基于相控阵的全空域多目标测控天线分析

基于抛物面天线的测控系统,已经不能满足全空域内同时多目标测控的需求。针对单站全空域多目标测控中存在的问题,提出了基于球面相控阵的全空域多目标测控天线体制。比较了全空域多目标相控阵测控天线形式,在研究球面相控阵天线原理的基础上,对辐射单元及子阵布局进行了分析与设计,对波束合成后的天线方向图进行了仿真。结果表明:基于球面相控阵的全空域多目标测控天线能够有效解决未来全空域多目标同时测控的需求。     

全空域球面数字多波束天线波束控制方法研究

为适应全空域导航星座的管理需求,提出了一种全空域球面数字多波束天线系统的方案,在全空域内同时形成多个波束,实现同时多目标测控。针对球面阵列天线波束控制问题,提出了"波束滑动扫描"算法,研究了球面阵波束交叉过渡、功率增强的方法。通过对波束方向图的仿真分析,验证了波束控制方法的可行性和正确性。     

全空域多目标测控天线零点约束方向图综合方法

针对全空域多目标测控天线相互干扰的问题,提出了一种基于零点约束的全空域多目标测控天线方向图综合方法.该方法对多个干扰目标方向进行零点约束,求取逼近给定方向图的最优权矢量的闭合解,生成具有干扰抑制能力的优化波束方向图.仿真结果表明,所提方向图综合方法在维持原有给定方向图特性的前提下,可在多个方向形成有效零点.在等效2m口径全空域多目标测控实物天线对该方法开展试验验证,结果表明在干扰方向抑制能力大于60 dB,证明了方法的正确性.     

全空域多目标测控天线技术研究

航天技术的快速发展使得在轨飞行器的数量迅速增长,传统上基于抛物面天线的测控技术已经不能满足未来全空域内同时多目标测控的需求,为此,提出了一种解决方案,采用共形阵列天线和数字多波束形成技术,在全空域内同时形成多个波束,每个波束指向一个测控目标,实现同时对多目标的测控。根据提出的方案,研制了原理样机,进行了外场试验,结果表明样机的功能和主要技术指标与设计相符合,证明了技术方案的正确性。     

全空域多面阵天线性能分析与遮挡判决

为适应全空域多目标测控对天线的需求,提出一种基于多面阵拼接的全空域覆盖天线。与球面阵天 线相比,多面阵天线在工程实现和波束控制方面具有明显优势。分析了不同阵面数对天线波束性能的影响。考虑 到实际应用中遮挡效应对天线方向图的影响,介绍了一种有效的遮挡判决算法。该算法首先将处于亮区的阵面投 影到来波投影面中,而后采用线段相交原理确定投影面是否相交,最后根据相交投影面景深大小判断它们的遮挡关 系。理论分析与仿真结果表明,多面阵天线全空域增益相对稳定,遮挡判决算法可行有效。     

球面全空域多波束天线的分析与验证

针对多星测控和高精度测量的需求,介绍了“半球面+柱面+全数字波束形成、收发一体的球形全空域多波束天线实现方案”的比较分析过程和实验验证结果。实验结果表明,采用该天线的测控系统能在实现多目标同时遥测遥控的同时大幅提高跟踪性能,测量精度与传统测控站相当,满足未来多星环境下全空域高可靠跟踪、高精度测量的要求。     

全空域测控系统数字波束形成技术研究

随着我国航空航天事业的飞速发展,无人机集群和卫星星座的出现给地面测控站提出了更高的要求。全空域多目标测控系统的建设提上日程。和其他波束形成方式相比,基于软件无线电的数字多波束形成技术在全空域测控系统中具有独特的优势,值得深入研究。介绍了全空域测控系统对波束形成设备的需求,进而提出了基于射频采样的波束形成模块的实现,并对共形球面阵数字波束形成技术进行了分析。实测结果验证了基于射频采样的数字波束形成方案的可行性。     

高速率移动通信的正交波束空间分集—OFDM方法

为进一步提高OFDM的传输速率，提出了正交波束空间分集—0FDM方法。利用智能天线的数字波束形成（DBF）技术，首先在时域构造出多个正交空分信道，然后对每个空分信道进行OFDM解调，最后根据选择性分集算法获得频域序列。理论分析和仿真结果都表明，至少有一个空分信道的频响特性优于全向信道的频响特性，并且各正交空分信道频响特性间的相关性很低，因而分集合成信道的频响特性明显优于全向信道、每个窄分信道的频响特性。与单天线OFDM系统相比，正交波束空间分集—0FDM方法能够实现更高的传输速率。     

全空域相控阵测控系统波束形成分析

全空域相控阵测控系统作为下一代地基航天测控系统发展趋势,其系统架构和波束形成等关键技术值得深入研究。介绍了全空域相控阵测控系统实现方案,分析比较了3种备选波束形成方法。在此基础上,对共形球面阵波束形成技术进行了分析与仿真,仿真结果验证了系统波束形成设计思路。     

一种DBF体制卫星接收共形相控阵天线

提出了一种全数字波束合成(digital beam forming, DBF)体制卫星接收共形相控阵天线设计思路.该天线采用半球形共形阵排布方式, 阵元采用双层微带贴片天线实现宽带圆极化.在半球形的布局下, 通过判断卫星信号来波方向在球面上的投影来选择工作的阵元, 形成与来波方向一致的波束, 在全空域(—75°~75°)的仰角内可实现增益起伏小于1.5 dB的波束覆盖; 后端采用射频数字一体化设计技术, 可同时形成多个波束, 实现了一个天线跟踪多颗卫星的能力.最后加工和测试了天线样机, 验证了共形半球阵的波束形成能力.提出的天线设计思路有助于拓展数字波束体制在卫星通信中的应用, 对全空域多波束相控阵天线的研制具有指导意义.     

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.