利用机体遮挡实现机载抗干扰通信

结合机载通信抗干扰设计的工程应用需求,分析了机体遮挡对机身前后左右典型安装位置VHF/UHF和L频段通信天线的影响程度,提出了一种当通信信号和干扰信号分别位于机身两侧时,应用机体遮挡对信号接收的抑制原理,通过选择指向通信信号一侧的左或右机翼天线实现抗干扰通信的方法。该方法仅需新增两副机翼天线和两个射频开关,具备较强的工程可实现性。仿真结果表明该方法能够有效抑制来自机身侧面干扰信号的接收,最大抑制达到35 dB,为机载通信抗干扰能力提升设计提供了新的技术途径和理论指导。     

馈源整体制冷技术在深空测控系统中的应用

深空探测器通信距离遥远,其返回信号微弱,因此要求接收天线具备尽量高的品质因数（G/T）。下行链路设备工作在低温环境中,有利于降低噪声温度,提高系统G/T值。针对35 m深空测控天线,首先分析了Ka频段天线增益、外部和内部噪声;在此基础上提出了Ka频段馈源整体制冷方案,并对馈源不制冷和馈源整体制冷两种方案进行了比对分析;最后总结了超低温馈源设计和制造关键技术。馈源整体制冷系统噪声温度测试结果小于45 K。分析表明采用馈源整体制冷方案能够提升系统G/T值1.03 dB,35 m深空测控天线Ka频段接收能力提高约21%。     

四线式宽频带短波基站天线及其性能分析

提出一种新型四线宽频带短波基站天线,该天线采用模拟加粗、末端加载和行波工作相结合的方案,有效地扩展了工作频段。对天线进行了仿真分析和实际测试,该天线在2~30MHz频带范围内满足电压驻波比小于2.0,相对增益可达3~5dBi,比普通宽带短波基站天线工作频带宽、辐射效率高。而且对应于不同的工作频段,该天线可以满足远、近不同通信距离的需要。     

L频段低仰角覆盖机载前舱卫通天线

目前用于机载前舱卫星通信的L频段终端系统设备,全部是由国外厂商提供,且多采用平面阵或机械扫描的方式。提出“屋顶”形天线阵列来实现超低仰角覆盖,设计并研制了L频段机载前舱卫通相控阵天线样机。地面静态对星试验结果表明,天线样机可与海事卫星实现稳定通信,通信速率为310 kb/s,通信质量良好。相比于以往的平面布阵或机械扫描方案,这是一种规模小、重量轻的低仰角覆盖方法,非常适用于L频段机载前舱卫通天线。     

GSM移动通信手机射频收发系统的设计与实现

提出了一种按照GSMPhase2 技术规范实现的GSM移动通信手机射频收发子系统的硬件方法。该系统采用了当今较为流行的DCR方案,并且支持GPRS应用,可工作在EGSM900和DCS1800双频段上。文中介绍了射频收发子系统的构成和基本原理,描述了系统设计实现的具体过程,为系统设计提供了必要的分析和计算。     

一种Ka频段高密度高集成瓦式T组件的设计

介绍了一种Ka频段瓦式T组件的设计方法和关键技术。采用多层印制电路板(Printed Circuit Board,PCB)技术,实现了无源网络和馈电网络集成在同一块多层电路板上,滤波功能层和天线一体化集成,利用毛纽扣实现了组件的三维垂直互联。采用互补金属氧化物半导体(Complementary Metal Oxide Semiconductor,CMOS)工艺与砷化镓（GaAs）工艺相结合的芯片异构集成方案,成功研制出16通道带滤波功能层天线的T组件,体积为22 mm×22 mm×12 mm,质量不超过13 g。与同频段同功能的砖式T组件相比,体积缩减75%,质量降至10%。该组件充分发挥CMOS工艺强大的数模混合集成能力和化合物半导体工艺优异的射频性能,并将两类芯片在平面内直接异构拼装,在集成密度、功能密度、射频性能以及可实现性等多个方面获得了良好的平衡。     

一种新型宽频带多频微带天线设计

目前,同时适用于蓝牙、射频识别、全球微波无线互联网和无线局域网这几大主流物联网通信技术标准的多频天线设计较少,为此,提出了一种新的小型化宽频带多频微带天线。该微带天线主要由一个矩形环、一个开口六边形环、三条矩形带以及缺陷地组成,可同时工作在蓝牙、射频识别、全球微波无线互联网和无线局域网的通信频段上。天线谐振频率分别为2.47 GHz、3.48 GHz和5.55 GHz,相应带宽为0.11 GHz(2.38～2.49 GHz)、0.86 GHz(3.19～4.05 GHz)和1.11 GHz(4.95～6. 06 GHz),增益最高达到5.75 dBi。实测结果显示,该天线在工作频段具有很好的辐射特性和增益,适用于当前应用的无线通信系统。     

一种新型平面结构的双陷波超宽带天线设计

为了避免现存的一些窄带通信系统对超宽带天线的干扰,提出了一种具有双陷波特性的超宽带天线结构。由于采用了渐变式阶梯阻抗匹配结构作为超宽带基础天线的馈电,使天线具有了宽阻抗匹配能力。通过在基础天线背面附加双偏T寄生单元和在辐射贴片上开窗的联合方法,实现了超宽带天线的双陷波特性。天线电流分布结果可以完全反映出在陷波频率下两种方法的谐振抑制作用,而且实验结果表明该结构的天线对 WLAN(5.15～5.825 GHz) 和WiMAX(3.4～3.69 GHz)频段的信号起到了有效的抑制作用,同时在工作频段内表现出较好的全向辐射特性。     

一种P/L频段高度综合化航空平台的设计

为进一步提升航空平台综合化程度,设计了一种用于航空平台的P/L频段功能高度综合化硬件平台方案。该方案通过射频直接采集2 GHz以下的低频射频信号,在数字域分离出探测、通信、导航、识别以及无源侦察等功能所需基带I/Q信号,最后通过软件完成各种信号的功能处理,实现了对探测、通信、导航、识别以及无源侦察等功能共信道和共信号预处理的高度综合设计。硬件实现验证了该方案能够有效降低硬件系统设计的成本和复杂性,降低系统功耗,有力推进了软件无线电在航空平台综合化中的应用。     

一种无人机载超视距通信系统

针对中、高空长航时无人机超视距通信系统普遍采用Ku频段卫星中继存在信号可用带宽有限、干扰源众多、机载端设备较大的现状，提出了一种基于Ka频段卫星的无人机超视距通信系统总体与分系统工程实现方案，并给出了关键设计要素。在详细推导链路计算公式基础上，以前向速率为51.2 kb/s、返向速率为8 Mb/s为例进行了链路余量预算与数值仿真分析，并与传统Ku频段方案在传输速率、抗干扰能力、天线口径等方面进行了分析比较。结果表明，在同等条件下所设计的系统性能可提高20%左右。飞行试验结果验证了该方案的合理性、可行性、有效性和工程可实现性，为无人机超视距通信系统总体设计和工程实现提供了思路与参考。     

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,     

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.     

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,