臺灣博碩士論文加值系統

本研究目標為在微型基地台中放入四支多輸入多輸出（Multiple-input–multiple-output，MIMO）天線，工作頻段為長期演進技術（Long term evolution，LTE）頻段；然而，大部分微型基地台的文獻所提出頻段為LTE較高的頻段（1710–2690 MHz），並且非四支天線MIMO系統。本論文提出兩種微型基地台MIMO天線，第一種天線工作頻率為LTE低頻段（700–960 MHz）的四支MIMO天線，並且在微型基地台中的接地面上放置五邊型的金屬擋牆，因此不只是提升天線之間的隔離度，也減少天線與其他電磁成分間的電磁干擾（Electromagnetic interference）；此天線的效率也至少60%以上，並且整個天線系統達到最佳化。第二種天線工作頻帶為LTE雙頻段（700–960 MHz、1710–2690 MHz）的四支MIMO天線，並且將第一種天線的基地台設計空間變小，並加入中和線（Neutralization lines）做為本研究的去耦合機制；然而，在過去文獻中並沒有使用中和線製作在四支工作在LTE雙頻帶的MIMO天線。再加入中和線後，除了天線效率在本研究目標頻帶內也達到50%以上外，天線效能也達到最佳化，進而非常適合應用在微型基地台中。

This thesis proposes two multiple-input–multiple-output (MIMO) antennas for femtocell long-term-evolution (LTE) base stations; one antenna aims at LTE lower frequency bands (698-960 MHz), and the other focuses on meeting the full LTE specification (698–960 MHz and 1710–2690 MHz). One antenna is not only operating in 698−960 MHz for femtocell LTE base stations, but it also employs four-unit antenna elements. A pentagonal conductor wall is established on the ground plane; accordingly, not only does isolation improve, but the electromagnetic interference between the antenna and other electronic components is reduced. We design a top-loading meandered monopole with dual sleeves attached to each side of the radiating body, optimizing the characteristics of impedance bandwidth and radiation efficiency concurrently. The other one is operating in full LTE specification for femtocell LTE base stations, using four elements to increase the channel capacity. The antenna configuration is optimized for good impedance matching and high radiation efficiency. In particular, we propose a simple structure, neutralization lines, with extremely low costs to enhance the isolation. This structure uses solid wires, which connect the position having strongest coupled current of two adjacent elements; accordingly, the suspended solid wires achieve isolation enhancement of 40 dB. All performance show that the proposed two MIMO antennas are very suitable to apply the femtocell base stations.

摘要 i
英文摘要 ii
誌謝 iv
目錄 v
表目錄 vii
圖目錄 viii
第一章 緒論 1
1.1 研究動機 1
1.2 文獻回顧 2
i. LTE低頻帶（700−960 MHz） 2
ii. LTE雙頻帶（700−960 MHz及1700−2690 MHz） 3
iii. 尺寸與單元數比較 7
1.3 論文之章節大鋼 8
第二章 涵蓋700−960 MHz的四單元微型基地台天線 9
2.1天線設計 9
2.2 實驗驗證 14
2.3 研究限制 26
第三章 涵蓋700–960 MHz及1710–2690 MHz的四單元微型基地台天線 28
3.1 天線設計 28
3.2 中和線的工作機制 34
i. 文獻回顧 34
ii. 中和線的關鍵參數 36
3.3 隔離度增強的四單元微型基地台天線 42
3.4 參數分析 47
3.5 實驗驗證 48
第四章 結論 64
4.1 論文總結 64
4.2 未來研究方向 65
參考文獻 66

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