國 立 交 通 大 學
電信工程研究所
碩 士 論 文
應用於無線網路之印刷式可切換場型與
波束天線之研究
Radiation Pattern Reconfigurable
Strip Monopole Antenna with
Switched Printed Parasitic
Elements
研究生:李玫翎
指導教授:鍾世忠 博士
Radiation Pattern Reconfigurable Strip Monopole
Antenna with Switched Printed Parasitic Elements
研究生:李玫翎
Student:Mei-Ling Lee指導教授:鍾世忠 博士
Advisor:Dr. Shyh- Jong Chung國立交通大學
電信工程研究所
碩士論文
A Thesis
Submitted to Institute of Communication
College Electrical Engineering and Computer Science
National Chiao Tung University
In Partial Fulfillment of the Requirements
for the Degree of Master of Science
In Communication Engineering
June 2007
應用於無線網路之印刷式可切換場型與
波束天線之研究
研究生:李玫翎 指導教授:鍾世忠 博士
國立交通大學 電信工程研究所
摘要
在本論文中,一種新型的智慧型天線(可切換場型及波束天線)被提出。這種 新型天線主要架構為八木天線並經過適度改良。一般傳統八木天線的現行天線架 構被平面式印刷電路取代而免除了複雜的立體製作過程。寄生元件也使用電路切 換直接改變其有效長度以發揮反射器(reflector)與導引器(director)的功能。藉由 這些功能性的寄生元件便可以達到場型可變的效果。本論文中一共提出三個天線 模組,以分別討論其改良式八目天線結構中的種種參數影響。從最簡易的三元件 天線陣列到五元件天線陣列,並於最後提出以十字型排列的九元件陣列。十字型 排列的九元件陣列不但可提供四種不同的模態分別的指向性,其中每一種更可以 藉由不同組合的電路開關切換使得主波束有九十度的旋轉可能。如此一來便可以 提供十六種不同的場型以配合實際應用所需。且各模態不僅可以互相獨立操作對 準目標訊號用以強化接收品質,還可以藉由模態間相互的切換產生具互補性且高 增益的全向性輻射場型,因此利用切換波束的設計方式比傳統利用分集式產生互 補式輻射場型的設計方式更具優勢。其中,在某些需要高增益的應用時,此天線 陣列可以有7.59 dBi 的高增益以資利用。Radiation pattern reconfigurable strip monopole
antenna with switched printed parasitic elements
S
tudent:Mei-Ling Lee Advisor:Dr. Shyh-Jong Chung
Institute of Communication Engineering
National Chiao Tung University
Abstract
A configuration of radiation pattern reconfigurable antennas is proposed in this work. The configuration is based on Yagi-Uda antenna and has been modified. In this paper, cylindrical monopoles are replaced by printed strip monopoles on the dielectric substrate, and the effective length of the printed parasitic monopole element is varied directly by switches, with which results in the radiation pattern reconfigurable. Three simple example antennas are presented, that is, a three elements array, a five elements array, and a nine elements array (shaped as a crisscross), and some experiments are validated. The measured results show that a maximum peak gain of 7.59 dBi is achieved by the nine elements array. The nine elements array provides multiple directivities and each directive pattern can be rotated by 90 degrees with different cases of switches states. The properties of antennas proposed in this paper are low cost, flexible design, easy-fabrication, and high gain.
誌謝
能夠順利的完成這篇論文,首先要感謝的就是我的指導教授鍾世
忠博士。更要感謝前瞻微波技術實驗室裡完善的研究資源,使得我可
以順利完成論文,由衷的感謝鍾教授的指導。
對於已經畢業但是曾經給予我許多幫助的:音樂才子張均富學長
(Q仔)、不愧是峰哥的徐民峰學長(峰哥)、我的楷模洪崇育學長(小
洪)、嘴砲魔獸達人第一代沈彥圻學長、偷把走砰砰的陳煥能學長(壞
人)、畢業跟沒畢業一樣的彥志學長、傳授王位給我的陳克強學長,
我都要表達謝意。另外更要感謝實驗室的夥伴:新居落成的何丹雄學
長(何博)、鎮室之寶的王侑信學長(小阿信)、動作迅速的菁偉學姊、
總是吃不飽的林明達學長(達叔)、行徑怪異幼稚的林靖凱學長(凱
凱)、充當管理員的呂永旭(旭哥)、坐在助理室的小黃、嘴砲魔獸達
人第二代陳信錩(小巴)、祝你跟嘟嘟幸福的陳諭正(小圓)、很愛看運
動比賽的吳建宏、我很羨慕髮量的楊淑君(砰砰)、老是愛嗆人的王耀
彬(小花)、還有學弟們:講話慢吞吞的馬義翔(小馬)、便當股長王思
本(阿本)、很有顏色的洪傳恩(阿雷)、我行我素的蘇紹軒(警棍)、還
有常常跟我聊天聊的很開心的助理陳珮華小姐(珮小華),當然還有我
的家人和朋友,這兩年內因為有你們一起分享著生活和研究的經驗,
讓我覺得過的很充實,謝謝你們。
Contents
Chapter 1 Introduction 1
Chapter 2 Theory of Yagi-Uda antenna and monopole 5
2.1 Yagi-Uda antenna• • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 5
2.2 monopole antenna•• • •• •• • •• •• •• • •• ••• • •• •• • •• •• • •• •• •• • ••• • •• •• • •• •• • •• •• •• • ••• • •• •• • •• •• • •• •• •• • ••• • •• •• • •• •• • •• •9
Chapter 3 Pattern reconfigurable antenna 13
3.1 pattern reconfigurable antenna configuration•••••••••••••••••••••••••••••••••••••••••••••••••13
3.2 three-element array•••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••14
3.3 five-element array••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••19
3.4 nine-element array••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••24
Chapter 4 Experimental results 29
4.1 three-element array••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••29
4.2 five-element array•••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••32
4.3 nine-element array••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••34
4.4 switch effects on radiation pattern••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••39
Chapter 5 Conclusion 40
List of Figures
Fig. 2.1.1 A two-element array of half-wave resonant dipoles, one a driver and the other a parasite. The currents on both are equal in amplitude and opposite in phase………. 6 Fig. 2.1.2 A half-wave dipole with a reflector………. 7 Fig. 2.1.3 A half-wave dipole with a director………... 7 Fig. 2.1.4 Three-element Yagi-Uda antenna consist of a driver dipole, a
reflector, and a director. The wire radius is all 0.001λ……….... 8 Fig. 2.2.1 A common half-wave dipole antenna……….. 10 Fig. 2.2.2 Quarter-wave monopole antenna………. 11 Fig. 3.2.1 Three-element array configuration……….. 14 Fig. 3.2.2. The simulated return loss of three-element array when L1 = s =
30mm………... 15 Fig. 3.2.3. The simulated radiation patterns of three-element array for the
two primary planes (a) yz plane, and (b) xy plane……….. 17 Fig. 3.2.4. The simulated return loss of the three-element array with
different values of s, when d1 = 20 mm, L1 = 30 mm……….. 18
Fig. 3.3.2. The simulated values of peak gain for different values of d1 /
L1, and d2 / L2 when L1 = L2 = 30 mm……….. 20
Fig. 3.3.3 The simulated return loss of the five-element array of d1 = 20
mm and different values of d2………. 21
Fig. 3.3.4 The simulated radiation patterns of the five-element array for the two primary planes with d1 = 20 mm. (a) yz plane, and (b)
xy plane………... 22 Fig. 3.4.1 Nine-element array configuration………... 24 Fig. 3.4.2 The simulated radiation patterns of nine-element array for the
four cases shown in Table Ⅳ on the xy plane. (a) case 1 (b) case 2 (c) case 3 (d) case 4……… 25 Fig. 3.4.3. The simulated return loss of the nine-element array with four
different cases……… 27 Fig. 4.1.1. Pictures of three-element array……….….. 29 Fig. 4.1.2. Return loss of three-element array……….. 30 Fig. 4.1.3. The measured pattern of the three-element array at its center
frequency, 2.45GHz. (a) yz plane (b) xy plane…………... 31 Fig. 4.2.1. Pictures of five-element array………. 32 Fig. 4.2.2. The measured return loss of the five-element array……… 33
Fig. 4.2.3. The measured patterns of the five-element array at its center frequency………. 33 Fig. 4.3.1. Pictures of nine-element array. 34 Fig. 4.3.1.1. The measured return loss of case 1. 35 Fig. 4.3.1.2. The measured patterns of case 1 at its center frequency,
2.29GHz. (a) φ = 315°plane (b) xy plane 36 Fig. 4.3.2.1. The measured return loss of case 2. 37 Fig. 4.3.2.2. The measured patterns of case 2. 37 Fig. 4.3.3.1. The measured patterns of case 3. 38 Fig. 4.3.3.2. The measured patterns of case 4. 38 Fig. 4.4.1. The switch effects on radiation pattern. 39
List of TABLES
TABLE Ⅰ THREE-ELEMENT ARRAY WITH DIFFERENT VALUES OF d1………..………. 18
TABLE Ⅱ FIVE-ELEMENT ARRAY WITH d1 = 20 mm AND
DIFFERENT VALUES OF d2………. 23
TABLE Ⅲ SIMPLIFIED NOTATION OF SWITCHABLE PARASITE FUNCTION………. 24 TABLE Ⅳ THE CASES OF THE NINE-ELEMENT ARRAY WITH