舰艇短波地波通信链路计算与分析

为评估海上舰艇短波地波通信的真实能力,将短波地波传播模型与天线仿真技术相 结合,采用矩量法计算舰载鞭天线的辐射特性,并将计算的天线的方向特性、辐射效率以及 测量的驻波比特性代入短波地波传播计算模型。计算结果表明,对应不同的通信距离,存在 一个最佳工作频段。     

一种“北斗”导航天线馈源的设计

现有的馈源设计方法设计出的馈源工作频段少，不能满足“北斗”导航天线馈源的要求。为此,在对模式展开法和模式匹配法理论研究分析基础上，提出了优化双槽深波纹喇叭槽参数的设计思路。分析和试验结果表明，该“北斗”导航天线馈源增加了工作频段，具有良好的电气性能，满足了“北斗”天线系统的需求，验证了设计方法的有效性。     

兼容4G/WiFi/WiMAX的新型宽带人工电磁媒质天线设计

设计了一款新颖的基于互补开口谐振环结构和条形缝隙的贴片天线。通过在金属贴片上蚀刻圆环形互补开口谐振环结构,并且在金属接地板上蚀刻条形缝隙完成天线的人工电磁媒质结构设计,它们和介质板共同作用将天线工作频段明显扩宽到1.7~2.98 GHz和3.99~5.34 GHz。该天线仅使用单层双面覆铜板即可完成加工,具有结构简单的特点。同时,天线的电尺寸仅有0.408λ0×0.408λ0×0.008 6λ0(在天线最低工作频率1.7 GHz处),且最大增益为6.04 dBi;可以同时兼容中国的第四代(4G)移动通信的所有频段(1.88~2.66 GHz)、WiFi频段(2.4~2.484 GHz)和微波存取全球互通(WiMAX)频段(2.5~2.69 GHz)。     

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。     

紧凑五-五单元天线阵设计

设计了一个五-五单元微带贴片天线,中心层叠天线单元结合矩形贴片表面电流分布 原理,由独立馈电实现工作。分析了天线的驻波比、轴比、增益、天线单元间的隔离度, 以及天线两个工作频段之间的隔离。实现了BD(B3)(“北斗”导航系统B3频段)和GNSS(全球 导航 卫星系统)两个导航定位频率的组合。不同频段天线单元复合布局,减小了天线的总体尺寸 ,能够应用于小型多功能接收机中。     

传统基站到有源天线基站的演进

随着无线网络的发展,基站架构也不断演进。详细介绍了传统基站、分布式基站、有源天线基站的架构,对比了其优缺点,说明了演进到有源天线基站的必然性。针对有源天线,明晰其概念,给出了设计思路,探讨了其技术优势。有源天线可通过波束成形覆盖更多小区,完全可满足未来低能耗、低成本绿色移动通信系统的发展要求,将成为基站演进的必然趋势。     

S/X/Ka三频段天线电轴不一致性对天线性能的影响

为满足测量船未来深空探测测控任务的需求,设计了三频段合用的波束波导天线。通 过计算各频段在4种情况下的波束不一致及增益损失,分析了多频同时工作时电轴不一 致对天线性能的影响,提出了天线尽量跟踪在高频段的使用建议,对实际应用具有极大意义。     

多频段背腔式半模基片集成波导弯折缝隙天线

针对需要安装在金属平台上的天线应用,提出了一种具有定向辐射特性的新型多频段背腔式半模基片集成波导缝隙天线。利用半模基片集成波导谐振腔的多模式特性实现了该天线多频段工作,通过在谐振腔的金属顶面蚀刻弯折形状的缝隙实现对外辐射,并可以通过调整弯折缝隙尺寸参数来减小天线尺寸。仿真和测试结果表明,该天线能同时工作在5.7/10.7/11.9/12.5/13.1 GHz,且在这5个频段的最低增益大于6.7 dBi。天线具有便于和平面电路集成、体积小、结构简单、成本低等优点,具有一定的工程应用价值。     

阵列天线在UXB系统标校中的应用

测量船基地现有标校塔与测量船距离只有980 m,无法满足高频段统一X频段（UXB）系统天线的远场标校距离条件。针对这一难题,提出了一种利用阵列天线合成准平面波的方法,实现在近场距离条件下的远场标校。在现有标校塔上架设安装阵列天线设备,利用16个单喇叭天线组成4×4的天线阵,并通过控制单个喇叭天线元的幅度和相位,使得传播到测量船UXB天线口面处由阵列天线合成的电磁波是准平面波,满足X频段天线远场标校要求。综合运用最优化理论和遗传算法,对阵列天线元的幅度和相位权值进行调节和优化,使得合成的电磁波更为接近准平面波。计算机仿真实验和外场条件下的实际测试均验证了该方法生成的准平面波能够满足UXB天线远场标校要求。     

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。     

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,     

Slimmed May Day Holiday

Last November the State Council of China decided to renew its holiday system by reducing the seven-day May Day holiday to three days and introducing three new one-day public holidays, namely the Qingming Festival, Dragon Boat Festival and Moon Festival. By doing so, the three golden-week holidays that were introduced in 1999, namely the Spring Festival, May Day and National Day, could be better distributed.