【作者】 郝彦博；

【导师】 李媛；

【作者基本信息】 天津大学 ， 电磁场与微波技术， 2008， 硕士

【摘要】 本论文结合973项目——“基带处理与天线协同”,侧重对方向图可重构分形天线进行了研究。提出了多种方向图可重构的天线方案,为可重构天线的进一步研究和应用提供了较好的研究基础。本文简要介绍了可重构天线和分形天线的产生背景以及国内外研究现状,对天线的辐射机理进行了介绍,并且介绍了微带天线的相关知识,重点包括微带天线的辐射机理、分析方法、馈电技术和当今微带天线的两个重要发展方向——宽带和小型化。接下来介绍了分形结构及分形天线的一些基本概念和理论。本文首先提出了一种新型的由Hilbert二阶曲线发展而来的贴片结构,并设计了三种不同形式的可重构方案,通过开关的通断调节天线的状态使天线均能实现E面方向图扫描。此天线相比高阶Hilbert曲线构造的天线具有频带宽,频率低,结构简单、易制作加工、性能良好等优点。随之分析了天线介质基片的介电常数和尺寸变化对天线性能的影响,所得结果均与理论分析相对应。本文其次对Hilbert二阶曲线构造而成的可重构微带天线进行了更为深入的研究,通过对Hilbert可重构天线方向图的观察,引入了另一种构造微带贴片的方案,并实现了E面方向图可重构的设计。除此之外,还取得了该贴片部分数据的改变对天线性能的影响,以及用几种不同的措施改善了天线性能。改善后天线的相对带宽由11.8%提高到87.3%,且谐振频率分别减小1.49GHz和2.14GHz。本文根据仿真的结果设计制作了天线,测试结果与仿真结果基本吻合。在介绍了前面各部分的基础上,本论文在最后部分对课题阶段所做的工作进行了总结,并对后续研究工作进行了展望。更多还原

【Abstract】 This dissertation, connected with 973 project,“cooperation of baseband and antennas”, is focused on the research of pattern-reconfigurable planar fractal antennas. And several schemes of pattern-reconfigurable antennas are presented in this dissertation. This work provides good basis for the future work.The dissertation briefly introduces some producing background and research status at home and abroad about the reconfigurable antennas and fractal antennas. Then, the basic theory of the antenna radiation is introduced, the theories about the microstrip antenna are introduced, such as the mechanism of the microstrip antenna radiation, two methods based on transmission line model and cavity model, which are used to analyze the microstrip antenna, and the feeding methods of microstrip antenna. Especially, recent development of wideband and miniature microstrip antennas is presented. Subsequently, the basic ideas and theory of fractal structure and fractal antenna are presented briefly.Firstly, three schemes of pattern reconfigurable Hilbert patch antenna are presented by introducing the new patch structure. By switching the states of the antenna, the radiation beams can scan in the E-plane in the upper space. Then, the analyses of dielectric constant and dimensional of dielectric substrates on antenna performance are given. The new antennas have strongpoint thereinafter: high frequency bandwidth, low frequency, simple making and good performance.Secondly, the deeper study in the research of Hilbert patch antenna is done by introducing another patch structure. At last, we introduced several different measures to improve the performance of antenna. The new antenna’s relative bandwidth is risen from 11.8% to 87.3%, and resonant frequency is reduces 1.49GHz and 2.14GHz. And the testing result of the experimental sample is agreement with the simulated results.At last, we give the summary of the research work and expect about the future work.更多还原