W频段二次谐波I/Q调制混频器的设计

基于自主研发GaAs肖特基二极管（SBD）设计了一款工作于W频段的二次谐波混频器,实现了对射频（RF）信号的I/Q调制。建立了二极管模型,利用电路结构走线长度控制信号流,实现了宽频带内的射频信号混频,并基于此通过HFSS和ADS联合仿真,完成了W频段二次谐波混频器设计。测试结果显示,采用45 GHz信号作为本振信号源,射频80~89 GHz与91~100 GHz的频带范围内变频损耗低于17 dB,最低变频损耗为12 dB;1 dB压缩功率大于11 dBm。仿真结果显示,80~89 GHz与91~100 GHz的镜频抑制效果明显,最好频点镜像抑制达到20 dB。相比于W频段GaAs pHEMT（赝晶型高电子迁移率晶体管）混频器,所设计的GaAs肖特基二极管混频器在较低变频损耗的情况下,具有工艺简单、易实现、高线性度、宽带匹配、高镜像抑制等优点,芯片尺寸仅为1 mm×1 mm。该款W频段混频器达到了目前国内较高水平。     

Ka频段宽带镜频抑制谐波混频器的设计

介绍了一种在Ka频段具有镜频抑制功能的四次谐波混合集成电路混频器的设计与实现.该混频器主要采用微带混合集成电路,由薄膜陶瓷基片制作.经测试,当中频固定在70 MHz,在射频大于4 GHz带宽内,变频损耗小于11.2 dB,镜频抑制度大于20 dB.     

低本振宽带混频器

本本介绍一种低本振电平(P_L为-5dBm～-15dBm),加偏置的宽带专用混频器。其典型指标为:在3.5～6.4GHz频带内,变频损耗(当P_L为-10dBm时)Lc约7.5dB、波动±1dB、并且可在3～7GHz频带内正常工作,L_c小于9dB,中频频率为100～200MHz。     

一种高线性短波宽带混频器的设计

采用双平衡场效应管结构和阻抗匹配技术设计了一种适用于短波宽带接收机的高线性 混频器,通过调整场效应管的沟道宽度和偏置电压优化了混频器的性能指标。该混频器射频 输入频率为15～30 MHz,本振输入频率为715～100 MHz,中频输出频率为70 MHz。测试结果表明：输入三阶截点高于40 dBm,变频损耗小于7 dB,1 dB 压缩点高于12 dBm,单边带噪声系数小于7 dB。     

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。     

5 mm高隔离鳍线单刀双掷开关

设计并实现了5 mm（U频段）单刀双掷（Single Pole Double Throw,SPDT）开关模块。该 开关模块采用鳍线并联PIN二极管电路结构形式,通过采用一种全新的高隔离度措 施,获得高隔离、低插损开关特性。经加工测试,开关模块在50～56 GHz频带内隔离度 大于50 dB,插损小于2.3 dB。该模块已应用于5 mm射频组件中。     

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。     

低损耗双谐振微带带通滤波器设计

为了既满足实现双谐振的零度馈电结构,又能实现阻抗匹配,采用双点双线馈电技 术和具有开口环、阶跃阻抗谐振双重特性的结构设计双通带滤波器。版图仿真结果表明：两 个谐振频率分别为2.7 GHz和5.05 GHz,符合射频电子标签所需的两路信号,其对 应的回波损耗分别为-38 dB和-49 dB,插入损耗为-0.2 dB和-0.4 dB,从 而实现了低损耗特性和尖锐的选择性。     

新型Koch岛分形耦合微带线带通滤波器

为抑制平面带通滤波器的二次谐波,实现高选择性和低插入损耗,提出了一种新型 Koch岛分形结构,并将其应用到平面耦合微带线带通滤波器的设计中。仿真及测试结果表明 ：所设计的新型Koch岛分形耦合微带线带通滤波器的中心频率为3 GHz,3 dB通带 宽度为10%;与传统的耦合微带线带通滤波器相比,该新型滤波器的二次谐波降低了1 1.5 dB,选择特性提高了5 dB/GHz,通带内最大回波损耗降低了4.7 dB,尺寸缩 小了近5%。该新型滤波器具有尺寸小、重量轻、成本低且性能好等优点。     

一种新型双频Wilkinson功分器的设计

为了实现功分器工作在任意两个频率的目的,设计了一种新型功分器。基于奇偶模分 析方法,利用微波网络理论推导了电路参数的设计公式,通过求解相应的非线性方程组获取 了具体电路参数。制作了一个工作频率为1 GHz和2.6 GHz的双频Wilkinson功分器 。实物测试结果表明,该功分器在两个中心频率的传输衰减小于3.3 dB,端口回波损耗 大于21 dB,端口隔离度大于28 dB,在中心频率100 MHz的通带范围内都具有良好性 能,验证了设计方法的可靠性。     

Public Financial Expenditure——A Reflection of the Livelihood Improvement

In recent years.China's public finance put social construction high on the agenda and attaches more importance on livelihood insurance and improvement.The 2003-2007 public financial expenditure reflects a fact that the government isputting more emphasis on livelihood andissues concerning the people.     

Voices from the MPC and CPPCC

"Crucial for economic growth.energy utilization has its role in all economic sectors and every aspect of people's daily life.Now we are in dire need of a new profession,namely energy manager.We not only need to have passion and responsibility,but also a scientific approach to conserve energy and cut emissions.APpropriate legislation should be in place.and a special profession should be introduced to ensure the implementation of these laws and regulations."     

Slowdown Trade Surplus Growth

According to Ma Kai＇s economic planning report submitted to the NPC session on March 5th,（Ma Kai is the Minister in charge of the National Development and Reform Commission）,the government has listed the slowdown in trade surplus growth and the steady expansion of external investment as major tasks for 2008.     

Ouyang Riping： A Hero Besides Entrepreneur

A bout fifty years ago. a baby＇s cry broke the sky of quietness, in a small and beautiful town of Hunan province, which surroundcd by green hills and clear water. Though his .birth brought his family great happiness and hope just as any new life, nobody knew that the little boy would get great achievement when he grow up. even start his business oversea, and earn international honor. Let＇s share with you the entrepreneur Ouyang Riping＇s story, which may insights thcsc people who want to succeed and complete oneself in favorite condition or adversity rather leave things to so-called fate.     

Belarus, A Chinese Fort in Europe

＂In recent years, we＇ve found increasing interest from Chinese investors in the Belarus economy. Please let China know, Belarus is always ready to be a true friend to China. We have built a fort in Europe for China,＂ the President of Belarus, Alexander Lukashenko told Zhou Xiaochuan, President of the Bank of China, during his visit to the capital of Minsk, on January 8th, he expressed his high praise and firm confidence in the development of Sino-Belarusian relations.     

What＇s Behind Spring Festival？

Similar to what the Christmas Day means for the westerners,the Spring Festival is the most important celebration for Chinese people.This big event according to Chinese traditional lunar calendar relaxes and pleases the whole country as the happiest gathering time of the year.National-wide crusade for going back home,too-difficult-to-get train tickets,generous family-going-out shopping,Miaohui laundering,New Year Eve reunion dinner,visiting friends and relatives,watching annual TV gala......each piece of clue reminds us of the smell of Chinese Spring Festival.     

KEY WDRDS for Foreign Investment in China

FDI(Foreign Direct Investment),a component of a country's national financlal accounts,is investment of foreign assets into domestic structures,equipment,and organizations.It does not include foreign investment into the stock markets,concession and subcontract.FDI iS thought to be more useful to a country than investments in the equity of its companies because equity investments are potentially "hot money"which can leave at the first sign of trouble,whereas FDI is durable and generally useful whether things go well or badly.     

Universal Coverage, Pinpoint Illustration and Profound Impact HTC 2008 Intermedia Recommendation and Introduction Meeting

Holding 88 percent of train media resources across China, based on "Time Cube", on the 2008 Intermedia Recommendation and Introduction Meeting on December 19, 2007, HTC announced its high-profile strategy of tour marketing and tapping the immeasurable potentials on the train. Meanwhile, HTC officially launched its brand new product Olympic Train on the meeting, providing a fabulous platform for all the brands that are prepared to do a smart marketing on the occasion of 2008 Olympic Games.     

Market presence in China strengthened Network growth and Dual-Chinese-Hub Strategy More frequet Flyer Benefit——Air China and shanhai Airlines Join Star Alliance

In the end of 2007, Air China Limited (hereinafter "Air China") and Shanghai Airlines, formally joined Star Alliance at a ceremony held in the new Terminal Three at Beijing Capital International Airport. With the addition of the two Chinese airlines, Star Alliance now has 19 member carriers operating 17,000 daily flights to 897 destinations in 160 countries.     

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.