Investigations on slot-Loaded Square Microstrip Patch Antennas For

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Microwave Electronics
INVESTIGATIONS ON SLOT-lOADED SQUARE MICROSTRIP
PATCH ANTENNAS FOR COMPACT DUAL FREQUENCY
DUAL POLARIZED OPERATIONS
Thesis suhmittedhy
BINOY G S
in partialfulfilment ofthe requirements
for the awardofthe degree of
DOCTOR OF PHILOSOPHY
DEPARTMENT OF ELECTRONICS
FACULTY OF TECHNOLOGY
COCHIN UNIVERSITY OF SCIENCE AND TECHNOLOGY
COCHIN682022,INDIA
JUNE 2002
'Dedicated.to my parents ant! teachers .
CERTIFICATE
This is to certify that this thesis entitled "INVESTIGATIONS ON SLOT-LOADED
SQUARE MICROSTRIP PATCH ANTENNAS FOR COMPACT DUAL FREQUENCY DUAL
POLARIZED OPERATIONS" is a bona fide record of the doctoral research work
carried out by Mr.BinoyGS, under my supervision in the Department of Electronics,
Cochin Universityof Science & Technology. The resultspresentedin thesisor part of
it havenot been presented for anyother degree.
~/7-
Dr.K Vasudevan
Supervising Teacher
Professor
Cochin 682 022 Department of Electronics
5th June 2002 Cochin University of Science and Technology
DECLARATION
I hereby declarethat the work presented in this thesis entitled "INVESTIGATIONS
ON SLOT-LOADED SQUARE MICROSTRIP PATCH ANTENNAS FOR COMPACT DUAL
FREQUENCY DUAL POLARIZED OPERATIONS" is based on the original work done
by me under the supervision of Dr. K Vasudevan in the Department of Electronics,
Cochin University of Science & Technology, and that no part thereof has been
presentedfor any other degree.
~
Cochin 682 022 BINOYGS
5th June 2002
Acknowledgements
At the time of presentation ofthis thesis, letme express my deepest sense ofgratefulness to my
research guide, Dr K. Vasudevan, Professor, Dept. ofElectronics, Cochin University ofScience and
Technology, Kerala, India forhis excellent guidance and the valuable support I received from him
duringthetenureofmydoctoralgraduation.
Itiswith deep sense ofgratitude, that Iexpress my heartfelt appreciation toDr. K. G. Balakrishnan,
Professor&Head, Dept. ofElectronics, Cochin UniversityofScienceand Technology, Kerala, Indiafor
hisardentencouragement.
Iamdeeplyindebtedto ProfKG Nair, DirectorSTIC, forhisvaluable suggestions and encouragements
during myresearch work.
Ialso would liketoexpress mysincere thanks toDr.P.R.S Pillai, Professorand FormerHead, Dept. of
Electronics, CUSATforhisenthusiasticsupport.
Words areinadequateto expressmythankfulnesstoDrP.Mohanan, Professor, Dept. ofElectronicsfor
his valuable suggestions and inspiration. Iwill neverforgetthe wonderful way in which has supported
mewheneverIneeded itthe most.
Sincere thanks are due to Dr.C.K.Aanandan, Reader, Dept of Electronics, CUSAT for his
timely suggestions and help.
Iam hereby recording myindebtedness to Prof. K.TMathew and Dr. Deepu Rajan faculty members of
thisdepartmentfortheircontinuous encouragement.
During the tenure ofresearch, my research fellowship was supported by Cochin University ofScience
and Technology through University JRF. Ihave also received aSenior Research Fellowship from the
Defense Research and DevelopmentOrganization. Ihonestlyacknowledge theirsupport.
Ihad the opportunity to participate in aYoung Collaborator training Programme, atthe International
Center for Theoretical Physics (ICTP), Italy. The exposure I received from the event isthankfully
remembered. Iwould like to mention with deep gratitude, the young scientist support, Ireceived from
Council ofScientificand Industrial Research-CSIR, which enabled metoattend and presentmyworkat
the 2001 IEEE AP-S SymposiumatBoston, USA
Itake this occasion, to place on high record the helps and encouragements Ireceived from my former
colleague MrBijukumar.S, Research Fellow, UniversityofHaddersfield, UK.
I am deeply indebted to Dr Joe Jacob, Research Associate, Dept. ofElectronics, CUSAT and Dr
Jacob George, Corning Inc., USAfortheirvaluable supportthroughout myperiod ofresearch.
I would also like to acknowledge with thanks the splendid cooperation I received from
DrU.Raveendranath, NAL-Banglore, DrKKNarayanan, S.D.College, Alapuzha, DrSebastian Mathew,
K.E College, Mannanam, Mr Cyriac M. Odackal, Lecturer, Dept. of Electronics, Dr.Thomaskutty
Mathew, Lecturer, MG University Regional Center, Edapally, and Mr. Girish. G, R&D Engineer, IBM,
Bangaloreand Mr. Girish Kumar. C, Lecturer, CollegeofAppl. Science, Peerumedu.
The support and cooperation received from Dr. Ratheesh, Scientist, CMET, Thrissur, Dr. Jagannath
Bhat, Scientist, STIC, and Mr. Paul. V. John, Scientist, STICarethankfullyacknowleged.
I would like toexpress my profound gratitude to Mr.ShajLS, Mr.Joseph MathaLC, Ms.Bindu.K, Saji
Augustine, Research Scholars Dept ofPhysics, CUSAT and Pyroja S, Dept.of Biotechnology for their
unreserved co-operation.
The encouragements and co-operation I received from my colleagues in DoE, CUSAT
Mr.ManLTK,MrVP.Devassia, Ms.MinLM.G, Mr.Deepu P, Mr.Binu George, Mr.Anand Raj, Mr.Anil
Lonappan, Dr. Jaimon Yohannan, Ms. Sona. O.K, Ms. Manju Paulson, Ms. Mridula. M., Ms. Binu Paul,
Mr, Shabeer Ali, Ms. Sree Devi, Dr. C. P. Anil Kumar, Mr. Sajith N. Pai, Mr. Prakash Kumar, Mr.
Jayaram Pand Ms. Latha Kumaryarethankfully acknowledged.
I am also grateful to Dr.Beena. C, Librarian, Dept. of Physics, Mr. Suresh, Librarian, Dept. of
Electronics, Ms. Jayanthi, STIC and Mr. Ibrahimkutty, Dept. ofElectronics fortheir whole-hearted co
operation and encouragements.
Let me also thank all the office and technical staffofthe Department ofElectronics, CUSAT for their
excellentsupportduring myresearch studies.
Finally, Ithank myparentsfortheirunderstanding.
BINOYG.S
CONTENTS
CHAPTERl
INTRODUCTION
CHAPTERII
EARLIER WORK IN THE FIELD- A BRIEF REVIEW 23
CHAPTERIII
METHODOLOGY- EXPERIMENTAL SET-UP, MEASUREMENT
TECHNIQUES AND ELECTROMAGNETIC MODELLING 46
CHAPTERIV
EXPERIMENTAL RESULTS AND OBSERVATIONS 63
CHAPTER V
THEORETICAL INTERPRETATIONS 128
CHAPTER VI
CONCLUSIONS 172
APPENDIX 178
REFERENCES
CHAPTERl
INTRODUCTION
1.1General ClassificationofAntennas 3
1.2Printed Structures 4
1.3Microstrip antennas 5
1.3.1 Radiation from aMicrostrip Antenna 6
1.3.2 Advantages and Disadvantages 7
1.3.3 Selection ofSubstrate Materials 8
1.3.4 Excitation Techniques 9
1.3.4.1 Microstrip Feed 9
1.3.4.2 Coaxial Feed 10
1.3.4.3 BuriedFeed (Electromagnetic Coupling) II
1.3.4.4 Aperture Coupling Feed II
1.3.5 Various Microstrip Antenna Configurations 13
1.3.5.1 Microstrip patch antenna 13
1.3.5.2 Microstrip Traveling wave antenna (MTA) 14
1.3.5.3 Microstrip Slot Antenna 14
1.3.6 BroadbandMicrostrip Antennas 15
1.3.7 Compact Microstrip Antennas 15
1.3.8 Dual Frequency Dual Polarized Microstrip Patch Antennas 16
1.3.9 Theoretical methods used in the analysis ofmicrostrip antennas 17
1.3.9 Theoretical methods used in the analysis ofmicrostrip antennas 18
1.3.9.1 Transmission Line Model 18
1.3.9.2 Cavity Model 18
I.3.9.3 Method ofMoments 18
1.3.9.4 Finite Element Method 19
1.3.9.5 Finite Difference Time Domain (FDTD) Method 19
1.3.9.6 Green's Function Method 20
1.4Electromagnetic Simulation 20
1.5SummaryofThe Present Work 21
1.6ChapterOrganization 21
CHAPTERl
INTRODUCTION
Since the first light of civilization, communication has been of prime
significance to human beings. Depending upon the distance of communication,
various acoustic methods such as drums, horns and optical communication methods
like smoke signals andfire works, utilizing the visibleportion ofthe electromagnetic
spectrum, were used. As technology advanced further, communication using the
electromagnetic spectrum outside the visible region has been explored.
It is strongly believed that electromagnetic theory is one of the chief
intellectual achievements ofhuman species over the last two centuries. James Clark
Maxwell (1831-1879) predicted that light and electromagnetic waves are due to one
and the same physical phenomenon and both can be explained by the waves
travelling at the same speed. Maxwell's partial differential equations of
Electrodynamics represent afundamental unification ofelectric and magneticfields
predictingan electromagnetic wavephenomenon [1j.
The notion ofantenna was first conceived in 1886, by Heinrich Rudolph Hertz,
the father ofElectromagnetics, in his Laboratory at the Technical Institute ofKalsruhe.
Hertz proved experimentally that the electrical disturbances could be detected with a
secondary circuit of proper dimensions for resonance and containing an air gap for
sparks to occur. He generated, transmitted and received electromagnetic energy by
means of an end loaded half-wave dipole (Hertzian Dipole) as transmitter and a
resonant square loop antenna as receiver.
Antennas are like Electronic eyes and ears [2]. They act as interface between
free space and circuitry. IEEE standards define an antenna as "a means for radiating or
receiving electromagnetic waves" [3]. An antenna is an integral part of any
communication device.
The talented Indian scientist Sir. Jagadis Chunder Bose (1858-1937) conducted
pioneering research work with millimeter waves in the 60-GHz range [4]. He developed
a new type ofantenna named as Hom antenna in1897 during his studies with millimeter
wave propagation. Even though Bose has contributed substantially to the millimeter and
microwave detection, his contributions were not adequately publicized and appreciated
by the large electronic communityin general. Although neglected somewhat inthe early
1900s, the hom antenna has drawn immense popularity in the late 1930s, due to the
interest in microwaves and waveguide transmission lines during the period of World
War II. The hom is widely used as a feed element for radio astronomy and satellite
tracking antennas installed all over the world. In addition to that they form an integral
part of phased arrays and serves as a universal standard for calibration and gain
measurements.
The challenging works by Bose and Hertz inspired Guglielmo Marconi (1874
1937), an Italian Electrical Engineer to use the Hertzian waves for communication
purposes. Marconi startled the scientific community in 1901 through his transatlantic
radio communication link. The set up consisted ofa transmitting antenna made out ofa
spark transmitter connected between the ground and a system of50 vertical wires. The
antenna used in a radio can radiate or receive electromagnetic waves, thereby can
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