用于ISM/UNNI频段的新型双频单极子天线设计

针对天线在ISM和UNNI频段的应用,提出了一种采用共面波导馈 电的新型单极子双频天线,在传统T型单极子天线上平行加载辐射贴片实现双频工作。分析 了天线尺寸变化对工 作频率的影响,得出所设计的天线频率比在1.67～2.67范围内可调。制作加工了工作于ISM/ UNNI频段的天线实物,测试结果与实验结果吻合良好。天线全向辐射性能良好,分别在低频 段和高频段获得了 21.28%和3.9%的相对带宽（S11≤-10 dB）,适用于无线通信领域。     

一种容性馈电宽带微带天线的设计与分析

通过使用容性馈电贴片、短路面和短路探针,设计并分析了一种宽带微带天线。该天 线的相对带宽达到47.3% (S11＜-10 dB),频段覆盖16～2.59 GHz。 工作频段内的3个谐振频率形成了足够大的带宽。仿真结果表明,容性馈电贴片对辐射贴片 表面电流的耦合效应会影响天线的性能,通过调节短路探针的位置可以获得稳定的辐射方向 图。该天线的工作频段和特性符合无线通信系统应用的要求。     

一种改进的小型化超宽带平面倒锥缝隙天线

提出了一种改进的超宽带平面倒锥缝隙贴片天线,通过调整倒锥缝隙和倒锥贴片的形 状,在更小尺寸条件下,实现了超宽带性能。天线总体尺寸为40 mm×40 mm× 1.5 mm。采用仿真软件分析了该天线的阻抗带宽、辐射方向图及增益特性。结果显示,该 天线的回波损耗小于-10 dB的带宽为2.2 GHz到大于16 GHz,在低频段具有全 向性,在3～14 GHz频段增益随频率的变化在4～7 dB之间。     

带引向器的非对称平衡对拓Vivaldi天线设计

设计了一副改进的非对称平衡对拓Vivaldi天线。辐射贴片外边缘用3阶多项式曲线修正，以实现很宽的阻抗带宽。在天线口径处嵌入一个金属贴片作引向器以改善天线的辐射特性。对辐射贴片引入非对称性，使得E面波束偏离得到进一步补偿。实测结果表明，该天线具有极宽的工作带宽，在2~40 GHz内的增益大于0 dBi，且在15~30 GHz内的增益大于14 dBi；E面的波束偏离在6~40 GHz频率范围内小于3°。该天线具有结构简单、尺寸紧凑（44 mm×98 mm）以及方向图稳定等优点。该天线能够较好地应用于相控阵、超宽带系统等。     

一种单层双频宽带GNSS测量型天线设计

基于单介质层结构,设计了一款双频宽带全球卫星导航系统（GNSS）测量型天线,天线采用单层高性能轻质复合材料作为双频微带天线共用的辐射介质基板。双频辐射贴片单元采用共面齿轮结构设计,并在天线单元外围设置一系列短路销钉来有效改善天线轴比带宽、低仰角辐射增益等参数,四馈点馈电技术和宽带耦合相移馈电网络的应用保证了天线相位中心稳定度更加可靠。设计结果表明,该双频天线单元大于等于5 dBi的辐射增益带宽均大于245 MHz,高低频3 dB轴比带宽分别为-76°~76°和-116°~116°,低仰角90°增益滑落均小于11.5 dB,经实物样机对比测试分析,实测结果与仿真结果基本吻合。实测频谱显示,该天线工作频段覆盖目前在运行的四大导航系统全部工作频点,较好满足GNSS精确测量与定位系统终端设备应用需求。     

新型超宽带单极子天线的设计

研制了一款超宽带印刷单极子天线,通 过在接地板上开方形槽,展宽带宽的同时也改善了带内特性。再在金属贴片顶部开扇形槽, 进一步在高频段展宽了频带。实测结果显示,改进后的天线-10 dB阻抗带宽为2.1～2 5.5 GHz,而原不加槽天线的仿真带宽为2～11.4 GHz,带宽展宽了14 GHz。仿真 和实测结果显示,天线在2.5 GHz、8 GHz、25 GHz的方向图对称性良好。     

采用新型馈电结构的双频宽带导航天线设计

基于新馈电结构,设计了一款覆盖全球四大卫星导航系统的双频宽带贴片天线。采用了一种四分八馈电线路,以8个同轴馈电探针两两相连的方式将两路天线馈电信号合为一路,有效简化了馈电网络的复杂性,同时保证了天线辐射的增益、带宽和轴比性能。该双频辐射贴片单元采用正八边形层叠式结构设计,并在每个天线单元边缘对称添加两组矩形调谐单元,有效增加了天线辐射的波束带宽。该双频天线单元在高频1.482~1.617 GHz（波束带宽155 MHz）和低频1.191~1.252 GHz(波束带宽61 MHz）频段范围内,都能保证良好的辐射增益;高低频的3 dB轴比带宽为-130°~130°,具备良好的圆极化性能。经实物样机对比测试分析,实测结果与仿真结果基本吻合。     

一种小型半U型缝折叠超宽带微带天线

提出了一种四分之一波长半U型缝隙折叠超宽带微带天线。该天线采用短路面加载半 U型缝隙以及折叠辐射贴片的方法,实现了小型超宽带特性;天线的尺寸为18 mm×7. 5 mm×7 mm,相对波长尺寸为0231λg×0096λg×009λg （λg是天线 带宽最低频率对应的介质中波长）。仿真显示,天线的阻抗带宽为393%,仿真辐射方向图 稳定,平均增益4.3 dB。由矢量网络适量分析仪E5071C实测天线模型,天线的带宽为3 86～6.47 GHz,相对带宽为5053%,并且从3.53 GHz到大于8.5 GHz频段上 电压驻波比小于3,相对带宽超过826%。     

基于SRR结构具有陷波特性的超宽带天线

在Yang X等人提出的SRR（Split Ring Resonator）天线结构基础上,在天线贴片上 设计出一个U型槽,通过改变该U型槽缝隙宽度、长度等参数,以不断调整阻带中心频率及带 宽,从而实现了一种具有陷波特性、能够屏蔽无线局域网（WLAN）信号干扰的超宽带天线。 仿真及测试结果 表明,改进前天线的工作频带为3～11 GHz（VSWR<2）,无陷波特性;而改进后的天 线在 4.4～5.7 GHz频率范围内具有良好的频带抑制特性,增益值最低可达到-15 dB, 并且在其它工作频段具有良好的辐射性能。     

应用于无线USB的小型超宽带阻带天线

设计了一种用于超宽带无线通信系统的小型化天线。该天线贴片尺寸为20 mm×15 mm ×3 mm,采用U形折叠结构和渐变结构相结合,可使天线具有超宽带特性。为 了减小对无线局域网（WLAN）系统5 GHz频带的干扰,天线采取了叉形谐振结构来实现对相应频带的抑制。采用仿真软件分析了该天线阻抗带宽和不同频点处的辐射方向图。仿真和实测结果显示,该天线在25～4.67 GHz和628～12 GHz内S11<-10 dB,在47～6.2 GHz内S11>-10 dB,因而有效产生带阻特性。     

Brown＇s Blossom in Britain-China

The overall strategic relationship between U.K. and China is ＂better than ever＂, China- Britain relations have maintained good momentum, with increased high-level exchanges and the reinforcement of strategic mutual trust, with more room for growth in the future.     

Challenge and Opportunity Go Hand in Hand——What Global Economic Agitation Brings to the China's Economy?

Domino effects of the global finance agitation As the origin of the subprime crisis,US financial institutions lost USS45 billion last year,accounted for over half of the total US,EU & Japan loss.Since January 15th,Chtigroup released its financial statement of the 4th quarter,showing a net deficit of USS9.83 billion,which marked the hisoric high of its quarterly deficit.     

Sinosteel：Extraordinary Moves in Industry Chess

Among the Fortune 500 firms,more and more images from China emerge out.On the 2008 list,Sinosteel Corporation,a landmark group of China industries quietly squeezes into the candidate line.As the largest steel service ＆ trade enterprise,its sales reached at RMB 111.24 billion,with a year-on-year increase of 83.03 percent,and the profit grew by 180.03 percent.On the Sinosteel 2008 Work Meeting,the president Huang Tianwen uttered,＂In the coming year,we will work for US$20 billion sales,and look forward to getting a position in Fortune 500 firms for ourselves.＂     

Walk Through Unusual Five Years—— An Exhibitor＇s Canton Fair Course

When the 103rd Canton Fair is approaching, an old friend of Canton Fair, Li Ying from Jiangsu prov-ince recollected his past five years＇ experiences to the grand trade meeting. Each year is special, with some unforgettable memories colored by the year.     

Public Financial Expenditure——A Reflection of the Livelihood Improvement

In recent years.China's public finance put social construction high on the agenda and attaches more importance on livelihood insurance and improvement.The 2003-2007 public financial expenditure reflects a fact that the government isputting more emphasis on livelihood andissues concerning the people.     

Voices from the MPC and CPPCC

"Crucial for economic growth.energy utilization has its role in all economic sectors and every aspect of people's daily life.Now we are in dire need of a new profession,namely energy manager.We not only need to have passion and responsibility,but also a scientific approach to conserve energy and cut emissions.APpropriate legislation should be in place.and a special profession should be introduced to ensure the implementation of these laws and regulations."     

Ouyang Riping： A Hero Besides Entrepreneur

A bout fifty years ago. a baby＇s cry broke the sky of quietness, in a small and beautiful town of Hunan province, which surroundcd by green hills and clear water. Though his .birth brought his family great happiness and hope just as any new life, nobody knew that the little boy would get great achievement when he grow up. even start his business oversea, and earn international honor. Let＇s share with you the entrepreneur Ouyang Riping＇s story, which may insights thcsc people who want to succeed and complete oneself in favorite condition or adversity rather leave things to so-called fate.     

Slowdown Trade Surplus Growth

According to Ma Kai＇s economic planning report submitted to the NPC session on March 5th,（Ma Kai is the Minister in charge of the National Development and Reform Commission）,the government has listed the slowdown in trade surplus growth and the steady expansion of external investment as major tasks for 2008.     

Jean-Pierre Duprieu： Willing to Be A Legate of Sino-French Business

Estaing, former French president, Valery Giscard d＇Estaing attended Sino-French Economic Seminar held in Shanghai in early April and said that the world center has shifted from the west to the east with many European and US companies entering into Asia, and China has the ability to play an important role in the world stage. Estaing, naming himself＂French Confucian＂, then said in Chinese that a cook-group includes 10 people in ancient Chinese soldier system and the cook is in charge of cooking for them. And people who belong to the same cook are actually ＂Partners＂.     

China''''s Stock Market Wave

The annual meeting of the World Economy Forum was held in Davos,a little town in Switzerland,on January 23rd to the 27th this year,with the theme"the Power fo Collaborative Innovation",over 2500 celebrates from ture political and cconomic circles of more than 80 countries and challengred logether to talk about the future of the global economy in 2008,A Forum for the problems and challenges that face whole world,some of the keywords which drew attention during the event were:the U.S.subprime mortgage crisis,soaring energy prices,the economic slowdown in the U.S.ermerging economic bodies,authority funds and the general unpredictable nature of the global economy.