摘要近年来特征模理论吸引了大量的学者，它具有清晰的物理意义且计算量小，能够有效的缩短计算时间，对天线设计意义重大。

本文主要围绕特征模理论，需要掌握用模式分析法分析天线基本性能，对实际简单的微带贴片天线进行特征模仿真并优化。

首先概述了特征模理论的国内外研究现状以及研究背景，并简单介绍了用传统模式分析法分析天线。

其次介绍了特征模理论中常用的方法——矩量法。并给出了经典特征模理论公式的推导过程，得出特征电流、特征电场，分析特征模在散射问题和雷达领域的应用。经典特征模理论提供了在导体表面形成加权正交系的特征电流，在无穷远球面上形成正交系的特征电场。43210

接着将特征模理论用于微带天线的设计中，简述了空腔模式与特征模的关系，并用FEKO对上述天线进行仿真，将两种方法在分析正三角形贴片天线、同心圆微带天线和双频微带贴片天线时做比较。

最后总结了论文的主要内容。

关键词  特征模  矩量法  微带贴片天线  圆极化天线

毕业设计说明书外文摘要

Title   Characteristic Modes applying in Electromagnetic Problems                      

Abstract

In recent years, Characteristic Mode Theory(CMT) has attracted much attention of the researchers. Characteristic Mode Theory has clear physical conception .What’s more, the amount of calculation is not big, so the computing time can be effectively reduced. It is of great significance to antenna design.

This dissertation is mainly focused on the characteristic mode theory. By mastering the basic performance of the antenna pattern analysis method, we can simulate the microstrip patch antenna and improve it.

Firstly, the research background and recent developments of CMT are reviewed. And a brief introduction of pioneering CM studies is given.

Secondly, a commonly used method in CMT is introduced----MOM. Then we give the derivation of CMT formula and get characteristic currents and characteristic fields as well as analysing CM in scattering problems and radar fields. The mode currents form a weighted orthogonal set over the conductor surface, and the mode fields form an orthogonal set over the sphere at infinity.

Then CMT is applied in the design of microstrip patch antenna. We briefly demonstrate the relationship between Cavity Model and Characteristic Modes ,then we apply them in analysing equilateral triangular patch antenna, concentric circular microstrip antenna and dual band stacked microstrip patch antenna.

Lastly, a summary of the whole dissertation is given.

Keywords  characteristic modes   Method of Moments(MOM)   microstrip patch antenna     circularly polarized antenna 

 目  次

1 引言 1

1.1 研究背景 1

1.2 特征模理论的研究现状 1 

1.2.1 天线领域的传统模式分析法… 1

1.2.2 特征模的定义… 1

2 特征模理论…2

2.1矩量法简介 2

2.2  经典特征模理论公式 … 3

2.2.1 特征电流 … 3

2.2.2 特征电场 4

2.2.3模式展开… 5

2.2.4 在雷达领域的应用… 6

2.2.5 在散射问题中的应用 7

2.3 特征模的运算 7

3  特征模在微带天线中的应用 10

3.1微带天线简介10

3.2 空腔模式与特征模式的关系11

3.3微带贴片天线的物理研究… 16

3.3.1正三角形贴片天线…16

3.3.2同心圆微带天线18

3.3.3双频微带贴片天线…19