【作者】 刘扬；

【导师】 项铁铭；

【作者基本信息】 杭州电子科技大学 ， 电磁场与微波技术， 2011， 硕士

【摘要】 随着通信技术的发展,各种电子器件的结构逐渐向小型化与微型化演变,以及多频段、宽带跳频等现代通信技术的应用,原有的窄带天线已经无法满足现代通信技术对设备宽带化与小型化的要求。宽带小型化天线具有通信容量大,抗干扰等优点,能够充分利用狭小的空间,而且对通信质量不会造成较大的影响。单极子天线凭借其结构简单、辐射具有全向性等诸多优点得到了广泛应用。但是如何在保证天线的性能的基础上,进一步减小天线的尺寸,展宽天线的工作带宽,是近年来研究的热点。本文概述了天线宽带化与小型化的发展过程,对目前实现天线宽带化与小型化的常用方法及各种技术指标等一些关键技术进行了探索。得出了一些重要的结论,如增大振子宽度,采用锥体结构、套筒结构,对天线进行不对称馈电等都可以增大天线的工作带宽,采用分形结构,能够有效地降低天线的谐振频率等。针对一些线结构的天线可以使用加载的方法并配合适当的匹配网络实现超宽带和小型化的性能。这些结论为本文研究天线宽带化与小型化提供了重要的理论和依据。本文对宽带匹配网络的设计进行了研究,介绍了宽带匹配网络设计的实频数据法。该方法只需要天线一些离散的频率点上获得阻抗输入值即可进行优化设计,工程应用性强,原理简单、可靠,而且不会忽略最优解,对于天线的宽带匹配网络设计该方法简单实用。在前人工作的基础上,本文针对线天线加载及匹配网络设计提出了一种全新的优化方法,利用FEKO的脚本命令对天线建模,计算输入阻抗、增益、效率实现对场分析,使用ADS调用FEKO产生的输入阻抗文件即实频阻抗值进行匹配网络的计算实现路的运算。由MATLAB编写的遗传算法程序分别调用这两个软件,实现了电磁场和电路的一体化仿真、优化。根据该方法,本文首先改进了两个工作在50-1000MHz和100-2000MHz的超宽带单极子天线,提高了天线的工作稳定性,制作了实物进行验证,证明了该方法的有效性。然后设计一个具有全向辐射特性的宽带折叠单极子短波天线,分析了加载误差对天线性能的影响,最后使用CST软件对仿真结果进行了验证。该方法简单、可靠,在工程上对天线加载及匹配网络一体化优化具有一定的指导意义。更多还原

【Abstract】 With the development of communication technology, the miniature and broadband of electrical devices become more significant than ever, and the original narrowband antennas could not meet the requirement of the modern communication technology, such as multi-frequency, jump-frequency, the broadband and miniature devices. The broadband and miniature antennas which have the characteristics with large communication capacity and good anti-interference capability not only make full use of limited space, but also could not cause considerable influence the quality of communication. Monopole antennas have been widely used in many applications due to their instrinsic advantage like simple structure, and omnidirectional radiation pattern. However based on the performance guarantee of the antennas, further reducing the size and improving the bandwidth of the antennas are the research hotspot in recent years.This paper summarizes the development of the broadband and miniaturization of antennas, and explores the realization of broadband and miniaturization and the crucial technology of the antennas. At last the paper obtains some important conclusions about increasing broadband of antennas, like increasing the width of vibrators, using the structure of cone or sleeve, feeding the antennas asymmetrically. Using the fractal structure could effectively lower the resonance frequency of the antennas. According to some of wire antennas can use the loading method cooperating the proper matching network for realizing the performance of ultra-wideband and miniaturization. These conclusions for broadband and miniaturization which is studied in this paper provides important theory and basis.This paper introduces a broadband matching network for Real Frequency Method of designing and optimizing it which only needs some measured impedance of antennas in discrete frequency in detail. It has more applications in engineering, simpler theory and does not ignore the optimization results. It is the ideal method of designing broadband matching network.This paper presents a new optimization method about wire antennas load and matching network on the basis of previous work, which uses the FEKO script commands for antennas modeling and computing input impedance, gain, efficiency, and then applies ADS invoking the input impedance files, that is real frequency impedance, in order to compute the matching network. The Genetic Algorithm programmed by MATLAB calls the two software for the purpose of realizing electromagnetic field and circuit integration automatically simulating and optimizing. According to that method, the paper improving the stability performance of two monopole antennas which work at 50-1000MHz and 100-2000MHz, and then manufacture the two antennas for testing and verifying the optimized results in order to prove the above-mentioned method valid. And more, this paper designs an omnidirectional radiation and broadband folded monopole shortwave antenna, and consequentially analyses the lumped components error performance of the shortwave antenna, using CST for verifying the results. This method is simple, reliable, but it has certain significance on load antennas and matching network integrated design and optimization.更多还原