基于分形结构的宽带天线设计

基于分形结构的宽带天线设计(任务书,开题报告,论文13000字)
摘要
随着无线通信技术的高速发展，人们对于天线的小型化与宽带化的要求越来越高。但是，传统的天线基本上都是基于欧式几何的形状设计的，这些天线的尺寸大多为半波长大小，而且最大的缺点就是带宽很窄。因此，需要探索一种新理论和方法来解决天线的宽带化以及小型化问题。而经过研究发现，将分形理论应用到天线技术中，可以有效的拓展天线的带宽。
本文首先介绍了宽带天线的研究背景以及国内外发展状况，并详细说明了几种天线宽带化技术，并在其中介绍了分形技术的一些特点以及近些年国内外所研究出的分形天线，接着又详细介绍了分形理论以及实现分形的数学方法。这些理论都为实现设计基于分形结构的宽带天线提供了理论支持。
其次，本文将分形理论与天线技术相结合，设计出了两款基于Koch分形结构的宽带天线。第一款天线将Koch分形结构与八边形辐射贴片相结合，其相对带宽达到97%。第二款天线是将Koch分形结构与单极子天线相结合，设计了一款谐振频率为2.45GHZ的宽带天线，其相对带宽达到32.7%。这两款天线都满足宽带天线的带宽要求。
最后，将设计出的天线进行加工，并测量其特性参数，其测量结果与天线的仿真结果基本相似，从而可以验证将分形结构与天线技术相结合确实可以有效拓宽天线的带宽。
关键词：分形结构；宽带天线；分形天线
 
Abstract
With the rapid development of the wireless communication technology, people are increasingly demanding the miniaturization and broadband of antennas. However, the conventional antennas designed are basically based on the shape of the European geometry. The size of these antennas is mostly half the wavelength, and the biggest drawback is that the bandwidth is very narrow. Therefore, it is necessary to explore a new theory and method to solve the problem of broadband and miniaturization of antennas. After research, we found that applying the fractal theory to antenna technology can effectively expand the bandwidth of the antenna.
Firstly，This article introduce the research background and development status of broadband antennas, and explained several antenna broadband technologies in detail, and introduced some characteristics of fractal technology and fractal antennas researched at home and abroad in recent years. It also introduces the fractal theory and the mathematical method of fractals in detail. These theories provide theoretical support for the design of broadband antennas based on fractal structures.
Secondly, this paper combines fractal theory with antenna technology and designs two broadband antennas based on Koch fractal structure. The first antenna combines a Koch fractal structure with an octagonal radiating patch, with a relative bandwidth of 82.7%. The second antenna is a combination of a Koch fractal structure and a monopole antenna. A broadband antenna with a resonant frequency of 2.45 GHz is designed, and its relative bandwidth is 22.7%. Both antennas meet the bandwidth requirements of broadband antennas.
Finally, the designed antenna is processed and its characteristic parameters are measured. The measurement results are basically similar to the simulation results of the antenna, so that it can be verified that combining the fractal structure with the antenna technology can effectively widen the bandwidth of the antenna.
Key Words：Fractal structure; wideband antenna; fractal antenna
 
目  录
第1章绪论    1
1.1 研究目的及意义    1
1.2 国内外天线宽带化的研究现状及发展历程    1
1.2.1 降低等效谐振电路Q值    1
1.2.2 表面刻槽技术    2
1.2.3 电磁耦合馈电    2
1.2.4 分形技术    2
1.3 本论文的结构安排    3
第2章相关理论概述    5
2.1 分形基本理论    5
2.2 分形的维数    5
2.3 常应用到天线中的分型结构    6
2.3.1 Cantor集合    6
2.3.2 Koch曲线    7
2.3.3 Siperpinski集    8
2.3.4 Peano曲线    8
2.4 天线的性能参数    9
2.4.1 输入阻抗    9
2.4.2 反射系数与驻波比    9
2.4.3 方向图    10
2.4.4 天线的方向性系数    11
2.4.5 天线的效率    12
2.4.6 天线的增益系数    12
2.4.7 天线的带宽    13
2.5 HFSS天线仿真软件简介    13
2.6 本章小结    14
第3章分形天线的设计    15
3.1 引言    15
3.2 天线一的设计与分析    15
3.2.1 介质基板材料的选择    15
3.2.2 天线一结构的设计    15
3.2.3 结果分析    20
3.2.4 天线一的制作与测量    21
3.3 天线二的设计与分析    22
3.4 小结    25
第4章总结与展望    26
参考文献    27
致谢    28