Hexagonal dielectric resonator antenna

235 Pages·2012·7.94 MB·English

by  Hamsakutty V

Microwilve Electronics
HEXAGONAL DIELECTRIC RESONATOR ANTENNA - A
NOVEL DR ANTENNA FOR WIRELESS COMMUNICATION
Thesis Submitted
by
V. HAMSAKUTTY
In partia[f ulfilment of tlie requirements for tlie aearee of
DOCTOR OF PHILOSOPHY
f\.nCROWAVE TOMOGRAPHY AND MATERIALS RESEARCH U ,BORATORY
DEPARTMENT OF ELECTRONICS,
FACULTY OF TECHNOLOGY
COCHIN UNIVERSITY OF SCIENCE AND TECHNOLOGY
KOCHI-682 022, INDIA
MARCH 2007
Dedicated
"To the two who gave me life" and
To the one who taught me love
CERTIFICATE
This is to certify that the thesis titled Hexagonal dielectric
resonator antenna - A novel DR antenna for wireless
communication is a bona fide record of the research work carried out
by Mr. V. Harnsakutty under my supervision in the Department of
Electronics, Cochin University of Science and Technology. The results
embodied in this thesis or pans of it have not been presented for any other
degree.
Dr. K.T. Mathew
(Supervising Guide)
Kochi- 22 Professor
16-03-2007 Department of Electronics
Cochin Uniyersity of Science and Technology
ii
DECLARATION
I hereby declare that the work presented in this thesis titled Hexagonal
dielectric resonator antenna - A novel DR antenna for
wireless communication is based on the original work done by me
under the supervision of Dr. K.T. Mathew, in the Department of
Electronics, Cochin University of Science and Technology, and no part
thereof has been presented for the award of any other degree.
Kochi - 22 ~
16-03-2007 v. HAMSAKUTIY
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Heartfelt thanks ...
Ho\\, little can mere words reveal of what our hearts most deeply
feels ....I t's natural that a lot of thanks come \\lith this thesis.
First I thank and praise the Lord Almighty for his mercy,
sustenance, and uncountable blessings.
I would like to express my gratitude to my Guide Professor KT
Mathew, who poured over every fine aspect of the thesis with painstaking
attention to details and made a semi-infinite number of helpful
suggestions. My special thanks go to Professor & Head of the department
Dr. K Vasudevan for his help and advice. i\Iany thanks to Dr. P.Mohanan,
Dr. C.K. Aanandan, Dr. K.G Balakrishnan, Dr. P.R.S Pillai, Dr. Tessamma
Thomas, Mr. James Kurian and 1\lrs. Suppriya who helped me in various
ways.
A thoughtful act and a kindness shown to others 1S never
forgotten, but remembered for ever - Dr. Joe Jacob, Sr. Lecturer
Newman's College, Thodupuzha, you are one of those people. I thank you
from the bottom of my heart. A bouquet of thanks to my colleagues Dr.
Jaimon yohannan, Mr. A.V Praveen Kumar, Mr. Rohith K Raj, Mr. Anil
Lonappan, Mr. Vinu Thomas, Mr. Robin Augustine, Mr. Cyriac M.O, Mr.
Anupam R. Chandran and Mr. Abdullah for their continuous advice and
help during the past several years.
Let me also remember at this moment, all the teaching, non
teaching staffs and research scholars of the DOE for their continuous
companionship. Now I wish to acknowledge the financial support of the
lice
through flP fellowship during the course of my doctoral studies.
I would also like to express my gratitude and thanks to the
members of my family, each of whom helped me in innumerable ways. My
parents were a constant source of inspiration and moral support. Their
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sacrifices and continuous prayers helped me throughout my life. Thanks to
my wife for her support, encouragement and prayers throughout all the
uncertain times. Her sacrifices helped me to complete this work. Special
thanks to my fathers-in-law and mothers-in-law, who gave me constant
support and encouragement, and also to all my dears and nears.
I would like to express my thanks and appreciation to the Manager,
and Principal Dr. A. Abdul Latheef of W.M.O College, Wayanad who
permitted me to undertake the research under FIP. Last but not least, I
would like to thank all the colleagues at \Xl.M.O College for their
continuous encouragement and support.
Though busy, you all had time to spare for me, to listen to me, to
discuss with me, to help me and to guide me. I want you (all) to know how
very grateful I am ...
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CONTENTS
Preface
CHAPTER I INTRODUCTION
1.1 Developments in Electromagnetics and Microwaves 7
1.1.1 Predecessor to Microwaves: Wireless and Radio 9
1.1.2 The Physicist's War: World War 1I 13
1.1.3 Microwaves and Telecommunication 16
1.2 Antennas 19
1.3 Dielectric resonator antennas 21
1.3.1 Features of dielectric resonator antenna 24
1.3.1.1 Resonant Frequency 24
1.3.1.2 Q-Factor 25
1.3.1.3 Bandwidth 26
1.3.1.4 Different geometries 28
1.4 Coupling methods to DRAs 29
1.4.1 Coaxial probe 30
1.4.2 Slot/Aperture coupling 31
1.4.3 Microstrip transmission line/proximity coupling 32
1.4.4 Coplanar feed 32
1.4.5 Waveguide feed 33
1.4.6 Con formal strip feed 32
1.5 Theoretical Considerations: Dielectric Resonators 35
1.5.1 Field Modes 3S
1.6 Numerical Methods 37
1.6.1 Overview 37
1.6.2 Finite Difference Method 39
1.6.3 Variational Methods 40
1.6.3.1 Method of Moments (1vloM) 40
1.6.3.2 Finite Element Method (FEM) 41
1.6.4 Method of Lines 41
1.6.5 Finite Difference Frequency Domain Method 42
1.6.6 Spectral Domain Approach 43
1.6.7 Mode Matching Method 43
1.6.8 Transmission Line l\Iethod 43
References 44
CHAPTER 11 REVIEW OF THE PAST WORK
2.1 Introduction 46
2.2 Different geometries of ORA 47
2.3 Different coupling methods to DRA 47
2.4 Theoretical Analysis of DRA 47
2.5 Miniaturisation of DRA 49
2.6 Bandwidth Enhancement Techniques 49
2.7 Circular polarization 50
2.8 Antenna Gain 52
2.9 Air gap Effect 52
2.10 Multi-frequency Operation 52
2.11 Conclusion 53
References 53
CHAPTER III METHODOLOGY
3.1 Introduction 62
3.2 Basic facilities utilized 62
3.2.1 HP 851 OC Vector Network Analyzer 62
3.2.2 Anechoic chamber 64
3.2.3 Automated turn table assembly for far field
measurements 65
3.3 Experimental set up 65
3.4 Measurement procedure 67
3.4.1 S-parameters, Resonat freyuency and Bandwidth 68
3.4.2 Radiation patterns 69
3.4.3 Gain 70
3.4.4 Polarization pattern 71
3.5 Ansoft HFSS 72
References
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CHAPTER IV SYNTHESIS OF DIELECTRIC RESONATORS
4.1 Introduction 74
4.2 Preparation of DR Pellet 74
4.2.1 Weighing and mixing 7S
4.2.2 Pre-heating 75
4.2.3 Binder addition and dry pressing 7S
4.2.4 Si ntering 79
4.2.5 Finishing 79
4.3 Microwave characterization of DR 80
4.3.1 Method of measuring the permittivity 80
4.3.2 Hakki and Coleman method 81
4.3.3 Cavity perturbation technique 84
References 86
CHAPTER V EXPERIMENTAL STUDY OF HEXAGONAL
DIELECTRIC RESONATOR ANTENNA
5.1 Introduction 88
5.2 Coaxial fed HDRA 88
5.2.1 Antenna Configuration 88
5.2.2 Effect of coaxial probe length on the
performance of HDRA 90
5.2.3 Effect of DR height on the performance of HDRA 91
5.2.3.1 Results and discussion 92
5.2.4 Effect of variation of Coaxial feed position on HDRA 96
5.2.4.1 Results and discussion 97
5.3 Microstrip fed HDRA 118
5.3.1 Antenna Configuration 118
5.3.2 Effect of microstrip feed position on HDRA 118
5.3.2.1 Results and discl1ssion 120
5.4 Radiation efficiency of the HDRA 133
5.5 Comparison of antenna performance between
HDRA and conventional Cylindrical DRA 133
5.6 Conclusion 133
References 13S
CHAPTER VI THEORETICAL ANALYSIS-FDTD
6.1 Introduction 136
6.2 Electromagnetic Analysis 138
6.2.1 Governing Equations 138
6.2.2 Finite difference equations 139
6.2.3 Normalized Maxwell's equations 142
6.2.4 The Perfect Matched Layer (PML) 145
6.3 Description of the microstrip fed HDRA 158
6.3.1 Modeling the materials 160
6.3.2 Boundary conditions 162
6.3.3 Source 163
6.3.4 Resistant source FDTD excitation 164
6.3.5 Flow chart for the simulation of HDRA 167
6.3.6 FDTD Results 170
6.3.6.1 Calculation of Return loss 170
6.3.6.2 Calculation of electric field distribution 176
6.4 Description of Coaxial Fed HDRA 177
6.4.1 Modeling the material 180
6.4.2 FDTD Results 182
6.4.2.1 Calculation of return loss 182
6.5 Conclusion 185
References 186
CHAPTER VII CONCLUSION AND FUTURE SCOPE OF
THE WORK
7.1 Highlights of the work 194
7.2 Possible applications 195
7.3 Scope of future work 195
7.4 Concluding remarks 1%
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