THE DESIGN OF 5G COUPLER IN CONSTRUCTING 4×4 BUTLER MATRIX BEAMFORMING SYSTEM FOR THE USE IN INTELLIGENT TRANSPORTATION SYSTEM (ITS)

THE DESIGN OF 5G COUPLER IN CONSTRUCTING 4×4 BUTLER MATRIX BEAMFORMING SYSTEM FOR THE USE IN

INTELLIGENT TRANSPORTATION SYSTEM (ITS)

Melvin anak Philip Attan

Bachelor of Engineering (Hons) in Electronics (Telecommunications)

UNIVERSITl MALAYSIA SARAWAK

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Final Year Pl'Oject Report.

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THE DESIGN OF 5G COUPLER IN CONSTRUCTING 4×4 BUTLER MATRIX BEAMFORMING SYSTEM FOR THE USE IN

INTELLIGENT TRANSPORTATION SYSTEM (ITS)

MELVIN ANAK PHILIP ATTAN

A dissertation submitted in partial fulfilment of

the requirement for the degree of Bachelor of Engineering (Hons) in Electronics (Telecommunications)

Faculty of Engineering

UNIVERSITI MALAYSIA SARAWAK 2017

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ACKNOWLEDGMENT ACKNOWLEDGMENT

I would like to express my appreciation to my supervisor, Dr. Dyg Norkhairunnisa Abang Zaidel, for guiding me throughout the process of completing my research under her supervision. Her willingness for sparing her time to help me in solving problem relating to my research.

Besides that, I also would like to thank my friends for their support, advices and motivation. Gratitude also extended to Faculty of Engineering, Universiti Malaysia Sarawak for the full support and guidance in this research.

Last but not least, I would like to thank my family for their constant support and encouragement from the beginning of the process of completing this research. I would never go this far without their support.

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ABSTRACT ABSTRACT

Development of intelligent transportation system (ITS) play major part in improving the quality and safety of our transportation sector. Communication between the vehicle become important aspect in ITS development. Thus with the improvement of cellular communication technology, 5G, where huge improvement in bandwidth and latency, offer ITS with suitable characteristic in developing real time communication and capable in handling massive number of device simultaneously. In order for the Communication system to operate in 5G technology, improvement need to be made in the hardware to support the technology by improving the bandwidth and reduce the size.

Nowadays, there are tremendous number of research have been made on branch line coupler for microwave system. Due to the advancement in telecommunication technology, many demand required to supply the current system; higher data rate, bigger bandwidth and compaction of component size. Branch line coupler is commonly use due to its simplicity. Reducing the size of the coupler not only provides in cheaper fabrication, but also more space can be utilize for performance improvement. Size of new design coupler expected to be reduced up to 10% compared to conventional branch line coupler. Increasing the bandwidth of the coupler allow the component to be fully utilize in more advanced communication technology such as 5^th Generation (5G) Technology. Bandwidth for new design coupler is expected to triple the bandwidth of conventional branch line coupler. The proposed design of branch line coupler will be designed by using Computer Simulation Technology (CST) Microwave Studio. This new design operates in 10 GHz frequency.

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ABSTRAK

Pembangunan sistem pengangkutan pintar (ITS) memainkan peranan besar dalam meningkatkan kualiti dan keselamatan di dalam sektor pengangkutan kita. Oleh itu, dengan peningkatan dalam teknologi komunikasi selular, 5G, di mana peningkatan dalam keluasan jalur dan kependaman, menawarkan karakteristik yang bersesuaian untuk ITS dalam membangunkan komunikasi masa sebenar dan kebolehan dalam pengendalian jumlah besar peranti pada masa yang sama. Supaya sistem Komunikasi untuk beroperasi dalam teknologi 5G, penambahbaikan perlu dibuat dalam perkakasan untuk menyokong teknologi dengan meningkatkan keluasan jalur dan mengurangkan saiz. Pada masa kini, terdapat banyak penyelidikan telah dilakukan ke atas pengganding branch line untuk sistem gelombang mikro. Disebabkan kemajuan teknologi di dalam sektor telekomunikasi, pelbagai permintaan diperlukan untuk memperbaharui sistem sekarang; kadar data yang lebih laju, keluasan jalur yang lebih besar dan pengecilan saiz komponent. Pengganding branch line sering digunakan kerana strukturnya yang mudah.

Dengan mengurangkan saiz pengganding bukan sahaja mampu mengurangkan kos pembuatan, malahan mampu mengoptimumkan ruang yang digunakan untuk meningkatkan prestasi komponent tersebut. Meningkatkan keluasan jalur membolehkan komponent tersebut berfungsi sepenuhnya dalam teknologi komunikasi yang lebih maju seperti teknologi generasi kelima (5G). Reka bentuk baru yang dicadangkan akan dibina menggunakan Teknologi Simulasi Komputer (CST) Microwave Studio. Reka bentu baru ini beroperasi dalam frekuensi 10 GHz.

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TABLE OF CONTENTS TABLE OF CONTENTS

ACKNOWLEDGMENT i

ABSTRACT ii

TABLE OF CONTENTS iv

LIST OF TABLE vi

LIST OF FIGURES vii

LIST OF SYMBOL ix

LIST OF ABBREVIATIONS xi

CHAPTER 1: INTRODUCTION 1

1.1 Background of Research 1

1.2 Problem Statements 3

1.3 Objectives 4

1.4 Scope of Research 4

1.5 Thesis Outlines 5

CHAPTER 2: LITERATURE REVIEW 6

2.1 Introduction 6

2.2 Intelligent Transportation System (ITS) 6

2.3 Application of 5G in Intelligent Transportation System (ITS) 7

2.4 Multi-Input and Multi-Output (MIMO) Technology 7

2.5 Butler Matrix Beam-Forming Network 8

2.5.1 Basic Concept 8

2.5.2 Main Component in Butler Matrix 9

2.6 Coupler 10

2.6.1 Conventional Coupler 11

2.6.2 Branch Line Coupler 11

2.6.3 Coupled Line Coupler 12

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2.6.4 Lange Coupler 13

2.7 Techniques in Improve the Coupler Performances 14

2.7.1 Stub Technique 14

2.7.2 Addition of Branch Line 15

2.7.3 Multilayer Technique 15

2.8 Summary 16

CHAPTER 3: METHODOLOGY 17

3.1 Introduction 17

3.2 Design Methodology and Flow Chart 17

3.3 Gantt Chart 20

3.5 Designing Conventional Branch Line Coupler 23

3.6 Stub Technique to Miniaturize Coupler Size 25

3.7 Addition of Branch Line Technique to Improve the Bandwidth 27

3.8 Initial Study 29

3.8.1 Adding Stub 29

3.8.2 Adding branch 30

CHAPTER 4: RESULT 31

4.1 Introduction 31

4.2 Conventional Branch Line Coupler 31

4.3 Miniaturize Branch Line Coupler by Adding Stub 33

4.4 Improved Branch Line Coupler Bandwidth with Additional Branch 35

4.5 Improved Branch Line Coupler Design Fabrication 40

4.6 Summary 41

CHAPTER 5: CONCLUSIONS 43

5.1 Conclusions 43

5.2 Future Works 44

REFERENCES 45

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LIST OF TABLE LIST OF TABLE

Table 3. 1: Gantt Chart for Final Year Project 1 20 Table 3. 2: Gantt Chart for Final Year Project 2 21 Table 3. 3: Design specifications 22 Table 4. 1: Comparison between Conventional Branch Line Coupler and Branch Line Coupler with Stub 41 Table 4. 2: Comparison between Branch Line Coupler with Stub and Branch Line Coupler with Additional Branch 42

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LIST OF FIGURES LIST OF FIGURES

Figure 1. 1: ITS Video Wall for State Department of Transportation ... 1

Figure 1. 2: MIMO Technology with Multiple Antenna to Transmit Signal to Multiple Direction ... 3

Figure 2. 1: Vehicle communicate with other vehicle or infrastructure in ITS ... 7

Figure 2. 2: Conventional Butler Matrix Network ... 9

Figure 2. 3: Block Diagram for Phase Shifter ... 10

Figure 2. 4: (a) Block Diagram for Power Division (b) Block Diagram for Power Combining ... 10

Figure 2. 5: Conventional Branch Line Coupler ... 12

Figure 2. 6: Coupled Transmission Line (a) Edge-coupled (b) Broadside Coupled ... 13

Figure 2. 7: The Lange interdigitated 3-dB coupler ... 13

Figure 2. 8: Branch Line Coupler with Stub ... 14

Figure 2. 9: Four Branch Coupler Geometry ... 15

Figure 2. 10: Multilayer Technique Layout... 16

Figure 3. 1: Flow Chart ... 18

Figure 3. 2: (a) Proposed equivalent structure. (b) Quarter-wavelength branch line ... 25

Figure 3. 3: Branch Line Coupler with proposed structure ... 26

Figure 3. 4: Dividing the Coupler into halves with Line of Symmetry ... 27

Figure 4. 1: Conventional Branch Line Coupler ... 32

Figure 4. 2: S-Parameter for Conventional Branch Line Coupler ... 32

Figure 4. 3: Phase Difference for Conventional Branch Line Coupler ... 33

Figure 4. 4: Branch Line Coupler Miniaturize with Stub Technique; (a) Patch (b) Ground ... 34

Figure 4. 5: S-Parameter for Branch Line Coupler with Stub ... 34

Figure 4. 6: Phase Difference for Branch Line Coupler with Stub ... 35

Figure 4. 7: Initial Design of Branch Line Coupler with Additional Branch; (a) Patch (b) Ground ... 36

Figure 4. 8: S-Parameter for Initial Design of Branch Line Coupler with Additional Branch ... 36

Figure 4. 9: S-Parameter S21 for W2 Parameter Sweep ... 37

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Figure 4. 10: S-Parameter S31 for W2 Parameter Sweep ... 37

Figure 4. 11: S-Parameter for Branch Line Coupler with Additional Branch (W2 = 0.2mm) ... 38

Figure 4. 12: Branch Line Coupler with Additional Branch ... 38

Figure 4. 13: S-Parameter for Branch Line Coupler with Additional Branch ... 39

Figure 4. 9: Phase Difference for Branch Line Coupler with Additional Branch ... 40

Figure 4. 15: New Design of Branch Line Coupler (a) Patch (b) Ground ... 40

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LIST OF SYMBOL LIST OF SYMBOL

S-parameter - Scattering-parameter

S21 - Scattering-parameter from port 1 to port 2 S43 - Scattering-parameter from port 3 to port 4

P1 - Power 1

P2 - Power 2

P3 - Power 3

α, Δ - Difference

Z0 - Initial Impedance

- Wavelength

- Quarter-wavelength - Characteristic Impedance - Shunt branch line impedance - Dielectric constant

mm - millimetre

- Ohm

C - Coupling value

- Operating frequency wavelength

c - Speed of light

- Operating frequency

- Microstrip patch width

h - Microstrip height

x

- Pi

ln - Natural algorithm

- Electrical length

± - More or less

S11 - Scattering-parameter from port 1 reflected back S41 - Scattering-parameter from port 1 to port 4

- matrices

- matrices

- matrices

Ae,Be,Ce,De - ABCD-parameter for even mode Γ - Reflection coefficient

T - Transmission coefficient

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LIST OF ABBREVIATIONS

LIST OF ABBREVIATIONS

ITS - Intelligent Transportation System IoT - Internet of Things

MIMO - Multi-Input Multi-Output

CST - Computer Simulation Technology FYP1 - Final Year Project 1

FYP2 - Final Year Project 2 4G - 4^th Generation Technology 5G - 5^th Generation Technology

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CHAPTER 1

INTRODUCTION

CHAPTER 1: INTRODUCTION

1.1 Background of Research

Intelligent Transport System (ITS) is a system that utilise communication technology to improve the efficiency and safety of transportation. The idea of ITS is to provide every car on the road the ability to communicate with each other to improve the performance and reliability of conventional transportation. By able to communicate, this enable vehicle to operate safely and well coordinate according to given information.

Recent ITS focus more on the security purpose. For example at United State, the government mostly involve in ITS prioritise on the

Figure 1. 1: ITS Video Wall for State Department of Transportation

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Homeland Security [1]. Majority ITS proposed involving the road surveillance and traffic management. With rapid increase in number of civilian in urban area, the density of traffic increase causing congestion in the urban area. Therefore, ITS play major role in smoothing the traffic especially during the mass evacuation due to casualty event such as terrorism or natural disaster. Figure 1.1 shows the ITS video wall at State Department of Transportation in the United State where the monitoring work is done via CCTV installed along the highway.

The most suitable communication technology to be apply to the ITS is a 5^th Generation (5G) technology. The advantage of 5G over it predecessor 4G include hundred times faster data rates especially for high mobility, massive connectivity in crowded areas, thousand times higher system capacity/km², less than 1ms reduced latency (virtually zero latency), energy saving and cheaper especially for terminals [2].

By the year of 2020, it is estimated that 50 billion device are connected to the internet with the foundation of Internet of Things (IoT) and 75% of it consist of traffic, where 90% of it is vehicle [2,3]. In order to handling simultaneous massive amount of devices connected to the internet at one time, next generation of communication technology is needed as our current technology (4G) is lack in many factors.

Since most microwave application in telecommunication sector used 4G technology, the 5G technology offer less interference. This is because of the frequency band occupied by 5G technology which is up to 60GHz compared to 4G technology which is only up to 20MHz [4]. As mentioned before, 5G technology has large frequency band, thus it has short range compare to 4G technology. The drawback of 5G technology is it offer short range due to it high frequency. Thus, multi-input multi- output (MIMO) technology is introduce to extend the range of 5G technology by concentrate the signal in certain direction. Since MIMO technology have multiple antenna, signal can be transmitted and received from multiple direction [4, 5]. Figure 1.2 illustrate the beam that has been concentrated using MIMO technology and been transmitted to multiple direction.

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Figure 1. 2: MIMO Technology with Multiple Antenna to Transmit Signal to Multiple Direction

Beam-forming network is the example of MIMO technology used to concentrating the receiving or transmitting directional signal instead of broadcasting the signal to wide area [6]. Beam-forming network consist of 4 main component which are antenna, coupler, phase shifter and cross over. Butler matrix is one of beam-forming network type. This type of beam-forming is popular and chosen by many researchers due to its circuit is simpler where small number of couplers are used in its topology compare to other type of beam-forming network.

The advantage of using branch line coupler are it is the simplest type of coupler, cheap to fabricate and many development and research have been done from it.

However, branch line coupler also has some disadvantage which consume too much unnecessary space in between the branch line and narrow operating bandwidth [7].

Therefore, this thesis present the new design of branch line coupler with the application of stub and additional branch technique which will miniaturized the size of coupler and increase bandwidth compare to conventional branch line coupler respectively. This thesis will focus more on the design of coupler in Butler Matrix beam-forming network.

For this research project, branch line coupler has been chosen.

1.2 Problem Statements

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The design of basic branch line coupler consume too much unnecessary space between the branch lines [8], thus result in large size of coupler design. By adding stub in between the branch line theoretically reduce the length of branch line which also result in more compact design and cheaper to fabricate. With the reduction of the design size allow the researchers to add more branch line to the coupler which leads to improve the operating bandwidth of the coupler [9].

1.3 Objectives

The objectives for this research are stated as follows:

i. To investigate on the branch line couplers design and operation.

ii. To design 5G branch line coupler that will be operated at 10 GHz frequency range.

iii. To miniaturize the size of the 5G branch line coupler by using stub technique.

iv. To improve the bandwidth of the 5G branch line coupler by using addition of branch technique thus will be implemented into Butler Matrix beam-forming for Intelligent Transportation System application.

1.4 Scope of Research

The scope of research for this project is to design 5G branch line coupler that operate at 10 GHz operating frequency. Substrate chosen for this project is Rogers RO4003C which is suitable for high frequency operation. The software used in this project is Computer Simulation Technology (CST) Microwave Studio. The simulation is performed after complete the initial stage in designing the new coupler. The behaviour of the performance and characteristic of the new designed coupler is observed

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through the execution of parametric study which includes the return loss, isolation loss, throughput, coupling and phase difference between output ports.

1.5 Thesis Outlines

This thesis is divided into 4 chapters. Chapter 1 is the introduction for this research. In this chapter, more elaboration on the project background, problem statement, objective and scope of work is explained.

Chapter 2, the literature review will be explaining more detail on the Intelligent Transportation System (ITS), application of 5G in ITS, basic concept of Butler Matrix and three main component in it, basic concept of Branch Line coupler and techniques that been used by other researcher.

Meanwhile, Chapter 3 will elaborate more towards the methodology of the research. The flow chart, gantt chart and design specification will also be explain. The techniques used in this project to design 5G coupler also will be explained.

The preliminary results of the research will be discussed in Chapter 4. The parameter of the new design will be shown in form of table and comparison will be made to select the most suitable parameter consist of coupler transmission length, width, resistance value and others to be used in the new design.

The last chapter, which is Chapter 5 will discuss about the achievement of the new design; size reduced and bandwidth increased in term of percentage compare to conventional branch line coupler. This chapter also will explain more on the future work to improve this research in future.

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CHAPTER 2

LITERATURE REVIEW

CHAPTER 2: LITERATURE REVIEW

2.1 Introduction

In this chapter, the concept of Intelligent Transportation System (ITS) is briefly explain with the application of Butler Marix in the system. Moreover, the application of 5G in internet of things (IoT) also will be covered with the explanation about how this project will improve the performance of the 10 GHz coupler on operating in 5G in the application of IoT technology. The application of coupler in 4×4 Butler Matrix beamforming system will be explained in detail about how it works and the requirement need to comply with 5G technology. This chapter also will cover more detail about type of coupler that used with it specification, advantages and disadvantages. Last but not least, previous works by other researchers to improve the performance of the coupler is also discussed in this chapter.

2.2 Intelligent Transportation System (ITS)

Intelligent Transportation System (ITS) is the system to improve the safety and effectiveness of transportation through the integration of advanced communications technologies into the transportation infrastructure and in vehicles [10]. Advanced communications technologies allow every vehicle to connect with situation occur on the road. For example, as shown in Figure 2.1, the vehicle is feed with information about traffic ahead and make better plan for efficient journey.

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Figure 2. 1: Vehicle communicate with other vehicle or infrastructure in ITS

2.3 Application of 5G in Intelligent Transportation System (ITS)

5th Generation (5G) technology is well known as faster than 4G in term of speed and latency [11]. In the application of ITS, timing are very crucial in delivering information to other vehicle. Example of application is the time period the vehicle in receiving information when front vehicle suddenly emergency brake, thus the vehicle require fast feedback from the front vehicle to stop. Its ability to support bigger bandwidth compare to 4G also plays an important role on the application in ITS. This is due to the massive number of vehicle connected on the road in urban area. Besides that, 5G technology provide less interference due to no other communication device are used in 5G frequency spectrum. Thus, the efficiency of communication in ITS will not be disturbed.

2.4 Multi-Input and Multi-Output (MIMO) Technology

Due to large frequency used in 5G technology which is up to 60 GHz, causing drawback in term of area coverage. Short wavelength causing the signal to travel in short distance. Thus, the larger the frequency, the smaller the area coverage by 5G technology. In order to increase the area coverage, the signal need to be concentrate and transmitted in many direction. Multi-Input Multi-Output (MIMO) technology is used to achieve greater distance coverage. In order to applied MIMO technology, beam-forming

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network is introduce which offer multiple number of input and output port. Few examples of beam-forming network are Butler Matrix, antenna array and Rotman Lens.

2.5 Butler Matrix Beam-Forming Network

In this section, a basic concept of Butler Matrix and the operation of the Butler Matrix will be elaborated more.

2.5.1 Basic Concept

Butler Matrix network has been used to produce multiple beams via various beam antenna linear array systems. The advantage of Butler Matrix over other beam- forming network is the simplicity of the circuit design which require less microwave couplers.

Butler Matrix is an N×N network which is N inputs and N outputs. Therefore, the total number of ports in Butler Matrix is 2N. Butler Matrix can easily transmitting various beams in different directions. Fast discrete electronic scanning of antenna pattern can be provided by the adaptive control unit in the antenna system of the Butler Matrix.

9 2.5.2 Main Component in Butler Matrix

Referring to Figure 2.2, the conventional Butler Matrix consist of three main components; 3-dB couplers, crossovers and 45º phase shifters.

Couplers in Butler Matrix are the component used to separate the signal in the beamforming network. The coupler used in Butler Matrix is a 3 dB branch line coupler which mean the output signal is half the input signal for each output port. This coupler consist of 4 port where port 1 and port 4 is connected to phase shifter and crossovers, meanwhile port 2 and port 3 is connected to output port of the Butler Matrix.

Crossovers are 0 dB couplers that is used to allow two microwave transmission line crossing while maintaining the isolation between them [12]. Crossovers can be construct by cascading two branch line coupler [13-14]. When one of input in Butler Matrix are fed with signal, all the output signal will have equal magnitudes and progressive phase shift between ports. Thus, by feeding signal from different ports will result in forming of different direction of beam [15].

Phase shifters are important microwave devices for phase modulators, electronic beam scanning phased arrays, microwave instrumentation, and many other industrial

Figure 2. 2: Conventional Butler Matrix Network