基于耦合加载的低剖面天线设计

设计了一种小型化双频天线。通过在单极子天线上引入寄生耦合的方法,即在单极子 顶部引入耦合加载板,既保证了单极子天线的辐射全向性又减小了电小天线的分布电容 ,从而使该天线具有宽频带、低剖面特性。采用仿真软件Ansoft HFSS进行仿真和优化,优 化结果表明：该天线工作频率为824～960 MHz/1 710～2 690 MHz（驻波比小 于等于2） 。根据仿真模型制作了一款天线,实测驻波带宽可达811～1050MHz/1580～2660 MHz,且在水平面内辐射全向方向图。该天线在限制尺寸的情况下有效地展宽了带宽。     

宽频带宽角域扫描的圆极化相控线阵设计

针对传统相控阵工作频带窄、圆极化波束扫描角度小的问题，设计了一款宽波束天线单元以及1×6相控线阵。采用叠层贴片技术展宽天线的阻抗带宽，设计新型的三维地结构拓展天线的波束宽度，利用介质匹配层技术改善天线在低仰角区域的阻抗匹配，并通过双点馈电实现圆极化辐射。仿真与实测结果表明，天线单元的3 dB波束宽度在4.3~5.6 GHz的频带内均大于115°。天线阵列在4.5~5.3 GHz的频带内，主波束的最大扫描范围为-57°~58.5°，其3 dB波束覆盖范围达到185°，在主波束的扫描范围内轴比小于6 dB，具有良好的宽频带宽角域的圆极化扫描特性，在卫星通信、移动基站等领域有广阔的应用前景。     

新型宽波束圆极化天线--微带介质天线

通过在微带天线中引入介质天线原理，提出了一种以简单方式展宽微带天线波束和提高低仰角增益的新方法，从而发明了一种新型宽波束天线－微带介质天线。该天线具有极宽的波束、较高的低仰角增益和波束范围内有较好的圆极化性能等特点。文中给出了天线的原理、设计公式和实验结果。     

新型Ka频段宽角扫描圆极化相控阵天线

提出了一种新型的Ka频段圆极化相控阵天线。天线单元以单馈电开槽贴片天线为基础实现圆极化,通过微带贴片表面加载介质和辅助辐射器,展宽了天线波束宽度并优化了单元轴比。以该天线为阵列单元,采用顺序旋转布阵技术优化得到的2×2子阵,其辐射方向图具有良好的旋转对称性,由该子阵扩展形成的相控阵天线,有效地实现了圆极化宽角扫描特性。以8×8矩形阵列为例,仿真分析了此类二维相控阵天线波束扫描过程中的方向图和极化特性。研究结果表明,天线在工作频段内可实现方位360°、俯仰±60°扫描,扫描范围内天线增益波动和轴比均小于3 dB,同时该天线具有低剖面（高度尺寸为0.08λ0,λ0为空气介质波长）、结构简单、易于加工和集成等特点,非常适合小型化或一体化相控阵天线系统应用。     

机载天线的方向图分析

计算了机载单极子天线的辐射方向图,通过与单极子天线在自由空间方向图的比较,分析了飞机对机载天线方向图的影响;在此基础上,计算了当飞机盘旋飞行时,机载天线对空间某一固定点辐射场强的变化情况.     

一种低轨卫星通信天线多工作模式波束实现技术

在分析低轨卫星通信系统中不同链路所需波束类型的基础上,将所需波束类型归纳为宽波束和可切换点波束两大类,进而提出了用一副相控阵天线来实现这两种波束的方式。以16×16单元顺次旋转切角阵为研究对象,采用最小二乘优化方法综合阵列方向图,得到对地等通量覆盖的宽波束;合理设计波束分布,采用相控阵常规的波束切换功能,得到点波束覆盖图。仿真结果表明,宽波束和可切换点波束均能实现对星下±55°范围的覆盖。相比常规的多天线方式,这种多工作模式波束实现技术大大降低了卫星系统的复杂度,降低了设计、集成、测试和维护卫星天线系统的时间和成本,降低了卫星平台天线布局的难度,因此具有重要意义。     

A multi-beam planar lens antenna for UAV relay datalink

龙伯透镜天线表面放置多个馈源即可在同一频段或跨频段同时产生多个扫描波束跟踪多个目标,针对这一特点,设计了适用于C频段无人机中继数据链的紧凑多波束平板透镜天线。采用矢量球面波函数展开法结合差分进化算法优化设计透镜天线,仿真分析了单个Vivaldi天线照射3层直径160 mm平板透镜天线,天线增益优于传统均匀分层的透镜天线。同时,采用16个Vivaldi天线组成半圆环阵照射平板透镜天线,通过扫描波束的馈电切换,实现宽角范围的多波束覆盖。仿真结果表明：平板透镜天线在宽频带（5.5～9.0 GHz）内具有良好的多波束辐射特性。     

一种共形宽带圆极化螺旋天线的设计

为满足共形天线低剖面特性的要求,设计并制作了一种低剖面的圆极化阿基米德螺 旋天线。天线利用单臂阿基米德螺旋结构实现圆极化辐射,并采用同轴探针馈电。实测结果 表明,天线在2～11.4 GHz的频率范围内回波损耗小于-10 dB,轴比小于3 dB 的频率范围为25～8.4 GHz。该天线结构简单,工作频带宽,且剖面极低,可作为多 种载体的共形天线使用。     

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。     

用于船舶自动识别系统的机载阵列天线设计

为了满足船舶自动识别系统抗干扰性能的要求,设计了一种机载阵列天线。天线阵列由5个单极子天线单元组成,整体尺寸为Φ720 mm×306 mm,天线单元沿圆周均匀排列。通过泰勒分布和牛顿优化算法,优化阵列的辐射幅度及相位,得到实测的方位面增益-15 dB抑制范围达到128°,-20 dB抑制范围达到77°;装机后-15 dB抑制范围在114°以上,-20 dB抑制范围在51°以上。该阵列天线结构简单,成本低,满足机载环境的使用要求。     

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,     

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,