10
II LITERATURE REVIEW
2.1 Introduction 4
2.2 Basic Antenna Parameter 4
2.2.1 Radiation Pattern 5
2.2.2 Directivity 8
2.1.3 Input Impedance 9
2.1.4 Return Loss Voltage Standing Wave Ratio VSWR 10
2.1.5Antenna Efficiency 12
2.1.6 Antenna Gain 12
2.1.7 Polarization 13
2.1.8 Bandwidth 15
2.3 Types of Antenna 16
2.4 Microstrip Antenna 16
2.5 Rectangular Patch and Transmission Line 19
2.5.1 Single Patch Antenna Design 19
2.5.2 Transmission Line Design 20
2.6 Antenna Array 21
2.6.1 Array Factor 22
2.6.2 Antenna Array and Beamforming 22
2.6.3 Feed Network 23
2.7 Leaky Wave Antenna LWA 24
2.7.1 Slit-Coupled LWA 25
2.7.2 Single Conductor Strip LWA 25
2.7.3 Flat Slotted Waveguide FSW 26
2.8 Microstrip Leaky Wave Antenna MLWA 27
11
III MICROSTRIP LEAKY WAVE ANTENNA DESIGN
3.1 Introduction 29
3.2 Design Methodology 29
3.3 Design Specification 32
3.4 CST Microwave Studio 33
3.5 Single Patch Antenna Design and Simulation 37
3.6 Design of 12 elements with different value of
β
40 3.7 Design for different number of elements N with fixed value
of
β
42
3.8 Design of 6 elements with variation arrangement of
β 42
3.9 Array Factor of MLWA 44
3.10 Fabrication Process 44
3.11 Measurement 48
3.11.1 Return Loss Measurement 48
3.11.2 Radiation Pattern Measurement 48
IV RESULT ANALYSIS AND DISCUSSION
4.1 Result Analysis for Single Patch Antenna 50
4.2 Design Analysis of 12 Elements with Different Value of β
51 4.3 Design Analysis for Different Number of Elements, N with
53 Fixed Value of
β = 45˚ 4.4 Design Analysis of 6 Elements with Variation of
β 57
4.5 Analysis for Design I and II 59
4.6 Analysis for Design III and Design IV 62
4.7 Array Factor Plot of 6 Elements with Different Value of β
64 4.8 Array Factor Plot for
β = 45º with different number of elements, N
66
4.9 Measurement Results 68
12
V CONCLUSION AND RECOMMENDATION
5.1 Conclusion 73
5.2 Recommendation 74
REFERENCES 75
APPENDIX 77
13
LIST OF TABLES
NO TITLE
PAGES
2.1 Advantages and Disadvantages of Microstrip Antenna
18 3.1
MLWA Design Specifications 32
3.2 Parameter Setup in CST
34 3.3
Calculated Dimensions for Single Patch 37
3.4 Calculated Dimensions for Transmission Line
38 3.5
Calculated and Optimized dimension for single patch 39
3.6 Value of d with respect to
β 40
3.7 Value of
β for each design 43
4.1 Difference of Original and Normalized Patch in terms of Return
Loss 50
4.2 Variation of Phase Difference
β° for 12 element patches 52
4.3 Variation Number of Elements, N
54 4.4
Beam Angle for Different Number of Elements 56
4.5 Variation of Phase Difference
β˚ for 6 Elements Patches 57
4.6 Beam Angle for Different value of
β 59
4.7 Simulation Result for Design I and Design II
60 4.8
Simulation Result for Design III and Design IV 62
4.9 Comparison of Beam Angles between Simulation and array
Factor for Variation of β
67
4.10 Comparison of Beam Angles between Simulation and array factor 67
14 for different number of elements, N
4.11 Comparison of simulation and measured return loss for Design 1 69
4.12 Comparison of simulation and measured return loss for Design I and II
70
4.13 Comparison of simulation and measured return loss Design III 70
15
LIST OF FIGURES
NO TITLE
PAGES
2.1 Antenna Radiation Pattern
5 2.2
Radiation pattern for isotropic antenna and omni directional antenna
6 2.3
Radiation Pattern of an omni directional antenna 7
2.4 Antenna Directivity
9 2.5
Equivalent circuit of transmitting antenna 11
2.6 Vertical and circular polarization in 3-D
13 2.7
Common antenna polarizations 14
2.8 Definition of antenna bandwidth in respect to return loss
measurement 15
2.9 Types of Antennas
16 2.10
Microstrip Antenna 17
2.11 Microstrip Antenna Radiation
18 2.12
Structure of a Microstrip Patch Antenna 19
2.13 Microstrip Transmission Line
20 2.14
Types of Array Feed Network 23
2.15 Types of Leaky Wave Antenna
24 2.16
Reduced equivalent circuit for slit-coupled MLWA 25
2.17 Single-conductor strip structure
26 2.18
Flat Slotted Waveguide FSW 27
2.19 Schematic diagrams of Microstrip Leaky Wave Antenna
28
16 3.1
Design Process 30
3.2 Project Methodology
31 3.3
Design Environment 33
3.4 Workspace Window
34 3.5
Brick parameter Window 35
3.6 Steps and Parameter Setup
35 3.7
Single Patch Antenna 37
3.8 Structure and Simulation for Single Patch Antenna a 2-D View,
b 3-D View 38
3.9 Response of return loss for single element
39 3.10
Structure for MLWA with 12 Elements in 2-D View 40
3.11 Figure 3.11 Simulation of MLWA for a 12 Elements, b 6
Elements 41
3.12 Simulation of MLWA for 3 elements
42 3.13
Design II a Structure, b Simulation 44
3.14 Example of Layout a CST Microwave Studio, b CorelDraw
Suite 12 45
3.15 Flow Chart for Fabrication Process
46 3.16
UV Exposure Unit 47
3.17 Return Loss Measurement Setup
48 3.18
Radiation Pattern Measurement Setup 49
4.1 Return Loss for Original and Optimized Single Patch
51 4.2
Structure for 12 Elements with β = 45°
51 4.3
Response of Return Loss for variation of β
52 4.4
Structure for 3 Elements with β = 45˚
53 4.5
3-D plot of radiation pattern 55
4.6 2-D Radiation Pattern Plot
56 4.7
Structure for 6 Elements 57
4.8 2-D plot of radiation pattern for
β = 15º, 30º and 45º 58
4.9 Structure for Design I
59 4.10
Response of S
11
for Design I and Design II 60
17 4.11
2-D plot of radiation pattern for increasing Design I and II 61
4.12 Structure for Design III
62 4.13
Response of S
11
for Design III and Design IV 63
4.14 2-D plot of radiation pattern for Design III and Design IV
63 4.15
Array Factor Plot versus Simulation Plot with β = 60º
64 4.16
Array Factor Plot versus Simulation Plot for 9 Elements 66
4.17 Fabricated MLWA
68 4.18
Radiation pattern for simulation and measurement result for Design 1
71 4.19
Radiation pattern for simulation and measurement result for Design I
71
4.20 Radiation pattern for simulation and measurement result for
Design II 72
4.21 Radiation pattern for simulation and measurement result for
Design III 72
18
LIST OF ABBREVIATIONS
LWA -
Leaky-Wave Antenna FPC
- Fabry Perot Cavities
FSS -
Frequency Selective Surface FSW
- Flat Slotted Waveguide
MLWA -
Microstrip Leaky-Wave Antenna MOS
- Microwave Office Sotware
PRS -
Partially Reflective Surface RL
- Return Loss
VSWR -
Voltage Standing Wave Ration WLAN
- Wireless Local Area Network
P -
Total Power Radiated S
- Power Density
U
i
- Radiation intensity for isotropic antenna
HPBW -
Half power beam-width FNBW
- First Null Beamwidth
D -
Directivity of Antenna Z
in
- Antenna impedance at the terminals
R
in
- Antenna resistance at the terminals
X
in
- Antenna reactance at the terminals
RL -
Return Loss L
- Length of Patch
W -
Width of Patch l
- Length of Transmission Line
19 w
- Width of Transmission Line
ΔL -
Length extension h
- Height of Substrate
β -
Phase different between two radiating elements N
- Number of elements
d -
Distance between elements θ
- Polar Angle
AF -
Array Factor φ
- Phase Shift
dB -
Decibel dBi
- Isotropic Decibel
C -
Speed of light in vacuum λ
- Free-space wavelength
20
LIST OF APPENDICES
APPENDIX TITLE PAGES
A Types of Antenna Review
77 B
MLWA Design 81
C Simulation Result
83 D
SigmaPlot Result 86
E Return Loss Measurement
88
21
CHAPTER I
INTRODUCTION
1.1 Project Introduction