Study of Radiation Pattern of A Horn Antenna Used in Microeave Applicator

本篇論文中的系統架設可分為兩大部分：linear-to-circular polarization converter，以及conical horn antenna。前者主要工作是將波源連接出的線極化波轉換成圓極化波，再將轉換成的導波導入號角天線；後者功用將前者導入的微波放射到微波暗室中照設樣品物，此天線的高指向性特色是我們選擇的依據。內容中會提到模擬以及實驗結果作比較，最後放置計畫的初步成果來觀察研究之可行性。In this thesis, there are two components will be mainly discussed in the system: linearto-circular polarization converter and conical horn antenna. The former matches the rectangular waveguide (linear polarization) which from microwave applicator to circular waveuide (circular polarization) which connected to horn antenna. The latter guides the circularly polarized wave from the former to an anechoic chamber to irradiate the sample , the basis of the horn antenna is high degree of directivity. In the content, we will examine results of experiment and simulation , and do conclusion.Contents 誌謝i 中文摘要ii Abstract iii 1 Introduction 1 2 Principle of Converter 4 2.1 Fundamental and Governing Equations . . . . . . . . . . . . . . . . . . . 4 2.2 Waveguide Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.2.1 Fundamentals of Cylindrical Waveguide . . . . . . . . . . . . . . 5 2.2.2 TE Wave of Rectangular & Circular Waveguides . . . . . . . . . 7 2.3 Theory and Mechanism of Converter . . . . . . . . . . . . . . . . . . . . 12 3 Principle of Horn Antenna 15 3.1 Antenna Fundamental Thoery . . . . . . . . . . . . . . . . . . . . . . . 15 3.1.1 Solutions of Radiation Problems . . . . . . . . . . . . . . . . . . 15 3.1.2 The Dipole Radiation Antenna . . . . . . . . . . . . . . . . . . . 20 3.2 Antenna Radiation Pattern and Parameters . . . . . . . . . . . . . . . . . 23 3.2.1 Determination of Far-Field . . . . . . . . . . . . . . . . . . . . . 23 3.2.2 Radiation Pattern Denfinties . . . . . . . . . . . . . . . . . . . . 26 3.2.3 Directivity and Gain . . . . . . . . . . . . . . . . . . . . . . . . 28 4 The Development and Measurement of Converter 33 4.1 Discussion on Process of Developing the Converter . . . . . . . . . . . . 33 iv CONTENTS v 4.2 The Seed Result of both Linear and Circular Converter in Experiment . . 35 5 The Results of the Horn Antenna Radiation Pattern 40 5.1 The Simulation of Radiation Pattern of The Horn Antenna . . . . . . . . 41 5.2 Examining Results of Simulation of The Horn Antenna by Measurement . 53 6 Summary 55 Bibliography 5