车载卫星天线扫描与跟踪系统设计

首先从车载天线接收系统总体设计方案进行阐述,给出了相应的系统框图,进而在论述中规划了车栽卫星天线接收主控系统的硬件设计模块．接着研究分析了此次硬件设计中使用到的接口：SPI、TWI、USART,完成了MEGA64主控模块的硬件设计,并给出系统板的原理图,最后,给出了车载卫星天线扫描跟踪算法设计．     

一种小型三频段印刷天线设计

设计了一种微带线馈电的三频印刷天线,其辐射体有3个尺寸不同的矩形框嵌套而成,调整这些矩形框的长度和位置可以改变独立的电流路径,形成的频段用于WLAN和WiMAX系统。该天线结构简单,尺寸易于调节。测量结果显示:天线10 dB阻抗带宽分别为400 MHz(2.2~2.6 GHz)、700 MHz(3.28~3.98 GHz)和1 310 MHz(5.15~6.46GHz),并且具有良好的辐射特性。     

车载卫星天线快速找星控制系统的研究与设计

为了在运动的载体上能接收卫星信号,综合应用GPS接收机、电子罗盘HMR3000、信标接收机等多种新技术,设计一种由STC12C5A60S2单片机组成的快速卫星天线找星与跟踪控制系统,并阐述了各部分的工作原理、设计方法与软件算法的实现过程。经检测证明该系统能快速、准确的寻找到卫星。     

基于MIMO系统的快速天线选择算法改进

基于MIMO系统的天线选择技术是对收发两端的多根天线根据算法不同,进行不同方式的天线选择,以此降低射频电路成本与复杂度。研究一种更低复杂度的快速接收天线选择算法的改进,它具有较好的系统性能。仿真结果表明,所研究的次优算法,对比于最优算法具有较低复杂度,并且它大大降低了系统硬件链路成本,而系统容量损失极小,并保留系统的优越性。     

The rocky terrain between delocalized and localized,duplication and originality: learning to write and learning to teach academic English

In recent years, a discourse is emerging in education that emphasises the study of the impact of in-service teacher education on student outcomes (more often than not student outcomes are seen in the form of test scores of academic achievement). Implicit in this discourse is the view that the impact of in-service teacher education is directly observable on students' outcomes, suggesting that the variables in a school or classroom are connected in some kind of a causal link. However, it is problematic to view variables in a social setting such as a school or a classroom as being in causal relationships because social settings are complex so that it is not possible to control the variables or the outcomes. Hence, one cannot convincingly study the outcomes without also studying the process and its complexity. In this article, I describe an action research study undertaken to study the impact in the classroom, of new teaching strategies introduced as part of an in-service teacher education programme in Karachi, Pakistan. By describing this study I mean to suggest that action research is an appropriate methodology to study the impact of in-service teacher education.     

一类上三角形矩阵可交换的充要条件

给出了一类上三角形矩阵可交换的充要条件 ,并由此得到了求其逆矩阵的一种简便方法 .且证明了该类矩阵不可对角化 .     

一种圆柱形介质谐振器天线阵列设计

在圆柱形介质谐振器天线单元分析的基础上,设计了一种4单元介质谐振器天线阵列。天线阵采用微带线馈电网络,保证单元之间满足相位匹配关系,使该天线阵列具有良好的定向辐射特性,而且在带宽方面满足要求。     

A new photonic bandgap cover for a patch antenna with a photonic bandgap substrate

INTRODUCTIONInvestigationofphotonicbandgap(PBG)materialsiscurrentlyoneofthemostactivefron-tiersinengineeringandphysics.PBGmaterialshaverecentlyemergedasanewmultidisciplinaryfieldofstudy(Kesleretal.,1996;Yablonovitch,1994;SimovskiandHe,2001).APBGstructurecanhaveabandgapwithinwhichelectromagnetic(EM)wavepropagationispreventedinalldirec-tions(Joannopoulosetal.,1997;Ozbayetal.,1994).Foratwo-dimensionalPBGmaterial,thepropagationofanEMwavewithinitsbandgapispreventedinalldirectionswithin…     

一种展宽波导裂缝天线带宽的新方法

辐射缝隙导纳及波导导内波长的频率特性，是影响裂缝天线带宽的主要因素。本文以改善这两个参数的频率特性为出发点，提出了一种展宽波导裂缝天线带宽的新方法，即用脊波导代替矩形波导作为辐射波导。仿真分析表明脊波导裂缝阵列的带宽有较大的改善，这与理论分析的结果是一致的。本文的研究成果为展宽波导裂缝天线的带宽提供了一个新的思路。     

矩阵法解线性微分方程组

运用矩阵的基本行变换和列变换将系数矩阵化为上（或下）三角矩阵,以此来求解线性微分方程组,并进一步利用矩阵的若当标准形,讨论更一般的线性微分方程组的解法．