一种高效宽带数字下变频器的设计与实现

针对雷达系统小型化和低功耗的应用需求,提出一种宽带雷达数字接收机中数字下变频器的设计方法.通过采用系统采样频率等于输入信号中心频率4倍的采样技术,结合混频器的特殊实现结构以及半带FIR滤波器抽头系数的特点,经过详细的理论推导后,给出该方法具体的硬件实现结构,能够显著降低数字下变频信号处理的复杂程度,有效减少对硬件逻辑资源,尤其是硬件乘法器的消耗.该方法在FPGA中实现时,与使用传统方法设计的数字下变频器相比,硬件逻辑资源消耗减少83.65%,功耗降低约110 mW.最后,设计实例结果验证了设计方法的正确性以及很好的工程实用性.     

宽带式隔板极化器

介绍一种宽频带隔板极化器的设计原理、设计思路及其设计实例。这种极化器具有频带宽、轴比小、圆极化端口隔离度高及体积小的特点。对其功率容量的高频仿真表明他能承受较大功率。他可广泛用于微波馈电网络系统。     

零偏置宽带检波器

本文简述了1～18GHz和18～40GHz检波器的设计考虑和实验结果.这两种检波器在零偏置、非调谐的工作状态下,都获得了正切灵敏度不低于-50dBm的结果.     

宽带多媒体数字信号处理器--MAP-CA

近年来,高速DSP(Digital SignalProcessor)发展很快,尤其是VLIW(超长指令字)结构成为高端DSP的主流技术,除了传统的通用DSP产品采用VLIW技术外,针对多媒体应用的专门化通用可编程DSP也有了长足进展,例如Philips的Tri-Media系列和Equa-tor的MAP_CA系列等,在我国都已经开始应用于多媒体系统设计中,本文以MAP_CA为例,分析一下这类多媒体处理器的特点和应用。     

Polarizer with Nonrectangular Grooves in the HE11 Mode Transmission Line

This paper presents experimental results on polarizers with nonrectangular grooves to be used in high power millimeter wave transmission lines for electron cyclotron heating (ECH) of fusion plasmas. A low-power test at a frequency of 106.4 GHz has been carried out for several polarizers with different groove depths. The polarization characteristics experimentally measured are in good agreement with numerical results in which the actual groove shape functions are taken into account. This confirms the design optimization for future polarizer. Favorable results have also been obtained in a 400 kW-level high-power test for the polarizer installed in an ECH transmission line of the Heliotron-E plasma device.     

宽带之浅探

简要地介绍了宽带技术，几种宽带接入方式及其它们之间的相互比较。     

C波段高频率稳定度宽带FET电压控制振荡器

本文叙述了用场效应振荡管和砷化镓常γ电调变容二极管及恒温控制电路等构成的C波段高频率稳定度宽带场效应管电压控制振荡器(VCO)的设计和电性能.通过合理的设计,VCO在4～6～8GHz的频率范围内,得到输出功率大于30mW,功率平坦度小于1dB,频率稳定度在10~(-5)量级.     

Attenuation and Radiation Characteristics of the HE /Sub 11/ - Mode

The asymptotic properties of the fundamental mode HE /sub 11/ inside a large waveguide of finite surface impedances are discussed. The analysis applies to corrugated waveguides, certain optical fibers and wave-guides with metal walls coated by a dielectric layer. It is shown that for k-->/spl infin/ the HE /sub 11/ mode has the following two properties: it is polarized in one direction and the field vanishes at the boundary. Because of these properties, it is useful in the design of microwave feeds, since it minimizes cross-polarization and edge illumination at the aperture. It is also useful for long distance communication because of its low attenuation constant. Both the far field of a feed and the attenuation constant are discussed. It is shown that rectangular apertures have negligible cross-polarization over wider bandwidth than circular apertures. Furthermore, if the medium inside a waveguide is Iossless, so that power is lost only at the boundary, then the attenuation constant is very small, it is asymptotic to (ka)/sup -2/ for large ka, where k= 2 pi/lambda and a is a characteristic dimension of the waveguide. A rectangular waveguide consisting of four metal plates coated with thin dielectric layers is shown to be attractive for long distance communication, because of its simplicity of fabrication and its low attenuation.     

构建宽带业务体系

中国互联网已进入宽带时代,针对宽带业务发展的现状及存在的问题,电信运营商应该根据宽带网络的构建原则,体系的特点以及宽带接入、内容应用、分发承载平台,业务支撑平台等几大关键环节,积极构建宽带业务体系。     

浅论宽带接入网

本文讨论了建设宽带接入网的必要性 ,简述了在无源光纤网络、不对称数字用户线和有线电视光缆 /同轴电缆混合网上实现宽带接入的方案 ,并探讨了B CDMA在宽带接入网中的应用。     

高速宽带频率综合源

<正>南京电子器件研究所模块电路事业部研制开发了一款全数字化的高速宽带频率综合源模块,该模块尺寸为152.4 mm×152.4 mm×29mm,如图1所示。频率范围2.0~22.0 GHz;频率步进10 kHz;输出功率≥10 dBm;跳频时间≤1μs,如图2所示。单边带相位噪声≤-95(dBc/Hz@1kHz),如图3所示。杂散≤-50 dBc,如图4所示。该模块可替代进口模块。     

宽带无线接入技术-WLAN

宽带无线接入技术是无线接入技术的重要分支。介绍了当前主要的宽带无线接入技术标准WLAN技术的特点,详细介绍了WLAN的各组成部分,并讨论了它的应用前景与发展趋势。     

TE /sub 11/ to HE /sub11/ Cylindrical Waveguide Mode Converters Using Ring-Loaded Slots

A theoretical parameter study is given of a TE/sub 11/ to HE/sub 11/ mode converter consisting of a section of cylindrical corrugated waveguide with ring-loaded slots. The analysis, using modal field-matching techniques to determine the scatter matrix of the converter, allows the return loss to be computed accurately. For a wide range of waveguide sizes it is shown that a bandwidth ratio of 1.5 with a return loss better than 30 dB is possible. The low-frequency performance of the converter is limited by the deterioration in return loss, while at high frequencies the generation of a small amount of unwanted EH/sub 12/ mode is the restriction. If the effects of this mode can be neglected, operation over a wider bandwidth is possible, particularly for larger waveguide size.     

UHF宽带同轴-矩形波导转换器新结构

研制了一种UHF波段宽带的同轴一矩形波导转换器.这种转换器采用了新结构,它的同轴探针呈阶梯状,并在波导宽壁上配有2个调谐螺钉.经测试,转换器在490～750 MHz的频段内(矩形波导TE<,10>单模工作带宽),回波损耗低于-31 dB,在483～782 MHz的频段内回波损耗低于-30 dB.     

宽带低频放大器的设计

文中讨论了宽带低频放大器的设计。宽带网络采用有源低通滤波器和有源高通滤波器组合而成。在电路设计中,有源滤波电路和放大电路采用同一放大模块,这样简化了电路,缩小了体积,提高了产品的可靠性。通过分析低通滤波器和高通滤波器的设计过程,给出了试验数据、滤波器波形和宽带低频放大器电路图,再经过调整得到较好的通频带波形。该放大器在10～85kHz这个范围内,有较好的增益平坦度和稳定的性能,电压增益为60dB,满足设计要求。     

宽带网络与服务质量（QOS）

通过对宽网络的服务质量（ＱＯＳ）参数的分析，论述了ＡＴＭ宽带网络是如何满足不同业务的服务质量ＱＯＳ要求的。     

宽带行波管可靠性预计模型研究

通过对批量生产的应用于电子对抗系统国产行波管的可靠性数据的收集、分析,得出其可靠性水平.依据收集到的可靠性数据,通过回归分析建立宽带行波管可靠性预计模型.比较所建立的宽带行波管预计模型与299C中行波管可靠性预计模型的基本故障.列举出宽带行波管主要故障模式,并初步分析其故障机理.     

具有分形特征的宽带人工磁导体结构

介绍了一种新型的具有分形特征的宽带 AMC 结构。这种结构是将普通 AMC 结构贴片的边缘用 Minkowski 环代替形成,结果发现使用这种结构可以得到更宽频带的电磁带隙。在3GHz 左右的频率,电磁带隙宽度可提高28%左右。这种结构可用于实际的宽带电路和天线中。     

宽带三波束双弯曲反射面天线

双弯曲反射面天线是一种经典的赋形反射面天线。本文对其偏焦和宽频带性能进行了研究。采用优化设计的方法,实现15％带宽、偏焦7.5°(6.25倍波束宽度)的偏焦波束.并在此基础上实现了天线的三波束工作。     

Development of Broad Band VCO at Ka-Band

A broad band VCO has been developed at Ka-band for FMCW Radar applications. To achieve a wide range of frequency variation, VCO has been designed in series configuration. Design steps have been presented. VCO exhibits a tuning range of 600 MHz with the power output of 50 mw, when the controlled varactor voltage varies from 7.5 volts to 15 volts. Frequency drift with temperature has been contained within 30 MHz using a proportionally controlled DC heater module over the temperature range of 0°C to +55°C. Phase Noise of the oscillator measured at the mid and extreme frequencies is about -70 dBc/kHz at 10 kHz away from the carrier. The experimental circuit and measured performance is also presented.