臺灣博碩士論文加值系統

本論文針對折疊偶極天線的設計方法提出改良，原始的折疊偶極天線是使用環形天線的架構，採用二分之一波長之長度進行設計，而寬為小於百分之一波長，但因現行產品空間不足，使得原始的折疊偶極天線不易被採用，所以本文中利用延伸接地線耦合效應，使天線上的電流分佈產生改變，並使用四分之一波長設計天線，將達到天線縮小化的目的。本文之改良型非對稱折疊偶極天線，以Return Loss小於10dB的條件，天線的操作頻段為以下頻率 : WLAN(2.4GHz~2.5GHz和5.1GHz~5.85GHz)以及WiMAX(3.3GHz~3.8GHz)，天線總體積尺寸為32.5mm*11mm，板材厚度為1.6mm，介電系數(εr)為4.4，正切損耗為0.0025m。本文利用簡易與低成本印刷電路板製作方法來完成天線，詳細的內容將在論文中逐步分析與討論。

This thesis focuses on the improvement of folded dipole antenna design. The original folded dipole antenna has a loop structure with a length of one-half wavelength and a width of less than one percent wavelength. However, it may not be used in small space of the product because of its size. The new design applies the coupling effect of ground-trace the current distribution on the antenna to generate change. The new antenna has been minimized to quarter wavelength.
This Improved asymmetric folded dipole antenna, conditions of less than 10dB Return Loss operating band for the following frequencies: WLAN(2.4GHz~2.5GHz and 5.1GHz~5.85GHz) and WiMAX(3.3GHz~3.8GHz), The total volume of the antenna size is 32.5mm * 11mm, sheet thickness to 1.6 mm, dielectric constant (er) of 4.4, loss tangent 0.0025m.
The new design uses simple and low-cost printed circuit board production methods to make the antenna. All details will be presented in the thesis.

摘　要 ii
ABSTRACT iii
致謝 iv
目錄 v
圖目錄 vii
第一章 緒論 1
1.1概述 1
1.2論文內容大綱 2
第二章 基本天線與電磁理論 3
2.1簡介 3
2.2偶極天線原理 5
2.3折疊式偶極天線 6
2.4環形天線原理 9
第三章 天線架構與設計概念 11
3.1原始環形陣列天線架構 11
3.2天線架構分析 12
3.2.1 地線長度變化對頻率之影響 13
3.2.2 迴圈大小分析對阻抗匹配之影響 15
3.2.3 耦合元件分析對阻抗匹配之影響 16
3.3耦合元件分析 18
3.3.1實作與驗證 20
第四章 改良型非對稱折疊偶極天線 22
4.1改良型非對稱折疊偶極天線之設計 22
4.1.1 雙頻天線設計 24
4.1.2雙頻天線與耦合元件設計 25
4.1.3 非對稱饋入與阻抗匹配 27
4.1.4 延伸地線(Ground-trace) 28
4.1.5 耦合元件分析 29
4.1.6耦合元件大小的分析 31
4.2改良型非對稱折疊偶極天線之參數分析 33
4.2.1 饋入位置對於雙頻特性之影響 33
4.2.2 迴路大小之錯位結構分析 34
4.2.3 阻抗匹配參數分析 35
4.3 延伸地線(Ground-trace) 分析 36
4.3.1 延伸地線(Ground-trace) 分析長度對阻抗特性之影響 36
4.3.2 延伸地線(Ground-trace)分析電流分佈之影響 38
4.3.3實作驗證 39
結論 41
參考文獻 42

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