臺灣博碩士論文加值系統

本論文首先提出具有低交叉極化之槽孔耦合微帶天線設計，天線利用T型微帶線耦合至接地面上的環形槽孔，再經由環形槽孔對稱激發最上層的輻射金屬片。當環形槽孔共振在全波長基本模態時，藉由選擇適當的T型微帶線尺寸，天線可在正向方向上可獲得極低的交叉極化。除此之外，沿著環形槽孔周圍加入額外的負載槽孔，可有效降低槽孔耦合微帶天線的背向輻射。實驗結果顯示此改良後的環形耦合槽孔可提昇微帶天線的前後比達5 dB以上。此外，我們將發展一個雙饋入雙極化微帶天線，兩極化是屬於矩形輻射金屬片的兩正交模態TM01及TM10，其中TM10是由包含負載槽孔的環形耦合槽孔以及T型微帶饋入線組成的饋入機制所激發，而TM01是藉由一對具有180度反相的區折探針所激發。從實驗結果得知，在10 dB的阻抗頻寬內兩饋入埠的隔離度可低於-40 dB，且兩線性極化都擁有良好的極化純淨。本論文所完成的天線設計均操作在2400 MHz頻帶，並都藉由模擬分析來驗證實驗結果。

The thesis first presents the performances of microstrip patch antennas excited by the aperture-coupling feed that is composed of a T-shaped microstrip feed line and an annular-ring slot. Because the annular-ring slot is designed at a full-wavelength resonant mode, a broad impedance bandwidth can be obtained by combing the resonant modes of the coupling slot and radiating patch; moreover, a low cross polarization is also observed, especially around the direction with maximum gain. Several prototypes of the proposed aperture-coupled microstrip antennas with different substrate thickness are constructed and measured, and their performances are demonstrated. For reducing the considerable back radiation induced by the resonant coupling slot, additional slots are introduced and embedded along the perimeter of the annular-ring slot, and a 5 dB improvement of front-to-back ratio is obtained. Then, a design of dual-feed dual-polarized microstrip antennas with low cross polarization and high isolation is proposed. The proposed design uses two different feed mechanisms to respectively excite dual orthogonal linearly-polarized modes of a single radiating patch. One of the two modes is excited by the ring-slot-coupled feed, and the other is excited by a pair of meandering strips with a 180° phase difference. The measured results show that the isolation between the two feeding ports is less than -40 dB across a 10dB-input-impedance bandwidth of 14 %. Details of the antenna designs and measured results are shown.

中文摘要………………………………………...………………………… i
英文摘要………………………………………...………………………… ii
致謝…………………………………………………………………………… iii
目錄…………………………………………………….……………………… iv
圖目錄………………………………………………….……………………… vi
表目錄……………………………………………………………..……………ix
第一章 序論……………………………………………..……1
1.1 概述…………………………………………….…………….1
1.2 文獻探討…………………………………………….…………3
1.3 內容提要………………………………..……………………7
第二章 微帶天線產生交叉極化主因……………………………9
2.1 概述…………………………………………………………….9
2.2 交叉極化產生主因…………………..……….….….....9
2.2.1 模擬分析與實驗結果…………………………………….12
2.3 交叉極化抑制…………………………………………………14
2.4 結論與心得……………………………………………………19
第三章 具有低交叉極化之槽孔耦合微帶天線設計........20
3.1 概述……………………………….………….………….….20
3.2 天線結構與分析………………….………….….………….21
3.3 環形槽孔實驗結果……………………….………………….26
3.3.1特性比較……………………………………….….………30
3.3.2參數探討…………………………………………………..32
3.4 結論與心得………………………………………….………40
第四章 槽孔耦合微帶天線降低背向輻射之設計……………41 4.1 概述…………………………………………………………..41
4.2 想法與設計…………………………………………………..41
4.3 天線結構與分析……………………………………………..44
4.4 模擬與實驗結果……………………..……..……………..46
4.5 結論與心得………………………………..………………….51
第五章 具良好特性之雙極化微帶天線設計………….………52
5.1概述…………………………………………………………….52
5.2天線結構與分析…………………………………………………53
5.3模擬與實驗結果………………………………….…………….56
5.4結論與心得………………………….………….…………….62
第六章 結論…………………………………………….………63
參考文獻……………………………………………….…….…….65
附錄………………………………………………….………………69

圖2.2.1 傳統探針饋入微帶天線幾何結構圖……………...…11
圖2.2.2 傳統探針饋入微帶天線於2400 MHz所模擬與量測的遠場輻射場
型圖……………………………………..………………..…….13
圖2.3.1 曲折探針饋入之微帶天線其電流分佈圖..……....17
圖2.3.2 各種饋入方式的微帶天線其輻射金屬片上的表面電流分佈圖……..18
圖3.2.1 環形槽孔耦合微帶天線幾何結構圖..………………23
圖3.2.2 兩種形狀的槽孔內部磁流分佈示意圖..……………24
圖3.2.3 圓形輻射金屬片上之電流分佈圖..…………………25
圖3.3.1 天線在不同基底厚度h下的量測結果………………29
圖3.3.2 傳統的細槽孔與180度反相雙細槽孔饋入之微帶天線幾何結構圖...34
圖3.3.3 參考天線A與B其z軸上交叉極化比的模擬與實驗結果…35
圖3.3.4 天線4與參考天線B在 E-plane和 H-plane 上非z軸上的交叉極化
比較圖……………………………………………….……………36
圖3.3.5 天線4與參考天線B於2400 MHz所量測的遠場輻射場型圖…….…37
圖3.3.6 參數ls變化對天線4的影響圖…...…………….…38
圖3.3.7 天線4中參數ls變化對極化特性和反射損失的影響圖…39
圖4.2.1 兩種形狀的耦合槽孔其演進過程圖。……………………43
圖4.3.1 具有6個H型負載槽孔的環形槽孔耦合微帶天線幾何結構圖……...45
圖4.4.1 天線5模擬與實驗結果。……………………….....……48
圖4.4.2 天線5模擬與實驗結果。……………….…………………49
圖4.4.3 天線5於2410 MHz所量測的遠場輻射場型圖…… ……50
圖5.2.1 雙饋入雙極化微帶天線之幾何結構圖。………………55
圖5.3.1 天線6模擬與實驗結果。………………….……………58
圖5.3.2 天線6埠1和埠2在z軸上交叉極化比的模擬與實驗結果…59
圖5.3.3 天線6操作在port 2時，於2420 MHz所量測的遠場輻射場型圖60
圖5.3.4 天線6操作在port 1時，於2420 MHz所量測的遠場輻射場型圖61

表1.2.1 雙極化天線使用不同饋入組合方式的特性比較表。……….6
表3.3.1 本論文天線不同基底厚度下詳細的尺寸。…………………28
表3.3.2 在不同基底厚度下天線的實驗結果比較表。………………28
表3.3.3 樣品天線與參考天線詳細的實驗結果比較表。……………31
表4.4.1 天線5與天線4和參考天線B的詳細實驗結果比較。………47
表5.3.1 天線6兩輸入埠的詳細實驗結果。…………...……………57

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