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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。 相似文献
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为了提高频综的频谱纯度,提出了一种新型多级子谐波混频锁相环的设计方法,研制了一款超低相噪频综。介绍了该频综的设计方案,分析了关键技术,仿真和论证了相位噪声和杂散抑制等主要指标,最后对该频综进行了研制和实际测试。测试结果如下:工作频率为4 500~7 600 MHz,频率步进小于1 kHz,相位噪声优于-123 dBc/Hz@25 kHz,频率切换速度小于75 μs,杂散抑制大于70 dB,均满足设计要求,设计方案比较合理可行。采用该方法设计的频综具有小步进、低相噪、换频速度快、低杂散等特点,可用于高性能电子战接收机中,具有广阔的应用前景。 相似文献
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为了让两个地面站通过卫星链路进行无线通信,设计了一个Ku频段卫星通信系统
,数据速率是512 kbit/s~4.096 Mbit/s,速率可调步进1 bit/s。选取了一
种较简洁的Ku频段地面
站设计方案,信道的本振为固定点频,调制解调器的中频范围是950~1 450 MHz。对卫
星通信
链
路功率进行了预算。地面站的组成设备,如调制解调器、低噪声放大器、上变频单元、下变
频单元等均选用成熟的商用货架产品,降低了设计风险和成本。本系统研制周期短,通信稳
定可靠,得到了用户的认可。 相似文献
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实现了基于LT5506下变频器和Cyclone IV FPGA的零中频接收机,采用射频、基
带一体化架构,尺寸仅为8 cm×6 cm×1.5 cm,重量仅为45 g,功耗仅为
800 mW,满足小型化
、低功耗的要求。针对零中频接收机中射频信号检波困难和传统AGC的调节时间受输入信号
幅度影响的缺点,由Cyclone IV完成信号检波,增加对数运算环节并改进环路滤波器的结构
,配合LT5506中的可变增益放大器仿真并实现固定调节时间的AGC,用8 MHz采样时钟对
1 MHz正弦波进行幅度控制,调节时间恒定为53 μs,不受输入信号幅度影响。 相似文献
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《中国对外贸易(英文版)》2008,(5):50-51
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. 相似文献
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Guo Yan 《中国对外贸易(英文版)》2008,(5)
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. 相似文献
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《中国对外贸易(英文版)》2008,(6):62-65
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." 相似文献
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Zang Kejia 《中国对外贸易(英文版)》2008,(7):16-17
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. 相似文献
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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". 相似文献
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《中国对外贸易(英文版)》2008,(5):12
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. 相似文献
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"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 《中国对外贸易(英文版)》2008,(10):16-17
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. 相似文献
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Guo Yan 《中国对外贸易(英文版)》2008,(12):62-63
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, 相似文献
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Liu Xinwen 《中国对外贸易(英文版)》2008,(7)
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. 相似文献
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Guo Yan 《中国对外贸易(英文版)》2008,(1):10-10
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, 相似文献