基于FEM的机载VLF单／双拖曳天线电磁辐射特性仿真

拖曳天线分为单拖曳天线和双拖曳天线．单拖曳天线由一条长天线组成,总长度为波长的一半;双拖曳天线（DTWA）由一条短天线（sTWA）和一条长天线（LTWA）共同组成．长短天线总长度为波长的一半。本文基于有限元算法（FEM）．建立机载VLF单／双拖曳天线系统模型．仿真比较单／双拖曳天线的电磁辐射特性．从而得出双拖曳天线的性能优于单拖曳天线的性能．为今后的研究有一定的参考意义。     

天线的测量校准方法

天线是测量电波辐射强度的必备工具．天线系数是用于场强测量和DEMI测量天线的重要参数。人们利用测量接收机读数、天线系数来计算电波辐射场强。在难以用理论计算的方法精确获得天线系数时．需要对天线的天线系数进行测量校准。本文介绍了常用的天线系数的校准方法．讨论了在天线校准中引起测量误差的各种因素．并总结了各种校准方法的适用范围及特点。     

不用天调的多波段温顿天线

什么是温顿天线温顿天线是由温顿在20世纪60年代发明的一种偏中心馈电的偶极天线，常见的温顿天线总长度一般设计为最低工作频率的1／2波长（142．6／f）。与普通中心馈电的1／2波长偶极天线相比，其馈电端点距离天线一端约1／3处．如80m波段温顿天线的基本尺寸由13．8m和27．7m两部分组成。天线通过50G同轴电缆，经4：1（或6：1）巴伦转换、阻抗匹配，然后接入天线主体。     

设计有源天线的一种新方法

本文对用一种负阻抗变换电路同电小天线导线相结合构成的有源天线进行了理论分析．并给出了该有源天线稳定的工作条件．分析结果表明：用该方法设计的有源天线具有较高的灵敏度和较小的最佳天线尺寸．实验结果证实该方法有效．     

相控阵天线指向精度试验研究

本文用统计的方法对多套相控阵天线的试验结果进行分析．根据测试数据．对本相控阵天线指向精度误差产生的原因做出分析．指出了相控阵天线指向精度随机误差产生的主要原因是生产和装配带来的．系统误差主要来自天线单元方向图影响的结论。     

一种双频多层微带天线的设计与分析

分析并设计了一种双频多层微带天线。该天线采用上下双层贴片、三层介质基板结构和背部探针馈电,并使用电磁仿真软件HFSS 10．0对所设计的天线进行了仿真。分析仿真结果表明,该天线的工作频段为1．31～1．39GHz和1．86—1．94GHz,具有较宽的相对带宽,该天线可作为双频天线工作,并能工作在射频频段。     

复杂平台上天线设计与分析的系统方法

地球和空间通讯的最新发展．通常要求天线安装在高塔或航天飞行器上有限的空间内．由于天线安装位置和结构变化决定整个通讯系统的性能，因此这种天线安装位置和结构变化的分析非常重要。人们关心的天线安装位置和结构变化通常位于天线的近场区，但多数天线的设计和分析工具是用远场分析方法。通用卫星通讯方案包括降低天线性能的散射器．如太阳能电池板或支撑结构．尤其是包括散射器和天线彼此之间能否相互移动。本文提出了在相互关联的天线环境设计中．用人们熟知的技术完成的系统设计和分析方法．以及图解说明。     

共面波导馈电矩形开口振子缝隙天线

为了展宽平面缝隙天线的带宽,设计一种X波段共面波导馈电的矩形宽缝隙振子天线,该天线是在缝隙振子天线的两端开矩形开口,与振子天线形成组合结构。使用高频仿真软件对设计的天线进行仿真分析,结果表明组合结构的天线性能比单一的振子缝隙天线或宽缝天线有大幅度的改善和提高。分析了天线主要参数对天线回波损耗的影响,并在带宽最优的条件下给出一组参数值,此时天线的-10dB带宽为41．14％（7．24～10．99GHz）,增益为7．5dB,在所计算的带宽频率内有较稳定的方向图和良好的交叉极化特性。     

1.8米极轴天线的安装与使用

由于工作的需要，最近装调了一付1．8米的C波段极轴天线．有了它确实带来了很多的方便。以前也曾装过几个极轴天线，有原来卧式的37米网状极轴天线，也有0．9米的Ku波段极轴天线，深知装配极轴天线重在调试，但这次安装这个1．8米的极轴天线还是费了一点周折。     

卫星电视接收设备及其参数(二)

（２）天线系统主要参数 天线参数有：天线增益、天线效率、天线Ｑ值、噪声温度、驻波比、方向图、主瓣宽度、副瓣电平、频带宽度及品质因素等。现在介绍几个主要参数。 天线增益Ｇ：它表示天线集中接收（辐射）的程度,是天线定向性和效率的重要参数。式中Ａ为天线口径面积［πＲ２ｃｍ］;λ（ｍ）为下行载波波长;η为天线效率,一般前馈抛物面网状天线η＝０．４５～０．５５,板状为０．５～０．６。从公式知增加天线口径,可加大Ｇ,但天线尺寸增加,使得成本高,风荷大,架设难,这一点需要考虑。 天线品质因素Ｑ：它表示天线等级标…     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Nanoimprint Lithography -A Next Generation High Volume Lithography Technique

IntroductionNanoimprint Lithography is a well-acknowl-edged low cost, high resolution, large area pattern-ing process. It includes the most promising methods,high-pressure hot embossing lithography (HEL) [2],UV-cured imprinting (UV-NIL) [3] and micro contactprinting (m-CP, MCP) [4]. Curing of the imprintedstructures is either done by subsequent UV-lightexposure in the case of UV-NIL or by cooling downbelow the glass transition temperature of the ther-moplastic material in case of HEL…     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

Influence of PVK ： NPB hole transporting layer on the characteristics of organic light-emitting devices

A doping system consisting of NPB and PVK is employed as a composite hole transporting layer （CHTL）. By adjusting the component ratio of the doping system, a series of devices with different concentration proportion of PVK ： NPB are constracted. The result shows that doping concentration of NPB enhances the competence of hole transporting ability, and modifies the recombination region of charge as well as affects the surface morphology of doped film. Optimum device with a maximum brightness of 7852 cd/m^2 and a power efficiency of 1.75 lm/W has been obtained by choosing a concentration proportion of PVK ： NPB at 1：3.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.     

Analysis of error performance on Turbo coded FDPIM

Due to variable symbol length of digital pulse interval modulation（DPIM）, it is difficult to analyze the error performances of Turbo coded DPIM. To solve this problem, a fixed-length digital pulse interval modulation（FDPIM） method is provided. The FDPIM modulation structure is introduced. The packet error rates of uncoded FDPIM are analyzed and compared with that of DPIM. Bit error rates of Turbo coded FDPIM are simulated based on three kinds of analytical models under weak turbulence channel. The results show that packet error rate of uncoded FDPIM is inferior to that of uncoded DPIM. However, FDPIM is easy to be implemented and easy to be combined, with Turbo code for soft-decision because of its fixed length. Besides, the introduction of Turbo code in this modulation can decrease the average power about 10 dBm, which means that it can improve the error performance of the system effectively.     

A method for calculating the center position of collimated light

It is a key problem to accurately calculate beam spots＇ center of measuring the warp by using a collimated laser. A new method, named double geometrical center method （DGCM）, is put forward for the first time. In this method, a plane wave perpendicularly irradiates an aperture stop, and a charge couple device （CCD） is employed to receive the diffraction-beam spots, then the geometrical centers of the fast and the second diffraction-beam spots are calculated respectively, and their mean value is regarded as the center of datum beam. In face of such adverse instances as laser intension distributing defectively, part of the image being saturated, this method can still work well. What＇s more, this method can detect whether an unacceptable error exits in the courses of image receiving, processing and calculating. The experimental results indicate the precision of this method is high.     

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.