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COMPACT ULTRA-WIDEBAND DIELECTRIC RESONATOR ANTENNAS
MOHAMMAD ABEDIAN KASGARI
A thesis submitted in fulfilment of the
requirements for the award of the degree of
Doctor of Philosophy (Electrical Engineering)
Faculty of Electrical Engineering
Universiti Teknologi Malaysia
FEBRUARY 2015
iii
To my beloved parents, who their enthusiasm and encouragement, I would never step
in this way
and
To my beloved, mindful understanding wife, Shadi, who supported me each step of the
way.
iv
ACKNOWLEDGEMENT
I would like to acknowledge my supervisor Associated Professor Ir. Dr. Sharul
Kamal Abdul Rahim who has given me support and guidance throughout the period of
this project. His patience and perseverance towards the outcome of this study is of the
highest standard. Without him this project report will not become a reality.
None of this would have been possible without the love, support and
encouragement of my family. Mom and Dad, I did it. I am forever thankful to them
for allowing me to fulfill my dream. To my sister, Roja, thanks for all the love and
support. I am sure you would be so proud of me if you were here. I love you.
Words fail me to express my appreciation to my beloved wife, Shadi Danesh,
whose dedication, love and persistent confidence in me, has taken the load off my
shoulder. I owe her for being unselfishly let her intelligence, passions, and ambitions
collide with mine. I can’t thank you enough. I love you.
Thanks all of you
Mohammad Abedian Kasgari
v
ABSTRACT
UWB communication systems were newly regenerated when the Federal
Communications Commission (FCC) defined the 3.1-10.6 GHz unlicensed band for
UWB applications. Based on an investigation in designing UWB antennas, researchers
have encountered more difficulties compared to a narrow band antenna. UWB antennas
should have extremely wide impedance bandwidth while preserving high radiation
efficiency with compact size. In some cases, a band-notched function should have
been created to avoid electromagnetic interference between nearby existing systems
and UWB systems. In this research, various promising UWB Dielectric Resonator
Antennas (DRAs) have been demonstrated to overcome several challenges. The
impedance bandwidth of the UWB DRAs has been improved for more than 110% by
using some techniques such as connecting a strip to the ground plane and modifying
structure of Dielectric Resonator (DR). The efficiency issue of UWB antennas is
overcome by implementing DR as a resonator element which is excited by various
shape structures feed lines to achieve more than 90% efficiency. The electromagnetic
interferences between UWB systems and nearby existing systems in the frequency
bands of 3.22-4.06 GHz, 4.84-5.96 GHz and 5.71-6.32 GHz are eliminated by using
a stub connected to the hollow centre of feed line, an inverted-T shape parasitic strip
near DR and modified metallic sheet underneath the DR, respectively. Compared with
UWB monopole antennas, UWB DRAs obviate the problem of radiation pattern by
utilizing dielectric resonator characteristics. In parallel, the broadside radiation pattern
is obtained by implementing various shapes of microstrip feed line at a proper location
to excite the DRA that provides symmetry radiation patterns with a consistent stability
across the desired bandwidth.
vi
ABSTRAK
Sistem komunikasi UWB adalah baru tumbuh semula apabila Suruhanjaya
Komunikasi Persekutuan (FCC) mentakrifkan 3.1-10.6 GHz band yang tidak berlesen
untuk aplikasi UWB. Berdasarkan kajian di dalam mereka bentuk antena UWB, para
penyelidik menghadapi lebih kesukaran berbanding dengan mereka bentuk antena
jalur sempit. Antena UWB harus mempunyai lebar jalur galangan masukan yang
sangat luas di samping kecekapan pada radiasi tinggi dengan saiz yang kompak.
Dalam beberapa kes, fungsi jalur-bertakuk dicipta untuk mengelakkan gangguan
elektromagnet di antara sistem sedia ada dan sistem UWB. Di dalam kajian ini,
pelbagai UWB bentuk Antena Penyalun Dielektrik (DRAs) dicipta bagi mengatasi
beberapa cabaran berkaitan UWB. Lebar jalur galangan masukan daripada DRAs
UWB dipertingkatkan dengan lebih daripada 110% menggunakan beberapa teknik
seperti menghubungkan jalur dengan satah tanah dan mengubah suai struktur Penyalun
Dielektrik. Isu kecekapan antena UWB diatasi dengan melaksanakan DR sebagai
elemen resonator yang teruja dengan pelbagai struktur bentuk talian untuk mencapai
kecekapan yang lebih daripada 90%. Gangguan elektromagnetik antara sistem UWB
dan sistem sedia ada yang berdekatan dalam jalur frekuensi 3.22-4.06 GHz, 4.84-
5.96 GHz, dan 5.71-6.32 GHz dapat dikurangkan dengan menggunakan puntung
yang dihubungkan dengan pusat berongga talian makanan bentuk-T terbalik jalur
parasit berhampiran DR dan lembaran logam diubah suai bawahnya DR, masing-
masing. Berbanding dengan UWB antena monopole, DRAs UWB menyelesaikan
masalah corak sinaran dengan menggunakan ciri-ciri resonator dielektrik. Pada masa
yang sama, corak sinaran selebaran diperolehi dengan melaksanakan pelbagai bentuk
garis jalur mikro di lokasi yang betul, untuk merangsang DRA yang menyediakan
corak sinaran simetri dengan kestabilan yang konsisten di seluruh lebar jalur yang
dikehendaki.
vii
TABLE OF CONTENTS
CHAPTER TITLE PAGE
DECLARATION iiDEDICATION iiiACKNOWLEDGEMENT ivABSTRACT vABSTRAK viTABLE OF CONTENTS viiLIST OF TABLES xiLIST OF FIGURES xiiLIST OF ABBREVIATIONS xviLIST OF SYMBOLS xviiiLIST OF APPENDICES xix
1 INTRODUCTION 11.1 Background of the Study 11.2 Problem Statement 21.3 Research Objective 31.4 Scopes of Project 31.5 Contribution of the Research 41.6 Signification of the Research 51.7 Thesis Outlines 5
2 LITRATURE REVIEW 72.1 Introduction 72.2 History of UWB Antennas 82.3 Dielectric Resonators Antennas 11
2.3.1 Geometries and Characteristics of Dielec-tric Resonator 122.3.1.1 Hemispherical DRA 13
viii
2.3.1.2 Cylindrical DRA 142.3.1.3 Rectangular DRA 15
2.4 Coupling Mechanisms of DRAs 182.4.1 Microstrip Feed Line 192.4.2 Coaxial Probe Feed 222.4.3 Coplanar Waveguide Feed 232.4.4 Dielectric Image Guide Coupling 242.4.5 Aperture Coupling 252.4.6 Summary of Coupling Mechanisms 27
2.5 Bandwidth Enhancement of DRAs 272.5.1 Single Element Methods 27
2.5.1.1 Modified Shape of the DRAs 272.5.1.2 Modified Feed Geometries 302.5.1.3 Introducing an Air Gap Be-
tween the DR and Ground Plane 322.5.1.4 Multi-Segment DRAs 342.5.1.5 Attaching Parasitic Patch on the
DRAs 362.5.2 Multiple DRAs 37
2.5.2.1 Stacked DRAs 372.5.2.2 Embedded DRAs 39
2.5.3 Hybrid DRAs 412.5.4 Summary of Bandwidth Enhancement 42
2.6 UWB Antennas with Band Rejection 432.6.1 Band Rejection Techniques 432.6.2 Summary of UWB DRAs with Band
Rejection 492.7 Summary 52
3 RESEARCH METHODOLOGY 533.1 Introduction 533.2 Methodology 533.3 Design of UWB DRA with and without Band
Rejection 563.3.1 Specifications of Design 563.3.2 Dielectric Resonator Specifications 573.3.3 Substrate Material 58
3.4 Software and Measurement Equipment 593.5 Summary 61
ix
4 DESIGN OF COMPACT UWB DIELECTRIC RES-ONATOR ANTENNA 624.1 Introduction 624.2 Design of Two-Segment Compact UWB DRA 63
4.2.1 Two-Segment Compact UWB DRA Con-figuration 64
4.2.2 Parametric Study of Two-Segment Com-pact UWB DRA 64
4.2.3 Experimental Results of Two-SegmentCompact UWB DRA 68
4.3 Design of a Compact UWB Rectangular DRA 724.3.1 Geometry of a Compact UWB Rectangu-
lar DRA 724.3.2 Parametric Study of a Compact UWB
Rectangular DRA 734.3.3 Experimental Results of a Compact UWB
Rectangular DRA 744.4 Performance Comparison Between Two-Segment
and Rectangular UWB DRAs 784.5 Summary 80
5 UWB DIELCTRIC RESONATOR ANTENNA DESIGNWITH BAND REJECTION FUNCTION 815.1 Introduction 815.2 UWB DRA with single Band-Notch for Upper
WLAN Band at 5.8 GHz 825.2.1 Geometry of Single Band-notch UWB
DRA 825.2.2 Parametric Study of Single Band-notch
UWB DRA 825.2.3 Experimental Results of Single Band-
notch UWB DRA 885.3 Compact UWB DRA with Dual Band Rejection
Characteristics for WiMAX/WLAN Bands 925.3.1 UWB DRA with Dual Band Rejection
Configuration 925.3.2 Parametric Study and Key Parameters of
UWB DRA with Dual Band Rejection 93
x
5.3.3 Experimental Results of UWB DRA withDual Band Rejection 102
5.4 Performance Comparison between Single and DualBand-notch UWB DRAs 106
5.5 Summary 106
6 CONCLUSION AND FUTURE WORK 1086.1 Conclusion 1086.2 Recommendations for Future Works 109
REFERENCES 110Appendix A 120
xi
LIST OF TABLES
TABLE NO. TITLE PAGE
2.1 Microstrip feed line technique to excite DRAs 202.2 Coaxial probe feed technique to excite DRAs 232.3 Coplanar waveguide feed technique to excite DRAs 242.4 Aperture coupling mechanism to excite DRAs 262.5 Modified shape of the DRAs 292.6 Modified feed geometries 312.7 Introducing an air gap between the DR and ground plane 332.8 Multi-segment DRAs 352.9 Attaching parasitic patch on the DRAs 372.10 Stacked DRAs 382.11 Embedded DRAs 402.12 Hybrid DRAs technique 422.13 Band rejection UWB antenna 503.1 Design specifications 573.2 Dielectric resonator specification 583.3 Substrate dimensions 594.1 Two-segment compact UWB DRA parameters 694.2 Compact UWB rectangular DRA dimensions 724.3 Compression of compact DRAs 804.4 Performances comparison between Two-Segment and Rect-
angular DRAs 805.1 Parameters of DRA with single band-notch 845.2 Dimensions of UWB DRA with dual band-notch 935.3 Performances comparison between Single and Dual Band-
notch DRAs 106
xii
LIST OF FIGURES
FIGURE NO. TITLE PAGE
2.1 Geometry of Lodge’s biconical antennas (1898). 92.2 Carter’s improved match biconical antenna configuration
(1939). 92.3 Lindenblad’s coaxial horn antenna configuration (1941). 92.4 Brillouin’s coaxial horn antenna configuration (1948). 102.5 Geometry of Stohrs ellipsoidal monople antenna (1968). 102.6 Geometry of Gibson’s vivaldi antenna (1979). 102.7 Various types of UWB antennas (a) planar monopole antenna,
(b) printed monopole antenna, (c) printed wide-slot antenna,and (d) dielectric resonator antenna. 11
2.8 Various shapes of dielectric resonator. 122.9 Hemispherical DRA excited by coaxial probe. 142.10 Geometry of the cylindrical DRA. 152.11 Geometry of the Rectangular DRA. 162.12 Electric and Magnetic Fields inside the Rectangular DRA for
the TEXδ11 Mode. 18
2.13 Microstrip feed line mechanism (a) side coupling and (b)direct coupling. 19
2.14 Probe coupling the DRA (a) RDRA (b) CDRA. 202.15 Coaxial probe feed. 222.16 Various shape of CPW for coupling to DRAs. 222.17 Dielectric image guide (DIG) for coupling to DRA. 252.18 Aperture coupling technique (a) various aperture slots (b)
embedded slot in the ground plane. 262.19 Prototype of inverted cup-shaped HDRA. 282.20 Schematic diagrams of Z-shaped DRA. 292.21 Geometry of dielectric ring resonator excited by L-shaped
microstrip feed line . 322.22 Photograph of the RDRA. 332.23 Exploded view of the MSDRA. 34
xiii
2.24 Photograph of MSDRA with a single insert. 352.25 Geometry of the HDRA with a parasitic patch, excited by
aperture-coupled. 362.26 Geometry of the staked CDRA, excited by coaxial probe. 392.27 Cross section of the embedded DRA and top view of the
narrow slot board. 402.28 Geometry of DR-loaded monopole antenna. 412.29 Geometry of DR-loaded microstrip patch antenna. 412.30 Geometry of the UWB DRA with dual band rejections. 442.31 Geometry of the UWB DRA with band rejection using hybrid
technique. 442.32 Configuration of the UWB DRA reconfigurable band
rejection. 452.33 Prototype of the UWB DRA excited by elliptical patch with
dual band notched characteristics. 462.34 Geometry of the UWB DRA excited by microstrip feed line
with dual band notched characteristics. 462.35 Configuration of the UWB DRA with band rejection
characteristics. 472.36 Geometry of the UWB DRA with band rejection characteris-
tics. 482.37 Geometry of the band-notched UWB rectangular DRA. 482.38 Geometry of UWB DR-loaded monopole antenna with band
rejection. 493.1 The flowchart of research methodology. 553.2 Chamber room (a) antenna under testing (b) reference
antenna (c) schematic diagram. 604.1 Geometry of proposed DRA. 654.2 Effect of ground plane length Lg on reflection coefficient. 664.3 Simulated radiation efficiency of proposed DRA excited by
two different feed lines. 664.4 Effect of changing dimension Lc on reflection coefficient. 674.5 Effect of changing dimension Ld on reflection coefficient. 684.6 Photograph of the proposed DRA. 684.7 Measured and simulated reflection coefficient of proposed
DRA. 694.8 Simulated radiation efficiency and measured gain of proposed
DRA. 70
xiv
4.9 Measured and simulated radiation patterns. H-plane (right)and E-plane (left) at (a) 3.5 GHz, (b) 6 GHz, and (c) 8.5GHz. Red and blue are measured and simulated results,respectively. 71
4.10 Geometry of proposed RDRA: (a) front, (b) back, (c) sideview. 73
4.11 Effect of microstrip feed line width W2 on reflectioncoefficient. 74
4.12 Reflection coefficient of proposed antenna; the antennawithout DR and inserted and planar RDRA with and withoutparasitic strip. 75
4.13 Reflection coefficient for various length of L4. 754.14 Reflection coefficient for various values of εd. 764.15 Prototype of the fabricated proposed RDRA. 774.16 Measured and simulated Reflection coefficient of proposed
RDRA. 774.17 Simulated radiation efficiency and gain of proposed RDRA. 784.18 Measured and simulated radiation patterns. H(xz)-plane (left)
and E(yz)-plane (right) at (a) 4 GHz, (b) 7 GHz, and (c) 10GHz. Blue and red are measured and simulated results (dB),respectively. 79
5.1 Geometry of inserted DRA without modified structure: (a)front, (b) back, (c) side view. 83
5.2 Schematic diagram of DRA: (a) back view of planar DRA,(b) back view of inserted DRA with modified structure, (c)side view of planar DRA. 83
5.3 Reflection coefficient for planar DRA with and without L-shaped strip and inserted DRA with and without metallicsheet. 85
5.4 Reflection coefficient for various L6. 865.5 Reflection coefficient for various W6. 865.6 Reflection coefficient for various L4. 875.7 Current distribution at notched frequency (5.8 GHz) (a) front
view (b) back view. 875.8 Reflection coefficient for various length of Ln. 885.9 Prototype of the fabricated proposed DRA. 895.10 Measured and simulated reflection coefficient of proposed
antenna. 89
xv
5.11 Simulated radiation efficiency and measured gain of proposedDRA. 90
5.12 Measured and simulated radiation patterns. H(xz)-plane(right) and E(yz)-plane (left) at (a) 4 GHz, (b) 6.5 GHz, (c)8 GHz and (d) 10.5 GHz. Blue and red are measured andsimulated results (dB), respectively. 91
5.13 Geometry of the proposed DRA; (a) front view, (b) back view,(c) 3D view. 94
5.14 Evolution of the proposed UWB DRA with dual bandrejections; (a) planar RDRA (front view), (b) inserted DRAwith Stub. (c) inserted DRA with Inverted T-shaped on theback plane, (d) inserted DRA with inverted T-shaped on theback plane and slot on the ground plane, (e) planar RDRA(3D view), and (f) proposed DRA (3D view). 95
5.15 Simulated reflection coefficient for planar and inserted RDRAand modified DRA with and without stub. 96
5.16 Simulated reflection coefficient for various stub lengths (Lb)with 1.4 mm stub width. 97
5.17 Simulated reflection coefficient for various stub widths (Wb)with 11.5 mm stub length. 98
5.18 Simulated reflection coefficient for various lengths of Lt. 985.19 Simulated reflection coefficient for various lengths of Ls. 995.20 Simulated reflection coefficient for inserted DRA with stub
and inverted T-shaped strip, separately. 1005.21 Simulated reflection coefficient for various lengths of Lb. 1015.22 Simulated reflection coefficient for various lengths of Lt. 1015.23 Current distribution at two notched frequencies (a) 3.45 GHz
(b) 3.45 GHz (all transparent), (c) 5.52 GHz, (d) 5.4 GHz (alltransparent). 102
5.24 Prototype of the fabricated proposed DRA. 1035.25 Measured and simulated reflection coefficient of proposed
DRA. 1035.26 Simulated radiation efficiency and measured gain of proposed
DRA. 1045.27 Measured far-field radiation patterns; H(xz)-plane (left) and
E(yz)-plane (right) at (a) 3.1 GHz, (b) 6.5 GHz, and (c) 9.5GHz. Red and blue are simulated and measured results (dB),respectively. 105
xvi
LIST OF ABBREVIATIONS
AR – Axial Ratio
BW – Bandwidth
CDR – Cylindrical Dielectric Resonator
CDRA – Cylindrical Dielectric Resonator Antenna
CRP – Circular Ring Patch
CPW – Co-Planar Waveguide
CST – Computer Simulation Software
dB – decibel
dBi – decibel (isotropic)
DIG – Dielectric Image Guide
DR – Dielectric Resonator
DRA – Dielectric Resonator Antenna
DWM – Dielectric Waveguide Model
EDC – Effective Dielectric Constant
EM – Electromagnetic
ESCSRR – Elliptic Single Complementary Split-Ring Resonator
FCC – Federal Communication Commission
FDTD – Finite Difference Time Domain
FEM – Finite Element Method
FSS – Frequency Selective Surface
GHz – Giga Hertz
HCLR – Hollow-Cross-Loop Resonator
HDR – Hemispherical Dielectric Resonator
HDRA – Hemispherical Dielectric Resonator Antenna
HFSS – High Frequency Structural Simulator
Hz – Hertz
IDCLLR – Interdigital Capacitance Loading Loop Resonator
IEEE – Institute of Electrical and Electronic Engineers
xvii
mm – Millimeter
MoM – Method of Moment
MSDRA – Multi-Segment Dielectric Resonator Antenna
MWM – Magnetic Waveguide Model
PCB – Printed Circuit Boards
PIN – Positive-Intrinsic-Negative
Q factor – Quality factor
RDR – Rectangular Dielectric Resonator
RDRA – Rectangular Dielectric Resonator Antenna
RF – Radio Frequency
RL – Return Loss
RSRR – Rectangular Split-Ring Resonator
SIR-DGS – Stepped Impedance Resonator-Defected Ground Structure
SRR – Split-Ring Resonator
TE – Transverse Electric
TLM – Transmission Line Matrix
TM – Transverse Magnetic
TSDRA – Two-Segment Dielectric Resonator Antenna
UWB – Ultra-wideband
VSWR – Voltage Standing Wave Ratio
WiMAX – Worldwide Interoperability for Microwave Access
WLAN – Wireless Local Area Network
–
xviii
LIST OF SYMBOLS
fc – Center frequency
ε – Dielectric constant
εeff – Effective permittivity
E − plane – Electric plane
δ – Fraction of a half-of-field cycle variation
G – Gain of antenna
H − plane – Magnetic plane
≥ – More than
fn – Notched frequency
φ – Phi angle
λ – Wavelength
λn – wavelength at the notched resonant frequency
π – pi
Γ – Reflection coefficient
f0 – Resonant frequency
c – Speed of light
θ – Theta angle
–
xix
LIST OF APPENDICES
APPENDIX TITLE PAGE
A LIST OF PUBLICATIONS 120
CHAPTER 1
INTRODUCTION
1.1 Background of the Study
The Ultra-Wideband (UWB) systems have developed intensely in the past two
decades which are implemented for both academic and industrial communities of
telecommunication applications. These antennas generally strive to be compatible the
Federal Communications Commission (FCC) which support an impedance bandwidth
of 7.5 GHz, i.e. from 3.1 GHz to 10.6 GHz in 2002 [1]. There are several advantages
of UWB communications compare to other technologies which make them excellent
candidate to present a further eloquent solution for wireless broadband applications as
follow [2–6].
First of all, the UWB systems can obtain an immense capacity of several
Gbps with a short range of 1 to 10 meters due to proportion of channel capacity
to bandwidth. Secondly, the UWB facilitates an extremely reliable communication
and secure solution due to possessing a spectral density in low power level, noise-
like, which causes slightly electromagnetic interference with longer-range existing
narrow-band systems. Thirdly, in UWB systems, a sufficient spatial resolution is
achieved by applying a short duration impulse. This characteristic is used in target
imaging to provide a potential capability to distinct targets from background clutter.
Fourthly, since the UWB signals have short duration pulse waveforms, no multi-
path cancellation will occurred because of passing the direct path signal through the
system before attaining the reflected path signal. Lastly, UWB systems compared
to conventional radio systems have an intrinsic capability for integration in low
2
complexity, low power, and low cost due to propagating without the requirement of
an additional RF components which providing considerably short time domain pulse.
On the other hands, dielectric resonators (DRs) have been applied in the
microwave circuits design such as oscillators and filters due to their high Q-factor
characteristic. Moreover, it is found that the DRs with low dielectric constant can
be used in antenna design as radiating element because of their low radiating Q-
factor [7]. In the last two decades, dielectric resonator antennas (DRAs) have received
agreeable consideration for UWB antennas due to remarkable characteristics such as
different excitation mechanisms [8–11], high radiation efficiency [12], nearly constant
gain [13, 14], and compact antenna size [15, 16]. The DRAs compared to microstrip
patch antennas (MPAs)have wider impedance bandwidth because of having very small
dielectric losses and lack of conductor losses, and also higher efficiency and less
radiation pattern distortions due to lack of existing surface wave phenomena. In
addition, DRAs compared with printed antenna provide small size ate expense of
thickness due to decreasing the maximum path length in a certain direction to other
directions.
1.2 Problem Statement
Based on investigation on ultra-wideband DR antenna, the researchers
encountered some difficulties. One of the main challenges is obtaining wide impedance
bandwidth more than around 91% with high radiation efficiency more than 90% while
sustaining compact size. For example, the DRA impedance bandwidth is mostly below
10% for a single-mode excitation, which is not sufficient for UWB applications. On the
other hands, existing electromagnetic interference of some narrow bands system such
as wireless local area network (WLAN) and worldwide interoperability for microwave
access (WiMAX) is a serious problem for UWB application systems. Some design
techniques have been developed for the band rejection UWB DRA antenna. However,
most of these approaches suffer from increasing size of antenna and lack of the
3
flexibility and separately of each band rejection with control the width of the band-
notch across the stop-band.
1.3 Research Objective
The objectives of this work focus on simulate and fabricate of a novel UWB
DRA which are :
i. Design of compact UWB DRA with high radiation efficiency while sustaining
wide bandwidth over whole desired frequencies.
ii. Design of UWB DRA with sufficient band rejection for existing
electromagnetic interference of nearby wireless communication systems such
as WiMAX (3.3-3.8 GHz) and WLAN (5.15-5.825 GHz).
1.4 Scopes of Project
This work focuses on the design of the UWB DRA which operates within
the frequency range from 3.1 GHz to 10.6 GHz. The development of the UWB
DRA is comprised by avoiding the electromagnetic interference of nearby narrow
band systems such as the worldwide interoperability for microwave access (WiMAX)
system operating at 3.3-3.8 GHz and wireless local area network (WLAN) system
operating at 5.15-5.85 GHz.
The rectangular DR with dielectric constant less than 15 is used to achieve wide
impedance bandwidth. The compact UWB DRAs is simulated and verified by CST
and HFSS in terms of return loss, gain, efficiency, and radiation pattern to improve its
performance. A parametric study of the different design of UWB DRAs was carried
out. The UWB DRA is optimized and fabricated with good agreement between the
measured results with simulated results.
4
1.5 Contribution of the Research
For this work, four contributions are introduced which include:
i. Design of a new compact two-segment Z-shaped DRA with different
permittivity excited by a U-shaped feed-line for ultra-wideband application
that the combination mechanism of the U-shaped feed-line and two-segments
DR (TSDR) characteristics provide firm omnidirectional radiation pattern and
high radiation efficiency with compact size while sustaining wide impedance
bandwidth.
ii. Design of a new simple compact rectangular dielectric resonator antenna
(RDRA) for ultra-wideband application that by applying a combination of
simple parasitic strip connected to the ground plane, microstrip feed line and
inserted RDR characteristic, a compact antenna size with a wide impedance
bandwidth, high radiation efficiency, nearly constant gain and consistent
omnidirectional radiation pattern over desired frequency range are achieved.
iii. Design of a new compact DRA with band rejection of 5.71-6.32 GHz (upper
WLAN band) using a modified metallic sheet for ultra-wideband application
that the combination mechanism of L-Shape strip connected to the ground
plane, proper position of microstrip feed line, inserted DR characteristic,
and metallic sheet underneath DR provide a wide impedance bandwidth and
compact antenna with consistent omnidirectional radiation pattern.
iv. Design of a new compact UWB DRA with dual band rejection of 3.22-4.06
GHz (WiMAX) and 4.84-5.96 GHz (WLAN) that by intently implementing a
combination mechanism of two inserted identical DRs, U-shaped excitation
performance, stub, inverted T-shaped parasitic strip, and slot in the ground
plane, ultra wideband characteristic with efficient dual band-notched and
miniature size of about 0.124λ × 0.31λ × 0.062λ at 3.1 GHz are achieved
simultaneously.
5
1.6 Signification of the Research
Dielectric resonator antennas would be chosen by more system engineers when
designing their wireless products due to possessing their considerable characteristics,
flexibility in design and easily available commercially at very low cost. Therefore,
DRAs have proved themselves to be ideal candidates for UWB antenna applications
such as local and personal area networks (LAN/PAN), roadside info-station, short
range radios and military communications.
1.7 Thesis Outlines
This thesis is organized in six chapters, which each chapter will describe on the
different aspects of the work. The outlines of the dissertation for each 6 chapter are
organized as follows.
Chapter 1 introduces an introduction of UWB system and a brief history
about the dielectric resonator antenna and also makes some view about the problem
statements, objective, and scope of this work.
Chapter 2 describes most prevalently used shapes of DRA and focuses on
surveys of coupling mechanisms, bandwidth enhancement techniques, and compact
techniques of DRAs through the literature to obtain some idea and achieve proper
design.
Chapter 3 focuses on the methodology of project and steps of design.
Moreover, the steps of the fabrication process and measurement procedure are
illustrated.
Chapter 4 depicts simulated and measured results of an ultra-wideband
dielectric resonator antenna design. Discussions about comparisons between simulated
and measured result through the diagram are illustrated.
6
Chapter 5 demonstrates a design of ultra-wideband dielectric resonator antenna
with WiMAX/WLAN band rejections. Parametric studies and discussions with
experimental results are illustrated.
Chapter 6 concludes this project and indicates some possible future works.
REFERENCES
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Commission’s Rules Regarding Ultra-Wideband Transmission System from
3.1 to 10.6 GHz. Federal Communications Commission. 2002.
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Science, 2010. 37(3): 304–314.
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7. Long, S. A., McAllister, M. W. and Shen, L. C. The resonant cylindricaldielectric cavity antenna. IEEE Transactions on Antennas and Propagation,1983. 31: 406–412.
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Antennas and Propagation, 2003. 51(8): 2144–2146.
9. Al Salameh, M., Antar, Y. M. and Seguin, G. Coplanar-waveguide-fedslot-coupled rectangular dielectric resonator antenna. IEEE Transactions on
Antennas and Propagation, 2002. 50(10): 1415–1419.
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