X波段柔性编码超表面设计与RCS缩减研究

设计了一种柔性非定向低散射2 bit编码超表面。将4 种具有不同反射相位的基本单元随机排列构成整个相位梯度超表面,其对入射电磁波形成无规则散射,实现RCS 缩减特性。实验结果表明:在频点8.40 GHz处,编码超表面的垂直入射反射率为-13.5 dB,偏离法线-30°-30°范围RCS平均缩减为10.0 dB。进一步的研究结果表明,编码超表面弯曲在直径为7 cm 的圆柱面上,RCS平均缩减可达7.8 dB。该超表面可实现曲面的RCS有效缩减。该柔性编码超表面在天线、电磁隐身等领域具有潜在的应用价值。     

基于人工磁导体的低RCS微带天线设计

基于人工磁导体(AMC)的工作机理,设计了一款工作频率在X波段的低雷达散射截面(RCS)微带天线。设计了一种AMC单元,经X和Y极化波垂直入射在8.6~14.6 GHz的频带范围内,获得180°±37°的反射相位差;将其进行正交排列组成AMC棋盘结构的反射屏,反射屏中AMC阵列块由3×3的单元组成。仿真结果显示,该反射屏较相同尺寸的PEC板具有更小的后向RCS,将此AMC结构与工作频点为10 GHz的微带天线共面排布,在保持原有天线良好辐射性能和剖面高度的同时,在8.4~14.8 GHz的频率范围内对两种极化波垂直入射实现了不低于7.5 dB的RCS缩减量。     

四叶草形超宽带漫散射编码超表面

该文提出了一种结构新颖的四叶草形编码超表面,并利用该超表面实现了超宽带漫散射。所提出的编码超表面具有旋转对称性,它对x极化和y极化波产生相似的反射特性。为了实现1比特编码超表面,该文设计了在15.5～40.5 GHz的频率范围内且相位差为180°±37°的两个超表面单元。采用优化算法得到阵列中单元的最佳排列,从而实现了宽带RCS的缩减。四叶草形编码超表面可以在15.5～26.5 GHz和30.5～40.5 GHz这两个频带内实现10 dB的RCS缩减。该文加工了该编码超表面并与仿真结果进行了比较,从而有效验证了所设计的四叶草形编码超表面可以在宽频带内实现RCS的缩减。      

一种锥型双频带通雷达罩的RCS 及电性能分析

文中介绍了一种双圆环结构的频率选择表面(FSS)锥型双频带通雷达天线罩的制造工艺及电性能测 试。该天线罩底面直径500 mm,垂直高度321 mm,壁厚2 mm。采用热压罐固化成型技术制作样件。主要测试了该 雷达天线罩在水平极化及垂直极化时,Ku 频段(中心频点f0 =13.28 GHz)的功率传输系数及瞄准误差。最终实验结 果表明,该天线罩在Ku 波段设计频点f0 最小功率系数为75%;大于70%带宽达到1. 1 GHz 以上;在设计频点垂直极 化下最大瞄准误差为18.87′,水平极化下最大瞄准误差为11.37′,小于20′带宽分别为0.5 GHz 和1.3 GHz。说明天 线罩在通带内的良好传输特性和通带外的良好截止特性,具有良好的瞄准性。同时,在HH/ VV 极化、前向±60°范围 内,测量纯介质曲面样件和双频带通FSS曲面样件的雷达散射截面( RCS) ,结果表明,点频RCS均值都小于 -10 dB,RCS 缩减量均不小于10 dB。     

基于极化旋转单元的宽带雷达散射截面缩减

提出并设计了一种基于非对称开口圆环形结构的极化转换单元，并以此为基础设计实现了超宽带雷达散射截面（radar cross-section，RCS）缩减电磁超表面.利用非对称开口圆环形结构极化转换单元可灵活设计转极化反射相位的特点，设计了两种极化转换单元以实现在超宽频带范围内满足反射相位相差接近180°，将这两种单元在平面上进行编码优化排布，使得入射电磁波产生漫反射效应从而实现超宽带后向散射RCS缩减.最后设计并加工了一个192 mm×192 mm尺寸的电磁超表面，仿真和实测结果表明该表面在11.2~24.1 GHz的宽频带内实现了10 dB以上的RCS缩减，最大缩减可达35 dB.     

一种加载超材料吸波体的新型三面角反射器设计

针对传统角反射器的性能强烈依赖于入射波长,难以对抗变频雷达探测的问题,设计了一种加载超材料吸波体的新型三面角反射器。在8 GHz与12 GHz两个频点,产生近似相同的后向雷达散射截面(RCS)。对该角反射器的性能进行测试验证。结果表明:加载超材料吸波体后,在12 GHz频点,其RCS值下降约3.6 dBsm,在8 GHz频点,其RCS值与普通角反射器相比,下降约0.1 dBsm。新型角反射器的性能满足设计要求,为有效对抗变频雷达对角反射器假目标的探测与识别提供了新的途径。     

基于优化算法的2-bit编码超表面缩减RCS研究

该文设计了一种“十字-圆环”型结构超表面,并利用该结构实现了2-bit编码的相位梯度超表面(PGMS)设计。结合超表面阵列的特点,提出了一种改进的遗传粒子群算法(GAPSO)与阵列模式综合(APS)的组合优化算法GAPSO-APS,得到超表面编码矩阵的最佳排列,从而实现了宽带雷达散射截面(RCS)的大幅缩减。对设计的超表面进行仿真,并与金属表面进行了对比。结果表明,设计的编码超表面可在3.1～29.7 GHz频带内实现10 dB的RCS缩减,有效地验证了所设计的编码超表面在宽频带内实现RCS的缩减以及算法的有效性。     

基于宽带棋盘型人工磁导体的微带天线RCS缩减技术

利用棋盘型人工磁导体（AMC）结构研究微带天线RCS的缩减技术。给出AMC耶路撒冷十字结构的等效电路模型,据此设计两个不同的AMC耶路撒冷十字,使其产生180°的反射相位差,并组成棋盘型结构。当平面波垂直入射到加载棋盘型AMC结构的微带天线表面时,实现了反射波的相消干涉。在天线带内和带外12~24 GHz都明显降低了微带天线的RCS,最大可以达到36 dB的缩减,并且天线的辐射特性基本保持不变。     

一种超宽带雷达散射截面减缩的超表面设计

提出一种具有超宽带雷达散射截面(RCS)减缩特性的超表面(MS)。该MS结构由聚四氟乙烯(Polytef)介质层、空气层和金属地板组成,同时在Polytef介质层的两侧刻蚀金属图案。为了拓展RCS,减缩带宽,设计两种几何结构相似但是工作在不同频段的宽带双频单元,两种单元的有效相位差区域得到极大拓展。采用经典的棋盘方式进行布阵,实现了超宽频带的RCS减缩。仿真和实验结果表明,与等尺寸金属平板相比,该MS在3.0～20.0 GHz的频带范围,后向RCS均有减缩,其中在5.3～17.7 GHz(107.8%)的范围,后向RCS减缩基本都在10 dB以上,证实了MS的超宽带RCS减缩特性。     

基于超表面的低雷达散射截面宽频贴片阵列天线设计

该文设计了一种基于超表面(MS)的低雷达散射截面(RCS)宽频贴片阵列天线。该天线由工作在不同频段的两种开缝贴片天线组成2×4的八元阵,以此实现天线小型化并扩展其带宽,根据相位相消原理,将两种人工磁导体(AMC)以棋盘布阵的方式组成超表面加载到天线阵周围,使其具有低RCS特性。实测和仿真结果表明:加载超表面后,天线工作带宽由5.7~6.2 GHz扩展为5.6~6.6 GHz,相对带宽增大1倍,辐射特性基本保持不变;当平面波垂直入射时,天线单站RCS减缩效果明显,其中,X极化波下3 dB减缩带宽为5.3~7.0 GHz,最大减缩量达31 dB,Y极化波下3 dB减缩带宽为5.8~6.9 GHz。     

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.