臺灣博碩士論文加值系統

本論文提出一種新型人造磁導體，其工作原理是利用螺旋元件的電感性電抗與金屬盒的電容性電抗組成一LC並聯共振電路，因此位於共振頻率時會產生磁牆的特性。且因螺旋元件在金屬盒形成週期性排列，所以在特定頻帶內也具有電磁能隙效果。
在本研究中首先利用一個由平面波正向入射、完美匹配層與週期性邊界條件組成的數值分析模型，計算無窮大人造磁導體的反射相位正負45度以下對應之有效頻帶。再藉由半波長偶極天線置於人造磁導體與磁牆上方的模擬與量測之輻射場型比對，最後可驗證新型人造磁導體在位於正向入射平面波反射相位正負45度以下對應之有效頻帶內確實能夠產生磁牆的特性，可維持磁牆特性的有效頻寬約800MHz。且天線的增益也因磁牆特性影響而獲得大幅的提升，提升前之天線增益只有1.97dBi，提升後之天線增益可達4.98dBi~7.3dBi。
此外，本研究也利用懸浮微帶線法觀察新型人造磁導體的電磁能隙特性，最後量測出的其中一個能隙頻帶為2.765GHz~2.934GHz。

In this thesis, we propose a novel artificial magnetic conductor(AMC) structure using wire helix in a metal box. This structure is equivalent to a parallel resonant LC circuit resulting in some kinds of characteristics like the perfect magnetic conductor(PMC) at resonance frequency. Due to the periodic arrangement of this structure, the electromagnetic band-gap(EBG) effect will appear in this specific band.
First, we calculate the effective AMC bandwidth with reflection phase between 45 degrees for AMC with infinite elements case by a numerical analysis model. Simulated radiation patterns for half-wavelength dipole antenna on the AMC is compared with those of the same half-wavelength dipole antenna on the PMC. Our proposed AMC structure is verified to have the characteristics of PMC from 1.95 GHz to 2.75 GHz.
We also study the characteristics of EBG of this AMC structure by suspended microstrip method. One of the measured EBG band is from 2.765 GHz to 2.934 GHz.

目錄
中文摘要 i
英文摘要 ii
致謝 iii
目錄 iv
圖目錄 vi
表目錄 x

第一章 緒論 1
1-1 研究動機 1
1-2 研究背景 3
1-3 文獻探討 5
1-4 論文大綱 7
1-5 研究方法與流程 8

第二章 新型2.5DAMC設計 12
2-1 概述 12
2-2 評估無窮大AMC反射相位對應有效頻帶之模擬 18
2-2-1 波導近似模型之原理與模擬方法 18
2-2-2 模擬結果與分析 24
2-3 電磁能隙效果之模擬與量測 27
2-3-1 懸浮微帶線法之概念與模擬方法 27
2-3-2 模擬與實驗結果分析 30
2-4 驗證新型2.5DAMC在有效頻帶內可視為PMC之方法 35
2-4-1 半波長偶極天線設計方法與置於PMC與 AMC之輻射特性比較 35
2-4-2 模擬與實驗結果分析 49

第三章 結論 56
參考文獻 57
作者簡歷 60

圖目錄
圖1.1 布拉格散射原理 9
圖1.2 一種在導體接地面上挖週期圓孔的平面式電磁能隙結構 9
圖1.3 缺陷接地面型電磁能隙結構 10
圖1.4 蘑菇型高阻抗電磁表面(Mushroom-like EBG) 10
圖1.5 共面緊湊型光子能隙(UC-PBG) 11
圖2.1 導體接地面非常靠近天線時的影響 15
圖2.2 天線與導體接地面間距提高為 15
圖2.3 導體接地面的感應表面電流所引起的多路徑干擾 16
圖2.4(a) 金屬貼片間隙之邊際電容與電流迴路電感 17
圖2.4(b) 等效LC並聯共振電路 17
圖2.5 波導近似模型 20
圖2.6(a) 單一元件 21
圖2.6(b) 完整模型 22
圖2.6(c) 以導體取代AMC之模型 23
圖2.7(a) 平面波正向入射導體之反射相位 25
圖2.7(b) 平面波正向入射導體之反射係數 25
圖2.8 平面波正向入射無窮大新型2.5DAMC之反射相位 26
圖2.9(a) 由9x9AMC組成的懸浮微帶線(頂視圖) 28
圖2.9(b) 由9x9AMC組成的懸浮微帶線(頂視圖2) 28
圖2.9(c) 由9x9AMC組成的懸浮微帶線(側視圖) 29
圖2.9(d) 由9x9AMC組成的懸浮微帶線(3D視圖) 29
圖2.10(a) 11x11AMC實作成品(3D視圖) 31
圖2.10(b) 11x11AMC實作成品(側視圖) 31
圖2.10(c) 由11x11AMC組成的懸浮微帶線實作成品(3D視圖) 32
圖2.10(d) 由11x11AMC組成的懸浮微帶線實作成品(側視圖) 32
圖2.11(a) 由9x9與11x11AMC組成的懸浮微帶線之S11的模擬與量測比較 33
圖2.11(b) 由9x9與11x11AMC組成的懸浮微帶線之S21的模擬與量測比較 33
圖2.12 傳播常數Beta之模擬與量測比較 34
圖2.13(a) 50ohm漸進式非平衡轉平衡轉換饋入2.45GHz半波長偶極天線(側視圖) 37
圖2.13(b) 50ohm漸進式非平衡轉平衡轉換饋入2.45GHz半波長偶極天線(3D視圖) 37
圖2.14(a) 50ohm漸進式非平衡轉平衡轉換饋入2.45GHz半波長偶極天線之反射損失 38
圖2.14(b) 50ohm漸進式非平衡轉平衡轉換饋入2.45GHz半波長偶極天線之輻射場型 39
圖2.15(a) 2.45GHz偶極天線置於7x7AMC(3D視圖) 40
圖2.15(b) 2.45GHz偶極天線置於PMC(3D視圖) 40
圖2.16 2.45GHz偶極天線置於Free space、PMC與7x7AMC之反射損失比較41
圖2.17(a) 1.58GHz偶極天線置於Free space、PMC與7x7AMC之反射損失比較 42
圖2.17(b) 2.9GHz偶極天線置於Free space、PMC與7x7AMC之反射損失比較 42
圖2.18(a) 1.58GHz偶極天線置於PMC(1.5GHz)與 AMC(1.4GHz)之輻射場型比較 43
圖2.18(b) 1.58GHz偶極天線置於PMC(1.5GHz)與7x7AMC(1.67GHz)之輻射場型比較 43
圖2.18(c) 1.58GHz偶極天線置於PMC(1.5GHz)與7x7AMC(2GHz)之輻射場型比較 44
圖2.19(a) 2.45GHz偶極天線置於PMC(2.34GHz)與7x7AMC(2.5GHz)之輻射場型比較 44
圖2.19(b) 2.45GHz偶極天線置於PMC(2.34GHz)與 AMC(2.4GHz)之輻射場型比較 45
圖2.19(c) 2.45GHz偶極天線置於PMC(2.34GHz)與7x7AMC(2.37GHz)之輻射場型比較 45
圖2.19(d) 2.45GHz偶極天線置於PMC(2.34GHz)與7x7AMC(2.34GHz)之輻射場型比較 46
圖2.19(e) 2.45GHz偶極天線置於PMC(2.34GHz)與7x7AMC(2.2GHz)之輻射場型比較 46
圖2.20(a) 2.9GHz偶極天線置於PMC(2.76GHz)與7x7AMC(2.7GHz)之輻射場型比較 47
圖2.20(b) 2.9GHz偶極天線置於PMC(2.76GHz)與7x7AMC(2.75GHz)之輻射場型比較 47
圖2.21(a) 50ohm漸進式非平衡轉平衡轉換饋入2.45GHz半波長偶極天線之實作成品(正面圖) 50
圖2.21(b) 50ohm漸進式非平衡轉平衡轉換饋入2.45GHz半波長偶極天線之實作成品(背面圖) 50
圖2.21(c) 2.45GHz偶極天線置於11x11AMC之實作成品(頂視圖) 51
圖2.21(d) 2.45GHz偶極天線置於11x11AMC之實作成品(3D視圖) 51
圖2.22 2.45GHz偶極天線置於PMC、7x7與11x11AMC的反射損失之模擬與量測比較 52
圖2.23(a) 2.45GHz偶極天線置於PMC(2.34GHz)、7x7AMC(2.5GHz)之模擬輻射場型與置於11x11AMC(2.5GH)之量測輻射場型比較 53
圖2.23(b) 2.45GHz偶極天線置於PMC(2.34GHz)、7x7AMC(2.4GHz)之模擬輻射場型與置於11x11AMC(2.4GH)之量測輻射場型比較 53
圖2.23(c) 2.45GHz偶極天線置於PMC(2.34GHz)、7x7AMC(2.37GHz)之模擬輻射場型與置於11x11AMC(2.37GH)之量測輻射場型比較 54
圖2.23(d) 2.45GHz偶極天線置於PMC(2.34GHz)、7x7AMC(2.34GHz)之模擬輻射場型與置於11x11AMC(2.34GH)之量測輻射場型比較 54
圖2.23(e) 2.45GHz偶極天線置於PMC(2.34GHz)、7x7AMC(2.2GHz)之模擬輻射場型與置於11x11AMC(2.2GH)之量測輻射場型比較 55

表目錄
表2.1 偶極天線置於Free space、PMC與7x7AMC的模擬增益比較 48
表2.2 2.45GHz偶極天線置於7x7AMC的模擬增益與置於11x11AMC的量測增益比較 55

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