介质埋藏平面对数周期天线的设计北大核心CSCD

介质埋藏天线可避免传统覆盖天线裸露在空气中受到氧化腐蚀等问题,同时增强了天线的隐蔽性、减小了天线的尺寸,扩展了天线的带宽、天线波束变窄,有助于提高天线的增益。使用电磁仿真软件Ansoft HFSS对该天线进行了优化设计和仿真实验,并制作了实物天线,进行了测试。仿真和实测结果表明:该天线S11≤-10 d B的相对带宽达到92.3%,具有超宽带特性。在工作频率处,增益可达到10.2 d B并且具有较好的定向辐射特性,可以满足工程项目的需要,具有一定的工程应用价值。     

无线移动通信的天线

天线是产生无线电通信必不可少的设备。你的天线可能是中间带线圈的普通移动电话天线,也可能是印制在寻呼机电路板周围的环路,或是“个人通信业务”(ＰＨＳ)基站用的多元方向性天线阵。每种天线各司其职,并有一套严格限制的设计参数。本文就影响设计的环境、费用、尺寸等方面,讲述几种常用无线移动通信天线。1　四种天线的主要特征无线通信主要有四种天线:偶极天线、单极天线、环形天线和嵌片天线。我们先看一下每种天线主要特性的简述。(1)偶极天线　　这是最小的自谐振天线结构,即一种工作频率为半波长的导线。由于导线尺寸、周围媒质的介…     

一种应用于n77/n78/n79频段的双频滤波天线

提出了一种基于双层结构的双频滤波天线,工作在n77/n78/n79频段。该天线由上层基板的2个矩形辐射贴片和下层基板的阶跃阻抗谐振器、2个“L”型枝节组成。2块介质基板材料均为FR4,且通过探针相连。上层介质基板上的2个矩形辐射贴片激发2个谐振模式,其中高频谐振用于形成n79频段,低频谐振用于形成n77/n78频段。为了获得双通带滤波效果,在下层介质基板中引入阶跃阻抗谐振器,在2个频段间形成带外辐射零点。此外,下层基板上的“L”型枝节可以引入额外的谐振点来扩大天线的带宽。该结构经过高频仿真软件(HFSS)优化,其仿真结果和测试结果均在3.37~3.53 GHz(n77/n78),4.55~4.64 GHz(n79)2个频段范围内,可用于6 GHz以下5G的无线通信应用。     

高辐射强度的带THz扼流圈的偶极天线阵列模拟分析

为了提高太赫兹辐射强度, 设计了带THz扼流圈的偶极天线阵列.模拟结果表明, 增加直线阵的阵元数对平均匹配效率影响很小, 却能线性增加相干辐射强度.加入THz扼流圈可减小进入到传输线的交流分量, 进而减小共振频率的偏移, 使平均匹配效率提升了两倍.相比于网格排列的平面阵, 交错排列的阵元在垂直方向上具有更小的耦合, THz发射谱更窄.通过使用聚酰亚胺透镜代替硅透镜, 可有效提高输入电阻, 并将总效率由25%提高到35%.     

宽带平面直角双频单极天线

对于超宽带系统,需要具备可工作频率为3.1~10.6GHz的宽带天线。本文介绍了四种宽带平面单极天线,分别为圆形平面单极天线、平面直角单极天线、平面双频单极天线和平面直角双频单极天线。其中平面直角单极天线兼具宽频和全向特性,平面双频单极天线和平面直角双频单极天线在两个谐振点都具有宽带特性,平面直角双频单极天线在整个频带内水平面的辐射方向图几乎都可以达到全向。     

用飞秒激光触发GaAs光电导体产生THz电磁波的研究

报道了用半绝缘GaAs材料研制的光电导偶极天线在飞秒激光脉冲触发下辐射THz电磁波的实验结果.GaAs光电导偶极芯片的两个欧姆接触电极间隙为3mm,采用Si3N4薄膜绝缘保护,在540V直流偏置下被波长800nm,脉宽14fs,重复频率75MHz,平均功率130mW的飞秒激光脉冲触发时产生THz电磁波.用电光取样测量得到了THz电磁脉冲的时域波形和频谱分布.THz电磁波的辐射峰值位于0.5THz左右,频谱宽度大于2THz,脉冲宽度约为1ps.     

用飞秒激光触发GaAs光电导体产生THz电磁波的研究

报道了用半绝缘GaAs材料研制的光电导偶极天线在飞秒激光脉冲触发下辐射THz电磁波的实验结果.GaAs光电导偶极芯片的两个欧姆接触电极间隙为3mm,采用Si3N4薄膜绝缘保护,在540V直流偏置下被波长800nm,脉宽14fs,重复频率75MHz,平均功率130mW的飞秒激光脉冲触发时产生THz电磁波.用电光取样测量得到了THz电磁脉冲的时域波形和频谱分布.THz电磁波的辐射峰值位于0.5THz左右,频谱宽度大于2THz,脉冲宽度约为1ps.     

双层手征介质板中电偶极天线的辐射特性

本文首先给出了电流源激励下双层手征介质中的并矢格林函数表达式。应用鞍点积分法,导出了有金属板衬底的双层手征介质中电偶极天线的辐射场表达式。分析了有、无空气隙时手征导纳对电偶极天线的方向图,＝0方向的最大场强和谐振频率的影响程度。结果表明,通过改变手征导纳参数,可以有效地调节电偶极天线的辐射特性。     

超薄高增益UHF 抗金属标签天线设计

设计了一款超薄的高增益UHF抗金属标签天线。标签天线以高介电常数的陶瓷为介质基板,由上层带有双T 型槽缝的金属贴片、介质基板和下层金属贴片组成,天线平面尺寸为80 mm×40 mm,厚度仅为0.8 mm。天线结构简单,不需要短路通孔、短路销钉或短路贴片将天线上层贴片与地板相连,通过改变天线上层贴片T 型槽缝的尺寸,可以对标签天线阻抗进行有效调节,并实现天线的低剖面。天线未加金属地板最大增益为3.4 dBi,加载金属地板最大增益为6.9 dBi,且加载金属地板前后天线的中心频率和阻抗带宽无明显变化。实际测试结果与仿真结果比较吻合,实测未加载金属地板状态下最大识别距离为4.5m,加载金属地板状态下实测最大识别距离为6.8 m。     

宽频带圆极化缝隙螺旋天线的设计

研究了一种宽阻抗带宽和宽圆极化轴比带宽的缝隙螺旋天线。天线印制在由FR4 介质基板构建的 方形柱状结构的内外表面,两组长短不同的缝隙螺旋臂印制在介质基板外表面并延伸至天线顶部;一条弯折的微带 线作为馈电网络印制在介质基板内表面,通过对各缝隙耦合馈电,实现天线宽阻抗带宽和轴比带宽。实测结果表 明:天线尺寸为0. 111λ0 ×0. 111λ0 ×0. 221λ0(λ0 为北斗B2 中心频率1. 207 GHz 对应的自由空间波长),S11 ≤ -10 dB 的阻抗带宽为1. 158~1. 778 GHz,轴比≤3 dB 的圆极化带宽为1. 133~1. 918 GHz。该天线采用缝隙螺旋结构,通过 简易的馈电网络实现天线小型化和宽频带特性,在卫星导航系统中具有较好的应用前景。     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Teleportation of an arbitrary unknown N-qubit entangled state under the controlling of M controllers

A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it.     

Diode-end-pumped Nd:YVO4/LBO lasers with 4.2W continuous-wave output at 457 nm

A continuous-wave (CW) 457 nm blue laser operating at the power of 4.2 W is demonstrated by using a fiber coupled laser diode module pumped Nd: YVO4 and using LBO as the intra-cavity SHG crystal With the optimization of laser cavity and crystal parameters, the laser operates at a very high efficiency. When the pumping power is about 31 W, the output at 457nm reaches 4.2 W, and the optical to optical conversion efficiency is about 13.5% accordingly. The stability of the out putpower is better than 1.2% for 8 h continuously working.     

Call for Papers

正Wireless Body-area Networks The last decade has witnessed the convergence of three giant worlds:electronics,computer science and telecommunications.The next decade should follow this convergence in most of our activities with the generalization of sensor networks.In particular with the progress in medicine,people live longer and the aging of population will push the development of wireless personal networks     

Call for Papers—Feature Topic,Vol.12,No.7,2015

正Information Centric Networking Information-Centric Networking(ICN) is an emerging direction in Future Internet architecture research,gaining significant tractions among academia and industry.Aiming to replace the conventional host-to-host communication model by a data-centric model,ICN treats data content as the first     

JOURNAL OF ELECTRONICS(CHINA)

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NEXT GENERATION WIRELESS NETWORKS–ESPECIALLY THE USE OF MILLI-MICROWAVE BANDS

The global bandwidth shortage of wireless communications has motivated the exploration of the naillimeter wave （ram-wave） frequency spectrum for the next generation wireless communications. Recent advances in RF CMOS technology and high speed baseband signal processing technologies have enabled tile extensive research and development of turn-wave wireless communications. The multi gigabit per second data rate of ram-wave system will lead to applications in many important scenarios, such as WPAN, WLAN,back-haul for cellular system. And the frequency bands include 28 GHz, 38 GHz, 45GHz, 60GHz, E-BAND and even beyond 100 GHz. The propagation and the imitation of the RF circuits design in these frequency bands make the directional antennas be inevitable for mm-wave communications.