天線是現代社會中廣泛使用的裝置，其常用於廣播和電視、點對點無線電通訊、雷達和太空探索等系統，通常作用於空氣以及外太空中，亦可於水下運作，甚至於在特定頻率下工作可傳播於土壤及岩石當中，天線通常作用於某特定方向加強增益，即朝某特定方向發射電磁波，因此考慮的重點應為天線增益值，為此我們透過設置不同形狀之模型進行模擬，以比較不同模型在同樣頻率下之天線增益值之差別。


本研究中透過不同模型數據分析來研判哪種模型可以獲得更大的天線增益值，同時透過論文中的電磁近場圖判斷模式TE以及TM的差別[1]，並整理不同mode的數據以及近場圖及遠場圖進行比對比較，獲得最佳化的天線增益分析，透過HFSS軟體分析獲得數據，再透過實體模型可以節省更多成本，獲得更佳的收益。

Antennas are widely used devices in modern society. They are commonly used in radio and television, radar, and space exploration systems. They are usually used in air and outer space. The work can be propagated in the soil and rocks. The antenna usually acts in a specific direction to enhance the gain. Therefore, the focus should be on the antenna gain value. For this purpose, we simulate by setting models of different shapes to Compare the differences in antenna gain values of different models at the same frequency.

In this study, through the analysis of different model data to determine which model can obtain a greater antenna gain value, through the electromagnetic near-field diagram in the paper [1] to determine the difference between the modes TE and TM, and sort the data of different modes and near The field map and the far field map are compared and compared to obtain the optimized antenna gain analysis.

摘　要 i
ABSTRACT ii
誌謝 iii
目　錄 iv
表　目　錄 v
圖　目　錄 vi
第一章 緒論 1
1.1 前言 1
1.2 研究動機與目的 2
1.3 天線之運作原理 2
1.3.1 天線的極化 2
1.3.2 電磁波 3
1.3.3 電磁波的傳遞方式 5
1.3.4 天線的增益、方向性以及效率 5
1.4 文獻回顧 7
1.4.1 透過號角天線的半對稱及四分之一對稱模型探討輸出特性 7
1.4.2 號角天線透過軸向萃取改變獲得接近70%高效率 9
1.4.3 Review of the relativistic magnetron 9
第二章 控制方程式與數值方法 10
2.1 簡介 10
2.2 麥克斯韋方程式 10
第三章 模擬步驟與參數設定 12
3.1 數值模型 12
3.2 計算區域與邊界條件 14
3.2.1 邊界條件設定 14
第四章 結果與討論 16
4.1 模擬結果 17
4.1.1 陰極尺寸10mm、頻率設置10 GHz 17
4.1.2 陰極尺寸15.8mm、頻率設置10GHz 22
4.2 討論 26
第五章 結論與未來展望 33
5.1 結論 33
5.2 未來展望 33
參考文獻 34

1.C. S. Lee, S. W. Lee, and S. L. Chuang, “Plot of modal field distribution in rectangular and circular waveguides,” IEEE Trans. Microwave Theory Tech., vol. MTT-33, pp.271-274, 1985

2.M. Daimon and W. Jiang, “Modified configuration of relativistic magnetron with diffraction output for efficiency improvement,” Appl. Phys. Lett., vol. 91, no. 19, p. 191503, Nov. 2007.

3.謝擁軍, 劉瑩, 李磊, 丁海強, 雷振亞, “ HFSS原理與工程應用”, 科學出版社, 2009, p.2-8.

4.Yun Wan and Ming-Chieh Lin.,, “Output Characteristics of a Circular Horn Antenna by Employing Half and Quarter Symmetries in HFSS. ” Member, IEEE, 2007.

5.Mikhail I. Fuks., and Edl Schamiloglu., “70% Efficient Relativistic Magnetron With Axial Extraction of Radiation Through a Horn Antenna, ” IEEE Trans on Plasma Science., vol.38, 2010

6.A. Palevsky and G. Bekefi, “Microwave emission from pulsed, relativistic e-beam diodes, II: The multiresonator magnetron,” Phys. Fluids, vol. 22, no. 5, pp. 986–996, May 1979.