基于改进差分进化算法的时间调制阵列多波束优化形成

提出了一种基于时间调制阵列的数字多波束形成方法。时间调制阵列会产生基波分量和各次谐波分量,通过调整各个单元的控制时序,实现谐波分量的幅度和相位综合,可以在正负第一次谐波处实现期望方向的波束形成。同时采用改进差分进化算法来优化控制时序,进一步降低最大旁瓣电平,实现两个指向不同的数字波束的设计。最后通过与时间调制阵列波束形成和基于基本差分进化算法的时间调制阵列波束形成对比,验证了该算法在数字多波束形成中的可行性和有效性。     

一维超宽带阵列天线时域波束扫描分析

宽带雷达作为一种新体制雷达,具有优越的反隐身能力、强的抗干扰能力、极高的距离分辨率等诸多优点.相对于传统相控阵雷达,超宽带雷达采用实时延时技术替代传统的移相器进行波束控制.该文章基于超宽带雷达相关理论进行了时域超宽带阵列天线波束扫描研究.采用对拓维瓦尔迪天线设计了四单元均匀直线超宽带阵列并进行了时域仿真及实验测试.结果表明,该阵列在X-Z平面可以实现±40°的波束扫描.阵列规模由天线单元间距决定,通过精确仿真分析天线单元间距使波束合成效果达到最优化.阵列的峰峰值方向图仿真验证了时域波束扫描理论是可行的,同时论证了实时延时技术可以被集成到时域雷达中以实现实时扫描.     

一种波束切换机载测控天线的设计方法

机载测控天线采用定向波束切换天线,不仅可以提高天线的增益,而且可以提高系统的抗干扰能力。采用全向天线单元组阵、通过简易波束控制实现的波束切换天线,具有电气性能好、控制方法简单和可实现性好等特点。介绍了7单元圆形阵列结构波束切换天线的工作原理以及采用简易相位控制实现波束切换的方法,并给出了天线的实测结果,验证了设计方法的正确性。     

频率分集阵列波束形成分析

传统相控阵天线阵列通过移相器改变相位实现波束扫描,频率分集阵列可省去复杂的移相系统,阵因子方向图与距离相关。通过改变单元间频率的增量来实现相位的改变,频率增量引入了距离维、时间维、角度维变量。探讨了频率分集阵列距离维的周期性特征,并分析了对单元馈电幅度不同加权下对阵因子的影响。最后分析了时间调制对频率分集阵列波束形成的影响,仿真给出了实验结果。     

一种新型和差旁瓣抑制阵列天线

针对传统和差阵列天线旁瓣抑制能力的不足,设计了一种应用于二次雷达的新型和差旁瓣抑制阵列天线.该天线主要由前向阵列、后向单元、波束形成网络和互连的射频电缆构成,其中前向阵列和后向单元共同形成差波束.采用遗传算法对各个天线单元的幅度和相位进行优化,使差波束在工作频带内能够覆盖和波束的旁瓣.仿真和测试结果表明:在13.2％相...     

基于阶梯波形的高效时间调制多波束天线

时间调制阵列(time-modulated array, TMA)可产生不同指向的边带多波束,但存在效率低、波束幅度一致性差等缺陷.本文基于阶梯波形提出了一种低成本高效率的时间调制边带多波束实现方法.首先根据任意多波束空间覆盖需求得到TMA的频谱和时域波形,然后基于数控衰减器和0/π移相器的硬件特性实现对理论调制波形的拟合,最终通过阶梯波形优化抑制无用边带功率和边带波动,实现稳定高效的多波束扫描.以8单元TMA为例实现基频、±1、±2次边带对应的5边带,通过调整数控衰减器的衰减步进值寻求调制波形最优解,最终仿真结果显示边带电平抑制在-31.20 dB,工作边带功率波动仅为0.68 dB.该多波束时间调制天线具有成本低、效率高、波束幅度一致性好、无用边带抑制度高等优点,提升了时间调制技术在多波束天线领域的应用价值.     

基于时域调制反射阵列的波束赋形技术

传统的反射阵利用相控器件与微带线实现波束赋形。为了降低相控成本与系统复杂度,提出基于时域调制阵列波束赋形技术。时域调制反射阵列是一种基于简单可重构反射单元的反射阵,它利用控制可重构反射单元的开与关,达到控制阵列输出,实现旁瓣抑制、波束赋形等功能。通过理论推导及仿真,结果表明,时域调制反射阵可以在不采用传统阵列中的相控器件及馈电网络的前提下,采用最小方差无失真响应波束赋形方法与时间调制法,生成理想的方向图,实现波束赋形功能。此特性将有利于推广波束赋形技术在毫米波频段反射阵的应用。     

K波段圆波导天线及阵列设计

设计了一种适用于雷达、通信等领域圆极化波导天线单元及天线阵列.采用阶梯型阻抗变换器进行了阻抗匹配,并通过矩形波导输出.在K频段内电压驻波比小于2.0:1,单元增益大于5 dBi,单元波束宽度大于95°.设计的天线阵列可实现±45°的波束扫描.采用介质加载的方式进行了小型化设计,满足阵列合成波束的扫描要求.对加工天线原理样机并进行了测试,测试结果与仿真结果吻合.     

一种天线配置软件定义雷达架构研究

针对目前雷达功能单一,品种较多,提升雷达功能需要更换大部分硬件(尤其天线系统)的问题,提出一种通过天线配置实现软件定义雷达的开放式系统架构。该架构的发射信号基于阵列单元通过软件任意产生,天线可按系统功能通过软件编码控制任意裁剪且可重构。天线单元阵列射频端直接连接二相编码调制器,通过正交二相编码调制,突破了单通道任意数字波束形成,解决了通道一致性问题,使得天线配置更加灵活。该架构不仅可应用于常规相控阵雷达, 还可应用于 MIMO、认知、雷达通信一体化等。通过软件定义开发的多路复用数字波束雷达系统平台,已经完成实际外场测试,表明基于软件定义的多路复用数字波束相控阵雷达技术系统应用可行。     

一体化侦测阵列天线技术研究

本文在一种宽带偶极子单元天线的基础上,对由单元天线组成的常规侦测阵列进行改进设计,通过组阵方式实现了一种新颖的一体化侦测阵列天线。文章运用HFSS 电磁仿真软件结合干涉仪测向原理分别对两种侦测阵列进行性能比较。结果表明,新颖的一体化阵列实现了既包括常规侦测阵列的功能,又利用其组阵后的波束形成及其控制灵活等特 点,较单元天线实现更高的天线增益,这对提高系统的灵敏度和多功能性有很大帮助,比较适合应用于宽带一体化侦测系统。     

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