共查询到20条相似文献，搜索用时 62 毫秒
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本文提出一种在高阻抗线上加载开路存根实现超宽带滤波的方案。该滤波器采用多模谐振(MMR)的方式,MMR是由加载的三个存根循环分流到一个高阻抗的微带线实现的,用叉指结构来耦合能量。采用FR4介质板的相对介电常数为10.8,介质板厚度为0.635mm。利用软件CST对设计方案进行验证与优化,得到通带范围为3.1-10.6GHz,带内插入损耗大于-0.5dB,回波损耗小于-15dB,上阻带宽度为14-26GHz。 相似文献
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设计一种新的基于分立器件的BPM(二相调制)脉冲超宽带发射机.脉冲超宽带发射机由单极性亚纳秒脉冲发生器、双极性脉冲产生电路及高速微波开关组成.发射机在时钟和数据“1”和“0”控制下分别输出正、负脉冲.测试结果表明,该发射机输出脉冲宽度＜ 400 ps,带宽＞1.5 GHz,可稳定输出BPM超宽带脉冲信号,码速率可达50 Mbps,可应用于脉冲超宽带通信系统. 相似文献
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《中国科技信息》2016,(18)
本文设计了一种可用于多模卫星导航系统(GNSS)的短路环状层叠圆极化天线。该天线能够工作在GPS,GLONASS,Galileo and Compass(1100MHz-1600MHz)频段。包括一个180°宽带移相器和两个90°宽带移相器的双层介质带状线作为天线的馈电网络。天线的10d B阻抗带宽能够从1.1GHz到1.85GHz,相对带宽为50.8%,3d B轴比带宽能够从1.07GHz到1.7 GHz,相对带宽为45.5%。天线的尺寸为70mm×70mm×28.5mm。在本设计中,短路环状层叠贴片作为辐射贴片可以获得稳定的增益带宽、宽波束以及宽角轴比特性。 相似文献
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当今通信频段越来越宽,在有限空间里安装多个天线即增加成本又浪费资源,因此宽带甚至超宽带天线设计已成为天线设计领域的一个重要研究方向,同时小型化、集成化已成为当今发展趋势,因此设计宽带小型化天线已成为热点。本文就此提出了一种基于基片集成波导(Substrate Integrated Waveguide,SIW)工作在X波段的新型角锥喇叭天线,采用电磁场仿真软件Ansoft HFSS 15对所设计的天线进行仿真,结果表明该天线在8 GHz~12GHz范围以内具有回波损耗优于-15 dB。该天线具有体积小,宽频带,结构简单的优点。 相似文献
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《中国科学院院刊(英文版)》2008,22(1):13-14
Aresearch project on the greenhouse cultivation of Swertia chirayita Buch Ham, a popular herbal drug used by the Tibetan people against liver and gallbladder diseases, recently passed the acceptance check by a panel of experts under the auspices of Qinghai Provincial S＆T Bureau. The feat was accomplished by researchers from the Lanzhoubased CAS Northwest Institute of Plateau Biology. 相似文献
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The research into the origins of domestic animals is of significance not only for understanding their development per se but also for making clear the human society evolution. Although there are evidences to show that pigs were independently domesticated in a variety of places throughout the world the detailed scenario of the origin dispersal of domestic pigs in East Asia remains unclear.…… 《中国科学院院刊(英文版)》2008,22(1):7-7
The research into the origins of domestic animals is of significance not only for understanding their development per se, but also for making clear the human society evolution. Although there are evidences to show that pigs were independently domesticated in a variety of places throughout the world, the detailed scenario of the origin and dispersal of domestic pigs in East Asia remains unclear. 相似文献
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Among the galaxy of research development organizations in northwest Beijing's Zhongguancun district known as China's Silicon Valley two are especially well-known to IT researchers: Microsoft Research Asia 《中国科学院院刊(英文版)》2008,22(1):47-49
Among the galaxy of research and development organizations in northwest Beijing＇s Zhongguancun district, known as China＇s Silicon Valley, two are especially well-known to IT researchers： Microsoft Research Asia （MSRA）, and, within a few blocks on the other side of the street, the CAS Institute of Automation （CASIA）. While most people in Chinese scientific organizations strive to move to a large foreign counterpart, Dr. Stan Z. Li （LI Ziqing） moves against the stream. 相似文献
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《中国科学院院刊(英文版)》2008,22(1):2-3
CAS should stick to the principle of rendering service to, and giving impetus for, the development of China＇s science enterprise by making S＆T innovations, said CAS President LU Yongxiang. The CAS president made the remarks in a recent talk to communicate the gist of the winter session of the Party＇s Leading-member Group at CAS, which was held from 7 to 11 January in Beijing. 相似文献
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《中国科学院院刊(英文版)》2008,22(1)
With great care, Dr. ZHOU Zhonghe takes out a package wrapped by cotton tissue from a drawer and says: "This is the gem of our collections: the fossil of a bird that lived 125 million years ago!" Then, pointing at a tiny mound, he explains: "Look, this is the claw and that is the head. It was in the egg shell and ready to hatch ... The species fell into a family of waterside inhabitants." 相似文献
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《中国科学院院刊(英文版)》2008,22(1):58-58
As a key component of the national initiative for basic S＆T data and infrastructure development, a nationwide survey on the lake water quality, volume and bio-resources has recently been kicked off. The move marks the systematic implementation of the secondround investigation of the country＇s lacustrine resources. 相似文献
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Bats the only mammals known to possess the real ability to fly have fascinated zoologists for a long time with their long-distance migration. How do they find their way home from an altitude of kilometers above sea level where their stunt of ultrasonic echolocation does not work?…… 《中国科学院院刊(英文版)》2008,22(1):3-4
Bats, the only mammals known to possess the real ability to fly, have fascinated zoologists for a long time with their long-distance migration. How do they find their way home from an altitude of kilometers above sea level, where their stunt of ultrasonic echolocation does not work？ Recent discoveries supported the theory that bats might be able to use magnetic clues to figure out their own position,just like what birds do. However, the latest results from a joint study by a group of researchers from the CAS, East China Normal University and University of Auckland reveal that bats apply an interesting strategy different from the one underlying birds＇ orientation technique, though they both are believed to derive information about their position from the subtle changes in the magnetic field of the Earth. 相似文献
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《中国科学院院刊(英文版)》2014,(3):252-252
<正>On February 12,2014,the international academic journal Cancer Research published an article online entitled"Latency Associated Nuclear Antigen of Kaposi's Sarcoma Associated Herpesvirus Promotes Angiogenesis through Targeting Notch Signaling Effector Hey1",as a result from the research conducted by Prof.LAN Ke’s lab at the Institut Pasteur of Shanghai,Chinese Academy of Sciences. 相似文献
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SONG Jianlan 《中国科学院院刊(英文版)》2014,(3):217-220
<正>Scientists from CAS and the Max Planck Society(MPG)met on May 13,2014 in Beijing to celebrate their four-decade-long ST cooperation and cherished friendship,anticipating further development of the bilateral relation.This partnership formally began four decades ago with a visit paid by then MPG President,Prof.Lüst to CAS,introduced CAS President BAI in his address at the celebration:"During the visit,CAS and MPG confi rmed the basic principles of cooperation,that is equality and mutual benefi ts for both sides,and reached agreement to develop a collaborative partnership."This occurred only two years after the establishment of the diplomatic relations between Germany and China,despite the shadow of the Cold War."Building up a partnership between Germany and 相似文献
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TANG Kun 《中国科学院院刊(英文版)》2014,(2):161-165
<正>The scientifi c goals of the Partner Group are to utilize large scale genomic polymorphism data to make fi ne inferences about human demographic history and various forms of natural selection in the human genome;and to understand the genetic basis and evolutionary mechanisms underlying the common variations in human facial morphology,both within and between populations. 相似文献