臺灣博碩士論文加值系統

本論文將研究並設計具有重置特性的全向性天線，分別針對全向性的場型提出具有頻率切換以及極化切換的兩種設計方式。對於頻率切換的設計是利用具有負載短路金屬片的單極天線來產生全向的輻射場型，並在短路金屬片四邊分別經由二極體連接一段開路殘枝，透過二極體的開關使電流路徑產生改變來達到頻率的變換。對於極化重置的設計，是由四個微帶天線所組成的環狀電流產生水平極化，再結合短路負載的單極模態所產生的垂直極化，形成全向性的圓極化輻射，而極化重置則是經由二極體控制短路牆的個數來達成。論文中所有的天線設計都藉由高頻電磁模擬軟體(HFSS)做數值分析並依照所獲得的尺寸製作天線樣品。從實驗結果得知，本論文所提出的可重置全向性天線，在頻率切換的部分，可以切換的範圍在1820~2480 MHz，在頻帶內皆具有良好的全向性輻射場型。而在極化切換的部分，當天線操作在2420 MHz為左旋圓極化，切換至右旋極化時，天線操作頻率為2900 MHz，在兩圓極化頻帶皆有良好的阻抗匹配以及軸比。

Designs of frequency and polarization reconfigurable microstrip patch antennas with conical radiation are respectively presented in this thesis. For the reconfigurable frequency antenna design, a monopolar patch antenna structure is used to generate conical radiation patterns. The frequency switching is realized by controlling four diodes to reconfigure the size of the shorted rectangular patch of the monopolar patch antenna. Each diode connects one side of the shorted rectangular patch and an open stub. For the reconfigurable polarization antenna design, the used antenna structure is single feed and involves two resonant modes, in which a 4-element-array loop antenna mode, producing horizontal polarization, and a monopolar patch antenna mode, producing vertical polarization. By properly exciting and coupling the two resonant modes, circular polarization radiation can be obtained. Moreover, the polarization switching is achieved by controlling four diodes to reconfigure the number of the shorting walls. Two prototypes for the abovementioned reconfigurable frequency and polarization antennas are implemented, respectively, and their dimensions are obtained by numerical analyzing with HFSS. From the measured results, the operating frequency of the reconfigurable frequency antenna has a tunable range from 1820 ~ 2480 MHz, and good omni-directional radiation patterns are observed across the available operating frequencies. As for the reconfigurable polarization antenna, the measured results exhibit the antenna prototype has the ability of switching polarization, and the operating frequencies of the right-hand and left-hand circular polarization occur at 2900 and 2420 MHz, respectively. Also, both the operating frequencies have a return loss of less than 10 dB and an axial ratio of less than 3 dB.

中文摘要 i
英文摘要 ii
致謝 iv
目錄 v
圖目錄 vii
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 5
第二章 具有頻率切換之全向性天線 7
2.1 概述 7
2.2 天線結構與分析 10
2.3 實驗結果 13
第三章 具有極化重置之全向性圓極化天線 30
3.1 概述 30
3.2 模態生成與分析 33
3.3 極化重置的實驗結果 49
第四章 結論 57
參考文獻 59
附錄 63


圖目錄
圖2.1 可切換頻率之全向性天線的幾何結構圖 12
圖2.2 可切換頻率之全向性天線成品圖 15
圖2.3 天線在不同模態時的反射損失圖 16
圖2.4 天線操作於模態1 於1820 MHz 的遠場輻射場型量測結果 19
圖2.5 天線操作於模態2 於1920 MHz 的遠場輻射場型量測結果 20
圖2.6 天線操作於模態3 於2000 MHz 的遠場輻射場型量測結果 21
圖2.7 天線操作於模態4 於2120 MHz 的遠場輻射場型量測結果 22
圖2.8 天線操作於模態5 於2200 MHz 的遠場輻射場型量測結果 23
圖2.9 天線操作於模態6 於2300 MHz 的遠場輻射場型量測結果 24
圖2.10 天線操作於模態7 於2400 MHz 的遠場輻射場型量測結果 25
圖2.11 天線操作於模態8 於2480 MHz 的遠場輻射場型量測結果 26
圖2.12 天線於x-y 平面遠場輻射場型
(a) 模態3, 2000 MHz ;(b) 模態6, 2300 MHz 27
圖2.13 天線於x-y 平面遠場輻射場型(a) 模態7, 2400 MHz ;
(b) 模態 8, 2480 MHz 28
圖2.14 天線在不同模態下的增益變化 29
圖3.1 具有極化重置之全向性圓極化天線的幾何結構圖 36
圖3.2 不具有短路牆的天線模擬與實作反射損失圖 37
圖3.3 不具有短路牆遠場輻射場型於2690 MHz 的模擬結果 38
圖3.4 操作於不同短路牆寬度的天線反射損失圖 39
圖3.5 w = 2 mm 時天線遠場輻射場型於2050 MHz 的模擬結果 40
圖3.6 天線A 之軸比模擬結果,θ = 30° 41
圖3.7 天線A 的遠場輻射場型於2440 MHz 的模擬結果 42
圖3.8 w4 = 12 mm 之軸比模擬結果, θ = 30° 43
圖3.9 w4 = 12 mm 的遠場輻射場型於2440 MHz 的量測結果 44
圖3.10 分析不同位置的短路牆天線反射損失圖 45
圖3.11 短路牆E,F,G,H 不同位置(s)的天線反射損失圖 46
圖3.12 天線B 之軸比模擬結果,θ= 30° 47
圖3.13 天線B 的遠場輻射場型於2860 MHz 的模擬結果 48
圖3.14 可切換極化之全向性圓極化天線的成品圖(a)正面；(b)背面 51
圖3.15 二極體截止時實驗與模擬結果的反射損失圖 52
圖3.16 二極體導通時實驗與模擬結果的反射損失圖 53
圖3.17 天線不同二極體狀態於θ= 30°的軸比圖 54
圖3.18 天線操作在左旋圓極化的遠場輻射場型於2420 MHz 的量測結果 55
圖3.19 天線操作在左旋圓極化的遠場輻射場型於2900 MHz 的量測結果 56

表目錄
表2.1 全向性天線特性分析 9
表2.2 具有頻率切換的全向性天線相關尺寸 17
表2.3 不同模態所對應的天線特性 18

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