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关键词： Antennas   Ferrites   Sensitivity   Windings   Permeability   Oils   RFID tags   Coil antenna   ferrite core   radio frequency identification (RFID)   voltage sensitivity  

摘要： As a very important part of the radio frequency identification (RFID) system, the tag antenna directly affects the performance of the whole RFID system. In this article, the design strategies for a high sensitivity ferrite-core RFID tag antenna using in oil well downhole applications is presented. Based on the derived formula of voltage sensitivity for the ferrite-core tag coil antenna, the parameters affecting the voltages sensitivity are studied. Then, through the theoretical analysis of the interactions between these parameters and sensitivity, the design of ferrite core and antenna coil winding are given in detail. Finally, the experiment results validate the proposed design strategies, and that a high sensitivity ferrite-core RFID tag antenna improves the performance of oil well downhole RFID system.

关键词： Inkjet   Meander theory   Polyimide   RFID tag   Split ring resonator theory   UHF  

摘要： A new Miniaturized RFID tag has been designed and optimized using meander theory and split ring resonator theory. The proposed RFID tag is designed and adapted for an UHF chip with Zchip=30.39-i*211Ohm. The proposed RFID tag is simulated using an EM solver and supported to operate in UHF sub-band [866.9-870.9MHz] with a band width of 4MHz. A prototype has been fabricated using inkjet method on a polyimide substrate and has been tested using a RFID base station which has proved an excellent agreement between theoretical reading range and experiment which is over up *** miniaturized RFID tag is highly suitable for applications require a middle range between 4 and 8m and a flexible compact RFID tag for integration on items such clothing application and access control. © 2022

关键词： Resonant frequency   Resonators   RFID tags   Codes   Encoding   RLC circuits   Wideband   Chipless radio frequency identification (RFID) tag   dual mode   frequency code   open-loop resonator (OLR)  

摘要： In this article, a novel and simple design procedure for multibit chipless radio frequency identification (RFID) tags is introduced, which is based on the characteristics of dual-mode loop resonator (DMLR) and open-loop resonator (OLR). By removing a small patch element from the symmetry axis of the DMLR, a simple geometrical transition to an OLR to obtain different frequency codes can be achieved. Since the DMLR and OLR provide dual- and single-resonant frequencies, three different frequency codes can be observed using one resonator. Thus, 3 $<^>{N}$ codes can be performed by coupling N resonators to input/output (I/O) ports. Even-odd mode analysis over the coupling mechanism of a single resonator is provided to characterize the frequency responses of the proposed resonators. To prove the proposed approach, two multiresonator circuits having four resonators were fabricated and tested in a good agreement. In the test environment, two horn antennas and a vector network analyzer have been utilized as transmitter and reader. Next, in order to achieve size reduction, meandered resonators are utilized instead of conventional DMLR and OLR. Based on these resonators, two RFID tags, including wideband monopole antennas integrated into the seven-resonator circuits on the same board, were also fabricated and tested.

关键词： 3D position measurement   ELM   MWCNN   RFID tag group   structure prediction  

摘要： In the field of RFID, the reading performance of tags is an important performance indicator for measuring tag. Related studies have shown that the tags' geometrical distribution has an important influence on the tags' reading performance. In order to optimize the tags' geometrical distribution and improve the tags' reading performance, this paper proposes a tag distribution optimization method based on multi-level wavelet-CNN (MWCNN) and extreme learning machine (ELM). First, this paper designs a tag distribution optimization system based on stereo-vision. Second, the stereo-cameras are used to capture the images of the tags. Aiming at the degradation phenomenon in the acquired images, MWCNN is used to recover the degraded tag images. On the basis of the image restoration, the template matching method is used to obtain the 3D coordinates of the tags. Then, ELM is used to model and predict the nonlinear relationship between 3D coordinates of the tags and the corresponding reading distance. The results show that the average prediction relative error is 0.56% and the time cost is 2.0 s. The average prediction relative error of ELM is smaller than GA-BP and PSO-BP. The time cost of ELM is smaller than the wavelet neural network.

关键词： ASK modulator   CMOS   current reuse VCO   injection locking   RFID  

摘要： A low power consumption Amplitude Shift Keying (ASK) modulator employing current reuse cross-coupled (CRC) LC-VCO topology and direct injection locking (IL) technique at 10.5-GHz frequency is presented in this paper. The modulator consumes 864 mu W with a DC supply of 1.2 V drawing an average current of 720 mu A. The differential VCO is composed of a PMOS-NMOS pair in stacked series cross-coupled connection enabling current reuse which results in reduction of the average current drawn from the power source. For comparison, the ASK modulator is also realized with conventional cross-coupled (CC) topology using NMOS pair. Both circuit approaches are carried out in GF 130-nm CMOS technology and the post-layout simulation results of 0.5 x 0.5 mm(2) integrated circuits (ICs) show that the CRC topology consumes less power and half of the average current compared to CC topology. Owing to low power requirements, the CRC ASK modulator can be used in self-powered active Radio Frequency Identification (RFID) tag transmitters for higher data rates.

关键词： 物联网   RFID技术   定位系统   人工鱼群算法   最优照明  

摘要： 近些年来随着人民生活水平的提高和社会经济的发展,人民对舒适的照明环境需求越来越高,楼宇照明作为建筑物的重要辅助组成部分,为室内用户提供舒适办公环境中扮演着重要角色。为满足用户对舒适度光照的定量需求,室内用户定位方法、融合室内灯具与自然光照的智能照明系统研究已然成为热点研究课题。论文基于射频识别(Radio Frequency Identification,简称RFID)技术,提出了采用高斯滤波技术对读写器接收到的电子标签射频信号进行预处理,再利用LANDMARC定位算法进行室内用户定位,并采用历史数据多项式拟合方式进行用户运动轨迹预测。最后搭建实验仿真平台,编写Matlab程序验证了本文采用的高斯滤波处理技术在提高LANDMARC定位算法定位精度上的有效性,并验证了本文提出的用户运动轨迹预测方法的有效性。为满足室内用户在特定位置的舒适光照定量需求,论文提出了基于人工鱼群算法的最优照明控制策略。首先根据点光源照度模型和窗户照度模型得到了室内照明的综合模型,然后从鱼的觅食、聚群、追尾等行为,介绍了人工鱼群算法在全空间内寻找目标函数最优值的过程。最后以室内灯具总亮度值为目标函数,室内各灯具亮度值为决策变量,特定位置的用户对照明定量需求为约束条件,采用人工鱼群算法进行数学模型求解。通过Matlab程序,仿真软件编写程序,验证文中给出的采用人工鱼群算法的最优照明控制策略的有效性。基于上述内容研究,可以实现室内用户定位以及用户运动轨迹预测,提前预测到用户下一步运动位置,进而制定室内灯具调整方案,待到达时完成灯具亮度值调整。同时,设计了基于PLC技术的室内灯具亮度控制系统,该方案为楼宇最优照明控制提供了重要的参考,具有工程推广价值。

关键词： Angular displacement sensors   cross-shaped matching network   microwave   microstrip patch antenna  

摘要： This paper presents a conversionless angular displacement antenna sensor node for chipless RFID applications. The sensor realizes sensing capability by altering the reflection coefficient of a patch antenna through a cross-shaped matching network with a rotatable stub. This cross-shaped network comprises two quarter-wavelength stubs, one vertical and one horizontal, allowing for compact impedance matching and providing a significant variation of an open-ended stub as a rotor. Combining the rotatable cross-shaped network and the antenna's reference antenna modifies the transmitted signal attenuation level, allowing for simple wireless angular displacement signal transmission. A prototype antenna sensor operated at 2.38 GHz for 90. sensing is designed using the conventional microstrip fed square patch antenna measured by 150 mm x 150 mm. When the rotor rotates from 0 degrees to 90 degrees, the corresponding return losses are 6.22 dB to 16.86 dB, with an average gain of 4.93 dB. The angular displacement measurement is intrinsically upconverted to 2.38 GHz without conversion circuitry and is easily detected with a reference receiving patch antenna in 100 cm wirelessly. Compared with the traditional sensor nodes for angular displacement measurement, the proposed sensor node eliminates the conversion circuits, thus making it suitable as a chipless RFID sensor.

关键词： Sensors   Radiofrequency identification   Permittivity   Resonators   Passive RFID tags   Sensor phenomena and characterization   Resonant frequency   Effective dielectric constant   effective length   coupling-based sensor   EM transduction-based sensor   RFID sensor tag   sensor performance measure  

摘要： In this paper, a review of frequency-coded (FC) passive chipless RFID sensors is presented. The prime aim of this review paper is to discuss the key concept of a passive chipless RFID sensor and its classification according to fundamental sensing parameters. The fundamental sensing parameter refers to the intrinsic characteristics of a sensor that is sensitive to an environmental parameter to be sensed. The widely used intrinsic parameters are effective permittivity, effective electrical length, and electromagnetic coupling. The categorization of frequency-coded passive chipless RFID sensors based on fundamental sensing parameters facilitates the future researcher to better understand the operating principle of the diverse RFID sensors. The improved understanding helps in the advanced design and implementation of RFID sensors. In addition, the key performance measures and recent areas of applications are discussed. This paper also focuses on existing challenges and the scope of the further developments of frequency-coded passive chipless RFID sensors.

关键词： 在线监测   双天线   RFID传感器   ALOHA算法   通信协议  

摘要： 随着电力物联网以及智能电网的快速发展,新型传感技术在电网中的应用逐渐增加,而RFID(Radio Frequency Identification)技术与传感器技术相结合的方式受到了越来越多学者的关注。RFID传感技术在物流、医药、服装等行业的应用已经非常成熟,用于电力设备在线监测上的RFID传感器还为数不多,主要受限于RFID传感器功耗要求很低、以及芯片技术的制约导致无法监测电场磁场等电气参量,但其优点也很明显,使用过程中与电力设备无电气连接、成本较低、无需复杂的辅助电路等。基于此,本文设计了一种双天线通信的RFID传感器,并考虑传感数据传输过程中的碰撞问题,研究了基于ALOHA的防碰撞算法,以在运变压器为实验对象,基于Io T协议进行了变压器振动与温度的在线监测并在阿里云平台实现了数据监控。本文主要工作如下:(1)提出了一种采用双天线通信方案下的RFID传感器设计思路,两个天线接收射频能量,一个天线进行通信;基于阻抗匹配原理和巴伦电路设计原理,完成了射频前端天线到50Ω特性阻抗之间的匹配、单端射频信号到差分信号的转换;此外,为了提高RFID传感器的通信性能,采用一块金属铝板作为传感器底座,以此来增加天线能量辐射方向的集中程度。通过测试,验证了所设计的RFID传感器具有一定的实用性。(2)考虑到在变电站等场景使用RFID传感器时,会出现多个传感器同时通信并出现数据碰撞问题,研究了四种不同ALOHA算法的吞吐率、碰撞率、空闲率,确定出适用于变压器在线监测的算法为帧时隙ALOHA算法;并基于OPNET软件,仿真还原了RFID实际通信过程中的数据包碰撞情况,验证了选择帧时隙ALOHA的正确性。(3)分析了变压器振动与温度从内部传递到箱体的规律,并确定出使用RFID传感器对变压器进行在线监测时需要将监测点布置于低压侧;搭建了从RFID传感器到阅读器、边缘网关、Io T平台的传感数据传输通道,完成了数据通信协议及其数据包格式的控制;最后使用本文所设计的RFID传感器对一台在运变压器进行在线监测,分析所得到的振动信号,并在阿里云Io T平台上实现了振动与温度数据的在线监控。