改进型超宽带Vivaldi天线设计与仿真

在传统Vivaldi天线结构的基础上,设计了两种适用于宽带信号收发系统的改进型渐变槽Vivaldi天线以及同轴馈电型对踵Vivaldi天线,并利用电磁仿真软件HFSS对这两种Vivaldi天线的性能进行优化分析.通过对不同结构Vivaldi天线的对比分析结果可以看出改进型渐变槽Vivaldi天线和同轴馈电型对踵Vivaldi天线在频段、带宽、驻波比等方面均达到宽带传输系统的设计要求.     

超宽带全金属Vivaldi 天线的设计

设计了一种全金属的Vivaldi 天线,当频率为3 ~17 GHz 时,其VSWR<2,在宽边扫描情况下,VSWR 小于2. 0 的带宽能达到11 GHz。它不仅具有频带宽、方向性好等特点;同时,它还能解决传统Vivaldi 天线制作工艺复杂、制作成本高、物理强度低等问题,能更好地应用于高功率雷达等领域。文中利用高频结构仿真软件HFSS 对设计天线的几何尺寸进行了优化,并进行了仿真与分析,通过计算天线的驻波比、方向图、增益等性能验证了天线的超宽带、宽边扫描的特性。     

用于超宽带介电常数测量的Vivaldi天线设计与仿真

在传统Vivaldi天线结构的基础上,设计了两种适用于混合材料介电常数测量的改进型渐变槽Vivaldi天线以及同轴馈电型对踵Vivaldi天线,并利用三维电磁仿真软件HFSS对这几种Vivaldi天线的性能进行优化分析。通过对不同结构Vivaldi天线的对比,分析结果可以看出这两种改进型渐变槽Vivaldi天线和同轴馈电型对踵Vivaldi天线在频段、带宽、驻波比等方面均达到超宽带介电常数测量系统的设计要求,可应用于测量混合材料的介电常数。     

关于Vivaldi超宽带天线设计方案的研究

文章对微带线馈电结构的Vivaldi超宽带天线进行了设计,并对设计的Vivaldi天线进行了计算辅助优化设计,同时制作了试验样机。仿真测试结果表明,该天线在规定的3.1GHz～10.6GHz频段内可以得到良好的传输性能和辐射性能,与理论设计吻合,达到宽频带特性的设计要求,为Vivaldi超宽带天线的设计提供了新的思路。     

基于频率选择表面的宽角扫描阵列

设计并加工了一种基于双层频率选择表面(frequency selective surface, FSS)的一维Vivaldi阵列天线.首先采用周期边界条件分析无限大阵列中的单元特性, 利用等效传输线原理和广义散射参数矩阵来设计优化加载在Vivaldi阵列上方的介质宽角匹配层.然后, 在所加载的双层介质匹配层表面直接印制FSS结构使阵列扫描特性得到极大改善.仿真和实测结果表明, 一维Vivaldi阵列中心单元在7~12 GHz的有源驻波比均小于2.5, 在8~10 GHz波束扫描范围能够达到±60°.仿真结果还表明:采用双层FSS结构的Vivaldi阵列与未加载匹配层的Vivaldi阵列相比, 在7~11.5 GHz增益有2~4 dB的提高; 同时在扫描至±60°时, FSS结构的加载使得阵列在对应扫描角下的交叉极化下降了5~10 dB.     

一种工作于1.6 GHz ~20 GHz 的高增益对跖Vivaldi 天线

设计了一款工作于1.6 GHz ~20 GHz 的高增益对跖Vivaldi 天线,该天线在常规对跖Vivaldi 天线的左右两端加载半椭圆贴片结构,改善低频驻波比特性,进而提高了天线的阻抗带宽;在天线主轴方向加载梯形基板,将天线表面电场约束在天线的主轴方向上,不但消除了天线增益峰值的偏移问题,而且提高了天线的增益值。实测结果表明:该天线在1. 6 GHz ~20 GHz 频段内电压驻波比小于2,增益为1. 5 dB ~11. 1 dB。此外,该天线增益峰值偏移现象得到明显抑制,具有辐射方向性好、增益高、交叉极化比小的优点。     

关于Vivaldi超宽天线设计方案的研究

文章对微带线馈电结构的Vivaldi超宽带天线进行了设计,并对设计的Vivaldi天线进行了计算辅助优化设计,同时制作了试验样机.仿真测试结果表明,该天线在规定的3.1GHz-10.6GHz频段内可以得到良好的传输性能和辐射性能,与理论设计吻合,达到宽频带特性的设计要求,为Vivaldi宽带天线的设计提供了新的思路.     

新型超宽带双极化电磁偶极子天线

设计了一款新型的超宽带双极化电磁偶极子天线。采用阶梯型馈电结构代替传统电磁偶极子的Γ形馈电结构,半椭圆电偶极子代替传统矩形电偶极子,从而获得了更宽的阻抗带宽。对该天线加工制作了天线样品并进行了测试,仿真和测试吻合良好。该天线的2个极化馈电端口阻抗带宽(驻波比SWR<2)分别达到90.8%(2.06~5.37 GHz)和84.4%(2.08~5.12 GHz);并在整个工作频段范围内,该天线呈现良好的定向辐射特性和稳定增益,2个馈电端口增益分别为(8.6±0.8) dBi和(8.85±0.85) dBi。     

一种新型2.4GHz频段加载贴片天线的设计

采用在贴片上开槽和加载的方法,设计了一种用于2.4GHz频段无线通信设备、内缩渐变线馈电的新型结构贴片天线.给出仿真设计的性能和多个天线样品的实测输入驻波比曲线和远区辐射特性图,详细研究分析了不同加载条件、不同辐射边尺寸对输入驻波比的影响.实测结果表明,该天线在2.4GHz频段上获得超过15%的相对带宽(VSWR<2),而且尺寸比相应频段的微带贴片天线更加微型化.     

一种具有三阻带特性的超宽带天线的设计与研究*

提出了一种紧凑型共面波导馈电的具有三阻带特性的超宽带天线。所设计天线的基本几何结构由共面波导(CPW)馈电线、菱形辐射贴片和矩形宽缝隙组成。通过在辐射贴片上刻蚀一个U型槽,以及在共面波导的接地面上增加两对L型的寄生旁枝结构来实现天线的三陷波特性。天线尺寸为32mm×32mm×0.508mm。仿真和实验结果表明,该天线在2.6~11.5GHz的频段内电压驻波比小于2,在3.15~3.80GHz、5.20~5.80GHz和8.2~8.7GHz三个频段内具有陷波特性,分别有效阻隔了Wi MAX系统、WLAN系统和ITU 8GHz频段信号对于超宽带(UWB)系统的干扰。在除三个阻带频段外的其余UWB工作频段范围内,具有良好的辐射方向特性和稳定的增益。仿真结果和实验结果表现出良好的一致性。     

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.     

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.     

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.     

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.     

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.     

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.