DESIGN OF A CIRCULAR POLARIZATION MICROSTRIP ANTENNA AT 2.4GHZ ZURAIDAH BT HARITH A project report submitted in partial fulfillment of the requirements for the award of the degree of Master of Engineering (Electronics and Telecommunication) Faculty of Electrical Engineering Universiti Teknologi Malaysia NOVEMBER, 2005
22
Embed
DESIGN OF A CIRCULAR POLARIZATION MICROSTRIP …eprints.utm.my/id/eprint/5355/1/ZuraidahHarithMFKE2005.pdf · 5.5 Return loss of the microstrip patch antenna 51 5.6 VSWR for the antenna
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
DESIGN OF A CIRCULAR POLARIZATION MICROSTRIP ANTENNA AT
2.4GHZ
ZURAIDAH BT HARITH
A project report submitted in partial fulfillment
of the requirements for the award of the degree of
Master of Engineering (Electronics and Telecommunication)
Faculty of Electrical Engineering
Universiti Teknologi Malaysia
NOVEMBER, 2005
iii
In the loving memory of my father…..
To my beloved family…..
iv
ACKNOWLEDGEMENT
In preparing this thesis, I was in contact with many people, friends and
academicians. They have contributed towards my understanding and thoughts. In
particular, I would like to express my gratitude to my supervisor, Dr. Mohd
Kamal, for encouragement, guidance, and critics. Without his continued support
and interest, this thesis would not have been the same as presented here.
I also would like to extend my sincere appreciation to all my friends
especially Nurul Rodziah, who have provided assistance at various occasions. To
my colleagues who have helped me through out this project, their views and tips
are useful indeed.
Finally, I would like to thank my loving mother and siblings. Their loves,
supports and prayers have given me strength to finish what I have started. Last but
not least, to my late father, who unable to witness this, you will always be in my
heart.
May Allah bless all of you.
v
ABSTRACT
Microstrip patch antennas represent one family of compact antennas that
offer a conformal nature and the capability of ready integration with
communication system’s printed circuitry. In this project, a 2.4 GHz circular
polarization microstrip antenna is designed, constructed and measured. The
microstrip antenna chose is a dual –fed circular polarized microstrip antenna. The
antenna consists of rectangular patch and 3 dB hybrid. The dual – fed circular
polarized microstrip antenna is etched on a FR4 with dielectric substrate of 4.5
with the height of 1.6 mm. Circular polarization is obtained when two orthogonal
modes are equally excited with 90° phase difference between them. Circular
polarization is important because regardless of the receiver orientation, it will
always able receiving a component of the signal. This is due to the resulting wave
having an angular variation.
vi
ABSTRAK
Antena mikrojalur mewakili salah satu kumpulan antena termampat yang
mempunyai sifat penyesuaian dan kebolehan untuk berintegrasi degan litar
bercetak di dalam sistem komunikasi. Dalam projek ini, antena mikrojalur polarisi
bulat pada frekuensi 2.4 GHz direka, difabrikasi dan diukur. Antena mikrojalur
yang dipilih untuk projek ini ialah antena mikrojalur dua – suapan polarasi bulat.
Antena ini terdiri daripada bahagian segiempat tepat dan 3 dB hibrid. Antena
mikrojalur dua – suapan polarasi bulat difabrikasikan di atas FR4 dengan pemalar
dielektrik 4.5 dan tinggi 1.6 mm. Polarasi bulat diperolehi apabila dua mod
bertentangan diuja bersama dengan 90° perbezaan fasa di antara mereka. Polarasi
bulat sangat penting kerana tidak kira kedudukan antena penerima, ia akan
sentiasa dapat menerima komponen isyarat. Ini kerana, gelombang yang
dihasilkan mempunyai variasi bersudut.
vii
TABLE OF CONTENTS
CHAPTER TITLE PAGE
TITLE i
CERTIFICATION ii
DEDICATION iii
ACKNOWLEDGEMENT iv
ABSTRACT v
ABSTRAK vi
TABLE OF CONTENTS vii
LIST OF TABLES xi
LIST OF FIGURES xii
LIST OF SYMBOLS xiii
1 INTRODUCTION 1
1.1 Introduction 1
1.2 Wireless Local Area Network (WLAN) System 2
1.3 Objective 3
1.4 Scope of work 3
1.5 Outline of thesis 4
1.6 Summary 5
2 MICROSTRIP ANTENNA 6
2.1 Introduction 6
2.2 Antenna properties 10
2.2.1 Radiation pattern 10
viii
TABLE OF CONTENTS
CHAPTER TITLE PAGE
2.2.2 Return loss 12
2.2.3 Gain 12
2.2.4 Half power beamwidth 13
2.2.5 VSWR 14
2.2.6 Efficiency 14
2.2.7 Bandwidth 14
2.3 Feeding methods 15
2.3.1 Microstrip line feed 16
2.2.2 Coaxial feed 16
2.3.3 Aperture coupled feed 17
2.3.4 Proximity coupled feed 18
2.4 Summary 20
3 MICROSTRIP ANTENNA POLARIZATION 21
3.1 Polarization type 21
3.1.1 Linear polarization 22
3.1.2 Circular polarization 25
3.1.3 Elliptical polarization 28
3.2 Circularly polarized microstrip antenna 29
3.2.1 Dual– fed circular polarization (CP) patch
antenna
31
3.2.2 Singly fed circular patches 32
3.3 Summary 33
ix
TABLE OF CONTENTS
CHAPTER TITLE PAGE
4 MICROSTRIP DESIGN, SIMULATION AND
FABRICATION
34
4.1 Design of antenna 35
4.2 Microstrip patch design 36
4.2.1 Rectangular patch 37
4.2.2 3 dB hybrid coupler 39
4.3 Feeding methods for the dual –fed CP patch antenna 40
4.4 Simulation 41
4.5 Fabrication process 41
4.5.1 UV exposure 43
4.5.2 Developing 44
4.5.3 Etching 45
4.6 Measurement 45
4.7 Summary 46
5 SIMULATION AND MEASUREMENT RESULTS 47
5.1 Designed antenna 48
5.2 Simulation results 51
5.3 Measurement 57
5.4 Summary 60
6 CONCLUSION 61
6.1 Conclusion 61
6.2 Future work 62
x
TABLE OF CONTENTS
CHAPTER TITLE PAGE
REFERENCES 63
APPENDICE
APPENDIX A Calculation of axial ratio
xi
LIST OF TABLES
TABLE NO. TITLE PAGE
2.1 Advantages and disadvantages of microstrip antenna 9
2.2 Comparing the different feed techniques 19
4.1 Performance of microstrip antenna 36
5.1 Length and width for the calculated microstrip patch
antenna
48
xii
LIST OF FIGURES
FIGURE NO. TITLE PAGE
2.1 Microstrip antenna 7
2.2 Common shapes of microstrip patch elements 7
2.3 Operations of a Microstrip Patch 8
2.4 3D representation of a radiation pattern 11
2.5 Microstrip Line Feed 16
2.6 Coaxial probe feed 17
2.7 Aperture coupled Feed 18
2.8 Proximity – coupled Feed 19
3.1 Linear polarized EM wave 22
3.2 Vertical linear polarization 22
3.3 Horizontal linear polarization 23
3.4 Linear polarization 23
3.5 Circularly polarize EM wave 25
3.6 Left – hand circular polarization 26
3.7 Right – hand circular polarization 26
3.8 Various type of circularly polarized microstrip