先使用SPICE模型对标签的射频电路和数字电路进行仿真设计,验证了制备一体化超高频RFID标签的可行性。接着通过ALD原子层沉积的方法制备了顶栅结构Zn O TFT器件,器件表现出优异的电学性能、均一性和稳定性;随后基于该增强型器件搭建了Dickson升压整流器,其表现出优异的电路性能,包括较高的输出电压和整流效率,同时其输入信号的最高频率可达2.6GHz。接着使用氧离子注入法和紫外照射法制备耗尽型负载反相器,这两种工艺制备的反相器均表现了全摆幅输出、大噪声容限和高电压增益,同时测试两种反相器的稳定性,发现虽然随着时间的推移,两种耗尽型负载反相器的性能会有所下降,但在可接受范围之内。最后,基于两种反相器工艺方法,制备并分层测试RFID标签芯片,标签芯片性能良好,编码数据均可正常输出,且输入信号的频率最高可达120MHz,工作速率最高达26Kb/s,所需功耗最高仅为51μW,实现了低功耗的目标;本研究为进一步实现低廉且实用的超高频TFT RFID标签提供了参考。

关键词： 圆极化天线   射频识别   可重构天线   宽带  

摘要： 射频识别(Radio Frequency Identification,RFID)技术是一种非接触式自动识别技术,它通过无线射频信号识别目标对象并获取相关数据。目前,随着RFID技术的迅猛发展以及为了适应不同的RFID频段,宽频带、可重构、多频段以及圆极化特性的天线逐渐成为研究的焦点。在无线通信系统中,天线的性能直接决定了整个通信系统的质量。因此对天线的稳定性和抗干扰能力提出了更高的标准。宽带圆极化天线和可重构天线因其在提高接收灵敏度、增强通信信道容量、减少多径效应干扰等方面的明显优势,已经在RFID系统被广泛采用。本文从实现圆极化理论基础和实现方法入手,对应用于射频识别的小型化宽带圆极化天线展开研究,主要包括以下工作内容: (1)双频宽带圆极化天线设计。设计了一种紧凑的用作于射频识别(RFID)阅读器的双频宽带圆极化天线。天线由弯折处理的矩形贴片、L形贴片和三角形地板构成,通过微带线进行馈电。两个辐射贴片分别独立控制高低两个频段,其轴比带宽也可独立调整,测试结果表明在超高频(UHF)频段该天线实现了49%(0.77～1.27 GHz)的阻抗带宽和46%(0.84～1.34 GHz)的轴比带宽,在无线局域网(WLAN)频段实现了47.5%(1.54～2.50 GHz)的阻抗带宽和24.2%(1.96～2.50 GHz)的轴比带宽,可以完整覆盖UHF和WLAN两个频段,具有良好的辐射特性。 (2)超表面极化可重构天线设计。设计了一款超表面天线单元,并将其组成了4×4的超表面层。随后,设计了缝隙天线,并通过对缝隙天线和极化原理的分析,将其与超表面结合,完成了极化可重构天线的设计。结果表明,在机械旋转超表面层时,当天线处于右旋圆极化状态时,阻抗带宽为2.30GHz至3.45GHz,轴比带宽为2.30GHz至2.72GHz。当天线处于线极化状态时,其工作频段为2.26GHz至3.52GHz。而当天线处于左旋圆极化状态时,阻抗带宽为2.32GHz至3.38GHz,轴比带宽为2.28GHz至2.60GHz。在工作频段内,具有良好的辐射特性。以上数据表明所设计的超表面极化可重构天线可以实现极化可重构功能,具有重要的应用价值。 (3)基于二极管的频率可重构天线。利用开口缝隙和蜿蜒的微带馈线实现了圆极化,且两个工作频点都是独立可调整,通过调整开口缝隙的长度,使得天线在所需的频段发生谐振。对缝隙进行折叠处理可以实现尺寸的小型化。二极管的闭合与断开,可以实现天线在WLAN/UHF频段间切换,从而实现天线的频率可重构特性。当天线开关接通时,阻抗带宽为0.77GHz至1.09GHz,轴比带宽为0.81GHz至1.11GHz。而当开关断开时,阻抗带宽为2.25GHz至2.87GHz,轴比带宽为2.37GHz至2.73GHz。此设计不仅实现了小型化和结构简单,同时可以完全覆盖UHF的通用频段和WLAN频段。 本文提出的三种圆极化天线,为应用于射频识别领域的小型化宽带圆极化天线设计提供了更多思路,具有一定的参考价值。

关键词： Hash functions  

摘要： This paper analyzes He et al.’s protocol, points out that its protocol cannot resist replay and asynchronous attacks, and proposes a lightweight RFID bidirectional authentication protocol;the proposed security protocol considers that the computing capacity of the tag end is limited, abandons the elliptic ECC encryption algorithm, and adopts a self-designed deformation Hash function algorithm to encrypt necessary digital Combined with the Hamming weight comparison of its parameters, different methods of reverse or exchange operations are carried out. Combined with the Hamming weight comparison of its parameters, different methods of reverse or exchange operations are carried out to reduce the introduction of parameters and also increase the difficulty of cracking security;performance and formalization analysis of the proposed protocol shows that the protocol is superior to other comparison protocols in terms of The security, performance, and formalization analysis of the proposed protocol shows that the protocol is superior to other comparison protocols in terms of security. The total calculation of performance is less than other protocols. © (2023) All Rights Reserved.

关键词： UHF RFID   patch-type tag   mutual coupling   coupling capacitance   admittance.  

摘要： In a context of high-density deployment of UHF RFID patch-type tag antennas, mutual coupling can have an impact on the detection rate due to the degradation of the link budget between certain tags and the reader. The aim of this paper is to analyze the performance of a system that takes account of electromagnetic mutual coupling as a function of the random positions of UHF RFID patch-type tag antennas in complex environments. The design of the patch-types tags, including the extraction of the Y admittance parameters, was studied using the HFSS electromagnetic simulation software. To validate the study approach, the results obtained were compared using MATLAB software. The results obtained provide additional information needed to gain an in-depth understanding of UHF RFID patch-type tag antenna systems to make them reliable and practical in a dense environment. Future research and development work may be inspired in the design of UHF RFID patch-types tag antennas for miniaturized applications.

关键词： 枪支管理   小型化   定位   RFID  

摘要： 枪支管理是社会安全管理中不可或缺的一部分,目前某金融押运公司存在枪支管理效率低下和安全性不足等方面的问题。主要原因是嵌入枪支的通导感测硬件终端集成度太低,功能太过单一。本文主要研究嵌入枪支的通导感测硬件终端高集成度、小型化和低功耗等方面问题,配合新升级的智能枪支软件管理系统,实现枪支信息的智能管理和枪支位置的实时监控。具体研究内容如下: 1.分析了金融押运行业中枪支的不同应用场景,针对各场景所需达到的技术指标设计了相应的硬件终端方案。为了实现押运过程中对枪支的监控设计了4G无线通信电路;为了实现对枪支的定位设计了GPS/北斗、4G基站多种定位电路;为了实现枪支出入库自动登记、枪库枪支集体盘存智能化管理设计了HF RFID和UHF RFID标签电路;为了实现终端低功耗设计了电源管理电路。 2.研究了枪支握把内部3D空间结构,目的是将硬件终端做到小型化能够放置在枪支握把处。通过SOLIDWORKS机械设计软件结合相关知识,先设计出各个功能模块的3D封装,再对各个功能模块封装进行装配体组合,最终设计出符合终端电路小型化的3D封装结构。设计的各个功能模块封装包括:枪支握把外壳3D封装结构;通信识别定位PCB板3D封装结构;电源管理PCB板3D封装结构;枪支握把底座3D封装结构和天线盖3D封装结构。 3.设计了终端嵌入式软件系统,目的是配合终端硬件平台实现对枪支的主动监管,以达到通信、定位和识别等相关技术指标的要求。设计的嵌入式软件系统具体包括了:射频识别单元嵌入式软件、定位单元嵌入式软件、通信单元嵌入式软件和MCU主控单元嵌入式软件。 4.搭建测试平台,进行通信、定位、识别和有线无线充电等核心模块功能测试。搭建了模拟实车驾驶的通信定位实验平台以及位于银行和库房门口的UHF RFID识别平台和位于枪库内部的HF RFID识别平台。测试结果显示,GPS/北斗电路能达到定位刷新频率:1分钟1次,UHF RFID电路在20m左右能有效识别枪支编号,HF RFID电路在10cm左右能有效识别枪支编号,并进行了终端有线无线充电电池状态测试。 本文研究设计的嵌入枪支的通导感测硬件终端具有高集成度、小型化和低功耗等特点,在小型化物联网,可穿戴设备等方面的研究均可提供相关参考。

关键词： 栖息行为   UHF-RFID   机器学习   多区域分类   高斯滤波  

摘要： 栖息行为是鸡只重要的生活习性之一。鸡只通过栖息行为恢复体力,维持社会秩序,并通过夜间休息保持生理和心理健康。因此,对其栖息行为的深入了解和准确识别显得尤为重要,尤其是在模拟自然环境下的立体式散养系统中。由于人工观察成本高、效率低,难以满足大规模养殖业的需求,因此需要一种新的技术手段来解决这一问题。为此,本文以河北省地方品种散养太行鸡为研究对象,采用超高频射频识别(UHF-RFID)技术,结合机器学习算法,构建了鸡只栖息行为采集系统,进而对鸡只栖息行为进行识别,为散养鸡行为监测和管理提供了技术支撑。 (1)构建了鸡只栖息行为采集系统。首先,基于UHF-RFID设备的原理以及试验环境选定设备的型号;然后,通过调整读写器的发射功率、天线的摆放角度以及天线与标签的距离,实现对天线识读范围的合理规划;最后,确定天线的最佳分布位置,并设计试验方案来探究立体式栖架散养鸡只个体栖息行为。 (2)鸡只栖息行为识别模型的构建与分析。针对UHF-RFID设备定位精度不足而影响识别模型性能的问题,提出了一种将栖架上鸡只个体定位转化为多区域分类的方法。首先,根据天线排列和RSSI值波动差异,使用高斯滤波结合最大值加权滤波算法对数据进行降噪处理。然后采用70区域分类方法得到鸡只的准确位置,对比验证了基于K-最近邻、决策树和支持向量机构建的行为识别模型。通过分析模型准确率、召回率、F1得分和平均定位精度来评估模型的性能。 (3)散养鸡栖息行为的规律与分析。本文基于支持向量机模型对散养鸡栖息行为数据进行分析,鸡只平均栖息时长为9.8小时至10.67小时,每只太行鸡所需的栖架长度约为15cm。鸡只具有选择高处栖息习性,鸡只在进行栖息行为时更偏好栖架的高层两侧区域,鸡只偏好性:高层两侧>高层中心>低层两侧>低层中心。 综上所述,本研究提出的结合UHF-RFID技术和机器学习算法的栖息行为识别方法,具有较高的行为识别准确性,能够为鸡只的行为学研究和福利评价提供技术支撑。

关键词： Rail transportation   Location awareness   Protocols   Antennas   Wireless communication   Radiofrequency identification   Omnidirectional antennas   bit error rate   ERTMS   localization   LoRa   packet error rate   positioning   railway   RFID   train integrity   transportation  

摘要： This work presents the design and validation of a compact wireless system, adopting a modular wireless system composed of three co-located antennas operating in the 2.4 GHz band. The system is designed to be exploited for positioning purposes in secondary railway lines where the European railway traffic management system (ERTMS) is not available. An omnidirectional antenna, cross-polarized with respect to the other two, is used for transferring positioning data among the train and intelligent poles placed along the railway, while two directional radiating elements are arranged back-to-back, to perform wagon-to-wagon communication for train integrity purposes. The omnidirectional antenna has a radiation efficiency of 97.8% and a gain of 4.2 dBi, whereas the directive ones have 79.3% and 5.4 dBi, respectively. The data communication is established by using LoRa systems, enabling low-power, long-range communication with acceptable latency for the application purpose. Due to possible adverse environmental conditions, such as presence of dust or ice, a suitable enclosure of the system is designed to be as much as possible electromagnetically transparent. The whole system has been tested both in laboratory environment and on board of the moving train, inside and outside the wagon, demonstrating the successful communication between wagons and with the poles located along the railway. The highest bit error rate monitored was 2.08 x 10(-4) in the worst testing configuration.