multiband mimo antenna for wireless...

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MULTIBAND MIMO ANTENNA FOR WIRELESS DEVICES

SARAH HASSAN KHALAF

A project report submitted in partial fulfilment of the

requirements for the award of the degree of

Master of Engineering (Electrical-Electronics & Telecommunications)

Faculty of Electrical Engineering

Universiti Teknologi Malaysia

JANUARY 2015

iii

“To the memory of my Uncle Razzak,

who sparked a passion that has not died.

To my beloved parents,

who gave it all to love me.

To my lovely brothers and sisters,

who always been there for me.

And finally to my lovely baby Jomana,

For keeping the life goes inside of me…

iv

ACKNOWLEDGEMENT

…It is impossible to start….

It cannot be argued with that the most influential person in my graduate career

has been my Supervisor, PROF. DR. THAREK BIN ABD RAHMAN’s passion,

guidance, and discipline have been indispensable to my growth as a scientist and as a

person over these past year. I am especially grateful to Prof. Tharek for his devotion

to his students’ education and success. I have not heard of another professor who goes

so far out of his/her way to make sure students are prepared for whatever the next step

in their journeys may be.

My sincere thanks also goes to all my lecturers for providing assistance,

experience and great knowledge at various occasions and leading me working on

diverse exciting projects.

Last but not the least; I would like to thank my family: my Husband Ebrahim,

for the love and spiritual support throughout my life with him.

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ABSTRACT

A Design of compact Multiple-Input-Multiple-Output (MIMO) Microstrip

Patch Antenna that has 4 ports, been designed and implemented. The proposed antenna

consists of four ports with two patches operates at LTE frequencies and two Patches

operates at WLAN frequency. The antenna is fabricated on an inexpensive FR4 a

dielectric constant ofεr = 4.4, loss tangent of tan δ=0.019, with thickness of substrate

that is 1.6-mm and the thickness of patch is 0.035 mm. The measured results represents

that the proposed antenna obtained a reasonable bandwidth for LTE and WIFI

applications defined by 10-dB return loss. Furthermore, The S-Parameters of antenna

are simulated and measured. In this project, design structure of the MIMO antenna four

ports and substrate has been employed to broaden the bandwidth. Since MIMO antenna,

high gain and directivity can be achieved. Simulation by using CST microwave studio

program and measurement on the final prototype antenna were carried out and compared.

A MIMO system characteristic evaluation of a four port MIMO antenna is performed.

A four port antenna for wireless applications is designed, the antenna shows good

pattern diversity low correlation coefficient.

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ABSTRAK

A Reka bentuk padat Multiple-Input-Multiple-Output (MIMO) Mikrojalur Patch

Antenna yang mempunyai 4 pelabuhan, telah dirancang dan dilaksanakan. Antena yang

dicadangkan terdiri daripada empat pelabuhan dengan dua patch beroperasi pada

frekuensi LTE dan dua Patches beroperasi pada frekuensi WLAN. Antena ini direka pada

FR4 murah yang ofε_r dielektrik berterusan = 4.4, kerugian tangen daripada tan δ =

0.019, dengan ketebalan substrat iaitu 1.6 mm dan ketebalan patch adalah 0.035 mm.

Hasil diukur mewakili antena yang dicadangkan diperolehi lebar jalur yang munasabah

untuk LTE dan aplikasi WIFI ditakrifkan oleh 10 dB kerugian pulangan. Tambahan pula,

The S-Parameter antena adalah simulasi dan diukur. Dalam projek ini, struktur reka

bentuk antena MIMO empat pelabuhan dan substrat telah digunakan untuk meluaskan

jalur lebar. Sejak MIMO antena, keuntungan tinggi dan directivity boleh dicapai.

Simulasi dengan menggunakan CST program studio gelombang mikro dan pengukuran

pada antena prototaip akhir telah dijalankan dan dibandingkan. Sistem MIMO penilaian

ciri-ciri yang MIMO antena empat pelabuhan dilakukan. Sebuah antena empat pelabuhan

untuk aplikasi tanpa wayar direka, antena menunjukkan kepelbagaian corak baik pekali

korelasi yang rendah.

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TABLE OF CONTENTS

CHAPTER TITLE PAGE

DECLARATION ii

DEDICATION iii

ACKNOWLEDGEMENT iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENTS vii

LIST OF TABLES xi

LIST OF FIGURES xii

LIST OF SYMBOLS

xiv

LIST OF ABBREVIATIONS

xv

1 INTRODUCTION

1.1 Project Overview 1

1.2 Problem Statement 2

1.3 Project Objectives 3

1.4 Project Outline 4

1.6 Summary 5

2 LITERATURE REVIEW

2.1 Introduction 6

2.2 Antenna Theory 7

2.3 MIMO Technology 9

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2.3.1 Polarization Diversity 10

2.3.2 Spatial Diversity 10

2.3.3 Directional Diversity 11

2.3.4 Basic Building Block of MIMO 12

2.3.5 MIMO Applications 14

2.3.6 MImo Limitations 14

2.4 LTE 15

2.5 LTE with MIMO 16

2.6 Microstrip Antenna 17

2.6.1 Advantages and Disadvantages 19

2.6.2 Facotrs Affecting Microstrip Antenna 20

2.6.3 Microstrip Discontinuity 21

2.6.4 Fringing Field 23

2.6.5 Feeding Techniques 24

2.6.6 Substrate Selection 27

2.6.7 Patch Dimension 33

2.6.8 Rectangular and square patch 33

2.7 Fundamental Antenna Parameters 34

2.8 Previous Works 40

2.9 Summary 41

3 METHODOLOGY

3.1 Introduction 42

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3.2 The Simulation Stage 45

3.3 Fabrication Stage 46

3.4 Measurement Stage 47

3.5 Summary 48

4 DESIGN AND SIMULATION

4.1 Introduction 49

4.2 Antenna Design 50

4.2.1 Design Calculations 50

4.2.2 Design Parameters 52

4.3 Substrate Specifications 55

4.4 Simulation Results 55

4.4.1 Return Loss 56

4.4.2 Isolation, Correlation and Diversity Gain 59

4.4.3 Radiation Pattern and Gain 64

4.5 Summary 70

5 RESULTS AND DISCUSSION

5.1 Introduction 71

5.2 Fabrication Process 72

5.3 Simulation and Measurement Comparison 72

5.4 Post Design Analysis 74

5.5 Summary 75

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LIST OF TABLES

TABLE NO. TITLE PAGE

2.1 Comparison of different feed techniques 30

2.2 Common Substrate Materials for Microstrip Antenna 31

2.3 Substrates Comparison 32

2.4 Previous works on the MIMO antenna 40

3.1 Project implementation 44

4.1 LTE patch dimensions 51

4.2 Wifi patch dimensions 52

4.3 FR4 Specifications 55

4.4 Results of return loss in (dB) 58

4.5 result of isolation parameters between antenna 60

4.6 Correlation Coefficient and Diversity Gain 63

6 CONCLUSION

6.1 Conclusion 76

6.2 Suggestions for Future Works 77

6.3 Summary 78

REFERENCES 79

xi

LIST OF FIGURES

FIGURE NO. TITLE PAGE

2.1 Various Antennas 8

2.2 MIMO system diagram 11

2.3 Building Blocks of a MIMO system 13

2.4 LTE (a) DL and (b) UL multiple access schemes 15

2.5 Structure of Microstrip Patch Antenna 17

2.6 Common Shapes of Microstrip Patch Elements 18

2.7 Fringing Electric Fields around Microstrip Patches 19

2.8 Open End Equivalent Circuit 21

2.9 Open End Equivalent Circuit For Step Discontinuity

22

2.10 Equivalent Circuit for Bend

23

2.11 Top View of the Electric Fringing 23

2.12 Side View of Microstrip Patch Antenna 24

2.13 Aperture coupled patch antenna. 25

2.14 Coaxial feeding mechanism. 25

2.15 Probe- fed rectangular patch antenna 26

2.16 Microstrip line feed. 27

2.17 Aperture coupled feed. 28

2.18 Proximity coupled feed. 29

2.19 Narrowband Square Patch Antenna using inset feed. 33

3.1 Graphical view of the project methodology 43

3.2 User Interface of CST MWS 46

3.4 Network Analyzer 48

4.1 Basic top view of micro strip patch antenna 50

4.2 Front and back view of the antenna 52

4.3 View of the proposed LTE Patch with the ground

transparence

53

4.4 View of the proposed WIFI Patch with the ground

transparence operates at 2.4 GHz.

54

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4.5 Return loss, S11 vs. Frequency 57




4.9 Isolation of port 2 61



4.12 3D far field at 1.8 GHz 64

4.13 3D far field at 2 GHz 64

4.14 3D far field at 2.4 GHz 65

4.16 ploar far field view at 1.8 GHz, phi=90 66

4.17 ploar far field view at 2 GHz, phi=90 66



5.1 Antenna Prototype 71

5.2 Simulation and Measurement Antenna Return Loss for

Port 1.

73

5.3 Simulation and Measurement Antenna Return Loss for

Port 4.

74

5.4 Measurement Antenna Isolation parameters 74

xiii

LIST OF SYMBOLS

h - Dielectric substrate thickness

L - Length

W - Width

Γ - Reflection coefficient

Z0 - Characteristic impedance

ZL - Load impedance

λr - Free-space wavelength

𝑉0− - Reflected volta

𝑉0+ - Incident voltage

εr - Dielectric constant of the substrate

t - Patch thickness

c - Speed of light 3x 10-8 m/s

G - Conductance

Л - Pi

η - Efficiency

G - Gain

D - Outer diameter of SMA connector

d - Inner diameter of SMA connector

W1 - Width of feed line

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LIST OF ABBREVIATIONS

FCC - Federal Communication Commission

UWB - Ultra-wideband

PD - Phase Difference

CP - Circular polarization

MPA - Microstrip Patch Antenna

Ω - Ohm

dB - decibel

CST - Computer Simulation Software

FR4 - Fire Retardant Type 4

BW - Bandwidth

BW% - Bandwidth percentage

PCB - Printed Circuit Boards

Hz - Hertz

GHz - Giga Hertz

mm - Millimetre

RF - Radio Frequency

IEEE - Institute of Electrical and Electronic Engineers

VSWR - Voltage Standing Wave Ratio

RL - Return Loss

HPBW - Half Power Beam Width

EM - Electromagnetic

UV - Ultraviolet

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CHAPTER 1

INTRODUCTION

This project work suggests the growth of multiband MIMO antenna with wireless

devices. The first chapter is about the background of the project providing the objective

and scope of this work.

1.1 Project Overview

The present communication systems such as 3G and 4G technologies require

larger data transfer rates with high speed and accuracy. The Multiple Input Multiple

Output (MIMO) technology is one of the advanced wireless communication systems,

which is very much capable to accomplish the demands of the present and emerging

communication systems like Wi-Fi, 3G and 4G etc. Patch antennas which are low cost,

low in weight, planar or conformal layout, easier to fabricate, and able to be integrated

with electronic or signal processing circuitry show good compatible with MIMO systems.

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Patch antennas can be designed in any desired shape like ring, circular, triangular etc.

Flexibility in patch antenna design makes it preferable for many modern wireless

communication applications. The placement of multiple antennas in small region in a

MIMO system cause mutual coupling. In this study, the physical aspects of the mutual

coupling between two identical patch antennas investigated.

Long Term Evolution (LTE) is a wireless broadband technology, which is

designed to support roaming Internet access via cell phones and handheld devices. As

LTE offers significant improvements over older cellular communication standards, for

instance a 4G (fourth generation) technology along with WiMax.

1.2 Problem Statement

Due to increase in the demand of wireless communication, today and future

wireless communications devices require to be equipped with compact size antenna that

can operate at multiple frequency bands. The decrease in the size of the antenna affects

the radiation (signal) performance. Hence, the designing of compact size antennas with

promising radiation characteristics are required. In this work new techniques are

employed for antenna miniaturization based on fractal geometries or by introducing

lumped elements to the printed monopole antenna design. Although, the microstrip patch

antennas have number of advantages such as low cost, light weight, simple

implementation process and conformability but it has drawback of narrow bandwidth.

The present work is mainly focused on the improvement of impedance bandwidth. The

impedance bandwidth of the patch antennas can be improved by various techniques like

introducing parasitic elements, increasing the thickness of substrate, modifying the shape

of the antenna and introducing slots on the patch. As the MIMO antenna, show significant

17

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improvement on the transmission rate can be achieved by employing MIMO techniques.

Another topic involved in this research work is to design compact multiband closed space

antenna. In this work, neutralizing and reconfigurable techniques are employed to design

printed monopole antenna .The proposed antennas are implemented and characterized.

The numerical simulations are conducted in the Finite Element Method (FEM)

based on electromagnetic simulation software package, CST Microwave studio, to verify

experimental results.

1.3 Project Objective

The main objective of this project work is to design compact multiband antennas

for future wireless applications.

The specific objective of this study are listed as follow:

To design, simulate and fabricate a compact antenna to support multiband

frequencies.

Characterization and performances evaluation of proposed antennas in term of

return loss, current distribution and radiation patterns.

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1.4 Scopes of project

Study of (MIMO) microstrip antenna to understand the concept and theoretical of

microstrip antenna.

Designed the antenna structure by using CST software tools to achieve a multiband

of 1.8, 2, and 2.6 GHz for LTE and 2.4 GHz for WIFI.

Simulation the antenna design by using electromagnetic software such as CST

microwave studio.

Fabricate the antenna proposed on the FR4 board with thickness 1.6 mm and

relative permittivity εr = 4.4.

Characterized and compared for the performing with simulation results.

1.5 Outline of Thesis

This thesis is structured into six chapters as follow:

The first chapter is an introduction, which presents datum regarding background

of the project, problem statement, objectives, scope of the study and the layout of

thesis.

The second chapter confers and reviews the literature of a lot of associated topics.

These were comprised: Antenna Theory, MIMO Theory, Narrow and wide Band,

microstrip patch antenna , Feeding Techniques ,LTE, ...etc.

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5

Third chapter contains the methodology in which the methods occupied and the

software's needed for this project are clarified. This were consists of also the design

and imitation results that present all the design specifications and product obtained

from manual calculation and simulation run. The imitation results and consequent

analysis are argued as well.

In the forth chapter, the simulation process and the design procedure been

introduced showing the software that been used.

In the fifth chapter, the fabrication method, results and analysis of the

measurement that compared with the simulation results are conversed.

At the sixth chapter, a conclusion for the work is introduced with a future work

and recommendation been given.

1.6 Summary

Concise introduction on the project and its scopes have been displayed. Some

associated project backgrounds have also been showed to simplify the direction of the

project. The synopsis of this thesis has also been explained.

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