design of multibeam antenna for …eprints.utm.my/id/eprint/11414/1/sitizuraidahibrahimmfke...antena...
TRANSCRIPT
DESIGN OF MULTIBEAM ANTENNA FOR WIRELESS LOCAL AREA
NETWORK APPLICATIONS
SITI ZURAIDAH IBRAHIM
UNIVERSITI TEKNOLOGI MALAYSIA
iii
ACKNOWLEDGEMENT
First of all, thanks to our creator, “Allah” for the continuous blessing and for
giving me the strength and chances in completing this project.
Special thanks to my project supervisor, Associate Prof. Dr. Mohamad Kamal
A. Rahim, for his guidance, support and helpful comments in doing this project.
My family deserves special mention for their constant support and for their
role of being the driving force towards the success of my project. My friends
deserve recognition for lending a helping hand when I need them. En. Thelaha and
En. Nazri, the closest colleagues at P18, deserves praises for their assistance in the
fabrication and testing of my project.
My sincere appreciation also goes to everyone whom I may not have
mentioned above who have helped directly or indirectly in the completion of my
project.
iv
ABSTRACT
The current trend in most access point in conventional wireless local area
network (WLAN) is to use omnidirectional antennas, which radiates and receives
power equally in all directions. This attribute however gives result of lower power
efficiency and decrease network performance due to co-channel interference that
arrived from undesired directions. One of the proposed solutions to overcome these
constraints is to use multibeam antenna on WLAN access points. Multibeam
antennas are antenna arrays that make use of beamforming networks to produce
multiple independent beams that directed to different directions. In this project,
multibeam antenna comprises of linear antenna array and beamforming network is
presented. It was designed at 2.4 GHz to suit the application of WLAN at 802.11b/g.
Butler Matrix 4 x 4 is chosen as a beamforming network which was designed to
provide four different progressive phase shifts, -45°, +135°, -135°, +45° that coupled
to antenna array. It is made up from four 90° hybrid coupler, two 0 dB crossover and
two -45° phase shifter. Each component is designed and simulated using Agilent
ADS software and fabricated on FR4 board. This network is then combined with a
linear antenna arrays with the aim to produce four independent beams at four
different directions. Three types of antenna array that having different kind of
radiation patterns have been implemented which are square patch antenna, 4 x 2
planar antenna array and dipole antenna. The obtained result shows that 4 beams are
generated by each design where square patch antenna array produce Half Power
Beamwidth, HPBW for each beams about 30° and manage to cover 120° of coverage
area, 4 x 2 antenna array has HPBW about 7° and cover 30° while dipole antenna
produce two kind of beams, broader and narrower beams. Finally, it can be
concluded that the objectives of this project are achieved.
v
ABSTRAK
Hala tuju kebanyakan titik akses pada Rangkaian Kawasan Tempatan
Wayarles (WLAN) masa kini masih menggunakan antena halaan-omni, di mana ia
menyebarkan dan menerima kuasa daripada semua arah. Keadaan ini bagaimanapun
telah menyebabkan kecekapan kuasa menjadi rendah, malah menyebabkan
penurunan prestasi rangkaian yang disebabkan oleh gangguan saluran utama
daripada arah yang tidak dikehendaki. Salah satu jalan penyelesaian kepada
kelemahan ini ialah dengan menggunakan antena pelbagai sinaran pada titik akses
WLAN. Antena pelbagai sinaran adalah tatasusun antena yang menggunakan
jaringan pembentuk alur untuk menghasilkan beberapa sinaran yang menghala pada
arah yang berlainan. Dalam projek ini, antena pelbagai sinaran yang diperbuat
daripada tatasusun antena dan jaringan pembentuk alur dibentangkan. Ia direka pada
frekuensi 2.4 GHz untuk applikasi WLAN pada 802.11b/g. 4 x 4 Butler Matrix
dipilih sebagai jaringan pembentuk alur dan direka untuk menghasilkan empat nilai
anjakan fasa progesif yang berbeza iaitu -45°, +135°, -135°, +45° yang digandingkan
dengan tatasusun antena. It diperbuat daripada empat komponen gandingan hibrid
90°, dua komponen garis silang 0 dB dan dua penganjak fasa -45°. Setiap komponen
direkabentuk dan disimulasi menggunakan perisian Agilent ADS and difabrikasi ke
atas papan FR4. Jaringan ini kemudiannya dicantumkan bersama antena bertatasusun
lurus dengan matlamat untuk menghasilkan empat sinaran yang berasingan. Tiga
jenis antena yang mempunyai corak radiasi berbeza telah digunakan iaitu antenna
tampalan segi empat sama, 4 x 2 tatasusun antena dan antena dua-kutub. Keputusan
yang diperolehi menunjukkan empat sinaran telah dihasilkan, yang mana antena
tampalan segi empat sama menghasilkan HPBW selebar 30° dan kawasan liputan
seluas 120°, 4 x 2 tatasusun antenna mempunyai HPBW selebar 7° dan kawasan
liputan seluas 30° dan antena dua-kutub menghasilkan dua jenis sinaran yang
berbeza, sempit dan lebar. Akhirnya, dapatlah disimpulkan bahawa objektif projek
telah dicapai.
vi
TABLE OF CONTENTS
CHAPTER 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
1 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
2 LITERATURE REVIEW 8
2.1 Smart Antenna Technology 8
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 15
2.1.2.2 Co-channel interference on
WLAN 18
2.1.2.3 Benefits of beam switching in
WLAN 20
2.1.3 Four Beams Multibeam Antenna 23
2.2 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 34
2.2.3.1 Uniform Linear Antenna Array 35
2.2.3.2 Beamswitching 43
2.3 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
2.4 Previous Work 56
2.4.1 Integration between conventional 4 x 4
Butler Matrix and Antenna Array 57
2.4.2 Development of 4 x 4 Butler Matrix 62
2.5 Chapter Summary 68
3 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 77
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
3.4.1 S-parameter 89
3.4.2 Radiation pattern 90
3.5 Comparison of the designed Butler Matrix with
other findings 91
3.6 Chapter Summary 95
4 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 117
4.6 The comparison between commercially used
antenna with designed multibeam antenna 122
4.7 Chapter Summary 124
5 CONCLUSION & FUTURE WORK 125
5.1 Conclusion 125
5.2 Proposed Future Work 127
REFERENCES 128
Appendices A – E 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 103
4.7 Numerical result of measured radiation patterns of using
4 x 2 antenna array 104
4.8 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 118
4.11 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 21
2.14 Simulation results of BER when utilizing switch-beam antenna
in AP 22
2.15 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 24
2.17 The generated radiation pattern by exciting current at one port at
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 with2λ
=d , 0=β and N = 4, 8 and 12 39
2.31 Plots of AF with, N = 4, 0=β 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
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) 114
4.16 Radiation pattern comparison between computed and measured
xiv
result (4 x 2 antenna array case) 115
4.17 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
antenna when multiple input activated simultaneously 137
E. Submitted papers for proceedings 139
CHAPTER 1
INTRODUCTION
This dissertation proposes the development of multibeam antenna that can be
implemented for WLAN application. In this first chapter, the background of the
project is discussed providing the problem statement, objective, scope of the study
and project contribution.
1.1 Project Background
In recent years, wireless networking has become a key solution to various
data communication needs. Wireless LANs are fast, flexible and cheap compared to
conventional wired LANs and they are still improving [1]. While in wireless
communications two most important restricting factors are interference and multipath
fading [2]. Multipath is a condition which arises when transmitted signal undergoes
reflection from various obstacles in the propagation environment which cause the
multiple signals arrive from different directions [3]. The result is degradation in
signal quality when they are combined at the receiver due to the phase mismatch. Co-
channel interference is the interference between signals that operate at the same
frequency.
2
Smart antenna is one of the most promising technologies that will enable
higher capacity in wireless networks by effectively reducing multipath and co-
channel interference [4]-[6]. This achieved by focusing the radiation only in the
desired direction and adjusting itself to change traffic conditions or signal
environment. The early smart antenna systems were designed for use in military
applications to suppress interfering or jamming signals from the enemy [3]. Since
interference suppression was a feature in this system, this technology was borrowed
to apply to personal wireless communications where interference was limiting the
number of users that a network could handle [3].
It has been studies [7] and tested [8], [9], that applying simple smart antenna
systems and algorithm to WLAN, would improve the performance worthily [1].
Taking into account that IEEE 802.11a WLAN the bit rate rises with an increase in
the Signal to Interference and Noise Ratio (SINR), developing a smart antenna
solution for WLAN application becomes more valuable [1]. Multiple beam antenna
array, a part of smart antenna system is known to be able to provide capacity
enhancement by means of interference reduction though spatial filtering [9]. It
provides a considerable increase in network capacity when compared to traditional
antenna systems or sector based systems [9].
The current trend in most access point in conventional WLAN is to use
omnidirectional antennas, which radiates and receives power equally in all directions
[10]. The implementation of this antenna is simple but it forms some limitations on
the performance of the network. As the direction is not specific, only small
percentage of the overall energy is reaching to the desired user which resulting the
lower power efficiency. It also suffers of co-channel interference as signals that
operate at the same frequency from undesired directions also capable to reach the
antenna. Due to the limited spectrum allocation in WLAN, co-channel interference
will become an issue which is the major problem of omnidirectional antenna
broadcast [11].
3
One of the proposed solutions to overcome these constraints is to use
multibeam antenna on WLAN access points, AP [12]. Multibeam antennas are
antenna array that make use of beamforming network to produce multiple
independent beams that directed to different directions. By offering independent
beams or channels, AP will switch between these channels to select the channel that
has the highest received power. This feature assist the antenna system to maximize
the power received in the desired directions.
The implementation of multibeam antenna is not new. In fact, it has been
implemented in Cellular Radio Systems in a few years back. It has been reported in
[6] that by having a multiple beam, the selected beam can reduce the interference,
increase the system carrier to interference level and then offer an opportunity for the
greater capacity by tighter frequency reuse. The increase in frequency reuse permits a
75% increase in the number of RF channels at the site and doubling the overall
number of the subscriber capacity [6].
As the implementation of multibeam antenna gives a tremendous result in
cellular communications, people interested to apply multiple beam antennas for
WLAN communications. So far, most studies had done on the simulation to observe
the performance in WLAN [1], [9], [12]-[15]. For example in [12], it has been
proved that the multibeam antenna is capable to reduce the value of Bit Error Rate
(BER). Compare to omni directional antenna application, the simulation results show
that utilizing switch-beam antenna in AP the BER performance improve about 2 dB
in light-of-sight (LOS) case, and 6 dB in non-light-of –sight (NLOS) case.
With the motivation gained from the simulation that has been done in
literature [1], [9], [12]-[15], this project aims to produce physical implementation of
multibeam antenna so that the actual performance of multibeam antenna in WLAN
could be observed in future.
4
1.2 Problem Statement
By applying omnidirectional antenna on the WLAN AP, it is suffering from a
number of disadvantages which can be summarized as follows:
I. Lower power efficiency
II. Capacity Limitation due to contribution of co-channel interference
These disadvantages can be overcome by using multibeam antenna on the
WLAN access point. This project will only focus on the development of the antenna
itself to meet the satisfied performance that can be used in WLAN system. Thus far,
a few studies has been done on the multibeam antenna, but most of them were
discussing more about beamforming network [16]-[23] which are in terms of
bandwidth and compactness while put less concentration on constructing the
multibeam antenna itself. The main task here is to design a multibeam antenna
system by integrating an antenna array with beamforming network so that the overall
performance of the multibeam antenna in terms of radiation pattern could be
observed.
1.3 Objective
The main objectives of this study can be divided into two goals;
I. To design an antenna system that capable to produce multiple beam of the
radiation pattern
II. To simulate and fabricate that antenna system design so that its performance
can be observed
This project is aim for WLAN application at 2.4GHz
5
1.4 Scope of Study
The first part of this study is to understand the concept of multibeam antenna.
The needed of multibeam antenna on WLAN, the function of the multibeam antenna
and implementation of the antenna system are studied.
In the second part of the study, the multibeam antenna is designed and
simulated. At this stage, the fundamental of antenna parameters, microstrip antenna
characteristics and the theory about multibeam antenna has been covered. After that,
the antenna array and Butler Matrix are designed and simulated.
The third part is the fabrication and measurement of the design. At this stage,
related equipment such as UV Light Equipment, Network Analyzer, Spectrum
Analyzer, Signal Generator, etc. are expected to be familiarized and well handled.
The last part of the study is the analysis part. It is expected that during the
study, the measured result and the theoretical should be compared and observed.
1.5 Project Contribution
The application of smart antenna is not limited to the WLAN network only,
but also can be implemented in most communication network. As provided in
Chapter 2, Section 2.4, most studies have been done on the improvement of
beamforming network [16]-[23] rather than constructing the multibeam antenna
itself. This dissertation will give a basic idea about the integration between antenna
array and beamforming network and the performance of multibeam antenna using 3
6
different types of antenna (directional antenna, omnidirectional antenna, and broader
beamwidth antenna) are observed. Previous works only show the result of using
omnidirectional antenna [24] and broader beamwidth antenna [25]-[27] which
constructed and discussed independently. The multibeam antenna produced by this
project could be integrated later with RF switch and controller part that constructed
by other parties so that a complete switched beam antenna system could be
constructed. Multibeam antenna also can be implemented in the case of Spatial
Division Multiple Access (SDMA) by injecting different signal to each input ports
[28], [29].
1.6 Organization of Thesis
The thesis is divided into five chapters. The first chapter is Introduction,
which provides information regarding the project background, objectives, scope of
project, project contribution and the layout of the thesis.
The second chapter is Literature Review. In this chapter, the concept of
smart antennas, antenna theory, beamforming network and related previous works
are thoroughly explained.
The third chapter is Methodology, in which the methods employed in this
project will be explained. The design procedures and simulation results for this
project will be presented in detail. The simulation results and subsequent analysis
will be discussed. Prototype fabrication and measurement setup are also presented.
7
Results and analysis of the fabrication and measurement are presented in
Chapter 4. The comparison between simulations, fabrication results, measurement
results, and computation result will be explained in this chapter.
The last chapter is Conclusion and Future Work. This chapter will conclude
the findings of the project and provide recommendations for future work.