investigations on a microstrip excitedrectangular dielectric resonator antenna

326 Pages·2014·8.5 MB·English

MICROWAVE ELECTRONICS
INVESTIGATIONS ON A MICROSTRIP EXCITED
RECTANGULAR DIELECTRIC RESONATOR ANTENNA
A thesis submitted by
MRlDULA.S
in partial fulfilment of the requirements for the degree of
DOCTOR OF PHILOSOPHY
Under the guidance of
Prof.P.Mohanan
DEPARTMENT OF ELECTRONICS
FACULTY OF TECHNOLOGY
COCHIN UNIVERSITY OF SCIENCE AND TECHNOLOGY
KOCHI 682 022, INDIA
JULY 2005
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CERTIFICATE
This is to certify that this thesis entitled “INVESTIGATIONS ON A
MICROSTRIP EXCITED RECTANGULAR DIELECTRIC RESONATOR ANTENNA"
is a bona fide record of the research work carried out by Smt. Mridula.S under my
supervision in the Department of Electronics, Cochin University of Science and
Technology. The results presented in this thesis or parts of it have not been
presented for the award of any other degree.
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Dr.P.MOHANAN
(Supervising Teacher)
Professor
Kochi - 682 022 Department of Electronics
7"‘ July 2005 Cochin University of Science and Technology
DECLARATION
I hereby declare that the work presented in this thesis entitled
"lNVESTIGATlONS ON A MICROSTRIP EXCITED RECTANGULAR DIELECTRIC
RESONATOR ANTENNA" is based on the original research work carried out by me
under the supervision of Dr.P.Mohanan, in the Department of Electronics, Cochin
University of Science and Technology. The results presented in this thesis or parts of
it have not been presented for the award of any other degree.
Kochi - 682 022 MRlDULA.S
7"‘ July 2005
ACKNOWLEDGEMENT
I remember with gratitude....
My supervising guide Dr P. Mohanan, Professor, Department of Electronics, Cochin University
of Science and Technology for introducing me to the fascinating wortd of Microwave Antennas. His
sincerity, devotion to work and tremendous support has been a steady source of inspiration to me. I was
able to persevere, complete the research and deliver this document because of his able guidance. I shall
forever cherish the period of my research work under his supervision.
Dr.K.G.Nair, Director, Centre for Science in Society, Cochin University of Science and
Technology and former Head, Department of Electronics, Cochin University of Science and Technology
for his blessings and good wishes. I gratefully acknowledge his advice while reviewing the thesis.
Prof.K.Vasudevan, Head, Department of Electronics, Cochin University of Science and
Technology for his whole-hearted support and for extending the facilities of the Department during my
research work.
Prof.C.S.Sridhar, Prof.P.R.S.Pillai and Prof.K.G.Ba|akrishnan, former Heads, Department of
Electronics, Cochin University of Science and Technology for their encouragement.
Prof.K.T.Mathew, Dr.C.K.Aanandan, and other faculty members, Department of Electronics,
Cochin University of Science and Technology for their timely advice and cooperation.
Dr.M.T.Sebastian, Scientist, Regional Research Laboratory, Thiruvananthapuram for his
generous support and for providing the Dielectric Resonator Samples.
Dr.H.Sreemoo|anadhan, Scientist-E, Advanced materials and Ceramics Division, Vrkram
Sarabhai Space Centre, Thiruvananthapuram and P.V.Bijumon, Senior Research Fellow, Ceramics
Technology Division, Regional Research Laboratory, Thiruvananthapuram for preparing the Dielectric
Resonator Samples and for the worthy discussions.
Dr.Babu.T.Jose, fonner Director, Centre for Engineering Studies and Smt. Shoba Cyrus,
former Principal, School of Engineering, Cochin University of Science and Technology for helping me
achieve my goal by granting study leave frorn my parent department.
Dr.R.Gopikakumari, Head of Division and all my colleagues at the Division of Electronics and
Communication Engineering, School of Engineering, Cochin University of Science and Technology for
their encouragement.
Dr. Jacob. George, Senior Research Scientist, Corning |nc., Corning, New York for his fervent
support and encouragement in my work. The discussions I had with him regarding the intricacies of
MATLAB® and its application to the problem were instrumental in developing the source code for the
numerical computation.
Mr.Deepukumar.M.Nair, Systems Engineer-Microwave/Millimeter Packaging, Delphi
Autosystems, lndianopolis. U.S., for initiating me to HFSS - the powerful simulation software. The
simulations included in this thesis were done with his patient help during my visit to the US.
Prof.T.K.Mani and Prof. Mini.M.G, Model Engineering college, Thrikkakara, Prof.V.P.Devassia,
Principal, College of Engineering, Chengannur and Dr.Joe.Jacob, Dept of Physics, Newman College,
Thodupuzha for their support.
My dear friend Binu Paul, for being there whenever I needed her.
The research scholars, Centre for Research in Electromagnetics and Antennas, Department of
Electronics, Cochin University of Science and Technology for their cooperation.
Mr.K.K.Suresh, Librarian, Department of Electronics, Cochin University of Science and
Technology for providing me with the necessary reference materials.
The technical and non-technical staff of the Department of Electronics, Cochin University of
Science and Technology especially, Mr. P.M. lbrahimkutty, Mr.C.B.Mura|eedharan and Mr. P.P.Russe|
for their timely help.
My parents and my mother-in-law for their motivation and encouragement.
Hari, Krishna and Rishi for their love, sacrifice and support.
Mn'du|a.S
PREFACE
The new millennium has begun with a revolution in wireless systems that no
one imagined a decade ago. Dielectric Antenna solutions for Mobile
Telecommunications offer the possibility of drastic size reduction compared to their
conventional counterparts. The Dielectric Resonator Antenna (DRA) is a resonant
antenna fabricated from a low-loss Microwave dielectric material, the resonant
frequency of which is predominantly a function of its size, shape and material
permittivity. DRA’s are very versatile elements that can be adapted to numerous
applications by the appropriate choice of design parameters. Small size, wide
bandwidth and absence of conductor losses make them attractive to antenna
designers. The DRA is available in various geometrical shapes; the hemispherical,
circular cylinder and the rectangular being popular. The greater dimensional degrees
of freedom of the rectangular geometry offer better design flexibility to meet
impedance and radiation requirements.
The thesis relates to the investigations carried out on Rectangular Dielectric
Resonator Antenna configurations suitable for Mobile Communication applications.
The main objectives of the research are to:
- numerically compute the radiation characteristics of a Rectangular DRA
- identify the resonant modes
- validate the numerically predicted data through simulation and experiment
0 ascertain the influence of the geometrical and material parameters upon the
radiation behaviour of the antenna
° develop compact Rectangular DRA configurations suitable for Mobile
Communication applications
Although approximate methods exist to compute the resonant frequency of
Rectangular DRA’s, no rigorous analysis techniques have been developed so far to
evaluate the resonant modes. In this thesis a 3D-FDTD (Finite Difference Time
Domain) Modeller is developed using MATLAB® for the numerical computation of
the radiation characteristics of the Rectangular DRA. The F DTD method is a
powerful yet simple algorithm that involves the discretimtion and solution of the
derivative form of Maxwell’s curl equations in the time domain.
The thesis comprises of six chapters. Chapter one serves as an introductory
chapter, sketching the important milestones in the history of antennas and their
practical applications. The relevance of Dielectric Antenna technology and an
overview of Mobile Communication along with various methods of Computational
Electromagnetics are explained.
The significant works in the field of Microwave Antennas are reviewed in the
Chapter two, with due emphasis on Dielectric Resonator Antennas and the methods
employed for their modelling.
Chapter three describes the characteristic features of the Dielectric Resonator
(DR), the Dielectric Resonator Antenna (DRA), design constraints, excitation
techniques and important applications. The scheme of work and measurement
techniques are also explained in this chapter.
The Numerical Computation of the radiation characteristics of the
Rectangular DRA is described in Chapter four. The fundamentals of FDTD method
and its adaptation to the present problem are explained.
The results of the theoretical and experimental investigations are presented in
Chapter five. Discussions on several DRA configurations suitable for wireless
applications are also carried out in this chapter.
Chapter six presents the conclusions drawn from the outcome of the
Numerical Computation and Experimental Observations. Suggestions for future work
in the field are also provided.
The experimental work done by the author in related fields are incorporated
as appendices in the thesis. Appendix A describes a compact very high permittivity
eye-shaped Dielectric Resonator Antenna for multi-band wireless applications. A
Microstrip Antenna with reduced radiation hazards for Mobile telephone handset
applications is outlined in Appendix B.
CONTENTS
Chapter 1
INTRODUCTION
1.1 Antennas
1.2 Dielectric antennas
1.3 Antenna applications
1.4 Mobile Communication — a glimpse of history
1.5 Computational Electromagnetics
1.6 Numerical methods for Electromagnetic modelling
References
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Chapter 2
REVIEW OF LITERATURE
2.1 Mobile communication handset antennas
2.2 Dielectric Resonators - the early years
2.3 Dielectric Resonator Antenna Configurations
2.4 Numerical analysis of Dielectric Resonator Antennas
References
Chapter 3
DIELECTRIC RESONATOR ANTENNA
3.1 Dielectric Resonator
3.2 Material Properties
3.3 The Resonance phenomenon
3.4 The Rectangular Dielectric Resonator Antenna
3.5 Excitation Techniques
3.6 Applications
3.7 Scheme of work
3.8 Measurement techniques
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References