分形微带天线的研究-信号与信息处理专业论文.docxVIP

万方数据 万方数据 摘要 随着通信技术的飞速发展，天线设计需求越来越多：要求天线具有体积小,易于制造、保 形、低成本、多频和宽频带特性。微带天线具有质量轻、体积小和易于制造等优点，已广泛 应用于个人无线通信中。但传统微带天线具有较窄的带宽难以满足现代通信对其频带的要求， 因此实现微带天线的多频、宽频带成为天线研究的重要课题。 传统实现天线小型化、多频和超宽带功能的方法过于单一化，往往以牺牲其它指标为代 价，难以满足现代通信系统的综合性指标要求。而分形天线的独特特性使其成为解决这一问 题的较佳选择，本文对采用分形技术的小型化多频天线和小型化宽带天线进行了深入的探究。 本文首先提出了一种多重分形天线结构，该结构是将经典Koch曲线和Sierpinski垫片以主 —次方式相结合形成的。由仿真结果可得，在1.5-15GHz频带内，拥有6个频率点，且在阻抗 匹配、尺寸缩减、增益和效率方面都比单一分形天线有较强的优势。此外，通过对参数设置， 设计了一款新型超宽带天线，其相对于传统三角贴片天线尺寸缩减了38.9%，实现了天线的小 型化。在3.76-5.81GHz的整个工作频率范围内呈现出稳定的辐射方向图，可以应用于PCS， UMTS，WLAN，WiFi，WiMAX等其他通信领域。以正多边形为原型设计了两种伪分形天线， 实现了天线的多频带和宽带特性，第一种新型超宽带天线的阻抗带宽为20-29.78GHz，具有 12.64GHz-14.38GHz，15.07GHz-15.71GHz，15.26GHz-16.46GHz，18.12GHz-19.24GHz多频带； 第二种天线实现了宽频带特性，天线带宽为3GHz-10.8GHz且结构简单，尺寸小且天线增益也 满足移动通信天线应用的要求尺寸小而方便应用于通信。 关键词：分形；多重分形；微带天线；多频；宽带 I Abstract With the coming of information age, there has been an increasing demand, in military as well as the commercial applications for such antenna design that possess the small size, ease of fabrication, conformal, low cost and wideband capabilities. As the microstrip antenna has the advantages of light weight, small volume and easy to manufacture, they have been widely used in personal wireless communication. But the traditional microstrip antenna with narrow bandwidth is difficult to meet the requirements on the frequency band of modern communication. Therefore, to achieve the microstrip antenna with multi frequency, broadband has become an important subject in the research of modern antenna. There are many methods proposed to realize the miniaturization and multiband characteristic of the antennas. However, these methods are so specialized that only some aspects of the demand can be met while the overall performance of the antenna is decreased to satisfy the communication system. To solve this dilemma, this dissertation proposes miniaturized, multi-band and wideband antennas based on fractal structures theory and discusses the problems during the research of the antennas’ design as follows. In