臺灣博碩士論文加值系統

此論文中提出兩種使用孔徑的天線，分別是圓形極化天線和線性極化天線。圓形極化天線中，共平面波導的饋入線彎成半圓形，並且接地面的兩個分支連在一起形成一個開放的孔徑，在這個孔徑不變的前提下,我們可以修改各項參數調整頻率。第二隻為線性極化天線，藉由調整中心方形的寬度和長度可以調整頻率。
這圓形極化天線被設計用來應用於2.45GHz的無線區域網路(WLAN)和2.5GHz頻段的全球互通微波存取(WiMAX)。10 dB的阻抗頻寬為22.04 ％ (2.22~2.77 GHz)，3 dB的軸向比頻寬為17.04 % (2.35~2.8GHz)，而在頻寬內天線的增益範圍在1~4.5 dBic之間。而線性極化天線則是設計用來涵蓋2.5/3.5/5.5GHz的WiMAX頻段和5.8GHz的WLAN。10 dB的阻抗頻寬為44.6 ％ (2.42~3.81 GHz)和16.33%(5.38-6.351GHz) 而在頻寬內天線的增益範圍在0.15~4.4 dBi之間。

In this thesis, two unique approaches are respectively applied to design a CPW-fed circularly and a linearly polarized antenna. For the circularly polarized antenna, center conductor of the CPW is bended into a semi-circular shape and two ground branches of the CPW are connected together to form an open-aperture. We may consider that center conductor of the CPW is modified to form the first type and is protruded into the aperture. By keeping this aperture, the center conductor of the CPW can be modified into the second type. The second type results in the linearly polarized antenna by extending and widening the width of the center conductor of the CPW.
The CP antenna is designed and implemented for WLAN standards of 2.4 GHz and WiMAX standard of 2.5 GHz (2.5-2.69GHz). The measured 10-dB return loss bandwidth is 22.04 %( 2.22-2.77GHz), the 3dB axial ratio is 17.4% (2.35-2.8GHz), and the in-band antenna gain lies between 1~4.5 dBic. The LP antenna is designed to cover 2.5/3.5/5.5 GHz of WiMAX bands and 5.8 GHz of WLAN bands. The measured 10-dB return loss bandwidth is 44.6% (2.42-3.81GHz) and 16.33% (5.38-6.351GHz), and the in-band antenna gain is around 0.15~4.4 dBi. The latter one may further improve the reception ability.

ABSTRACT ii
摘要 iii
LIST OF FIGURES v
LIST OF TABLE viii
CHAPTER 1
INTRODUCTION 1
1.1 Motivation 1
1.2 Introduction for WiMAX 2
1.3 Introduction for WLAN 2
1.4 Basic Description of IEEE 802.16 and 802.11 3
1.5 Coplanar Waveguide 6
1.6 Chapter Outline 7
CHAPTER2
CPW-FED CIRCULARLY-POLARIZED ANTENNA FOR WIMAX/WLAN BAND 8
2.1 Antenna Design 8
2.2. Experimental Results and Discussion 15
2.2.1 Return Loss 16
2.2.2 Axial Ratio 17
2.2.3 Gain 19
CHAPTER3
CPW-FED ANTENNA FOR WIMAX BAND AND GAIN ENHANCE BY ADDING AN OUTER RING 23
3.1 Antenna Geometry and Design 23
3.2 Experimental Result 35
3.2.1 Return Loss 35
3.2.2 Gain 37
3.2.3 Working Principle 40
CHAPTER4
CONCLUSION 42
REFERENCES 43

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