采用变容管端接微带谐振器的L波段低噪声VCO理论分析与设计

本文在对振荡器相位噪声分析的基础上,从影响相位噪声的因素出发,选择了微带结构的克拉波电路;在满足振荡条件的基础上,采取了加大负反馈电容的办法,使振荡器的输出相位噪声改善约-5dBc/Hz/10kHz,在相对调谐带宽10%～20%时,获得相位噪声优于-95dBc/Hz/10kHz,功率波动±1dBm.     

基于PE3236频率锁相源的X波段四倍频器研制

目前毫米波倍频器在毫米波频率合成器中已经得到了广泛的应用,利用毫米波倍频器可以获得具有宽带特性的毫米波频综及多点的频率输出。文中主要介绍一种基于高性能数字集成芯片PE3236设计的X波段四倍频器。通过将高稳定度频率合成器输出的S波段信号四倍频,并滤除杂散和谐波以达到倍频的效果。文中所设计的毫米波四倍频器输出功率为-11.356 dBm,相位噪声为-78.4 dBc/Hz@1 kHz,对杂散的抑制优于-45dBc。     

CMOS负阻补偿型压控振荡器关键技术研究

采用TSMC 0.18μm CMOS工艺,设计了一个中心振荡频率为2.46GHz的负阻补偿型LC压控振荡器。该压控振荡器采取差分负阻结构,利用反型NMOS电容实现频率调谐。通过对可调电容的特性研究,振荡器实现2.08GHz~2.84GHz的宽频率覆盖范围调谐,同时通过调节负阻器件的宽长比、优化片上螺旋电感几何参数获得高品质因数等方法提高振荡器的相位噪声性能。在1.8V供电电压下对电路仿真,相位噪声小于-120dBc/Hz@1 MHz,最低可达-125dBc/Hz@1 MHz,工作平均电流为3.74mA。在1.6V供电电压时工作正常,满足单芯片跳频频率综合器的应用要求。     

15GHZ高线性、低相噪压控振荡器研究

本文在对克拉泼电路的理论分析基础上，运用Microwave Office软件仿真、优化出耦合元件Lgx、Cg的取值范围，用封装的场效应管、变容二极管设计、研制出15GHz压控振荡器，在14.7-15.4GHz调谐带宽内，振荡器的线性指标达到1.15，功率输出为15dBm，偏离载频100KHz,相位噪声倨于-80dBc/Hz。     

一种容易实现的微波介质谐振器 FET 振荡器

本文比较了微波介质谐振器 FET 振荡器的几种不同设计方法,介绍一种简易可行的设计,并给出一个5GHz 振荡器的实例。     

单层反射模式蓝宝石腔体的9.7GHz频率基准

分析了多层圆柱形蓝宝石腔体谐振器为实现Bragg谐振模式需满足的尺寸条件。仿真并设计了单层腔体,利用teflon支撑件将蓝宝石固定在内部镀银的金属腔体内。其在9.7GHz频点实现了Bragg包含模式,Q值高于200 000。利用该谐振器作为带通滤波器构建了室温下的X波段振荡器。该振荡器还包括低噪放、滤波器和手动移相器。通过合理选择谐振器的插入损耗和调节移相器,该振荡器成功实现了稳定输出。测试结果表明,该振荡器具有低的相位噪声但易受环境温度影响。由于采用了极高Q值的蓝宝石谐振器,该振荡器可能成为目前最低相噪的X波段室温频率基准。     

基于ADF4360-X的频率合成器设计

结合锁相环的基本原理,介绍了高集成整数分频频率合成器芯片 ADF4360-X 的特性,该系列芯片集成了 VCO 非常利于设备的小型化;以 ADF4360-7为例,给出了实际应用中的设计要点、实现方法和实现电路时的注意事项。测试结果显示,设计的频率合成器覆盖范围达到400 MHz,步进1 MHz,偏离中心频率1 kHz 处相位噪声达到-93 dBc/Hz。     

低调谐增益变化的10 GHz电感电容式压控振荡器设计

基于0.18μm CMOS工艺,设计了一种应用于无线通信和雷达系统的低变化调谐增益的电感电容式压控振荡器。该电路包括分布式偏置可变电容阵列和开关电容阵列,合理选择偏置电压扩展电容-电压曲线覆盖范围,在整个调谐电压范围内,可有效降低调谐增益。三位开关电容阵列将整个可调频率范围分为8个子频带,通过控制可变电容实现子频带内频率的调谐范围。同时采用开关可变电容阵列,有效抑制了电感电容式压控振荡器调谐增益的变化。基于1P6M 0.18μm工艺模型的后仿真结果显示该10 GHz压控振荡器调谐增益变化率表现优异,低至21.5%,调谐频率范围为9.13～11.15 GHz,同时该压控振荡器能够实现较低的直流功耗9 m W(1.8 V电源电压),相位噪声在10 GHz时为-105 d Bc/Hz@1 MHz。     

一种改进的SIR双频带通滤波器设计与实现

文章介绍了阶梯阻抗谐振器SIR(Stepped-Impedance-Resonators)的结构和原理,分析了这种结构谐振器的优越性,在此基础上采用3级半波长(λg/2)谐振器设计了一种应用于无线局域网WLAN(Wireless LocalArea Network)系统(IEEE-802.11a/b/g)的双频带通滤波器,这种滤波器的特点是其寄生响应可通过阻抗比(RZ)和谐振器的长度进行调节。使用仿真软件HFSS进行仿真,并对其进行加工测试,仿真结果和测试结果的稳合很好,在两个中心频率为2.4 GHz和5.2 GHz的通带内,插入损耗分别小于0.6 dB和0.9 dB,相对带宽分别为7.8%和7.7%,且两通带间的抑制特性好,频率为3.5 GHz～4.2 GHz之间的抑制损耗达到60 dB,各项指标满足工程设计要求。     

一种用于传送电视信号的微波介质振荡器调制器

介质谐振器作稳频的振荡器(DRO)以其特有的成本低、体积小、可靠性高、功耗低等优点,在通信、雷达、导航等领域得到了广泛的应用.但在目前新型的微波通信设备中,往往要求微波固态源具有调制性能,以便能插入次基带或超基带公务信号,以提高频谱利用率.另外,在载波上直接进行调制后,可简化通信设备,降低成本和提高设备可靠性.本文介绍的微波介质振荡器调制器是为某电视信号传送电路而研制的,其工作频段在X波段,调制带宽可达27MHz以上,输出功率17kBm以上,频率温度特性为±1.75ppm/℃.     

Helping hands: civil–military cooperation and Italy's military operation abroad

In the Post-Bipolar Era the growing complexity of the military operations requires a new approach for the resolution of international crises. Since the end of the Cold War, peace support operations (PSO) have become the mainstay and principal occupation of most Western armies. At the same time, Italy has been one of the most important actors in such an area. The article focuses on the cooperation between military and civil components (a process called CIMIC) as a key variable in the Italian PSOs. We will analyse in detail the main lessons learned from past military interventions as well as the general context in which new tendencies are taking place. The maintaining of a minimum security frame becomes essential to fulfil activities ‘collateral’ to the mission: reconstructing services and infrastructure, food distribution, water and medication, law and order, de-mining, training of local forces, and supporting local institutions. These are the main tasks to obtain thrust and support from the population.     

Terrorism,insurgency, kidnapping,and security in Africa's energy sector

Energy continues to serve as the bedrock of modern economies and the main driver of modern society. For Africa, the production and supply of energy resources such as crude oil, natural gas, uranium, coal, biomass, biofuels and other renewables are an important source of employment, rents, taxes, royalties and profits. This sector brings in several tens of billions of dollars of revenue annually. The production and delivery of such resources, however, depend on critical infrastructures such as pipelines, refineries, processing plants, terminals, rigs, electrical energy pylons, substations, pump stations, vessels, and tankers. These infrastructures have been attacked by terrorists, insurgents, vandals and saboteurs, all of whom see them as targets against which to register their grievances and extract concessions from the state. This paper is a chronological account of some of the documented incidents of terrorism, insurgency, kidnapping, destruction, sabotage, and human casualties suffered in the oil and gas sectors in Africa between 1999 and 2012. It is based on data extracted from the databases of the RAND Database of World Terrorism Incidents and the University of Maryland's Global Terrorism Database (GTD).     

Tacit support for terrorism: The rapprochement between the USSR and Palestinian guerrilla organizations following the 1967 war

This article demonstrates the inconsistent and wavering Soviet attitude towards national liberation movements in general and the Palestinian organizations in particular. Until the late 1960s, the Soviets viewed these organizations with suspicion, hesitating to engage in political dialogue with them. However, in the 1970s, political and military events in the region, as well as modifications in the Kremlin's Cold War strategies, led to a general shift towards the Middle East in Soviet foreign policy. Soviet leaders showed increased willingness to provide certain Palestinian organizations with arms with which to conduct terrorist activities against Israeli, pro-Israeli, Jewish and Western targets. The article explores the complex relations between Palestinian organizations and the USSR in the field of international terror. The study also exposes and analyzes the nature and content of Soviet–Palestinian arms dialogues and transactions. It provides clear evidence that Soviet policymakers and other luminaries were fully informed of, and sometimes directly involved in, these transactions and dialogues at the highest levels.     

A1 Qaeda and the radical Islamic challenge to western strategy

The September 11 global crisis prompted by the attacks on the World Trade Center and the Pentagon raises major questions concerning the nature and trajectory of terrorism in the post-Cold War global order. Hitherto, terrorism has been largely debated by analysts at the level of nation states. Terrorist and insurgent movements have also been largely anchored in nationalist and ethnic power bases even when they have sought to mobilise a transnational ideological appeal on religious or class grounds. There have been a few exceptions to this pattern such as the alliance between the German Baader-Meinhof group and the Japanese Red Army Faction, but even such international alliances as this did not, until at least the 1980s, presage anything like a global terrorist network necessitating a global strategic response. This study examines terrorism and global strategic responses.     

Reviews

Douglas S. Derrer, We Are All the Target: A Handbook of Terrorism Avoidance and Hostage Survival. Annapolis, MD: US Naval Institute Press, 1992. Pp. x+135, notes, index. $14.95. ISBN 01–55750–150–5

Ian Knight, Zulu: Isandlwana and Rorke's Drift, 22–23 January 1879. London: Windrow & Greene, 1992. Pp.136, 150 illus., incl 8 colour plates, maps, biblio. £35. ISBN 1–872004–23–7

Ian Knight, By the Orders of the Great White Queen: Campaigning in Zululand through the Eyes of the British Soldiers, 1879. London: Greenhill Books and Novato: Presidio Press, 1992. Pp. 272, 17 illus., 1 map. £18.95. ISBN 1–85367–122–3

Manfried Rauchensteiner and Erwin A. Schmidl (eds.), Formen des Krieges: vom Mittelalter zum ‘Low‐intensity’ Conflict’. Graz : Verlag Styria, 1991. Pp.208. DM35. ISBN 3–22–12139–7

Harold J. Kearsley, Maritime Power and the Twenty‐First Century. Dartmouth: Dartmouth Publishing Company, Limited, 1992. Pp.xv + 203, 13 diagrams, index. £32.50. ISBN 1–85521–288–9     

Helping hands: external support for the KNU insurgency in Burma

This article analyses to what extent the Burmese KNU insurgency made use of external support from states, refugees, and diasporas. Based on extensive fieldwork it is concluded that support from neighbouring states and refugees has for years kept the Karen rebellion alive. Western countries perceived forms of resistance to the illegitimate Burmese regime as just and have therefore played a crucial role in the continuation of conflict in Karen State. It is important that policymakers and donors as well as executing organizations continue to reflect critically on the way they exercise their work.     

基于GTST-DMLD-ESD的装备RMS建模仿真

装备的RMS是装备的重要设计参数,是影响战备完好和保障能力的关键因素.引入GTST-DMLD作为主要建模工具,建立起装备系统的RMS描述模型,以ESD为补充和扩展,对维修过程进行建模.并以GTST-DMLD-ESD模型作为装备RMS仿真的核心,对装备RMS仿真模型的总体框架进行了研究,并对各模块进行了较为详细的探讨.     

Panjwai: a tale of two COINs in Afghanistan

The US Army has two approaches to counterinsurgency operations in Afghanistan. One is hard, or combat-focused, and the other is soft, or development-focused. This study examines two US Army task forces deployed to Panjwai District, Afghanistan from 2012 to 2013. CTF 4-9 and 1-38 offer a meaningful comparison because they pursued these contrasting approaches among the same population and against the same enemy at the same time and place. The study compares each unit’s approach and finds that neither approach was successful absent the other. The article concludes by recommending further research into combining the approaches at the operational level.