無線通訊的技術發展迅速，天線作為無線傳輸系統的介面，是無線通訊產品不可或缺的重要元件之一。天線的微小化與穩定性是無線通訊產品研發的趨勢，也是本論文研究的主要目標。
本論文第一部分設計兩種有穩定性高的天線設計，應用於筆記型電腦或平板電腦，在天線的性能和場型上都有自平衡的特性，可降低外在環境對天線的干擾。　　第一種天線是可以整合至射頻前端模組(RF front-end)的差動耦合饋入平面印刷環圈天線，比起現有的差動天線設計，有微小化的優點。天線尺寸是13 mm×27 mm，接地面尺寸是4.5 mm×4.5 mm，並實作在低成本的FR4板上，同時擁有差動饋入優點，可減輕同軸傳輸線上產生的漏電流。第二種天線是單端饋入的環圈天線，特別的是此設計天線不用接地面，改用同軸線直接饋入，可以只激發自平衡的模態。高階模態的輻射場型比起有接地面的天線，場型完整幾乎沒有side lobe，同時擁有寬頻的特性，頻寬在2.4 GHz有380 MHz，在5.2 GHz有1270 MHz。頻寬容忍度高，實際量測與模擬也相當吻合。
本論文第二部分針對MIMO天線去作設計，應用802.11n無線通訊標準，傳輸速率最大可以達到300 Mbps。一開始設計了兩項微小化單天線，應用在MIMO的雙天線設計。MIMO天線設計的尺寸只有19 mm×30.3 mm，使用了兩種去耦合的方法來增加隔離度: 一個是特別的接地面尺寸，可以使隔離度增加到18.9 dB;另一個是去耦合金屬片，可以使隔離度在全部的操作頻率都增加到24.6 dB，最好達到31.4 dB。此去耦合金屬片可以獨立調整需要去耦合的頻率點，而不會影響原本天線的共振頻率和返回損失。實際在微波混響室(Reverberation Chamber)量測，通道容量(Channel Capacity)可以有效的增加，總輻射效率(Total Radiation Efficiency)大約60 %左右，有效分集增益(Effective Diversity Gain)在7dB上下。此MIMO天線設計可以實際應用在USB dongle上。

In rapid wireless communication technology development environment, antennas, the interface among many wireless communications, are an indispensable component for wireless systems. Miniaturization and functionality stability (high tolerance to environmental variations) of the antenna are fast becoming the design trends in research and development of wireless communication systems. They are also the main objectives of this thesis.
In the first part of this thesis, we designed two highly stable antennas, which can be used in notebook computers or tablet PCs. The antenna has self-balanced characteristics, where the environmental interference is minimized, in its performance/functionality and patterns. The first antenna design, which can be easily integrated into an RF front-end board, employed capacitive coupling, differential feed printed loop configurations. Comparing to the existing differentially fed antenna design, our designs are much more miniaturized: the antenna size was 13 mm × 27 mm, the ground size was 4.5 mm × 4.5 mm. Implemented on a low-cost FR4 board, the antenna reduced the leakage current formed on coaxial transmission line, due to the advantage of being differentially fed. The second antenna design, fed by coaxial cable (single-ended fed), and without a ground plane, excited only self-balanced modes. The radiation patterns of higher modes in this antenna design are complete and without side lobes. This antenna design also has wide bandwidth characteristics: at 2.4 GHz it had 380 MHz, and at 5.2 GHz it had 1270 MHz bandwidths of high tolerance (stability). The actual measurement validated our simulation results.
In the second part, MIMO antennas were designed for 802.11n wireless standards with maximum transfer rates of up to 300 Mbps. First, we designed two small single antennas, which were applied later in MIMO antenna designs. The size of our MIMO antenna designs was only 19 mm × 30.3 mm. In MIMO antenna designs, we employed two methods to increase the isolation between the two MIMO antennas: one manipulated the ground plane size, in which the isolation reached 18.9 dB; the other utilized a decoupling metal, where the overall isolation reached 24.6 dB in all of the operating frequencies, with the best isolation being 31.4 dB. The frequency of the coupling/decoupling for the decoupling metal can be adjusted independently; thus not affecting the original resonant frequency and the return loss of the two MIMO antennas. Actual measurements conducted in the microwave chamber (Reverberation Chamber) have verified the channel capacity were effectively increased, the total radiation efficiencies were about 60%, and the effective diversity gain was about 7dB. The MIMO antenna designs can practically and easily applied in the USB dongles.

論文審定書 ...................I
誌謝 ...................II
中文摘要 ...................III
英文摘要 ...................IV
第 一 章 緒論 ...................1
1.1論文大綱 ...................1
1.2單端訊號傳輸簡介 ...................2
1.3差動訊號傳輸簡介 ...................3
1.4差動阻抗推導計算 ...................5
1.5多輸入多輸出通訊架構 ...................7
1.6 MIMO量測系統介紹 ....................8
1.7研究方法 ...................12
第 二 章 單端饋入及差動饋入環圈天線之研究 ...................13
2.1研究動機 ...................13
2.2差動饋入之環圈天線 ...................14
2.3單饋饋入之環圈天線 ...................17
2.4人體對環圈天線和PIFA天線效能的影響 ...................20
2.5接地面大小對環圈天線和PIFA天線的影響 ...................23
2.6章節與討論 ...................25
第 三 章 差動耦合饋入環圈天線設計 ...................27
3.1研究動機 ...................27
3.2天線設計與原理 ...................27
3.3天線實驗及量測結果 ...................30
3.4章節與討論 ...................36
第 四 章 同軸單端饋入之雙頻環圈天線設計 ...................37
4.1研究動機 ...................37
4.2天線設計與原理 ...................37
4.3天線實驗及量測結果 ...................40
4.4章節與討論 ...................46
第 五 章 應用於USB Dongle之平面印刷單環圈天線設計 ...................47
5.1研究動機(單端直接饋入環圈天線) ...................47
5.2天線設計與原理(單端直接饋入環圈天線) ...................47
5.3天線實驗及量測結果(單端直接饋入環圈天線 ...................48
5.4天線設計與原理(單端耦和饋入環圈天線) ...................52
5.5天線實驗及量測結果(單端耦和饋入環圈天線) ...................53
5.6章節與討論 ...................60
第 六 章 應用於802.11n之微小化平面印刷MIMO環圈天線設計 ...................61
6.1研究動機 ...................61
6.2天線設計與原理 ...................62
6.3天線實驗及量測結果 ...................64
6.4章節與討論 ...................74
第 七 章 總結與未來工作 ...................75


參考文獻 ...................77

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