甚低频发射系统同步调谐研究

甚低频通信受发射天线固有带宽限制,信息速率低,为了提高甚低频通信速率,采用了不同于载频调谐的同步调谐方法,理论上分析并计算了在不同信息速率下甚低频发射机载频调谐系统和同步调谐系统的输出信号谱及信号传输效率。结果表明采用同步调谐可使天线系统在固有带宽不变的条件下提高了甚低频发射天线系统的有效带宽,从而提高了甚低频通信系统的信息传输速率和传输效率。     

基于阻尼振荡法的甚低频天线阻抗测量

为了准确测量甚低频发射天线在实际工作环境和工作频点上的输入阻抗,本文提出了一种基于RLC阻尼振荡法的阻抗测量方法,并推导了天线阻抗、电容、电感和电阻的测量公式;该测量方法可通过提高测量电压来提高测量信噪比和测量精度;测量系统谐振于被测天线的工作频点或其附近,使甚低频发射天线输入阻抗的测量值更接近天线在实际工况下的真实值.试验表明,本文提出的测量方法简单可行,具有较高的精度和稳定性,可实现甚低频发射天线输入阻抗的现场测量.     

T型甚低频多调谐发射天线电容与电感研究

甚低频天线理论认为,采用多调谐方式,T型甚低频多调谐天线可以基本按比例增加天线电容,在实际工程中常用五组或六组天线.本文利用甚低频天线输入电抗的实测值,计算了在不同频率下天线所呈现的等效电容和等效电感,研究了T型甚低频发射天线的等效电容、电感、功率容量与天线组数及频率之间的关系.研究结果表明T型甚低频多调谐天线的组数过...     

强噪声环境下测量甚低频天线阻抗方法的研究

比较了在强噪声环境下测量甚低频发射天线输入阻抗二种方法, 提出一种新的矢量谐振测量方法, 这种新方法比传统的阻抗电桥法具有更高的精度.在此基础上研制出基于计算机数据采集与处理的天线输入阻抗实际测量系统, 该系统通过对测量网络各节点电压采样与处理, 自动计算天线输入阻抗并显示在计算机上.实测结果表明, 该系统具有优良的精度和稳定性.     

机动甚低频天线性能的矩量法结合复像法的研究

提出一种加载机动甚低频天线的方式,对加载参数进行了优化.采用矩量法结合修正的镜像法,分析了加载后的天线在有耗地面上的辐射性能,提高了计算速度.仿真计算及模型实验结果表明,理论上通过合适的加载可改变电流分布,增加天线辐射电阻,提高天线效率.     

甚低频发信系统工作性能仿真研究

针对甚低频发信系统工作性能的研究,建立了甚低频发信系统仿真模型,利用模型对甚低频电子管发信系统工作在假负载模式、天线模式、固定调谐方式及动态调谐方式分别进行了仿真计算,分析了不同方式、不同载频及不同码元速率下的系统传输性能。计算结果表明甚低频发射天线动态调谐系统具有比固定调谐方式传输效率高,系统允许的信息传输速率可得到大幅提高。     

一种高效率宽负载双极化整流天线的设计

文中提出了一种宽负载的双极化整流天线,能够有效地应用于微波电磁能量传输。该整流天线主要 由阻抗压缩电路、匹配电路、肖特基二极管和谐波抑制电路构成。其中,阻抗压缩电路由两段短路枝节线组成,该电 路能够在负载500~3500 Ω 范围内减小输入阻抗的变化、减小负载对匹配的影响,从而提高整流效率。ADS2020 软 件仿真结果显示:在频率2. 45 GHz 且两端的输入功率均为10 dBm 时,该双极化整流电路RF-DC 的转换效率最高达 到81%;负载在1000~3000 Ω 变化时,整流效率均高于60%;只有一端输入功率时,负载整流效率依然大于50%。实 测与仿真结果基本吻合,进一步验证了该设计方案的可行性。实测发现,天线姿态或端接负载在较大范围内变化 时,该整流天线依然能够输出稳定的直流电压。本设计具有结构简单、易于制造、双极化、宽负载等特性,可实际应 用于无线传感节点、物联网等领域的无线供电技术中。     

甚低频T形面型天线电气性能分析

运用三维全波电磁仿真软件对甚低频T形面型天线进行电磁建模和仿真分析计算,分析了天线的输入阻抗、有效高度、电容等电气参数。在建模时考虑了铁塔及不同顶容线模型的影响,并对有无铁塔及不同铁塔类型、以及天线不同形式时天线的输入阻抗进行对比分析。     

一种发射天线的更换方法

调频广播天线常采用双偶极子反射板阵列天线,维修和更换天馈线造成停播常常是难以避免的事情,为有效避免以上情况出现,我们尝试分组更换发射天馈线的方法.采用相位差旋转馈电技术和电气下倾技术,使系统具有频带宽、功率大、增益高、场型好等优点.系统改造后天馈系统的工作稳定性和可靠性大大提高,有效的提升了本台的社会效益和经济效益.     

高效平面印刷毫米波段整流电路设计与实验

利用微带线设计了一种Ka波段毫米波整流电路.整流电路由输入阻抗匹配网络、整流二极管及输出直通滤波器构成,输入端口为50 Ω微带线,便于实验及与天线集成.利用等效电路模型理论分析了肖特基二极管在Ka波段的整流特性,设计并加工电路.实验测得,在32.5 GHz工作频率和20 dBm输入功率下,整流电路在350 Ω负载上获得57％的毫米波直流(MMW-DC)转换效率;在输入功率大于8 dBm时,整流效率均大于30％.该整流电路采用传统的印制电路板(Printed Cireuit Board,PCB)制作工艺,具有造价低和易集成等优点,且整流效率高,可应用到毫米波无线输能系统中.     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

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.     

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.     

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.     

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.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

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.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.     

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