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。     

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。     

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。     

发烧友谈馈源技术（四）——正馈天线Ku波段接收技术（下

笔者曾用2．1m网状天线（细网C／Ku兼容）收视Ku波段．结果高价的正馈Ku头和普通偏馈Ku头的收视效果没什么区别．始终就是0．9m偏馈天线的水平。算一下这面2．1mC／Ku兼容天线的Ku波段效率,查表可知：2．1m天线Ku波段效率50％（正常效率）。增益达45．5dB（注：这是表中天线的最低可查效率）,实际只相当于0．9m偏馈．效率70％．增益39．5dB．     

一种S波段的多频微带天线的分析与设计

提出了一种s形微带天线,分析并设计了一种工作于S波段的多频微带天线,并采用基于有限元法的电磁仿真软件HFSS10．0对所设计的天线进行了仿真分析对比研究。仿真分析结果表明,该天线-10．0dB的阻抗带宽分别为1．79～1．90GHz、2．08～2．27GHz和2．82～2．95GHz,天线的相对带宽分别达到了5．96％、8．78％和4．81％,天线可以当作宽带天线,用于无线宽带技术通信系统中。     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

Critical Stage Rule-Based Real Time Dispatch（RTD）System in Highly-Mixed-Products （HMP） FAB

An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB.     

GaAsSb/InAlAs PA DHBTs Grown by Production MBE

The epi material growth of GaAsSb based DHBTs with InAlAs emitters are investigated using a 4 × 100mm multi-wafer production Riber 49 MBE reactor fully equipped with real-time in-situ sensors including an absorption band edge spectroscope and an optical-based flux monitor. The state-of-the-art hole mobilities are obtained from 100nm thick carbon-doped GaAsSb. A Sb composition variation of less than ± 0.1 atomic percent across a 4 × 100mm platen configuration has been achieved. The large area InAlAs/GaAsSb/InP DHBT device demonstrates excellent DC characteristics,such as BVCEO＞6V and a DC current gain of 45 at 1kA/cm2 for an emitter size of 50μm × 50μm. The devices have a 40nm thick GaAsSb base with p-doping of 4. 5 × 1019cm-3 . Devices with an emitter size of 4μm × 30μm have a current gain variation less than 2% across the fully processed 100mm wafer. ft and fmax are over 50GHz,with a power efficiency of 50% ,which are comparable to standard power GaAs HBT results. These results demonstrate the potential application of GaAsSb/InP DHBT for power amplifiers and the feasibility of multi-wafer MBE for mass production of GaAsSb-based HBTs.     

Technology innovation and process integrations for sub-100nm gate patterning

This paper presents a brief overview of the Applied Centura(R)DPS(R)system,configured with silicon etch DPS Ⅱ chamber, with emphasis on discussing tuning capability for CD uniformity control. It also presents the studies of etch process chemistry and film integration impact for an overall successful gate patterning development. Discussions will focus on resolutions to key issues, such as CD uniformity, line-edge roughness, and multilayer film etching integration.     

White organic light-emitting devices based on fac tris（2- phenylpyridine） iridium sensitized 5,6,11,12-tetraphenylnap -hthacene

We have fabricated the white organic light-emitting devices （WOLEDs） based on 4,4＇ -bis（2,2 -diphenyl vinyl）-1,1＇ - biphenyl （DPVBi） and phosphorescence sensitized 5,6,11,12,-tetraphenylnaphthacene （rubrene）. The device structure is ITO/2T-NATA （20 nm）/NPBX （20 nm）/CBP： x%Ir（ppy）3：0.5% rubrene （8 nm）/NPBX （5 nm）/DPVBi （30 nm）/Alq（30 nm）/LiF（0.5 nm）/A1. In the devices, DPVBi acts as a blue light-emitting layer, the rubrene is sensitized by a phosphorescent material, fac tris （2-phenylpyridine） iridium [Ir（ppy）3], acts as a yellow light-emitting layer, and N,N＇ -bis- （1-naphthyl）- N,N＇ -diphenyl -1, 1＇ -biphenyl-4,4＇ -diamine （NPBX） acts as a hole transporting and exciton blocker layer, respectively. When the concentration of Ir （PPY）3 is 6wt%, the maximum luminance is 24960 cd/m^2 at an applied voltage of 15 V, and the maximum luminous efficiency is 5.17 cd/A at an applied voltage of 8 V.     

Complete approach to automatic identification and subpixel center location for ellipse feature

To meet the need of automatic image features extraction with high precision in visual inspection, a complete approach to automatic identification and sub-pixel center location for similar-ellipse feature is proposed. In the method, the feature area is identified automatically based on the edge attribute, and the sub-pixel center location is accomplished with the leastsquare algorithm. It shows that the method is valid, practical, and has high precision by experiment. Meanwhile this method can meet the need of instrumentation of visual inspection because of easy realization and without man-machine interaction.     

小角度扩展相关性近似算法分析

本论文提出一种在多天线MIMO信道相关性建模中小角度扩展近似理论算法,并应用于分析MIMO系统性能。分析中分别对三种不同角能量分布情况下的空间相关性研发快速近似计算法,并同时提出双模(Bi-Modal)角能量分布情况下的近似运算。通过分析这些新方法的近似效率,可以得到计算简单、复杂度低、而且符合实际的MIMO相关信道矩阵,对系统级的快速高效计算法的研究和系统级的评估以及误差分析具有重要的意义。     

Noise character analysis and the restraint of self-pulsation laser diodes

We calculate the Langevin noise sources of self-pulsation laser diodes, analyze the effects of active region noise and saturable-absorption region noise on the power fluctuation as well as period fluctuation, and propose a novel method to restrain the noise effects. A visible SIMULINK model is established to simulate the system, The results indicate that the effects of noise in absorption region can be ignored; that with the increase of DC injecting current, the noise effects enhance power jitter, and nevertheless, the period jitter is decreased; and that with external sinusoidal current modulating the self-pulsation laser diode, the noise-induced power jitter and period jitter can be suppressed greatly. This work is valuable for clock recovery in all-optical network.