一种基于倒“T”形贴片结构的WLAN天线设计

提出了一种基体背面有电磁带隙结构的倒“T”形双频微带天线。研究发现该天线具有双频带特性,其双频工作频率分别为2.4 GHz和5.2 GHz,相应的带宽为805 MHz (2.099~2.944 GHz) 和831 MHz (4.568~5.409 GHz),增益达到3.1 dBi。仿真和测试结果基本吻合,表明该天线可以很好地满足WLAN工作频段标准要求,具有很好的应用前景。     

一种单层贴片式双频双极化滤波天线

设计了一种单层式跨频段双频双极化滤波天线。该天线在同一平面上的高频低频辐射贴片共用一个馈电端口，且均可以在两个垂直方向馈电实现交叉方向的线极化辐射。该天线通过在馈电点与低频辐射贴片之间插入一个低通滤波器，明显提高了高频辐射贴片的交叉极化隔离度。研究结果表明，带滤波结构的天线在两个频率点的反射系数小于-20 dB，4.9 GHz的最大增益大于4.8 dBi，26 GHz的最大增益11.7 dBi，〖JP2〗两个辐射频率的辐射方向图均体现良好的线极化特性，且主极化比交叉极化大20 dBi。该天线可作为未来微波与毫米波共用的5G通信终端天线或5G通信基站的MIMO天线阵元，相关技术和结论对于研制一体化集成的双频交叉极化相控阵天线也有重要参考价值。     

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。     

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。     

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。     

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。     

可用于物联网的高隔离度双频MIMO天线

设计了一种高隔离度双频多输入多输出（MIMO）天线,该天线覆盖2.4 GHz和5 GHz无线局域网频带,可以应用于移动物联网之中。天线包含两个相同的辐射单元天线,采用微带馈电的方式进行馈电。单元天线使用单极子天线作为基本辐射器,其包含一根长的和短的单极子天线,分别谐振在低频和高频频段。通过在两个单元天线中间加载T型隔离器提高了单元天线之间的隔离度。天线的辐射振子、馈电以及T型隔离器都印刷在同一块微波板材上,从而方便了天线的制作和加工。仿真结果表明,该天线在1.9~2.8 GHz以及4.7~6.2 GHz频带范围内能实现良好的双频工作特性,天线隔离度近20 dB,可以广泛应用于物联网系统中。     

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。     

Ka频段低噪声接收前端设计

介绍了一种应用于卫星通信的Ka频段低噪声接收前端的设计方法。通过合理选择器件组合 和电路形式,优化输入连接和电路级间匹配,最终研制完成了Ka频段低噪声接收前端。接收 前端的接收信号频率在30 GHz附近。在0.8 GHz工作带宽内,噪声系数小于2.2 d B,增益大于60 dB,带内增益波动小于1 dB。3套样机的测试结果验证了设计的 有效性。     

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.     

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.     

Trade Promotion from Neighborhood

If you are considering to trade with companies in Japan or expanding your .business to Japan, we are ready to help from the very beginning.＂ You will find this greeting at the first sight on the Chinese website of Japan External Trade Organization （JETRO）. JETRO has committed itself in delivering highly efficient and quality services to meet the demand of internal and external customs including Japanese companies, hence winning a good reputation in the international trade arena. In recent years, with its priority in advancing business cooperation in South and East Asia, JETRO has made great achievement in promoting trade between China and Japan. Therefore, China＇s Foreign Trade interviewed Mr. Yoichi Maine, Deputy Director General of JETRO BEIJING.     

Auto Parts Market Potential Coming into Surface

Looking at the increasingly fierce competition in the world auto market. global automobile manufacturing industry, taking Europe, the U.S. and Japan as representatives, is gradually forming a new type of relationship, mutual cooperation between whole vehicle and parts manufacturers. We can clearly see that auto parts manufacturers have become independent from the whole vehicle manufacturing companies, which means that the former structure of auto industry has greatly changed, and a new relationship,     

Domino Effect on Electricity and Coal Prices

In the middle of last December, the key purchase contracts for coal used in power generation in 2008 were signed, reflecting a demand for more than 1.085 billion tons. It is important to note that the country＇s five biggest power producers, China Huaneng Group, China Guodian Corporation, China Power Investment Corporation, China Huadian Corporation and China Datang Corporation, had settled on the prices on their purchase contracts, and they are expected to consume 290 million tons of coal for generating electricity,     

China's Auto Industry Steps Forward

Last year,the volume of China's auto trade reached US$66.878 bil- lion,of which imports accounted for US$25.982 billion,a year-on- year increase of 24.45 percent;while ex- ports totaled US$40.896 billion,growing by 45.31 percent.The China Association of Automobile Manufacturers(CAAM) predicts that the number of autos sold in 2008 will break the 1 million barrier for the first time in history,representing an increase of about 20 percent.