Study of patch antena for WLAN - eprints.utm.myeprints.utm.my/id/eprint/5485/1/YiiMingLeongMFKE2007_StudyofCircularly...STUDY OF CIRCULARLY POLARIZED PATCH ANTENNA FOR WIRELESS LOCAL

STUDY OF CIRCULARLY POLARIZED PATCH ANTENNA FOR

WIRELESS LOCAL AREA NETWORK

ACCESS POINT APPLICATION

YII MING LEONG

A project report submitted in partial fulfillment of the

requirements for the award of the degree of

Master of Engineering

(Electrical – Electronics and Telecommunications)

Faculty of Electrical Engineering

Universiti Teknologi Malaysia

NOVEMBER 2007

PSZ 19:16 (Pind. 1/07)

UNIVERSITI TEKNOLOGI MALAYSIA

DECLARATION OF THESIS / UNDERGRADUATE PROJECT PAPER AND COPYRIGHT

Author’s full name : Yii Ming Leong

Date of birth : 6th November 1977

Title : Study Of Circularly Polarized Patch

Antenna For Wireless Local Area

Network Access Point Application

Academic Session : 2007/2008

I declare that this project report is classified as :

CONFIDENTIAL (Contains confidential information under the Official Secret

Act 1972)*

RESTRICTED (Contains restricted information as specified by the

organization where research was done)*

OPEN ACCESS I agree that my project report to be published as online open

access (full text)

I acknowledged that Universiti Teknologi Malaysia reserves the right as follows:

1. The project report is the property of Universiti Teknologi Malaysia.

2. The Library of Universiti Teknologi Malaysia has the right to make copies for the purpose

of research only.

3. The Library has the right to make copies of the project report for academic exchange.

Certified by :

SIGNATURE SIGNATURE OF SUPERVISOR

771106-13-5065

Prof. Dr. Tharek bin Abdul Rahman

(NEW IC NO. /PASSPORT NO.) NAME OF SUPERVISOR

Date : Date :

NOTES : * If the project report is CONFIDENTAL or RESTRICTED, please attach with the letter from

the organization with period and reasons for confidentiality or restriction

√

“I hereby declare that I have read this project report

and in my opinion this project report is sufficient

in terms of scope and quality for the award of the degree of

Master of Engineering (Electrical – Electronics and Telecommunications)”

Signature :

Name of Supervisor : Prof. Dr. Tharek bin Abdul Rahman

Date :

STUDY OF CIRCULARLY POLARIZED PATCH ANTENNA FOR

WIRELESS LOCAL AREA NETWORK

ACCESS POINT APPLICATION

YII MING LEONG

A project report submitted in partial fulfillment of the

requirements for the award of the degree of

Master of Engineering

(Electrical – Electronics and Telecommunications)

Faculty of Electrical Engineering

Universiti Teknologi Malaysia

NOVEMBER 2007

ii

I declare that this project report entitled

“Study of Circularly Polarized Patch Antenna for Wireless Local Area Network

Access Point Application”

is the result of my own research except as cited in the references. The project report

has not been accepted for any degree and is not concurrently submitted in

candidature of any other degree.

Signature :

Name : Yii Ming Leong

Date :

iii

My Beloved Family

and

Jacinta Yeo

iv

ACKNOWLEDGEMENTS

All glory and honor to my Lord and Saviour Jesus Christ!

This project was initiated by Professor Dr. Tharek Abdul Rahman, the

Director of Wireless Communication Centre (WCC). I sincerely appreciate his

supervision and guidance throughout the project. His simple and strait forward

comments gave me clear sign posts to aim for results.

I would like to thank also to the team of WCC staff who gave me their best

support. They are Puan Azliza, En. Mohamed, En. Khomeini, and En Ghani,

To my ex-lecturer En. Thelaha who gave me unreservedly his competent

technical knowledge. The research officers En. Nazri, En. Osman, En. Huda and my

friends who motivated me with their competitive spirit.

I owe much to my parents, my family members, and Jacinta for their

emotional, financial, prayers, and loving support.

.

v

ABSTRACT

Circular Polarized (CP) antennas are attractive for wireless communication

applications because no strict orientation between the access point and the mobile

unit are required. The purpose of this project is to make a comparative study

between a CP patch antenna and a standard monopole antenna for Wireless Local

Area Network Access Point (WLAN AP) applications at 2.4 ~ 2.485GHz frequency

band. Circularly polarized operation is achieved by truncating two opposite corners

of a square patch and airgap with a long probe feed is used as bandwidth

enhancement technique. The best 3dB axial ratio bandwidth and 10dB impedance

bandwidth reached 8.55% and 8.9% respectively, for gain of 6dBi with airgap

thickness of 5mm. Details of the antenna design, the process involved, and the

simulation and experimental results are presented.

vi

ABSTRAK

Antena kutup berpusing (CP) amat menarik untuk applikasi perhubungan

tanpa wayar kerana ia tidak memerlukan orientasi antena yang tepat di antara tempat

masuk (AP) dan unit mobil. Tujuan projek ini adalah untuk membuat kajian

perbandingan di antara antena monopol standard dengan antena CP untuk kegunaan

applikasi tempat memasuki rangkaian setempat tanpa wayar (WLAN AP) pada jalur

frekuensi 2.4 ~ 2.485GHz. Operasi kutup berpusing telah dicapai dengan memotong

dua pepenjuru bertentangan pada satu tampal segi-empat sama dan gap udara dengan

suapan prob yang panjang digunakan sebagai teknik memperbesarkan julat jalur.

Julat jalur terbaik yang dicapai untuk 3dB Axial Ratio(AR) dan 10dB impedance

adalah 8.55% dan 8.9% masing-masing untuk 6dBi tambahan pada ketebalan gap

udara 5mm. Rekaan antena, proses berkenalan serta keputusan-keputusan simulasi

dan ujikasi yang terperinci telah dibuat.

vii

TABLE OF CONTENTS

CHAPTER TITLE PAGE

DECLARATION ii

DEDICATION iii

ACKNOWLEDGEMENTS iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENTS vii

LIST OF TABLES xi

LIST OF FIGURES xii

LIST OF APPENDICES xv

1 INTRODUCTION 1

1.1 Overview 1

1.2 Objective 2

1.3 Scope of Study 2

1.4 Problem statement 2

2 LITERATURE REVIEW 4

2.1 Important Features of Microstrip Patch Antennas 5

2.1.1 Patch Shapes 5

2.1.2 Substrates 6

2.1.3 Feeding Structures 6

2.2 Transmission-line model 7

2.3 Circular polarization 11

viii

2.4 Polarization measurements 13

2.4.1 Polarization Loss Factor 13

2.5 Recent works of Circularly Polarized Antennas 14

2.5.1 Effects Of Circular And Linear Polarized Antennas

On Wideband Propagation Parameters In Indoor

Radio Channel 14

2.5.2 Study Of Broadband Cp Patch Antenna With Its

Ground

Plane Having An Elevated Portion. 14

2.5.3 Low-Cost Broadband Circularly Polarized Patch

Antenna 15

2.5.4 A Broadband Planar Patch Antenna Feb By A Short

Probe Feed. 16

3 DESIGN OF A CICURLARY POLARIZED ANTENNA 18

3.1 Introduction 18

3.2 Design methodology 19

3.3 Selection of antenna structure 20

3.4 Design specifications 20

3.5 Theoretical Calculations 21

3.6 Modeling and simulation 23

3.6.1 Design Entry 23

3.6.2 Optimizations 24

3.7 Fabrication Process Flowchart 25

3.8 Comparison of result 26

3.8.1 Return Loss (S11) 26

3.8.2 Impedance Bandwidth 27

3.8.3 Radiation Pattern 28

3.8.4 Axial Ratio (AR) Bandwidth 30

3.8.5 Gain 31

3.9 Conclusion 32

4 MEASUREMENTS RESULT AND ANALYSIS 33

ix

4.1 Introduction 33

4.2 Parametric Studies 33

4.2.1 The Effect of Different Sizes of Ground Plane on

Return Loss 35

4.2.2 The Effect of Different Patch Length on Return Loss 36

4.2.3 The Effect of Different Truncated Sizes on Return

Loss 37

4.2.4 The Effect of Different Feed Location on Return

Loss 38

4.2.5 The Effect of Different Airgap Thickness on

Return Loss 39

4.2.6 The Effect of Different Dielectric Constant on

Return Loss 40

4.2.7 Summary of Parametric Study 41

4.3 The effect of Plastic enclosure 42

4.3.1 Return Loss 42


4.4 System level measurement 44

4.4.1 Experiment Purpose 44

4.4.2 Experiment Setup and Procedures 44

4.4.3 Experiment Result 46

4.5 Consistence Measurement 48



4.6 Second prototype 50



4.6.3 Axial Ratio 53

4.6.4 System Level Measurement 54

4.7 Comparison for two Prototypes 55



4.7.3 Axial Ratio Bandwidth 57

x

4.7.4 Gain 58

4.7.5 Prototype Costing 59

4.8 Conclusion 59

4.8.1 Lesson learned 59

4.8.2 Project Constraints 61

5 CONCLUSION AND FUTURE WORKS 62

5.1 Final product specifications 62

5.2 Future work 63

5.2.1 Miniaturization of the Patch Dimension 63

5.2.2 Parasitic Element As Way To Improve Gain 63

5.2.3 CP Patch Antenna Array 63

REFERENCES 64

Appendices A-B 66 - 71

xi

LIST OF TABLES

TABLE NO. TITLE PAGE

3.1 Design Specifications 20

3.2 Theoretical Calculations 22

3.3 Return Loss Comparison 27

3.4 Radiation Pattern Comparison 29

3.5 Axial Ratio Comparison 31

3.6 Transfer Gain Measurement 32

4.1 Summary of Parametric Studies 41

4.2 Effect of Plastic Enclosure on Return Loss 42

4.3 Effect of Plastic Enclosure on Radiation Pattern 43

4.4 Winbox Experiment Results for 1st Prototype 47

4.5 Return Loss Comparison of Two Identical Antennas 49

4.6 Radiation Pattern Comparison of Two Identical Antennas 50

4.7 Second Prototype Return Loss 51

4.8 Second Prototype Radiation Pattern 52

4.9 Second Prototype Axial Ratio 53

4.10 Experiment Result for 2nd Prototype 54


4.12 E-Co Radiation Pattern Beamwidth 57


4.14 Gain Comparison 58

4.15 Prototypes Costing 59

5.1 Final Prototype Specifications 62

xii

LIST OF FIGURES

FIGURE NO. TITLE PAGE

2.1 Basic Structure of a Microstrip Patch Antenna 5

2.2 Shapes of radiators 5

2.3 Types of feeding structure used in microstrip patch antennas 6

2.4 Microstrip antenna 8

2.5 Microstrip line and its electric field lines, and effective

dielectric constant geometry 9

2.6 Physical and effective length of rectangular microstrip patch 9

2.7 Suggested arrangements for CP operation 12

2.8 Polarization unit vectors of incident wave and antenna 13

2.9 (a) Geometry of the proposed broadband circularly polarized

patch antenna having an elevated ground plane portion;

(b) cross-sectional view in the x-z plane. 15

2.10 Geometry of the proposed broadband circularly polarized patch

antenna. 16

2.11 Geometry of the proposed broadband probe-feed patch antenna 17

3.1 Design Methodology Flowchart 19

3.2 Mathcad calculation 21

3.3 Designed EM structure 23

3.4 Design results 25

3.5 PCB Fabrication Flowchart 25

3.6 Return Loss Measurement Experiment Setup 26


3.8 Anechoic Chamber 28

3.9 Radiation Pattern Comparison 29

xiii


3.11 Transfer Gain Measurement 31

4.1 Areas of Parametric Studies 34

4.2 Simulation and Measurement Settings for Different Ground

Plane Sizes 35

4.3 Effect of Differing Ground Plane Size 35

4.4 Simulation and Measurement Settings for Different Ground

Plane Sizes 36

4.5 Effect of Differing Patch Length Size 37

4.6 Simulation and Measurement Settings for Different Truncated

Sizes 37

4.7 Effect of Differing Truncated Size 37

4.8 Simulation and Measurement Settings for Different Feed

Location 38

4.9 Effect of Differing Feed Location 38

4.10 Simulation and Measurement Settings for Different Airgap

Thicknesses 39

4.11 Effect of Differing Airgap Thickness 39

4.12 Simulation and Measurement Settings for Different Dielectric

Constants 40

4.13 Effect of Differing Dielectric Constant 40

4.14 Effect of Plastic Enclosure on S11 42

4.15 Effect of Plastic Enclosure on Radiation Pattern 43

4.16 System Performance Experiment Setup 44

4.17 Client Antenna Orientations 45

4.18 Sample Bridge Performance Reading from Winbox 46

4.19 Return Loss Comparison of Two Identical Antennas 48

4.20 Radiation Pattern Comparison of Two Identical Antennas 49

4.21 Second Prototype 50

4.22 Second Prototype Return Loss 51

4.23 Second Prototype Radiation Pattern 52

4.24 Second Prototype Axial Ratio 53


xiv

4.26 E-Co Radiation Pattern Comparison 56


4.28 Gain Comparison 60

4.29 Modified Design Methodology 60

5.1 Prototype with Inside Enclosure 62

xv

LIST OF APPENDICES

APPENDIX TITLE PAGE

A Parametric Study 68

B Radiation Pattern 71

64

REFERENCES

[1] Rackley,S., “Wireless Networking Technology:From Principles to Successful

Implementation” Elsevier, pg 1, Oxford, 2007.

[2] T.S. Rappaport & D.A. Hawbaker, “Effects of circular and linear polarized

antennas on wideband propagation parameters in indoor radio channels”

IEEE journal pp. 1287 - 1291 vol.2 GLOCOM 2-5 Dec 1991.

[3] Balanis, C.A., “ANTENNA THEORY ANALYSIS AND DESIGN,” John

Wiley, 3rd Ed. pp 75, 811-872, New Jersey, 2005.

[4] Chen, Z. N. & Chia M. Y. W., “Broadband Planar Antennas: Design and

Applications”, John Wiley, West Sussex, 2006

[5] Yu-Bo Tzeng, Che-Wei Su, and Ching-Her Lee, “STUDY OF

BROADBAND CP PATCH ANTENNA WITH ITS GROUND PLANE

HAVING AN ELEVATED PORTION,” APMC 2005 Proc., Vol. 4, Dec.

2005

[6] F.S. Chang, K.L. Wong, and T.W. Chiou, “Low-Cost Broadband Circularly

Polarized Patch Antenna,” in IEEE Trans. Antennas and Propagat.,Vol. 51,

pp. 3007-3009,Oct 2003.

[7] P.L. Teng, C. L. Tang, & K.L. Wong, “A Broadband Planar Patch Antenna

Feb by A Short Probe Feed,” APMC 2001,vol. 3,pp. 1243-1246, 2001.

65

[8] Barclay, L.W., “Propagation of Radiowaves”, IEE, 2nd Ed., pp 38-44, London,

2003.

[9] Garg, R., “Microstrip Antenna Design Handbook”, Artech House, pg 357,

London,2001.

[10] Sung, M.K., Ji, M.S., Hyuck, J.K., Woon, G.Y., “Design and Implementation

of Dual-Band Square Patch Antenna for Wireless LAN of 2.4GHz and

5.7GHz” APMC 2005 Proc., vol. 5, 2005.

[11] Z.N. Chen, “Impedance characteristics of a probe-fed L-shaped plate

antenna,” Radio Science, vol. 36, no.6, pp. 1377-1384, 2001.

[12] Pozar, D.M., “Microwave Engineering,” John Wiley & Sons, 2nd Ed., Canada,

July 1997.

[13] Wong, M.L, Wong, H., Luk, K.-M, “Small circularly polarized patch

antenna,” IEE, vol. 41, no. 16, pp. 7-8, April 2005.

[14] Row, J.S., “Design of square-ring microstrip antenna for circular

polarization,” IEE, vol.40, no.2, pp. 93-95, Jan 2004

[15] Tanaka,T., Takahashi, M., Ito, K., “Study on the Radiation Characteristics of

a Miniaturized Circularly Polarized Circular Sector Patch Antenna” IEEE, pp

1561-1564, 2006.

71

2. 2nd Prototype

angle e-co e-cross

0 -52.82 -53.94

4 -52.82 -54.06

8 -53.26 -53.92

12 -53.32 -54.14

16 -53.52 -53.94

20 -53.97 -54.58

24 -54.53 -54.67

28 -55.003 -55.52

32 -55.44 -55.97

36 -55.92 -56.92

40 -56.94 -57.62

44 -57.97 -57.89

48 -59.09 -58.76

52 -59.84 -59.66

56 -60.34 -60.15

60 -60.17 -60.57

64 -60.88 -61.94

68 -62.13 -62.5

72 -62.39 -63.82

76 -64.12 -64.87

80 -64.84 -64.87

84 -66.44 -65.61

88 -67.89 -66.7

92 -67.16 -66.49

96 -67.43 -67.3

100 -66.83 -67.68

104 -66.76 -67.44

108 -66.89 -66.66

112 -67.18 -67.85

116 -66.88 -67.21

120 -67.16 -67.64

124 -67.9 -68.39

128 -67.75 -68.15

132 -66.92 -67.61

136 -65.88 -68.56

140 -65.48 -66.64

144 -64.19 -66.29

148 -64.3 -66.57

152 -65.07 -66.44

156 -65.63 -65.45

160 -65.86 -66.41

164 -66.79 -66.59

168 -66.94 -66.79

172 -66.55 -67.8

176 -67.15 -67.05

180 -67.13 -67.19

184 -67.21 -67.54

188 -66.61 -66.95

192 -65.71 -68.52

196 -65.99 -67.18

200 -64.85 -68.2

204 -66.33 -67.81

208 -66.22 -67.76

212 -66.79 -67.32

216 -66.8 -66.69

220 -66.99 -66.24

224 -68.14 -67.73

228 -67.84 -68.4

232 -67.46 -68.15

236 -65.72 -67.09

240 -65.5 -67.09

244 -64.66 -65.78

248 -64.78 -65.66

252 -64.1 -64.32

256 -64.09 -64.33

260 -64.38 -63.65

264 -64.18 -63.8

268 -64.88 -63.82

272 -64.69 -62.93

276 -63.75 -63.07

280 -63.51 -62.53

284 -63.41 -61.98

288 -62.04 -61.26

292 -61.71 -60.3

296 -60.51 -59.66

300 -60.17 -58.99

304 -59.46 -58.85

308 -58.86 -58.85

312 -58.2 -58.56

316 -57.23 -57.43

320 -56.5 -56.54

324 -55.92 -56.05

328 -55.25 -55.76

332 -54.83 -55.09

336 -54.31 -55.06

340 -53.9 -54.07

344 -53.69 -54.39

348 -53.4 -54.16

352 -53.15 -54.14

356 -53.08 -53.97

360 -52.88 -53.73

Study of patch antena for WLAN - eprints.utm.myeprints.utm.my/id/eprint/5485/1/YiiMingLeongMFKE2007_StudyofCircularly...STUDY OF CIRCULARLY POLARIZED PATCH ANTENNA FOR WIRELESS LOCAL

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