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MINIATURIZED FRACTAL PATCH ANTENNA FOR WIRELESS

APPLICATIONS

WONG WEI JIAN

This Report Is Submitted In Partial Fulfilment Of Requirements For The Bachelor

Degree of Electronic Engineering (Wireless Communication)

Faculty of Electronic and Computer Engineering

Universiti Teknikal Malaysia Melaka

June 2016

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UNIVERSTI TEKNIKAL MALAYSIA MELAKA

FAKULTI KEJURUTERAAN ELEKTRONIK DAN KEJURUTERAAN KOMPUTER

BORANG PENGESAHAN STATUS LAPORAN

PROJEK SARJANA MUDA II

Tajuk Projek : MINIATURIZED FRACTAL PATCH ANTENNA FOR WIRELESS

APPLICATIONS

Sesi Pengajian

: 1 5 / 1 6

Saya …………WONG WEI JIAN……………………………………………………………………….. mengaku membenarkan Laporan Projek Sarjana Muda ini disimpan di Perpustakaan dengan syarat-syarat kegunaan seperti berikut:

1. Laporan adalah hakmilik Universiti Teknikal Malaysia Melaka.

2. Perpustakaan dibenarkan membuat salinan untuk tujuan pengajian sahaja.

3. Perpustakaan dibenarkan membuat salinan laporan ini sebagai bahan pertukaran antara institusi

pengajian tinggi.

4. Sila tandakan ( √ ) :

SULIT*

*(Mengandungi maklumat yang berdarjah keselamatan atau

kepentingan Malaysia seperti yang termaktub di dalam AKTA

RAHSIA RASMI 1972)

TERHAD**

**(Mengandungi maklumat terhad yang telah ditentukan oleh

organisasi/badan di mana penyelidikan dijalankan)

TIDAK TERHAD

Disahkan oleh:

__ ________________________ ___________________________________

(TANDATANGAN PENULIS) (COP DAN TANDATANGAN PENYELIA)

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“I hereby declare that the work in this project is my own except for summaries and

quotations which have been duly acknowledge.”

Signature : ....................................................... Author : WONG WEI JIAN Date : .......................................................

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“I acknowledge that I have read this report and in my opinion this report is sufficient in term of scope and quality for the award of Bachelor of Electronic Engineering

(Wireless Communication) with Honours.”

Signature : ....................................................... Supervisor’s Name : MADAM NORBAYAH BINTI YUSOP Date : .......................................................

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To My Loving and Caring Family

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ACKNOWLEDGEMENTS

I would like to express my gratitude to my advisor Madam Norbayah Binti

Yusop, for her constant support, guidance and valuable advice for the completion of

this work and my graduate studies.

I am very grateful to my co-advisor Dr. Mohd Azlishah Bin Othman for his

valuable ideas and expertise and to introduce me to researches in antenna.

I thanks to all those who have helped to make this thesis possible. Warmest

regards to my family members for their seamless caring encouragement and moral

support that has made this journey possible.

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ABSTARCT

The study of microstrip patch antennas has made great progress in recent years.

Compared with conventional antennas, microstrip patch antennas have more

advantages and better prospects. They are lighter in weight, low volume, low cost, low

profile, smaller in dimension and ease of fabrication and conformity. Moreover, the

microstrip patch antennas can provide dual and circular polarizations, dual-frequency

operation, frequency agility, broad band-width, feedline flexibility, beam scanning

omnidirectional patterning.

This thesis proposes a miniaturized fractal antenna using Koch curves. The

structure of the proposed antenna is the result of the modifications made with the basic

fractal square curves and using Rogers RO4003 as substrate. The design and

simulation have been performed using a full-wave 3-dimensional electromagnetic

simulator. The antenna can be used for most handheld devices and thus finds wide

applications in the field of wireless and mobile communication.

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ABSTARK

Kajian mikrostrip antena patch telah mencapai kemajuan besar dalam tahun-

tahun kebelakangan ini. Berbanding dengan antena konvensional, antena mikrostrip

patch mempunyai lebih banyak kelebihan dan prospek yang lebih baik. Mereka lebih

ringan dalam berat badan, jumlah yang rendah, kos rendah, profil rendah, dimensi yang

lebih kecil dan kemudahan fabrikasi dan pematuhan. Selain itu, antena mikrostrip

patch boleh menyediakan polarisasi dual dan pekeliling, operasi dua frekuensi,

kekerapan ketangkasan, luas band-lebar, fleksibiliti feedline, rasuk imbasan

pencorakan omnidirectional.

Tesis ini mencadangkan satu antena fraktal bersaiz kecil menggunakan keluk

Koch. Struktur antena yang dicadangkan itu adalah hasil daripada pengubahsuaian

yang dibuat dengan keluk persegi fraktal asas dan menggunakan Rogers RO4003

sebagai substrat. Reka bentuk dan simulasi telah dilakukan dengan menggunakan

simulator elektromagnet gelombang lengkap 3 dimensi. Antena itu boleh digunakan

untuk peranti yang paling pegang tangan dan dengan itu mendapati permohonan yang

luas dalam bidang komunikasi tanpa wayar dan mudah alih.

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CONTENTS

CHAPTER ITEM PAGE

PROJECT TITLE i

REPORT STATUS APPROVAL FORM ii

DECLARATION iii

SUPERVISOR APPROVAL iv

DEDICATION v

ACKNOWLEDGEMENT vi

ABSTRACT vii

ABSTRAK viii

CONTENTS ix

LIST OF TABLES xii

LIST OF FIGURES xiii

LIST OF ABBREVIATIONS xvi

I INTRODUCTION

1.1 BACKGROUND 1

1.2 PROBLEM STATEMET 2

1.3 SIGNIFICANCE OF PROJECT 3

1.4 OBJECTIVES OF PROJECT 3

1.5 SCOPE OF PROJECT 4

1.6 THESIS OUTLINE 4

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II LITERATURE REVIEW

2.1 INTRODUCTION 6

2.2 MICROSTRIP ANTENNA (MSA) 6

2.2.1 Feeding Methods 8

2.2.2 Structural Analysis of MSA 12

2.2.3 Fringing Effects 13

2.3 FRACTAL ANTENNA 15

2.3.1 Features of Fractal 17

2.3.2 Classes of Fractal 18

2.3.3 Fractal Dimension 21

2.3.4 Similarity Dimension 22

2.3.5 Iterative Function System 22

III METHODOLOGY

3.1 INTRODUCTION 24

3.2 METHOD 24

3.3 SIMULATION OF CST MICROWAVE STUDIO SUITE 26

3.3.1 Finite Element Method (FEM) 26

IV RESULT AND DISCUSSION

4.1 INTRODUCTION 27

4.2 ANTENNA DESIGN 28

4.2.1 1st Iteration 29

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4.2.2 2nd Iteration 34

4.2.3 3rd Iteration 39

4.2.4 Summary 43

4.3 SUSTRATE 44

V CONCLUSION

5.1 INTRODUCTION 46

5.2 CONCLUSION 46

5.3 FUTURE WORK 47

REFERENCES 49

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LIST OF TABLES

NO TITLE PAGE

2.1 Features of fractal antennas 17

4.1 Various parameters of square shaped fractal antenna 28

4.2 Dimensions for Koch Fractal Antenna Model (1st iteration) 29

4.3 Dimensions for Koch Fractal Antenna Model (2nd iteration) 34

4.4 Dimensions for Koch Fractal Antenna Model (3rd iteration) 39

4.5 Comparative result for 1st iteration antenna, 2nd iteration antenna and 3rd iteration antenna 44

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LIST OF FIGURES

NO TITLE PAGE

2.1 Microstrip antenna, (a) top view (b) side view 7

2.2 Different shapes of microstrip patches 8

2.3 Microstrip line feed 9

2.4 Equivalent circuit of microstrip feed line 9

2.5 Coaxial line feed 9

2.6 Equivalent circuit of coax feed line 10

2.7 Aperture coupled feed 11

2.8 Equivalent circuit of aperture coupled feed 11

2.9 Proximity coupled feed 12

2.10 Equivalent circuit of proximity coupled feed 12

2.11 Microstrip line 13

2.12 Microstrip E-field lines and its effective dielectric constant 14

2.13 Sierpinski Gasket with subsequent stages showing initiator and Generator 16

2.14 Classes of fractals 18

2.15 Different fractal geometries (a) Koch curve, (b) Minkowski Loop, (c) Sierpinski Gasket, (d) Fractal loop, (e) Cantor set and (f) Hilbert 20 Curve 21

3.1 Flow chart for designing a microstrip antenna 25

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4.1 Simulated design of square shaped fractal antenna (a) first iteration, (b) second iteration and (c) third iteration 29

4.2 Geometry of Koch Fractal Antenna (1st iteration) 30

4.3 1st iteration return loss 30

4.4 Smith Chart (1st iteration) 31

4.5 Simulated 2D directivity at 2.93 GHz frequency 31

4.6 Simulated 2D directivity at 5.12 GHz frequency 32

4.7 Simulated 3D directivity at 2.93 GHz frequency 32

4.8 Simulated 3D directivity at 5.12 GHz frequency 32

4.9 Simulated 2D gain at 2.93 GHz frequency 33

4.10 Simulated 2D gain at 5.12 GHz frequency 33

4.11 Simulated 3D gain at 2.93 GHz frequency 33

4.12 Simulated 3D gain at 5.12 GHz frequency 34

4.13 Geometry of Koch Fractal Antenna (2nd iteration) 35

4.14 2nd iteration return loss 35

4.15 Smith Chart (2nd iteration) 36

4.16 Simulated 2D directivity at 2.4 GHz frequency 36

4.17 Simulated 2D directivity at 5.823 GHz frequency 36

4.18 Simulated 3D directivity at 2.4 GHz frequency 37

4.19 Simulated 3D directivity at 5.823 GHz frequency 37

4.20 Simulated 2D gain at 2.4 GHz frequency 37

4.21 Simulated 2D gain at 5.823 GHz frequency 38

4.22 Simulated 3D gain at 2.4 GHz frequency 38

4.23 Simulated 3D gain at 5.823 GHz frequency 38

4.24 Geometry of Koch Fractal Antenna (3rd iteration) 39

4.25 3rd iteration return loss 40

4.26 Smith Chart (3rd iteration) 40

4.27 Simulated 2D directivity at 2.46 GHz frequency 41

4.28 Simulated 3D directivity at 5 GHz frequency 41

4.29 Simulated 3D directivity at 2.46 GHz frequency 41

4.30 Simulated 3D directivity at 5 GHz frequency 42

4.31 Simulated 2D gain at 2.46 GHz frequency 42

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4.32 Simulated 2D gain at 5 GHz frequency 42

4.33 Simulated 3D gain at 2.46 GHz frequency 43

4.34 Simulated 3D gain at 5 GHz frequency 43

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LIST OF ABBREVIATIONS

LAN - Local Area Network

PSM - Projek Sarjana Muda

CST - Computer Simulation Technology

MSA - Microstrip Antenna

WLAN- Wireless Local Area Network

MPA - Microstrip Patch Antenna

EDC - Effective Dielectric Constant

IFS - Iterative Function System

DS - Similarity Dimension

DH - Hausdorff Dimension

DB - Box-counting Dimension

EM - Electromagnetic

FEM - Finite Element Method

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CHAPTER I

INTRODUCTION

In this chapter, a summary of this project is presented. The objective of this

project is explained briefly. The dissertation overview of this thesis also provided in

this chapter.

1.1 BACKGROUND

Wireless communication assumes a major part to our daily existence, with

antennas being of ceaselessly expanding importance. Microstrip antennas are a type of

antennas that is popular with wireless communication equipment. This is because of

its outstanding physical properties. Microstrip antennas are light weight, low profile,

low production cost, conformability, reproducibility, reliability, also simplicity in

fabrication and integration with solid state devices and wireless technology

equipments [1]. However, the size of a conventional microstrip antenna is normally

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large when composed in microwave frequency regime creating issues for mounting on

transmitter/receiver and repeater systems. These antenna types also bring impediments

as far as their narrow bandwidth, low gain, and weak radiating patterns. The gain

reduction is brought about by the general diminishment in the antenna size. It might

additionally make attributed to the substrate characteristics which might prompt

surface wave excitation and hence a reduction in gain. Therefore, it is trying to outline

microstrip antennas to have better transmitting properties and in the same time have a

smaller size. There are several techniques used to diminish the size of the radiating

patch which prompts to a smaller antenna size, for example: using super-substrates to

produce high dielectric constant [2], incorporating a shorting pin in a microstrip patch

[3], using short circuit [4], cutting slots in radiating patch [5, 7], by in part filled high

permittivity substrate [8], or by fractal microstrip patch configuration [1, 9, 10]. Still,

it remains entirely hard to miniaturize microstrip antennas since these endeavours by

and large clash for electrical limitations or cost considerations [1]. The main goal of

this thesis is to propose a size reduction technique for microstrip antennas by using a

novel fractal radiating patch.

1.2 PROBLEM STATEMENT

Antenna miniaturization is an important aspect in modern communication

system design. With developing requirement for compact and small sized transceiver,

manufacturers find it hard to design smaller antenna. For this, few techniques have

been considered to reduce the antenna size, for example, the use of shorting pins,

material loading and geometry optimization. Thusly in this project, the idea of a fractal

has been applied to reduce the size of antenna. The minimization is the issue that

should be focus on.

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1.3 SIGNIFICANCE OF PROJECT

The microstrip patch antennas are well known for their execution and their

robust design, fabrication and their extent usage. The benefits of this microstrip patch

antenna are to conquer their demerits such as simple to design, light weight and so on,

the applications are in the different fields for example in the medical applications,

satellites and obviously even in the military systems just like in the rockets, aircrafts

missiles and so on. The usage of the microstrip antennas are spreading broadly in all

the fields and areas. Now they are booming in the commercial aspects because of their

low cost of the substrate material and the fabrication. It is also expected that due to the

increasing usage of the patch antennas in the wide range this could take over the usage

of the conventional antennas for the maximum applications. Thus, it is expected to

provide a smaller in size, better compact and multi-frequency antennas which suitable

for low powered devices like cellular phones. The same design approach can also be

used for designing antennas for other applications such as multi-frequency wireless

LAN and maritime antennas.

1.4 OBJECTIVES OF PROJECT

The aim of this project is to provide solution to the antenna requirements

mainly for wireless communication systems ensuring size reduction and multiband

characteristics. In order to achieve this, some of objectives need to be as accomplished.

i. To modify and stimulate microstrip fractal patch antenna for wireless

application.

ii. To study and analyze antenna parameters for antenna miniaturization.

iii. To investigate a square patch antenna using fractal geometry.

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1.5 SCOPE OF PROJECT

The scope of project regarding title is by developing the antenna using fractal

patch technique. The scope itself has divided into two parts which is Projek Sarjana

Muda 1 (PSM 1) and Projek Sarjana Muda II (PSM II).

As for PSM I, the literature review should be able to do before initiate the

project. Literature review needs to be done in order to understand the concept and

theory, as well as the applications, characteristics, operations, specifications and

design procedures of an antenna. It is also including the research of the antenna

calculation. The formula in order to make sure the output will best meet the

specification required. The software used for the simulation is CST Microwave Studio

Suite. The parameter should be study to get familiar when applying to the project.

As for PSM II, the scope of project is focusing on modifying and analyzing the

antenna. When modifying the antenna, the parametric study methods that have been

made are applied. Later, the analyzing needs to be performed. The analyzing is

important in order to assure the output of frequency response is in meet the requirement,

which are 2.4GHz and 5GHz.

1.6 THESIS OUTLINE

For the thesis outlines, it will be cover on the whole thesis. This report is

divided into a certain part. Each part will cover on a topic required.

Chapter 1 presents the introduction of the project. A little bit of explanation

will be done due to the project. It also includes the objectives, problem statement,

scope of project and the thesis outline of the project.

Chapter 2 presents the basic theory of MSAs, including the basic microstrip

patch geometries, features and different feeding methods describing their

characteristics. This chapter also deals about fractal geometry. Fractal antenna

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engineering represents a relatively new field of research that combines attributes of

fractal geometry with antenna theory. Chapter presents basic theory of fractals

describing its features, classes, and dimensions and explained about Iterative function

schemes (IFS).

Chapter 3 presents the methodology of the project. Flow chart of project will

be presented in this chapter with description as well.

Chapter 4 deals with the design and stimulation of the antenna. It also presents

a discussion on its simulated results.

Chapter 5 presents the conclusion of this project after all the theoretical and

analysed result is achieved. The future work also involved in this chapter.

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CHAPTER II

LITERATURE REVIEW

2.1 INTRODUCTION

In this chapter, an investigation of the microstrip antenna has been presented.

This includes the basic geometries, feeding techniques, features and applications of

these antennas. The fractal geometry also has been studied in this chapter.

2.2 MICROSTRIP ANTENNA (MSA)

The concept of microstrip antenna was traced in 1953 [11] and a patent in 1955

[12], but it received considerable attention in the start of 1970s. It used in aircraft,

spacecraft, satellite and missile applications which to obtain result in high performance.

Microstrip antenna can be used in order to meet size, weight, cost, performance and

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ease of integration, low profile antenna [13]. The antennas discussed earlier are 3-

dimensional antennas which are bulky and need more space to be deployed. MSA are

the modern generation of antennas having attractive features as low profile, low cost,

light weight and simple to fabricate. These features make them ideal components of

modern cellular and WLAN applications [14].

The interest for compact and low-cost antennas has conveyed the MSA to the

forefront because of expanding necessities for personal and hand-held mobile

communications. A MSA in its simplest form comprises of a radiating patch on front

side of a dielectric substrate and a ground plane on the back side. The top and side

views of a rectangular MSA (RMSA) are shown in Figure 2.1. The microstrip antennas

are likewise alluded to as patch antennas. The radiating elements and feed lines are

generally photoetched on the dielectric substrate. The radiating patch may be square,

circular, triangular, semi-circular, sectoral, and annular ring shapes illustrated in

Figure 2.2.

Besides, evaluation of the basic properties of microstrip patch antennas (MPA)

has been numerously discussed in literature [15, 16]. There are essentially two sorts of

radiator: broadside and end-fire radiator. Broadside radiators are those whose

maximum pattern is normal to the patch or axis of the antenna. For end-fire radiators,

they are those whose maximum is along the axis of the antenna. The strip and ground

plane are separated by a dielectric sheet as demonstrated in Figure 2.1.

(a) Top view (b) Side view

Figure 2.1 Microstrip antenna, (a) top view (b) side view [15]

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Figure 2.2 Different shapes of microstrip patches [16]

There are few substrates that can be used for the design of microstrip antennas.

The dielectric constants are commonly in the range of 2.2 ≤ 휀𝑟 ≤ 12. A good antenna

performance can be produced by using thick substrates with dielectric constant which

is low because they provide better efficiency, larger bandwidth, loosely bound fields

for radiation into space. However, it will cost us in larger element size. For thin

substrates with higher dielectric constants, they are also used for the microwave

circuitry as they require tightly bound fields to minimize undesired radiation and

coupling which lead to smaller element sizes, but they are less efficient and have

relatively smaller bandwidths on account of greater losses [17].

2.2.1 Feeding Methods

There are few feeding techniques employed to feed the microstrip antennas.

The most popular techniques are microstrip line, coaxial probe, aperture coupling and

proximity coupling [13]. The microstrip feed line is also called conducting strip, which

is much smaller width compared to the patch. The microstrip line feed is easy to

fabricate and simple to match by controlling the inset position and rather simple to

model. However as the substrate thickness increases surface waves and spurious feed

radiation increase, which for practical designs limit the bandwidth (typically 2-5%). A

typical microstrip feed line and its equivalent circuit are demonstrated in Figure 2.3

and Figure 2.4 respectively.