对数周期偶极子天线相位中心的分析和计算

本文通过对对数周期偶极子天线(LPDA)相位中心的分析和计算,得出了该天线不存在完整的相位中心,但却存在视在相位中心,该相位中心均位于有效区内,并随着频率的变化而沿集合线移动.文中计算了LPDA不同频率处的E面和H面视在相位中心的位置.     

计算对数周期偶极子天线相位中心的变步长法

为了提高计算对数周期偶极子天线(LPDA)视在相位中心的速度和精度,提出一种计算LPDA视在相位中心的变步长法,井计算LPDA的E面、H面视在相位中心,给出了E面、H面方向图半功率波瓣宽度内的最大相位差.最后,根据计算出的相位中心重新计算LPDA在E面、H面的相位方向图,在天线功率波瓣宽度内相位值平坦,表明该方法是有效的.     

基于模拟退火算法的对数周期偶极天线相位中心计算

采用模拟退火算法(SA)结合矩量法精确计算对数周期偶极天线(LPDA)的视在相位中心,并对某LPDA的视在相位中心随不同频率的变化特性进行了分析,给出了天线E面和H面半功率波瓣宽度内的相位方向图.良好的计算结果表明,该方法是有效的.     

对数周期偶极子天线的可变相位中心

导出了直线阵列存在相位中心的条件,为了能把不存在相位中心的定向天线单元应用到干涉仪测向系统,提出了可变相位中心概念,并给出了对数周期偶极子天线可变相位中心计算实例。文中还讨论了把可变相位中心应用到干涉仪测向的方法。     

超宽频带小尺寸对数周期偶极子天线设计分析

文章研究了超宽频带对数周期偶极子天线(LPDA)的结构,对15～110MHz超宽频带对数周期偶极子天线的尺寸参数进行了设计,根据设计分析,对于超短波波段超宽频带对数周期偶极子存在的天线纵向尺寸较大的问题对该天线纵向尺寸进行了设计创新,从而使天线在包括工作带宽、增益、方向图等电特性参数不变差的前提下使纵向尺寸设计值从29...     

一种车载对数周期阵列天线的结构设计

对车载对数周期阵列天线(LPDA)结构设计方案进行了详细论述。阵列天线整体外形成四棱锥状,由4个对数周期天线单元按同一角度阵列而成,每个对数周期天线单元的集合线作为四棱锥的四条棱。使用Pro/E对其进行了实体造型,对空间阵列天线关键部件进行了静力分析。为了验证其安全性,对其强度和刚度进行校核,在此基础上完成了空间阵列天线的结构设计。阵列天线工作可靠,结构紧凑,便于车载拆装,很好地满足了预期的使用性能要求。     

对数周期偶极子天线在航向覆盖中的作用

对浦东机场使用的NORMAC公司生产的24单元航向天线阵的信号合成和信号覆盖进行分析与计算。通过不同的合成方法进行优化,获得了与对数周期偶极子天线(LPDA)场型分布高度吻合的分布函数。使用对数周期偶极子天线的水平方向的分布特征,来对比全向天线阵的信号合成与对数周期偶极子天线阵的信号合成的差别。分析结果表明:对数周期偶极子天线能够明显抑制大角度旁瓣信号的辐射,从而降低机场附近因信号折射造成的干扰,并能够有效提高航向覆盖区内的射频。     

大张角宽带对数周期天线的优化设计

文章运用矩量法对大张角对数周期天线的电性能进行了分析。经过优化设计制作的大张角宽带对数周期偶极子天线(LPDA,Log Periodic Dipole Antennas),经测试测量值与计算值吻合得较好,已用于混波室测试。     

采用改进的标准场地法测量LPDA

采用改进的标准场地法针对LPDA和复合天线分别进行了测试和比较分析.分析了采用ANSI C63.5:2006测量对数周期天线LPDA和复合天线的自由空间天线系数Fa时,由相位中心引起的误差;对CISPR 16-1-6 (CDV)中的计算公式进行了改进,使得即使配对中的天线结构不相同也可以进行比较准确的测量;然后分别针对LPDA和复合天线进行了试验,并与使用CISPR 16-1-6(CDV)中垂直方法的测量结果进行了比较.结果表明:在200 MHz ～2 GHz范围内大部分频段小于0.6 dB,首末频点差别小于0.9 dB.为了便于工程应用,还提供了背景噪声的抑制措施、电缆的选用原则等.     

半模基片集成波导馈电的对数周期偶极子天线

设计并研制了一种基于半模基片集成波导(Half-mode Substrate Integrated Waveguide:HMSIW)馈电的单层宽带印刷对数周期偶极子阵列(Printed Log-Periodic Dipole Array:PLPDA)天线.对数周期偶极子阵列(PLPDA)天线具有频带宽、剖面低、重量轻等优点,但是其馈电需要平衡线结构.半模基片集成波导具有平面集成、主模带宽宽、损耗低、尺寸小等优点,同时自身天然具有平衡结构.文中设计并制作了工作频率为15GHz～40GHz的HMSIWPLPDA天线,测试结果和仿真结果吻合.     

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.     

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.     

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.     

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.     

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.