Three-dimensional simulation method of multipactor in microwave components for high-power space application

Based on the particle-in-cell technology and the secondary electron emission theory, a three-dimensional simulation method for multipactor is presented in this paper. By combining the finite difference time domain method and the panicle tracing method, such an algorithm is self-consistent and accurate since the interaction between electromagnetic fields and particles is properly modeled. In the time domain aspect, the generation of multipactor can be easily visualized, which makes it possible to gain a deeper insight into the physical mechanism of this effect. In addition to the classic secondary electron emission model, the measured practical secondary electron yield is used, which increases the accuracy of the algorithm. In order to validate the method, the impedance transformer and ridge waveguide filter are studied. By analyzing the evolution of the secondaries obtained by our method, multipactor thresholds of these components are estimated, which show good agreement with the experimental results. Furthermore, the most sensitive positions where multipactor occurs are determined from the phase focusing phenomenon, which is very meaningful for multipactor analysis and design.     

基于波长扫描的差分吸收光纤煤矿瓦斯传感系统设计

以1 330 nm波段的超辐射发光二极管为光源,利用可调谐光纤法珀滤波器为滤光元件,设计了一套光纤煤矿瓦斯传感系统.该系统采用了参考测量方法和差分吸收技术:一路参考光被引出用以消除光源波动的影响;扫描光纤法珀滤波器获得信号光波长和参考光波长,在实现差分吸收测量的同时,避免了不同滤光元件性能差异和中心波长漂移的影响.实验结果表明,所设计的光纤煤矿瓦斯传感系统的最低可探测甲烷浓度为0.15%.     

利用霍尔元件测量金属丝的弹性模量

将霍尔元件应用于拉伸法测弹性模量实验,直接测量了微小位移.结果表明,霍尔元件在均匀梯度磁场中霍尔电压与微小位移有良好线性关系,采用拟合法计算得到钢丝弹性模量为1.96×1011 Pa.     

A Multiple Resonant Mode Film Bulk Acoustic Resonator Based on Silicon-on-Insulator Structures

With the rapid development of wireless technol- ogy, the demand for integrating multi-band devices has spurred substantial research interest. Research on CMOS compatible radio-frequency （rf） devices has also attracted significant attention. The resonant frequency of film bulk acoustic resonators （FBARs） is mainly determined by the thickness of the piezo- electric film, complicating the integration of differ- ent frequencies on a single chip. One report real- ized multiple resonant frequencies around 2.0 GHz by changing the quality of the electrode. Another re- port obtained the 2.5 GHz main frequency response with a quality factor （Q） of 101.8 and some spuri- ous resonances, while these spurious resonances were irregular.     

成都光电所“表面等离孚体超衍射光学光刻基础研究”通过省科技厅成果鉴定

中国宇航学会光电技术专业委员会联合其他相关单位定于2009年11月在杭州召开"2009年先进光学技术及其应用研讨会"。本次会议具体由中国宇航学会光电技术专业委员会和浙江工业大学联合承办。     

EXR卡片长焦 富士FinePix F75EXR

该款相机在国外发布的型号是FinePix F70EXR。我们可以把它看作是F200EXR的同系列中的最新款产品。与上款产品相比，FinePixF75EXR的外形设计有所提升，看起来更显时尚。     

HUBER＋SUHNER微波系列产品又出新品

针对客户对高质量、高频率的连接元件以及整体连接方案的显著需求，HUBER＋SUHNER近日推出用于可靠性要求较高的测试、测量场合或者高频系统连接中的新产品——低无源互调标准器、衰减器等。     

速度与激情：三款CMOS图像传感器小型数码相机

小型数码相机图像传感器的改朝换代时间已经到来？已经窥视已久的CMOS无疑想极力证明这一点。2009年，CMOS终于发动了引擎，并且希望靠速度超越前辈     

亚洲半导体代工产能利用率下降

据财务管理公司Robert W Baird＆Co．半导体元件组的分析，半导体代工产能利用率目前是40．50％，而且12月可能进一步下降。报告指出，目前订单的能见度很少能超过四周。     

BGA评估中使用的分析方法

球珊阵列（BGAs）在印刷电路板（PCB）组件上已经相当常见，进而带来了新的故障模式，要求新的分析工具或方法，以便正确评估这些元件。传统式SMT元件，如SOICs或OFPs，允许以可视方式检测焊点，查找异常情况；而BGAs则做不到这一点，因为大多数焊点隐藏在元件下面，人眼是看不到的。本文讨论了STI实验室遇到的部分故障模式，以及进行调查使用的工具和方法。