隨著傳輸速率的要求不斷的上升，傳統的SISO天線已經不能支援下一世代的通訊系統規範。取而代之的是MIMO天線，而MIMO天線在手機內將會占據兩倍或是兩倍以上的面積，再加上3GPP所提出的4G LTE700頻段，比GSM850/900的物理共振波長還要長，因此如何讓天線面積縮小化但是又必須有寬頻寬以及良好增益是一個很重要的議題。本論文在第四章會提出一個縮小化且操作在LTE700/2300/2500 的天線，其中在低頻主要利用磁流線圈共振來增加低頻頻寬。第五章則是提出一個可以有效改善MIMO天線隔離度的架構，且隔離的耦合微帶線只佔一小部分面積。不用佔用兩天線中間的空間，讓其可以放置手機其他元件或是模組。

With the elevation of data rate of wireless system, antennas for next- gen
application will be MIMO(multiple-in-multiple-out) type. Placing multiple antennas in a handset wireless communication device, miniaturizing of antenna area becomes very important. In chapter 4 of this thesis, a compact antenna for LTE700/2300/2500, which consists of a magnetic current spiral to enhance bandwidth in the lower band (LTE700), will be proposed. The proposed MIMO antenna, which consists of parasitic strips to improve isolation, will also be discussed and simulated in chapter 5.

Chinese Abstract iii
English Abstract iv
List of Figures viii
List of Tables xi
Chapter 1 Introduction 1
1-1 Research Motivation 1
1-2 Synopsis 2
Chapter 2 Basic antenna theorem and LTE introduction 3
2-1 Antenna 3
2-1.1 Hertzian Dipole 3
2-1.2 Half-Wavelength Dipole 5
2-1.3 Antenna Efficiency 7
2-2 SAR(Specific absorption rate) 7
2-3 4G MIMOantenna for LTE Band 8
2-4 Envelope Correlation Coefficient and Diversity Gain 8
Chapter 3 Techniques for Miniaturizing Planar Antenna 9
3-1 Coupling Feed 9
3-2 Widening the End of Strip 12
3-3 Chip Inductor 13
Chapter 4 Proposed Antenna for LTE 15
4-1 Design Process 15
4-2 Proposed Design 16
4-2.1 Structure Specification 16
4-2.2 Simulated S11 and Measured S11 19
4-3 Antenna Investigation 20
4.3.1 The Mechanism of Magnetic Current Spiral 20
4-3.2 Widening the End of Monopole Antenna Strip 24
4-3.3 Clearance 25
4-3.4 Coupling Feed 26
4-3.5 Extended Strip Connecting with Feeding Patch 28
4-3.6 Tilt Radiation Pattern 29
4-3.7 3D Vertical Strip 31
4-3.8 Current Distribution on the Monopole Part 33
4-3.9 Investigation of Radiation Efficiency 34
4-4 Measurement Result 36
Chapter 5 Proposed Design for MIMO Application 40
5-1 Structure 40
5-2 Investigation of the Coupling Phenomenon 41
5-2.1 The MIMO Antenna without Parasitic Strip 41
5-2.2 Investigation of the Coupling Phenomenon 42
5-2.3 Parasitic Strip for Curbing Near-Field Radiation 43
5-3 The Effect of Ground Size to the Radiation Efficiency 46
5-4 Simulation and Measurement 47
5-4.1 S Paremeters 47
5-4.2 Antenna Efficiency 47
5-4.3 Pattern Diversity 48
5-4.4 Envelope Correlation Coefficient and Diversity Gain 49
5-5 Comparison 51
Chapter 6 Conclusion 52
Reference 53

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