臺灣博碩士論文加值系統

本論文提出一具有雙頻帶操作的微帶單極天線設計，其主體結構是由一直線段及對稱地摺疊曲線段的微帶線所組成。近幾年，個人通訊蓬勃發展，且訴求輕薄短小，所以在天線的體積設計上要小型化，本論文將對縮小化的天線作分析與模擬。
近幾年來由於微帶天線具有尺寸小、重量輕、成本低的特性，已廣泛應用於商業用途上，在無線通訊的應用上也扮演著重要的角色，相當適合在台灣發展。微帶天線係共振式的天線，通常限制了阻抗頻寬。所以擴大頻寬是微帶天線一大重點。本論文針對雙頻天線在有限尺寸的接地面上，對其阻抗頻寬和輻射場型等特性做研究與探討。並提出一簡單的天線設計概念，以矩形微帶天線為基礎，利用微帶線饋入之雙頻帶微帶單極天線(Dual-Band Microstrip Monopole Antenna)以提供藍芽(Bluetooth)(802.15)與無線區域網路(WLAN)(802.11b/g)以及(802.11a)的規格使用。由IE3D軟體模擬並與實驗結果比較得知，可以發現其響應非常吻合。

This thesis proposes a design of microstrip monopole antenna with dual-band operation. The proposed antenna is composed of a straight-line section and a balanced fold-line section. In recent years, the demand for portable radio communication has been increasing which required low profile, light weight and small size antennas. Therefore, the size of the antenna is required to be as small as possible.
Microstrip antennas have the advantage of light weight, small size and low cost and have been used in commercial products extensively. They have played the important role in wireless communicating applications recently.Microstrip antennas can radiate in broadside and act in resonant mode but restricted by its impedance bandwidth. Therefore, how to increase the bandwidth of microstrip antenna has been the major researching topic. In this thesis, we have investigated and analyzed the characteristics of the impedance bandwidth and radiation pattern of a compact size dual-band antenna with a small ground plane. All the properties of the dual-band antenna include the bandwidth, radiating pattern, and gain variation can satisfy the Bluetooth and IEEE 802.11a/b/g specifications for WLAN applications. Experimental results show good agreement to simulation predictions obtained from commercially available IE3D software.

ABSTRACT.....................................................i
摘要........................................................ii
誌謝.......................................................iii
TABLE OF CONTENTS...........................................iv
LIST OF FIGURES...........................................viii
LIST OF TABLE..............................................xii
CHAPTER1 INTRODUCTION........................................1
1.1Survey....................................................1
1.2Motivation and background.................................4
1.3Thesis organization.......................................5
CHAPTER2 ANTENNA OPERATION PRINCIPE AND DESIGNING............7
2.1The basic characteristics of antenna......................7
2.1.1Return loss.............................................8
2.1.2Radiation patterns......................................9
2.1.3Directivity and Gain...................................10
2.1.4Antenna radiation efficiency...........................11
2.2Principles explaining....................................12
2.2.1Basic concepts.........................................12
2.2.2Design analysis........................................13
2.2.2.1Marginal effects.....................................13
2.2.2.2Equivalent length and resonant frequency.............15
2.3Operation procedure......................................20
2.4The simulation and measurement equipments................21
2.4.1IE3D simulation software...............................21
2.4.2Network analyzer.......................................22
2.4.3The signal generator...................................22
2.4.4Arrangements for measuring pattern and gain............23
CHAPTER3 SIMULATIONS AND MEASUREMENTS.......................26
3.1Design and antenna structure.............................26
3.2Experimental results analysis and discussion.............30
3.2.1The current distribution...............................30
3.2.2Return loss............................................34
3.2.3Radiation pattern......................................40
3.2.4Antenna efficiency and gain............................47
3.3Discussion...............................................50
CHAPTER4 CONCLUSIONS........................................61
REFERENCES..................................................62

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