缝隙阵列的时域溅射特性研究

时域溅射,是散射体结构不同部分产生的散射回波在远场叠加时,其时域波形在开始部分出现的不稳定的现象.对于低散射目标,只有在回波叠加稳定后,其散射电场的幅度才变得很低,而在开始的几个电波周期内会有比较强的散射电场.本文对缝隙阵列的时域溅射特性进行研究,采用周期边界时域有限差分（Finite-Difference Time-Domain,FDTD）算法对不同尺寸的缝隙阵列的时域溅射特性进行了仿真,提取了其等效电路参数,并采用等效电路法分析了缝隙宽度引起的并联电容对正弦波时域溅射和高斯脉冲时域散射特性的影响.分析结果发现：当并联电容降低的时候,时域反射系数的包络值下降速度增加,导致溅射现象的最大值降低.理论结果得到了实验验证.     

基于模式项散射的吸波结构

天线雷达散射截面(RCS)的缩减是隐身平台实现低散射特性的关键.吸波结构是缩减目标RCS的重要技术手段,而又难以避免对天线辐射性能产生恶化影响.针对微带天线提出了基于模式项散射的吸波结构设计方法,利用吸波结构模式项散射与微带天线的结构项散射进行对消,达到天线带外雷达散射截面缩减的效果.通过仿真验证,在工作中心频率为10...     

采用FDTD法研究微带天线雷达散射截面的减缩

采用时域有限差分法(FDTD)方法以及新的含有内阻的磁流环激励同轴馈电模型研究了微带天线的辐射及散射特性,分析了集总负载加载和贴片表面开槽对微带天线雷达散射截面(RCS)的影响,研究了微带天线RCS减缩前后的回波损耗、增益及方向性的变化.研究表明,集总负载加载能降低谐振频率点的RCS,开槽方法能在天线辐射性能改变不大的情况下对微带天线的RCS具有较好的减缩作用.     

单端口天线散射理论研究

本文给出单端口天线的频域和时域散射理论分析,通过时域和频域分析清晰地说明了天线散射的机理.分析过程中包含了探测天线和接收天线对被测天线散射的影响.天线的时域散射特性直观地区分了结构模式项散射场和天线模式项散射场.以该分析过程和结论为基础,讨论了天线散射控制的指导思想.     

馈电网络对微带天线阵列时域散射特性的影响

利用时域有限差分(FDTD)方法,研究了入射脉冲分别为水平和垂直极化时,探针馈电和微带馈电两种结构对于微带贴片阵列天线后向散射场的影响.给出了散射场的时域波形以及频谱特征.结果表明:微带天线阵列的每个贴片都通过馈电探针直接端接负载时,阵列的散射场峰值和能量都有所减小;而阵列通过馈电网络进行馈电时,馈电网络末端有无端接负...     

一种新的雷达目标散射截面宽带和宽角同时外推技术

雷达散射截面(RCS)既与频率有关又与角度有关.采用矩量法(MOM)结合降维展开格式(RDES)和渐近波形估计技术(AWE),可同时获得单站RCS的频域和角度域特性.首先,建立了关于目标表面电流的电场积分方程(EFIE),并采用MOM将EFIE离散为线性代数方程组;其次,基于RDES技术,可将目标表面电流展开为关于频率与角度及其各阶导数的叠加;再次,基于AWE技术,可快速获取目标表面电流的频域与角度域特性;最后,由目标表面电流计算远区散射场及RCS.本方法至少具有两个明显的优点,其一是能得到RCS的解析表达式,其二是明显降低计算机仿真时间.     

左手微带天线设计及其RCS计算

基于左手传输线结构,设计了左手微带天线单元及其4×4阵列,并对单元天线和阵列天线的辐射特性和散射特性进行了数值仿真计算与实际测量。数值仿真与实测结果表明,相比于矩形微带天线,左手微带天线在不影响辐射性能的情况下,大幅度地降低了天线带外的雷达散射截面(RCS)。左手微带天线克服了现有微带天线RCS缩减技术中的不足和缺陷,是在不损失天线辐射性能的前提下降低RCS的有效选择方案。     

天线远场散射特性计算模型的分析研究

研究了天线散射特性的仿真计算问题,重点对天线所特有的模式项雷达散射截面积(RCS)进行了分析与计算。首先从天线的散射机理出发,给出了天线散射分析的流程,分析比较了三类典型的天线散射分析方法,并以微带天线为例,采用三类典型的天线散射分析方法,分别得到了天线结构散射截面积和天线模式散射截面积,证明了三类散射分析方法的一致性和正确性。仿真结果为进一步分析研究天线目标的宽带散射特性及对天线的检测和识别问题奠定了基础。     

双频HIS的设计及其在微带天线RCS减缩中的应用

设计了一种新型双频高阻抗表面(HIS)结构,并将其应用在双频微带天线的带内雷达散射截面(RCS)减缩中.通过在蘑菇状EBG结构的表面贴片开槽实现两个同相反射相位带隙,将该HIS结构加载在双频微带天线周围.仿真和实测结果表明,当天线周围加载HIS结构后,天线辐射性能基本不变,同时带内RCS分别获得5.5dB和6.5dB的减缩.     

NURBS曲面建模的电大目标的宽带RCS快速计算

该文采用物理光学方法(PO),快速计算了非均匀有理B样条 (NURBS) 曲面建模的电大目标的时域瞬态散射和宽带雷达截面(RCS)。通过对频域物理光学散射场表达式进行逆傅里叶变换推导出卷积形式的瞬态散射表达式;对频域物理光学积分进行逆傅里叶变换得到时域物理光学积分的表达式。为了避免数值积分的使用,将NURBS曲面等参数离散为一组三角面片,运用Radon变换得到了时域和频域物理光学积分的精确闭式表达式。遮挡消隐时使用改进的z-buffer方法进行了加速。对时域瞬态散射场快速傅里叶变换得到目标的宽带RCS。文中计算了高斯脉冲平面波入射下模型的瞬态散射响应和宽带RCS,数值结果表明该文方法具有很高的计算精度,且计算速度快于传统时域物理光学法(TDPO)。     

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