A new broadband differential phase shifter fabricated using a novel CRLH structure

Broadband phase shifters are mostly proposed and fabricated based on the scheme proposed by Shiffman, which uses a coupled line with far ends connected together and a uniform transmission line to give a differential phase shift. Based on the unique dispersion property of the composite right/left-handed (CRLH) metamaterial structure, a new configuration is presented in this paper for fabricating the broadband differential phase shifter, which employs a novel CRLH metamaterial structure as one of the differential phase-shift arms, instead of the conventional coupled line. The new circuit can achieve a phase shift of 90° in an operational bandwidth as broad as one octave and its phase deviations are quite small. An original design of the novel broadband phase shifter is presented, in which the artificial CRLH structure was implemented by microstrip quasi-lumped elements. Both the simulated and measured results of the 90° broadband differential phase shifter are presented.     

宽带啁啾脉冲放大理论研究

从麦克斯韦方程组出发,推导了宽带啁啾脉冲放大的理论模型方程.该方程和非线性Schr dinger方程有相同的形式,可用分步傅里叶算法对其在数值上求解.     

中科大超宽带项目通过验收 脉冲速度可达400Mpps

由中国科学技术大学牵头承担的国家863计划重大项目“基于脉冲体制的超宽带无线通信关键技术研究与系统演示”，于近日通过国家863计划通信技术主题专家组的验收。该项目由中国科学技术大学和清华大学共同承担，中国科学技术大学信息学院王卫东教授担任课题组长。     

Optimal design on wideband directional coupler

Combining the modified Bethe small holes coupling theory with McDonald thickness theory and field averaging correction factor, it is accurate to design the weak coupling waveguide directional coupler. While the coupling is tight, the decrease of the field strength in the main waveguide caused by aperture should not be neglected. For a −6 dB directional coupler is described in this article, the theoretical value of coupling is good agree to the simulation value, by simulated and optimized with the professional software computer simulation technology (CST). In the designed waveband, the error of coupling between theoretical value and simulating one is less than 0.25 dB. The error of coupling between simulation value and designed value is less than 0.5 dB. To improve the isolation, some spaces between two adjacent holes are turned from the traditional ? centre guided wavelength. The performance of isolation has 5 dB improvement, and length of the coupling area is only 51.06 mm.     

LMDS：宽带无线接入

过去10年中，随着通信行业千方百计地努力满足世界各地对带宽日益增长的需求，通信行业经历了一个飞速发展的革新时代。若干动向——包括因特网的迅速扩大、对数据的依赖日益加深以及全球性的通信行业解控潮流等——正在为这一增长推波助澜。     

宽带IP城域网规划与建设研究

本文主要对宽带IP城域网的规划与建设问题进行了研究。本文首先分析了宽带IP城域网的技术,然后探讨了宽带IP城域网的IP地址规划和路由规划问题,最后对宽带IP城域网的建设问题进行了研究。     

流媒体在视频新闻传播中的应用

本文从流媒体的特点及相关技术入手，对流媒体技术在网络视频新闻传播中的应用现状进行了研究；并通过分析其网络传播中存在的难点及对策，初步探讨了流媒体新闻的发展前景。     

四种有线宽带接入网的比较

有线宽带接入网包括ISDN(以56Kbps为定界)、ADSL、Cable Modem和DDN四种,本文从概念、特点、安全等方面对四种有线宽带接入网作一比较。 1、概述 1.1 ISDN。ISDN(Intergrated ServiceDigital Network)综合业务数字网,是在IDN的基础上,实现用户线路传输的数字化,提供一组标准的用户/网络接口,使用户能够利用已有的一对电话线,连接各类终端设备,分别进行电话、传真、数据、图像等多种业务通信,或者同时进行包括话音、数据和图像的多媒体业务通信。ISDN分N—ISDN(窄带)和B—ISDN(宽带)两种。宽带ISDN主要是指基于ATM的能提供150Mbps以上速率接口的业务,但必须改     

无线接入技术--发展农村通讯的有效手段

我国农村因为经济落后、地域辽阔、地形复杂、村落和人口分散，用传统的有线接入技术解决用户终端的通讯网络接入十分困难，直接影响了农村的通讯基础网络的建设。采用无线接入与有线接入相结合的模式去解决农村用户终端的“最后一公里”接入，是现阶段我国发展农村通讯的有效手段。