vi
TABLE OF CONTENTS
CHAPTER
1
2
TITLE
PAGE
DECLARATION
ii
ACKNOWLEDGEMENT
iii
ABSTRACT
iv
ABSTRAK
v
TABLE OF CONTENTS
vi
LIST OF TABLES
ix
LIST OF FIGURES
xi
LIST OF ABBREVIATIONS
xv
LIST OF SYMBOLS
xvii
LIST OF APPENDICES
xix
INTRODUCTION
1
1.1
Background of the problem
1
1.2
Problem Statement
4
1.3
Objective
4
1.4
Scope of the Study
5
1.5
Project Contribution
5
1.6
Organization of the Thesis
6
LITERATURE REVIEW
8
2.1
8
Smart Antenna Technology
2.1.1 Motivation towards Smart Antenna
11
2.1.2 Smart Antenna Applications in WLAN
14
vii
2.1.2.1
Standard of WLAN
2.1.2.2
Co-channel interference on
WLAN
2.1.2.3
2.2
2.4
18
Benefits of beam switching in
WLAN
20
2.1.3 Four Beams Multibeam Antenna
23
Antenna Basic
26
2.2.1 Microstrip Antenna
26
2.2.2 Antenna properties
27
2.2.2.1 Radiation Pattern
28
2.2.2.2 Half Power Beamwidth
32
2.2.2.3 Polarization
32
2.2.2.4 Bandwidth
34
2.2.3 Antenna Array
2.3
15
34
2.2.3.1 Uniform Linear Antenna Array
35
2.2.3.2 Beamswitching
43
Beamforming Network
46
2.3.1 Blass Matrix
48
2.3.2 Butler Matrix
48
2.3.2.1 90° Hybrid Coupler
52
2.3.2.2 0 dB Crossover
54
2.3.2.3 Phase Shifter
56
Previous Work
56
2.4.1 Integration between conventional 4 x 4
Butler Matrix and Antenna Array
2.4.2 Development of 4 x 4 Butler Matrix
2.5
3
Chapter Summary
57
62
68
METHODOLOGY
69
3.1
Project Methodology
69
3.2
Design development and software simulation
70
3.2.1 Development of Antenna Array
71
3.2.1.1 (4 x 1) Square Patch Antenna
71
3.2.1.2 4 x (4 x 2) Antenna Array
75
viii
3.2.1.3 (4 x 1) Dipole Antenna
77
3.2.2 Development of Butler Matrix
3.2.2.1 The design of 90° Hybrid
78
3.2.2.2 The design of 0 dB Crossover
81
3.2.2.3 Phase Shifter
83
3.2.2.4 Construction of Butler Matrix
85
3.3
Prototype Fabrication
88
3.4
Measurement Setup
89
3.5
3.6
4
3.4.1 S-parameter
89
3.4.2 Radiation pattern
90
Comparison of the designed Butler Matrix with
other findings
91
Chapter Summary
95
EXPERIMENTAL RESULTS & DISCUSSION
96
4.1
Result of Return Loss
96
4.2
Result of Butler Matrix
99
4.3
Radiation Pattern
100
4.4
Result analysis
107
4.5
Comparison of the measured radiation pattern with
other findings
4.6
4.7
5
77
117
The comparison between commercially used
antenna with designed multibeam antenna
122
Chapter Summary
124
CONCLUSION & FUTURE WORK
125
5.1
Conclusion
125
5.2
Proposed Future Work
127
REFERENCES
Appendices A – E
128
133-152
ix
LIST OF TABLES
TABLE NO.
TITLE
PAGE
2.1
IEEE WLAN standards
16
2.2
The center frequency defined by 802.11b/g specifications
17
2.3
The operation of multibeam antenna
25
2.4
The effect of varying parameter N
39
2.5
The effect of varying parameter d
40
2.6
The effect of varying parameter β
41
2.7
An example of power divider result in ideal case
44
2.8
Progressive phase difference corresponds to each input port
of Butler
44
2.9
Numerical value for 2 x 2 Butler Matrix
50
2.10
Numerical value for 4 x 4 Butler Matrix
50
2.11
Numerical value for 8 x 8 Butler Matrix
51
2.12
S-parameter for ideal case 90°hybrid coupler
53
2.13
S-parameter for ideal case 0 dB crossover
55
2.14
Previous work on the integration between conventional
4 x 4 Butler Matrix and Antenna Array
58
2.15
Previous work on the development of 4 x 4 Butler Matrix
64
3.1
Specifications for the FR4 board
70
3.2
Simulated result analysis for 4x1 square patch antenna
74
3.3
Radiation pattern of 4 x1 square patch interpretation
75
3.4
Simulated result analysis for 4x2 antenna array
76
3.5
Width value for each impedance value in hybrid coupler
78
3.6
The numerical result of simulated hybrid coupler
80
x
3.7
The numerical result of simulated hybrid coupler
83
3.8
The numerical result of simulated 45° phase shifter
84
3.9
The numerical result of simulated 0° phase shifter
85
3.10
Design Specification of the Butler Matrix
86
3.11
The simulated output phase of Butler Matrix (schematic)
87
3.12
Computed phase error (schematic simulation)
87
3.13
The simulated output phase of Butler Matrix (momentum)
87
3.14
Computed phase error (momentum simulation)
87
3.15
The comparison between designed Butler Matrix and other
Findings
92
4.1
The numerical result of square patch antenna
98
4.2
The numerical result of 4 x 2 antenna array
98
4.3
The numerical result of dipole antenna
99
4.4
The measured output phase of Butler Matrix
100
4.5
Computed phase error (measurement)
100
4.6
Numerical result of measured radiation patterns of using
square patch
4.7
Numerical result of measured radiation patterns of using
4 x 2 antenna array
4.8
103
104
Numerical result of measured radiation patterns of using
dipole antenna
105
4.9
AF equations correspond to each β
108
4.10
The comparison between measured radiation patterns of the
design with other findings
4.11
118
The comparison between commercially used antenna with
designed multibeam antenna
122
xi
LIST OF FIGURES
FIGURE NO.
TITLE
PAGE
2.1
Radiation pattern of smart antenna
9
2.2
The functional block diagram of smart antenna
10
2.3
Radiation pattern of Omnidirectional Antenna (Top view)
12
2.4
Directional Antenna Coverage Pattern
12
2.5
Antenna diversity
13
2.6
The motivation towards smart antenna implementation
14
2.7
WLAN with two APs
15
2.8
3 non-overlap channels in 802.11b/g
18
2.9
Devices that cause interference to WLAN AP
18
2.10
APs with 3 non-overlap channel
19
2.11
WLAN with more than 3 APs
19
2.12
An example of multibeam antenna coverage on WLAN
20
2.13
Comparison of throughput between switched beam and traditional
AP
2.14
Simulation results of BER when utilizing switch-beam antenna
in AP
2.15
21
22
The plot of CIR (carrier to interference ratio) as a function of
the cellular frequency reuse factor, K, and the number of beams, m 23
2.16
Block diagram of 4 ports multibeam antenna
2.17
The generated radiation pattern by exciting current at one port at
24
instant
24
2.18
4 beams radiation pattern
25
2.19
Rectangular patch antenna
26
2.20
Various feeding technique
27
xii
2.21
Coordinate system for radiation pattern measurement
28
2.22
Principle and E/H pattern cuts
29
2.23
2D radiation pattern
30
2.24
Radiation pattern of omnidirectional antenna
31
2.25
E-plane linear polarized
33
2.26
Various antenna array configuration
35
2.27
An example of pattern multiplication theorem
36
2.28
N element along x axis
36
2.29
Uniform Linear Array Configuration
37
2.30
Plots of AF with d =
2.31
Plots of AF with, N = 4, β = 0 and d = 0.25λ, 0.5λ, λ, 1.25λ
40
2.32
Plots of AF with, N = 4, d = 0.25λ
41
2.33
Phase scanning block diagram
42
2.34
A switched line phase shifter
42
2.35
The operation of power divider in terms of S-parameter
43
2.36
4 x 4 Butler Matrix configuration
44
2.37
Progressive phase difference corresponds to each input port of
λ
2
, β = 0 and N = 4, 8 and 12
39
Butler Matrix (block diagram form)
45
2.38
Radiation pattern obtained
46
2.39
Flow chart of the type beamformer
47
2.40
Blass Matrix configuration
48
2.41
AF plot for 2 x 2 Butler Matrix (N = 2, β = ±90°)
49
2.42
Block Diagram of 4 x 4 Butler Matrix
50
2.43
AF plot for 4 x 4 Butler Matrix (N = 4, β = ±45°, ±135°)
50
2.44
Block Diagram of 8 x 8 Butler Matrix
51
2.45
AF plot for 8 x 8 Butler Matrix (N = 8, β = ±22.5°, ±67.5°,
±112.5°, ±157.5°,)
51
2.46
Geometry of 90° hybrid coupler
52
2.47
Geometry of 0 dB crossover
54
2.48
Illustration that represents the function of 0 dB crossover
55
3.1
The flow chart of the operational framework
69
3.2
The block diagram of the complete design configuration
70
3.3
The flow chart of the design development of the project
70
xiii
3.4
Square patch antenna configuration
72
3.5
Simulated Return Loss for 4 x 1 square patch antenna
73
3.6
Radiation pattern of 4 x 1 square patch antenna
74
3.7
Layout of 4 x 2 antenna array
75
3.8
Return Loss of 4 x 2 array patch
76
3.9
E-plane co-polarization radiation pattern of 4 x 2 array patch
76
3.10
The flow chart of the Butler Matrix implementation
78
3.11
Designed hybrid coupler
79
3.12
The simulated result of hybrid coupler
80
3.13
Designed 0 dB crossover
82
3.14
The simulated result of amplitude and phase of 0 dB crossover
83
3.15
Designed 45° phase shifter
84
3.16
Designed 0° phase shifter
85
3.17
The block structure and layout of the Butler Matrix.
86
3.18
Fabricated prototype
89
3.19
The configuration of the project
90
4.1
Measured return loss of square patch antenna correspond to
each port
97
4.2
Measured return loss of each 4 x 2 antenna array
98
4.3
Measured return loss of each dipole antenna
99
4.4
Measured radiation pattern of single antenna
101
4.5
Measured radiation patterns of using square patch
102
4.6
Measured radiation patterns of using 4 x 2 antenna
103
4.7
Measured radiation patterns of using dipole antenna
104
4.8
Overlapped radiation pattern
106
4.9
The computed radiation pattern of AF corresponds to each β
108
4.10
Computed radiation pattern of AF
109
4.11
Conversion of array pattern from linear unit to dB
110
4.12
Pattern multiplication of square patch antenna case
111
4.13
Pattern multiplication of 4 x 2 antenna array case
112
4.14
Pattern multiplication of dipole antenna case
113
4.15
Radiation pattern comparison between computed and measured
result (square patch antenna case)
4.16
Radiation pattern comparison between computed and measured
114
xiv
result (4 x 2 antenna array case)
4.17
115
Radiation pattern comparison between computed and measured
result (dipole antenna case)
116
xv
LIST OF ABBREVIATIONS
2D
-
Two dimensional
3D
-
Three dimensional
3G
-
Third Generation
AF
-
Array Factor
AP
-
Access Point
BER
-
Bit Error Rate
BPSK
-
Binary Phase Shift Keying
CCK
-
Complementary Code Keying
CIR
-
Carrier to Interference Ratio
CPW
-
Co-planar waveguide
DBPSK
-
Differential Binary Phase Shift Keying
DQPSK
-
Differential Quadrature Phase Shift Keying
DSSS
-
Direct Sequence Spread Spectrum
FCC
-
Federal Communications Commission
FR4
-
Fire Retardant Type 4
FHSS
-
Frequency Hoping Spread Spectrum
GFSK
-
Gaussian Frequency Shift Keying
HPBW
-
Half-power beamwidth
IEEE
-
Institution of Electrical and Electronic Engineer
IF
-
Intermediate Frequency
ISM
-
Industrial, Scientific, Medical
LAN
-
Local Area Network
LOS
-
Line of Sight
NLOS
-
Non line of sight
OFDM
-
Orthogonal Frequency Division Multiplexing
xvi
QPSK
-
Quadrature Phase Shift Keying
QAM
-
Quadrature Amplitude Modulation
RF
-
Radio Frequency
SDMA
-
Spatial Division Multiple Access
SINR
-
Signal to Interference and Noise Ratio
SIR
-
Signal to Interference Ratio
SLL
-
Side lobe level
SNR
-
Signal to Noise Ratio
UV
-
Ultra Violet
VoWi-Fi
-
Voice over Wide Fidelity
WLAN
-
Wireless Local Area Network
xvii
LIST OF SYMBOLS
dB
-
decibel
1R
-
First beam on the right side of polar plot
1L
-
First beam on the left side of polar plot
2R
-
Second beam on the right side of polar plot
2L
-
Second beam on the left side of polar plot
W
-
Width of rectangular patch antenna
L
-
Length of rectangular patch antenna
εr
-
Dielectric constant
h
-
Substrate height
λg
-
Guided wavelength
(r,θ,φ) -
Spherical coordinate system
E
-
Electric
H
-
Magnetic
P(θ)n -
Normalized radiated power pattern
P(θ)
θ component of the radiated power as a function of angles θ
-
P(θ)max -
The radiated power maximum value
Eθ
-
E field existing θ direction
Eφ
-
E field existing φ direction
fu
-
Upper cutoff frequency
fl
-
Lower cutoff frequency
N
-
Number of elements
d
-
distance between antenna elements
θ
-
phase
β
-
phase difference between antenna elements
k
-
wave number
xviii
λ0
-
wavelength in free space
l
-
transmission line length
Zo
-
characteristic impedance
w
-
transmission line width
εeff
-
effective dielectric constant
c
-
velocity of light in free space
fr
-
operating frequency
tan δ
-
dissipation factor
Leff
-
Effective length
∆L
-
length extension
BW% -
bandwidth in percentage
xix
LIST OF APPENDICES
APPENDIX
TITLE
PAGE
A.
FR4 general technical specifications
133
B.
Simulation result of Butler Matrix
134
C.
H-Co measured radiation pattern for square patch
136
D.
E-Co measured radiation pattern for square patch
E.
antenna when multiple input activated simultaneously
137
Submitted papers for proceedings
139