Cactus-Shaped Frequency Reconfigurable Antenna for Sub 10 GHz Wireless Applications

This paper presents,a novel cactus shaped frequency reconfigurable antenna for sub 10 GHz wireless applications.PIN diode is utilized as an electrical switch to achieve reconfigurability,enabling operation in four different frequency ranges.In the switch ON state mode,the antenna supports 2177-3431 and 6301-8467 MHz ranges.Alternatively,the antenna resonates within 2329-3431 and 4951-6718 MHz while in the OFF state mode.Radiation efficiency values,ranging from 68%to 84%,and gain values,ranging from 1.6 to 4 dB,in the operating frequency bands.the proposed antenna satisfy the practical requirements and expectations.The overall planner dimensions of the proposed antenna model is 40×21 mm^(2).Moreover,the measurement results from the prototype support the simulation results.Based on the frequency ranges supported by the antenna,it can be used for multiple wireless standards and services,including Worldwide interoperability and Microwave Access(WiMAX),Wireless Fidelity(Wi-Fi),Bluetooth,Long Term Evolution(LTE)and satellite communications.This increases its applicability for use in mobile terminals.

OWC/RF混合通信系统研究进展

无线光/射频混合通信系统克服了单一通信系统的局限性,在最大发挥无线光通信优势的同时弥补了射频通信的不足,显著提高了链路的可用性和可靠性,为未来高速大容量的信息传输提供了独特的解决方案。对近年来无线光/射频混合通信系统的研究进展进行了综述,首先介绍了不同混合通信系统模型的工作原理与应用,然后讨论了混合通信系统所面临的挑战和解决方法,最后展望了无线光/射频混合通信系统的未来发展趋势,旨在为无线光/射频混合通信系统的进一步研究和发展奠定基础。

无线传感网络中一种基于RF-GAN模型的入侵检测算法

针对现有无线传感网络入侵检测算法存在的效率低、精度差等问题,提出基于RFGAN模型的无线传感网络入侵检测算法。首先,采集无线传感网络运行数据,通过去噪、缺失补偿等步骤,完成对原始数据的预处理;然后,利用RF-GAN模型提取无线传感网络运行特征;最后,通过提取特征与检测标准的匹配,得出网络入侵检测结果。理论分析及实验结果表明:优化设计方法的入侵类型误检率明显更低,入侵数据量检测误差为0.015GB,相较于现有检测算法具有一定优势。

Photonics-assisted THz wireless communication enabled by wide-bandwidth packaged backilluminated modified uni-traveling-carrier photodiode

This paper presents a wide-bandwidth back-illuminated modified uni-traveling-carrier photodiode(MUTC-PD)packaged with standard WR-5 rectangular waveguide for high-speed wireless communications.With optimized epitaxy structure and coplanar waveguide electrodes,the fabricated 4-μm-diameter PD exhibits ultra-flat frequency response and high saturation power.Integrated passive circuits including low-loss bias-tee and E-plane probe are designed to package the PD into a compact module with waveguide output.The packaged PD module has demonstrated a flat frequency response with fluctuations within±2.75 dB over a broadband of 140-220 GHz and a high saturated output power of-7.8 dBm(166μW)at 140 GHz.For wireless communication applications,the packaged PD is used to implement 1-m free space transmission at carrier frequencies of 150.5 and 210.5 GHz,with transmission rates of 75 and 90 Gbps,respectively.

频率捷变调频引信抗DRFM干扰设计

针对传统调频引信易被数字射频存储(DRFM)干扰,从引信发射波形去周期化角度出发开展了调频引信抗DRFM干扰方法研究,设计了一种m状态序列编码的频率捷变三角波调频引信抗DRFM干扰总体方案,提出一种补零FFT频谱细化提取谐波时序判决的信号处理方法,根据总体设计方案,完成了频率捷变调频引信样机信号处理系统的硬件电路设计与程序开发。实验结果表明,所设计的频率捷变引信抗DRFM干扰方法可以在保证定距精度的同时大幅提高抗DRFM干扰性能。

基于RF芯片的通信技术在分布式网络传感器中的应用

文章旨在探讨基于无线射频(Radio Frequency,RF)芯片的通信技术在分布式网络传感器中的应用。传统的分布式网络传感器系统通常使用有线连接或基于特定通信协议的无线传输技术,但这些方案在部署和维护上存在一定的限制。因此,采用RF收发一体化芯片作为通信技术的载体,实现分布式网络传感器之间的无线数据传输具有重要意义。文章围绕传输终端硬件设计基础,提出一种具体的方案,包括硬件选型、通信协议设计、功耗管理以及安全性考虑等方面,以实现高效稳定的分布式网络传感器无线数据传输。

激光与RF链路融合异质通信网络构建策略

文章探讨了激光与射频(Radio Frequency,RF)链路融合的异质通信网络构建策略。首先,分析异质通信网络中链路异构、资源管理和性能保障等问题。其次,提出激光与RF链路融合网络架构,包括网络层次框架和空间资源映射机制的建设。再次,在资源协同管理方面,引入链路状态信息获取与更新机制,以及基于业务优先级的资源调度技术。最后,采用软切换决策算法和切换过程中的业务保障技术,解决异质网络切换问题。设计的策略可以提升通信网络的整体性能,提高资源利用效率,为未来异质通信网络的发展提供可行的解决方案。通过激光与RF链路的协同,实现更高效的数据传输和稳定的切换,为通信技术的创新提供有力支持。

基于WSN和RFID的矿井作业人员健康监测系统设计

针对煤矿井下工作场景恶劣复杂、人员健康及环境参数监控难度大、易造成安全事故等问题,采用物联网技术,设计了一种基于无线传感器网络(Wireless Sensor Networks,WSN)和射频识别(Radio Frequency Identification,RFID)的矿井作业人员健康监测系统。该系统利用WSN实时监控人体的心率、血氧及井下环境温湿度、气体浓度等数据;利用RFID技术定位井下作业人员;将所采集信息数据传输至服务器实时检测,实现安全预警并及时定位救援,从而远程监测作业人员健康。

基于纳米材料的无源RFID温度传感器设计

射频识别(RFID)技术与传感器的一体化设计,具有数据采集便捷和部署方便等优点,在智慧农业和食品溯源监测领域具有潜在应用价值。提出一种基于氧化锌(ZnO)/还原氧化石墨烯(RGO)的无源RFID一体化温度传感器设计,传感器天线和电极主要采用微带贴片天线制作,天线及电极结构通过HFSS软件进行仿真设计及优化,然后利用热转印技术在环氧树脂覆铜板上通过化学刻蚀制备图形化电极;传感器的温敏材料为水热法制备的ZnO/RGO纳米复合材料。ZnO/RGO温敏材料阻抗随环境温度发生变化,从而引起RFID射频谐振中心频点偏移,以射频回波损耗和归一化频移来度量环境温度的变化,在10℃~60℃量程范围内,该传感器的温度灵敏度可达0.86 dB/℃,线性度R2=0.99。

一种X波段三叉H型低电压RF MEMS开关设计

针对射频电路系统所需要的低电压,高隔离度,低插入损耗的应用需求,通过对开关正对面积对驱动电压产生的影响进行探究,设计了一款应用于X波段三叉H型的RF MEMS开关。开关具有六条悬臂梁作为支撑,通过增大上极板面积来降低开关的开启电压。分别使用HFSS和COMSOL对开关的射频性能和机械性能进行仿真,开关最终优化后,在8-12 GHz内,插入损耗为0.26~0.57 dB,隔离度大于31.30 dB。在10.1 GHz达到最优值,插入损耗为0.40 dB,隔离度为50.25 dB。开关电压在11V时就能够实现状态转换,开关的响应时间为18μs。此开关可与射频可重构器件结合,应用于新一代射频微波领域。

Multi-frequency point supported LLRF front-end for CiADS wide-bandwidth application

The China initiative Accelerator Driven System,CiADS,physics design adopts 162.5 MHz,325 MHz,and 650 MHz cavities,which are driven by the corresponding radio frequency(RF)power system,requiring frequency translation front-end for the RF station.For that application,a general-purpose design front-end prototype has been developed to evaluate the multi-frequency point supported design feasibility.The difficult parts to achieve the requirements of the general-purpose design are reasonable device selection and balanced design.With a carefully selected low-noise wide-band RF mixer and amplifier to balance the performance of multi-frequency supported down-conversion,specially designed LO distribution net to increase isolation between adjacent channels,and external band-pass filter to realize expected up-conversion frequencies,high maintenance and modular front-end generalpurpose design has been implemented.Results of standard parameters show an R2 value of at least 99.991%in the range of-60-10 dBm for linearity,up to 18 dBm for P1dB,and up to 89 dBc for cross talk between adjacent channels.The phase noise spectrum is lower than 80 dBc in the range of 0-1 MHz;cumulative phase noise is 0.006°;and amplitude and phase stability are 0.022%and 0.034°,respectively.

应用标签并行识别技术的RFID防碰撞算法

针对RFID传统算法一次只能识别一个标签、吞吐率低、饿死率高的不足,文中提出一种RFID系统防碰撞算法,即利用伪ID码分组,并应用标签可并行识别技术的防碰撞算法(PILD算法)。PILD算法利用伪ID码对待识别标签进行分组,当出现碰撞现象时,运用并行识别算法对出现碰撞的标签进行识别。该算法能避免因帧长过大造成吞吐率下降的问题,并提高RFID识别技术的吞吐率。首先对PILD算法的识别过程进行理论分析,再运用Mathematica软件对PILD算法进行仿真。理论分析及仿真结果表明:当标签总数为2000,单次碰撞标签数小于等于6时,标签平均查询次数近似为1.26次;该算法的吞吐率较稳定且达到0.791092,与基于伪ID码的树型防碰撞算法和Logistic⁃DFSA算法相比,所提算法吞吐率分别提高28.82%、4.74%;当标签数大于1400时,PILD算法的标签总查询次数最少,标签平均查询次数最少。所提算法中伪ID码分组能够减少单个标签因多次碰撞发生“饿死现象”的概率,与基于伪ID码的树型防碰撞算法和Logistic⁃DFSA算法相比,PILD算法饿死率最低。

Effect of driving frequency on electron heating in capacitively coupled RF argon glow discharges at low pressure

A one-dimensional（1D） fluid model on capacitively coupled radio frequency（RF） argon glow discharge between parallel-plates electrodes at low pressure is established to test the effect of the driving frequency on electron heating. The model is solved numerically by a finite difference method. The numerical results show that the discharge process may be divided into three stages： the growing rapidly stage, the growing slowly stage, and the steady stage. In the steady stage,the maximal electron density increases as the driving frequency increases. The results show that the discharge region has three parts： the powered electrode sheath region, the bulk plasma region and the grounded electrode sheath region. In the growing rapidly stage（at 18 μs）, the results of the cycle-averaged electric field, electron temperature, electron density, and electric potentials for the driving frequencies of 3.39, 6.78, 13.56, and 27.12 MHz are compared, respectively. Furthermore,the results of cycle-averaged electron pressure cooling, electron ohmic heating, electron heating, and electron energy loss for the driving frequencies of 3.39, 6.78, 13.56, and 27.12 MHz are discussed, respectively. It is also found that the effect of the cycle-averaged electron pressure cooling on the electrons is to ＂cool＂ the electrons; the effect of the electron ohmic heating on the electrons is always to ＂heat＂ the electrons; the effect of the cycle-averaged electron ohmic heating on the electrons is stronger than the effect of the cycle-averaged electron pressure cooling on the electrons in the discharge region except in the regions near the electrodes. Therefore, the effect of the cycle-averaged electron heating on the electrons is to ＂heat＂ the electrons in the discharge region except in the regions near the electrodes. However, in the regions near the electrodes, the effect of the cycle-averaged electron heating on the electron is to ＂cool＂ the electrons. Finally, the space distributions of the electron pressure cooling the electron ohmic heating and the electron heating at 1/4 T, 2/4 T, 3/4 T, and 4/4 T in one RF-cycle are presented and compared.

Frequency control and pre-tuning of a large aperture 500 MHz 5-cell superconducting RF cavity

The 500 MHz 5-cell superconducting RF(SRF) cavity was designed aiming to be a candidate cavity for high current accelerators. A copper prototype cavity and a niobium cavity were fabricated at SINAP in 2012. In order to ensure these cavities get the desired frequency and a good field flatness higher than 98%, frequency control was implemented in the manufacturing process and pre-tuning has been done using a simple pre-tuning frame based on the bead-pull pre-tuning method. Then, TM010-π mode frequency within 5 kHz from the target frequency was achieved and the field flatness reached 98.9% on the copper prototype cavity. Finally, the same procedure was applied to the niobium cavity to obtain a field flatness better than 98% which benefited the cavity performance in the vertical testing.

基于门限判断机会调度的多用户PLC/RF系统性能分析

针对融入译码转发中继技术的混合电力线通信(Power Line Communication, PLC)与射频(Radio-Frequency, RF)传输系统,首先提出了一种基于门限判断的多用户机会调度方案。其次,在PLC和RF链路信道衰落分别服从对数正态分布和相关莱斯分布的条件下,推导出采用所提调度方案的PLC/RF系统中断概率和归一化平均反馈负载的闭合表达式。接着,还通过分析高信噪比条件下系统中断概率的渐进性能,得到系统分集度和阵列增益的简单闭合表达式。最后,计算机仿真不仅验证了理论分析的正确性,而且进一步揭示了所提方案能够在尽量减少反馈负载的同时获得较优的中断性能,从而为实际的系统设计提供参考和依据。

Frequency hopping in IEEE 802.15.4 to mitigate IEEE 802.11 interference and fading

In this paper, we investigate the issues of initialization and deployment of wireless sensor networks（WSNs） under IEEE 802.11 b/g interference and fading channels using frequency hopping（FH）. We propose an FH algorithm for WSNs, which is implemented and tested with a pair of nodes employing IPv6 over low power wireless personal area networks（6 LoWPAN） standard.The merits and demerits of the proposed FH scheme in WSNs are studied under strong IEEE 802.11 b/g interference and frequency selective fading channels. We compare the performance results of the proposed FH scheme with those obtained by single-channel radio in WSNs, and show that FH maintains very reliable data rates in the presence of adverse conditions where the single-channel radio fails. We determine a minimum center frequency offset of channels between IEEE 802.15.4 and IEEE 802.11 b/g-based networks, which guarantees the error free network operation of IEEE802.15.4 using a single channel. We design a second FH procedure comprising only four free channels（15, 20, 25, and 26） of IEEE 802.15.4 standard, and show that in the presence of nearby IEEE 802.11 b/g interference, the IEEE 802.15.4 data rate using this method is always 98% and more.

Designing Wireless Charger Circuit for Hearing Aids Using Radio Frequency Waves

In this paper, an attempt has been made to produce a recipient system of wireless charge for a simple hearing aid so that electrical signal would be generated through detecting and receiving radio frequency waves (RF). The purpose of this design is to receive wireless charge for hearing aids and basically for any electronic device which is not required to a high energy for being setup. In this study, it has been demonstrated that as the amount of radio receiving energy increases, distance of receiver from antenna should be decreased;otherwise, either maximum amount of the receiving energy, or signal power density of the transmitter should be increased. Since it is impossible to be performed, it is decided to set up an energy receiving system constructed by rectenna and charge Circuit and to adjust their parameters to provide energy requirements for a device with low-power consumption. In this paper, different components of an energy receiving system from radio frequency band have been mentioned and a diagram block has been suggested. Subsequently, input impedance of designed antenna has been adjusted by provided relations. This impedance should be adjusted with the total impedance of regarded hearing aid Circuit by which the highest amount of received signal power is transferred to the battery of hearing aids. Received signal is converted to a dc voltage by rectifier diode. Finally, by applying a voltage regulator which has been designed using a common-collector amplifier not only the output voltage is kept constant, but the power is also strengthened. The battery of the hearing aids will be charged using the obtained power and voltage.

PLC-RF无线传输网络中的能效最优设计方法

针对电力线通信(PLC)和射频(RF)无线通信混合传输的室内通信场景,提出了一种基于角度信息的信道状态信息(AI-CSI)的能效优先传输方案。首先,Wi-Fi无线网络和PLC网络分别作为主网络和次级网络,并且采用认知无线电技术来提高频谱效率的情况下,建立次级网络总能效最大化为目标函数的优化问题。其次,为了求解该问题,通过基于AI-CSI的迫零波束成形方法,获得波束成形权矢量,并进一步提出Dinkelbach与拉格朗日乘子法相结合的优化方法,进行最优的功率分配。最后,计算机仿真结果不仅验证了所提方案的有效性和优越性,而且分析了中继天线数和用户个数等典型参数对系统能效带来的影响,从而为实际系统设计提供了参考和依据。

基于译码转发的PLC-VLC/RF混合传输系统中断性能分析

针对译码转发(Decode and Forward,DF)协议下室内电力线通信(Power Line Communication,PLC)-可见光通信(Visible Light Communication,VLC)/射频(Radio Frequency,RF)的混合传输系统,考虑接收端采用最大比合并(Maximal Ratio Combining,MRC)和选择合并(Selection Combining,SC)两种方案,并分析这两种方案下的系统中断性能。首先,在考虑路径损耗、信道衰落和用户随机分布的情况下,分别给出MRC和SC两种方案的输出信噪比表达式。接着,推导出这两种方案下系统的中断概率闭合表达式。最后,利用计算机仿真验证理论分析的正确性,分析不同参数对系统中断性能的影响,从而为PLC-VLC/RF混合传输系统的实际应用提供理论依据。

Wireless Energy Harvesting Using Rectenna Integrated with Voltage Multiplier Circuit at 2.4 GHz Operating Frequency

In this paper, we utilized villared rectifier technique to harvest wireless energy to overcome previously used RF-WEH rectenna. Our design focuses mainly on a multiple-stage Villard voltage multiplier model to rectify the output voltage of the rectenna and transferred it to a dc load. As a starting point, optimization and parameter analysis offer a novel and small antenna for the 2.45 GHz ISM band that precisely matched. Moreover, the fabricated prototype has measured and simulated results have confirmed the antenna’s accuracy in the reflection coefficient. Second, a highly efficient antenna may effectively harvest the electrical energy by combining with the two-stage voltage multiplier circuit presented at the ISM band. Furthermore, the proposed rectenna has the optimum performance compared to state of art rectennas in terms of efficiency, power range, and impedance bandwidth showing pronounced achievement and increasing the DC output power significantly. The prototype is fabricated and experimentally tested to confirm the concept. Measurement results show that the proposed rectenna can be used for RF energy harvesting applications.