臺灣博碩士論文加值系統

本論文的前半部分提出一全新架構之多頻印刷偶極天線設計，不同於傳統偶極天線由中間饋入訊號的方式，透過印刷偶極天線結合改良之環形微帶線分合波器，實現由兩端饋入訊號之新型態偶極天線架構。由於訊號在環形微帶線分合波器的兩輸出端埠，會隨著操作在不同的頻段而有不同的相位差與振幅比，平衡與非平衡的訊號將進而形成不同的共振模態與相對等效輻射路徑，且環形微帶線分合波器在輸入端埠具有超過80%的10dB反射損耗頻寬。本論文即結合以上特性，藉由巧妙的整合與設計，成功實現印刷偶極天線多頻段、寬頻帶的操作。

本論文的後半部分提出一天線縮小化新方法。透過加入摺疊偶極天線適當大小形狀之對稱性環形寄生金屬，環形寄生金屬上會產生感應之映像電流延長輻射路徑，並形成環形天線模態共振輻射同時會提供自身之電阻與摺疊偶極天線串聯。在此過程結構本身帶有的封閉電流迴路將產生電感性電抗補償低頻時電容性的偶極天線，成功達到大幅降低天線共振頻率之目標。以共振頻率為1.4GHz之單邊繞折印刷摺疊偶極天線設計作為中心根基天線，結合環形寄生金屬後，共振頻率可降至0.87GHz且仍維持良好的輻射特性。本論文研究中，將針對寄生環形金屬對印刷折疊偶極天線的影響，以及造成降頻的物理機制與原理，作深入的探討。

Multi-band printed dipole antennas with brand-new structure are presented in first part of this thesis. Unlike traditional dipole antenna fed from the center, a printed dipole antenna integrated with modified microstrip ring hybrid can realize a novel model of dipole antenna which is fed from end to end. Because the phase difference and magnitude ratio of signals from two output ports of microstrip ring hybrid vary from frequency to frequency, balanced and unbalanced signals will be produced to form different resonant mode and relative effective radiaton path. Furthermore, there is more then 80% -10dB return loss bandwidth in input signal of microstrip ring hybrid. This thesis combines above aspects with sophisticated integration and design to achieves a target of multi-band and wideband operation of printed dipole antenna successfully.

A new method of antenna miniaturization is presented in second part of this thesis. Adding symmetric annular parasitic conductor of appropriate shape and size to folded dipole, image current will be induced in annular parasitic conductor while the total radiation length will be increased. Moreover, annular parasitic conductor with induced current working as loop antenna will be resonated to radiate and provide its resistance in series with folded dipole simultaneously. Among above process, the inductive reactance will be produced by the structure carrying closed current loop to compensate capacitive dipole antenna at lower frequency, and it eventually attains the objective of bringing about large amount of drop in resonant frequency of proposed antenna successfully. The design of 1.4GHz printed folded dipole antenna with one side meandering is taken as elementary antenna. After integrating elementary antenna with annular parasitic conductor, the resonant frequency can drop from 1.4GHz to 0.87GHz, and the good radiation property still be maintained. The effect of annular parasitic conductor toward printed folded dipole antenna and the physical mechanism and principle which cause frequency drop will be further discussed in our research of this thesis.

第一章 導論‥‥1
1.1 工程背景與研究動機‥‥2
1.2 內容提要‥‥3

第二章 偶極天線理論‥‥4
2.1 偶極天線概論‥‥4
2.2 理想偶極天線的輻射效應‥‥4
2.3 短偶極天線與半波長偶極天線‥‥7
2.4 摺疊偶極天線‥‥11
2.5 偶極天線的饋入‥‥13
2.5.1 偶極天線與平衡非平衡轉換器‥‥13
2.5.2 微帶式印刷偶極天線‥‥14
2.6 單波長環形天線‥‥15

第三章 環形微帶線分合波器饋入新型印刷偶極天線設計‥‥18
3.1 天線設計概述‥‥18
3.2 天線設計理論‥‥19
3.2.1 四埠環形微帶線分合波器‥‥19
3.2.2 作為饋入網路之改良式三埠環形微帶線分合波器設計與分析‥23
3.2.3 電流向量分析法‥‥26
3.2.4 兩端饋入式新型多頻帶印刷偶極天線設計‥‥30
3.3 模擬與量測結果分析‥‥33
3.4 心得與討論‥‥42

第四章 開路環形微帶線分合波器饋入多頻印刷偶極天線設計‥‥43
4.1 天線設計概述‥‥43
4.2改良式開路三埠環形分合波器設計‥‥43
4.2.1 四埠環形分合波器高頻散射係數矩陣推導與分析‥‥44
4.2.2 改良式開路三埠環形分合波器散射係數矩陣推導與分析‥‥47
4.2.3 作為饋入網路之改良式開路三埠環形分合波器設計與分析‥50
4.3 天線設計理論‥‥53
4.3.1 雙頻帶新型印刷偶極天線設計‥‥53
4.3.2 三頻帶新型印刷偶極天線設計‥‥55
4.3.3 多頻帶新型印刷偶極天線設計‥‥56
4.4 模擬與量測結果分析‥‥58
4.4.1 雙頻帶新型印刷偶極天線模擬與量測結果分析‥‥58
4.4.2 三頻帶新型印刷偶極天線模擬與量測結果分析‥‥66
4.4.3 多頻帶新型印刷偶極天線模擬與量測結果分析‥‥71
4.5 心得與結論‥‥81

第五章 縮小化印刷摺疊偶極天線設計‥‥82
5.1 概述‥‥82
5.2 印刷摺疊偶極天線設計‥‥83
5.2.1 天線設計理論‥‥83
5.2.2 模擬結果‥‥84
5.3 結合圓環形寄生金屬之縮小化印刷摺疊偶極天線設計‥‥85
5.3.1天線設計概論‥‥85
5.3.2 結合圓環形寄生金屬之印刷摺疊偶極天線最佳化設計‥‥87
5.3.3 模擬結果討論與分析‥‥88
5.4 結合圓環形寄生金屬之縮小化印刷摺疊偶極天線降頻原理分析‥94
5.4.1 史密斯圖分析與等效電路模型‥‥94
5.4.2電感性電抗之產生機制分析‥‥97
5.5 整合平衡非平衡轉換器之等效縮小化摺疊偶極天線設計‥‥100
5.5.1 結合圓環形寄生金屬之縮小化印刷摺疊偶極天線等效架構‥100
5.5.2 整合平衡非平衡轉換器之摺疊偶極天線設計‥‥103
5.5.3 模擬與量測結果‥‥105
5.6 心得與討論‥‥111

第六章 縮小化印刷摺疊偶極天線進階研究與改良設計‥‥112
6.1 概述‥‥112
6.2 圍繞不同內徑之圓環形寄生金屬對摺疊偶極天線降頻效應分析‥‥112
6.2.1不同環內徑結構所產生之電感性電抗分析‥‥112
6.2.2 輸入電阻分析‥‥118
6.3 結合方形環狀寄生金屬之改良式縮小化印刷摺疊偶極天線設‥‥119
6.3.1 天線設計原理‥‥120
6.3.2 結合方形環狀寄生金屬之印刷摺疊偶極天線最佳化設計‥‥121
6.3.3 模擬結果與討論‥‥121
6.4 整合平衡非平衡轉換器之改良式等效縮小化摺疊偶極天線設計‥‥126
6.4.1整合平衡非平衡轉換器之改良式縮小化摺疊偶極天線設計‥‥127
6.4.2 模擬與量測結果‥‥127
6.5 心得與結論‥‥131

第七章 結論‥‥132
參考文獻‥‥134

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