i

DEVELOPMENT OF COMPACT, HIGHLY EFFICIENT RECTENNA FOR WIRELESS POWER HARVESTING OF 2.45 GHz FOR LIGHTLY POWERED

WIRELESS TAGS

MUHAMAD SAMSURIA BIN ABDUL DAIM

This report is submitted in Partial Fulfillment of Requirement for Award of Bachelor of Electronic Engineering (Wireless Communication) With Honours

Faculty of Electronics and Computer Engineering

Universiti Teknikal Malaysia Melaka

JUNE 2015

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UNIVERSTI TEKNIKAL MALAYSIA MELAKA

FAKULTI KEJURUTERAAN ELEKTRONIK DAN KEJURUTERAAN KOMPUTER

BORANG PENGESAHAN STATUS LAPORAN

PROJEK SARJANA MUDA II

Tajuk Projek :

DEVELOPMENT OF COMPACT, HIGHLY EFFICIENT RECTENNA

FOR WIRELESS POWER HARVESTING OF 2.45 GHz FOR

LIGHTLY POWERED WIRELESS TAGS

Sesi Pengajian : 1 4 / 1 5

Saya MUHAMAD SAMSURIA BIN ABDUL DAIM 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)

Tarikh: ……………………….. Tarikh: ………………………..

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“I hereby declare that this report is the result of my own work except for quotes as cited in the references.”

Signature :

Author : Muhamad Samsuria bin Abdul Daim

Date : 15 June 2015

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

(Wireless Communication) With Honours.”

Signature :

Author : Dr. Mohammed Saeed Jawad

Date : 15 June 2014

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For my dearest mother, Rahmah bt Ahmad,family, beloved lecturers and friends.

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ACKNOWLEDGEMENT

First of all, I am thankful to Allah S.W.T for giving me guidance and strength

internally and externally to enable me to finish my final year project successfully. I would

like to convey my greatest gratitude to my dearest supervisor Dr. Mohamed Saeed Jawad

for his guidance, brilliant ideas and his expertise in this field are sincerely appreciated.

I also want to express my special thanks for my lovely dad and my lovely family because

they always support me and their advice become an inspiration and strength to me in

completing this research successfully. Lastly, I dedicate a valuable thankful to my

classmates, friends and colleagues at this university who always support me directly or

indirectly.

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ABSTRACT

Power source in battery nowadays have become part of human life. The short

lifetime of battery sometime can be a problem. Even though nowadays, there are many

others technique of energy harvesting such as solar panel, wind energy and other

renewable source, but it is not convenient to use large power source to power up low

power level application such as sensors and wireless tags. Therefore solution of other

energy harvesting that is small yet efficient must be achieved. Rectenna is a solution to

create small energy harvesting tools that can be applied to low power level application.

Rectanna is basically a device that used to capture and convert signal into DC power and

used as receiving terminal. Rectenna is combining of rectifying circuit and antenna. Both

of rectifying circuit and antenna design will determine the overall performance of

rectenna. Proposal of this project is to harvest enough energy that can power up low level

application such as wireless tags at 2.45 GHz. Rectenna will be design using CST studio

software and fabricated on FR4 board. RF Schootky diode will be used to construct

rectifying circuit. The matching of the Schootky diode will be in stub matching form

which will be design on FR4 board. The horn antenna will be used as a transmitter that

resonate at 2.45 GHz for the input power level at -20dBm to 20dBm. Rectenna then will

be used to convert the signal into DC voltage.

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ABSTRAK

Pada masa kini, sumber kuasa di dalam bateri menjadi sebahagian daripada

kehidupan manusia. Jangka hayat yang pendek kadang-kadang boleh menjadi masalah.

Walaupun begitu, terdapat banyak lagi teknik penuaian tenaga seperti panel solar, tenaga

angin dan sumber yang boleh diperbaharui yang lain, namun ia tidak mudah untuk

meningkatkan aplikasi tahap kuasa yang rendah seperti sensor dan tag tanpa wayar dengan

menggunakan sumber kuasa yang besar. Oleh itu, penyelesaian penuaian tenaga lain yang

kecil tetapi berkesan haruslah dicapai. Rectenna adalah penyelesaian untuk mewujudkan

alat penuaian bertenaga kecil yang boleh digunakan untuk aplikasi kuasa tahap rendah.

Rectenna pada dasarnya adalah alat yang digunakan untuk menangkap dan menukar

isyarat ke dalam kuasa DC dan digunakan sebagai pangkalan penerima. Rectenna adalah

gabungan daripada litar penerus dan antenna. Kedua-dua litar penerus dan reka bentuk

antenna akan menentukan keseluruhan prestasi rectenna. Cadangan projek ini adalah

untuk menuai tenaga yang cukup untuk meningkatkan aplikasi tahap rendah contohnya

tag tanpa wayar pada 2.45GHz. Rectenna akan di hasilkan dengan menggunakan CST

Studio Software dan fabrikasi pada papan FR4. Diod jenis Schottky akan digunakan untuk

membina litar penerus. Padanan daripada diod Schootky akan berada dalam bentuk

puntung (stub), yang hampir sama yang akan direka bentuk di papan FR4. Horn antenna

akan digunakan sebagai pemancar yang bergema di 2.45GHz pada tahap kuasa input di

2dBm hingga 20dBm. Rectenna kemudiannya akan digunakan untuk menukar isyarat

kepada voltan DC.

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TABLE OF CONTENTS

CHAPTER TITLE PAGE

PROJECT’S TITLE i

CONFIRMATION FORM OF THESIS

ii

DECLARATION iii- iv

DEDICATION v

ACKNOWLEDGEMENT vi

ABSTRACT vii

ABSTRAK viii

TABLE OF CONTENT ix

LIST OF TABLES xii

LIST OF FIGURES xiii

LIST OF ABBREVIATIONS xv

LIST OF SYMBOL xvi

LIST OF APPENDICES xvii

I INTRODUCTION 1

1.1 Project introduction 1-3

1.1.1 Overview of Rectenna 3

1.2 Objectives 4

1.3 Problem statement 4-5

1.4 Project Scope 5-6

1.5 project Significance 6-7

1.6 Methodology 7-9

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1.7 Thesis outline 9-10

II LITERATURE REVIEW 11

2.1 Introduction to Rectenna 11-12

2.1.2 Antenna Design 12

2.1.3 Antenna parameter 13

2.1.3.1 Return Loss 13

2.1.3.2 Radiation Pattern 13

2.1.3.3 Gain 14

2.1.3.4 Bandwidth 14

2.1.3.5 Impedance Matching 14

2.2 Rectifying circuit 15-16

2.3 Previous study analysis. 16-21

III METHODOLOGY 22-25

3.1 Materials

26

3.1.1 FR-4 board 26

3.1.2 Schottky diode 26-27

3.1.3 Load 27

3.2 Equipment 27

3.2.1 Network Analyzer 28

3.2.2 RF cable 28

3.2.3 Horn antenna 28

3.2.4 Digital multimeter 29

3.3 Design of antenna 30-33

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3.4 Parametric study 34

3.5 Design of rectifier circuit 34-35

3.6 Experimental Setup 36

IV RESULTS AND DISCUSSION

37

4.1 Introduction 37

4.2 Results for antenna 38

4.2.1 Parametric study result 39-41

4.3 Simulation and measurement results

of the antenna

41

4.3.1 Return loss 41-42

4.3.2 Bandwidth 42-43

4.3.3 Gain and Directivity 44-45

4.3.4 Radiation Pattern 45-47

4.3.5 Impedance matching and

surface current

47-48

4.4 Measurement of output power of

Rectenna energy

48

4.4.1 Simulation result of the rectenna 48-49

4.4.2 measurement result of the

rectenna at different distance

49-52

4.4.3 Analysis on rectenna 52-53

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V CONCLUSION 54

5.1 Introduction 54

5.2 Conclusion 54-55

5.3 Recommendations and Future Works 55-56

REFERENCES 57-60

xiii

LIST OF TABLES

NO TITLE PAGE

1.0 Comparison of rectifier 18

2.0 Comparison of the previous study findings 21

3.0 Board characteristic 26

3.1 Dimension of microstrip patch antenna 31

3.2 Dimension and parameter of antenna 34

4.0 Comparison of antenna design 38

4.0.1 Comparison between simulation and measurement of antenna

47

4.1 Output voltage at 25 cm 50

4.2 Output voltage at 50 cm 50

4.3 Output voltage at 75 cm 51

4.4 Output voltage at 100 cm 51

4.5 Comparison of the measured voltage output of the

rectenna

52

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LIST OF FIGURES

NO TITLE PAGE

1.0 Rectenna basic component in block diagram 5

1.1 Flow chart of designing process and method

when carrying the project.

8

2.0 Single stage Dickson voltage charge pump

rectifier design

16

3.0 The flow chart of the project 23-24

3.1 Figure 3.1 shows Schottky Diode HSMS 2860

B configuration

27

3.2 RF resistor used in the design 27

3.3 Network analyzer 28

3.4 Horn antenna 29

3.5 Digital multimeter 29

3.6.0 Options that provided in CST Studio Suite 2014 30

3.6.1 The workspace of the software 30

3.6.2 The view of the antenna 31

3.7.1 Stub matching 35

3.7.2 Design of rectenna 35

3.8.0 Measurement setup 36

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4.0

(a), (b), (c),

(d), (e) , (f)

Parametric study of Wg, W and Ls 39-40

4.3.0 Measured return loss for antenna 42

4.3.1 Simulation result of return loss 42

4.3.2 Simulation bandwidth 43

4.3.3 Result of measurement and three markers is

added to calculate the bandwidth achieved.

43

4.3.4 Gain of antenna 45

4.3.5 Directivity of antenna 45

4.3.6

(a), (b) and

(c)

Radiation pattern of antenna in simulation 46

4.3.7 The impedance achieve for this antenna 48

4.4.0 Simulation result of the desired rectifier 49

4.4.1 The antenna is tested at distance of 25 cm 49

4.4.2 Fabricated rectenna 53

xvi

LIST OF ABBREVATIONS

RECTENNA - Rectifying antenna PCB - Printed circuit board VHF - Very high frequency GSM - Global system for mobile RFID - Radio Frequency Identification ISM - Industrial, Scientific and Medical IEEE - Institute of Electrical and Electronics

Engineering FR-4 - Flame retardant ADS - Advance Design System

xvii

LIST OF SYMBOLS

λ - Wavelength Ω - Ohms ℇeff - Effective permitivity ℇr - Effective dieletric constant Z - Impedance f - Frequency c - Speed of light; 3 × 108

xviii

LIST OF APPENDICES

NO TITILE PAGE 1 Project planning flow chart 23-24

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CHAPTER 1

INTRODUCTION

This chapter will give an overview about the project as project background,

project objectives, project scope, project methodology and summary of the project. This

chapter will explain briefly about project details.

1.1 Project introduction

Nowadays, there are many items which can be used to harvest energy as a source

including RF signal and microwave. In most area, wireless signal such as microwave and

RF signal is mostly used for internet surfing, but these signal can be converted to DC

voltage using proper tools and technique.

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There is an active research in investigating several methods significantly

extracting ambient energy from surrounding and convert it into electrical energy [1] for

energizing low power wireless sensors which can get the required power from rectenna

circuit. Indeed, RF energy scavenging from the ambient will become more beneficial at

future of microelectronic which will be flexible of green electronics devices due to self-

powered wireless sensor and energy autonomous [2]. In fact, there are many energy from

external sources such as solar power, magnetic, vibration and RF energy. The advantage

harvested RF energy from the ambient because the energy is feely available in space.

Thus, RF energy is captured by a receiving antenna and rectified into a usable DC voltage.

The application of project is to use rectenna to convert wireless signal into DC

(direct current) and power up low power application such as wireless tags. Rectenna

received/captured signal which is transmitted from the transmitter using horn antenna at

a frequency of 2.45 GHz. This project is carry out to develop and design a compact and

high efficiency rectenna for wireless power harvesting of 2.45 GHz for lightly powered

wireless tags.

RF energy harvesting system is made up of microwave antenna, prerectification

filter, rectifying circuit and DC pass filter that rectifies incoming electromagnetic waves

into DC current. The rectifying circuit can be in any types like full-wave bridge rectifier

or as a single shunt full-wave rectifier [5][6].

In order to obtain an optimum power transfer, a low pass filter between the antenna

and rectifier will be used. The purpose of using this filter is to achieve impedance

matching between them. Then, after signal is rectified, a DC low pass filter will be used

to smooth the output DC voltage and current by attenuating the high frequencies

harmonics that present in the RF signals or generated by the highly nonlinear rectifying

process itself. The best is collecting the maximum power before deliver it to the rectifying

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diode, and then to suppress the harmonics generated by the diode that reradiate from the

antenna as the power lost [6].

Rectenna with DC power conversion could provide a new revelation for power

source technology. Generally, communication devices have omni-directional radiation

pattern of antennas that propagate RF energy in most direction thus maximizes the

coverage for mobile applications. The energy harvesting system design promotes a

promising future in low power consumer of electronics devices and wireless sensor

networks.

1.1.1 Overview of Rectenna

The rectenna has been advancing in recent years, as the microwave integrated

circuit and monolithic microware integrated technologies become more mature allowing

for high level integration. The rectenna term is actually a combining of an antenna and a

non-linear rectifying circuit where these two element integrated into one single circuit.

Rectenna is capable to receive and detect microwave power and convert the signal into dc

voltage at high frequencies [1]. Rectenna which can capture and convert electromagnetic

power to electric power plays an important role in free space wireless power

transmission(WPT).This feature is an attractive solution to supply a node in wireless

sensor network(WSN) or the electronic circuit of the wireless tags such as radio frequency

identification (RFID) tags. The development of rectenna focused on its efficiency for great

power reception and conversion [2].

The crucial factor of the rectenna is antenna itself. The frequency selected for

antenna is 2.45 GHz which means antenna is able to work in that frequency. Frequency

2.45 GHz is selected as operating frequency as to get high frequency. Rectifying circuit

design and the diode use also affect the performance of the rectenna. Rectifying circuit

consisted Schootky diode and the load resistor for power measurement.

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1.2 Objectives

The objective of this project is to design a highly efficient rectenna as small size

and relatively high gain enough to power up wireless tags from received signal energy.

Another objectives is to evaluate the performance of the proposed rectenna in software

simulation as well as experimented analysis and testing of the rectenna. This rectenna

design will convert captured signal into DC power which is use to power a low power

level device such as wireless tags and sensor. Rectenna also can contribute in in reduction

of waste (in this case: battery) and can be develop as a green technology. Due to the green

technology that highly demands these days, the project can be used to generated new

power and rectenna can be used as alternative power source in future.

1.3 Problem statement

The research regarding rectenna had been done long time ago, but there are certain

problem that can be improve for better performance. For example , Rakesh Kumar Yadev

and etc in their journal stated that broadband and large arrays antenna enables to receive

high signal however a mismatch of polarization arises between antenna size and radiation

gain. S. Riviere, F. Alicalapa, and etc in their journal of compact rectenna only achieved

efficiency of 34% using simple aperture coupled patch antenna at low power level of -

10dBm and to find a correct match between antenna and the rectifying circuit is an issue.

It is clearly find that still need for improvement on the size of antenna, efficiency and the

mismatch of the circuit

The problem of this research can be stated as to develop a compact but have high

efficiency. Other problem of the research is ambient frequency of 2.45 GHz must have

enough power to produce high output DC yet small size rectenna. This project is

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undertaken as a solution for wireless energy harvesting without other source. This project

is also undertaken as a solution for problem reported in related journal about designing a

good antenna.

1.4 Project Scope

The scope of this project is to find a solution to convert the energy from wireless signal

to DC power and to increase the efficiency of power conversion. This project is a forecast

on the wireless harvesting for low level application device. Frequency of interest is at 2.45

GHz. This project involve in designing antenna and rectifying circuit component of

proposed rectenna. The implementation of this work is first implemented in software as

simulation in CST studio.

Figure 1.0 shows rectenna basic component in block diagram

The antenna is used to capture the input incoming signal and delivered to the

rectifier circuit. The rectifier circuit which consist filter and Schottky diode is use to

convert the voltage that in form of AC to DC. The properties of diode determine the

overall performance.

The Schottky diode is chosen for rectifying circuit because that diode have lower

built-in voltage that would realized a higher rectifying efficiency. The function of filter in

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rectifier circuit is to block any harmonic generated by diode and antenna. The filter is also

used to make the output smoother. However this project only involve in wireless energy

harvesting to power up low power level device such as wireless tags.

Antenna used in this project is microstrip patch antenna and rectifier circuit that is

used in this project is two stage Dickson charge pump voltage doubler circuit.

1.5 project Significance

This project gives high commercial values since the active research motivated for the

search for an alternative source of energy to power wireless sensor network especially at

2.45GHz frequency band (Industrial, Scientific and Medical) application that requires

sensors to be installed for a long duration where battery replacement is not practical. The

antenna design at this frequency band is important to work in for many applications. The

microstrip patch antenna design at different frequency band between [9] and [10] is

compare which is the operating frequency is at 5.25GHz and 2.4GHz in term of method

that they used. Researcher in [9] design microstrip patch antenna without slot whereby

researcher in [10], introduced additional slots to rectangular patch in order to achieve

single band functionality.

Then, the performances of antenna gain which same operating frequency of antenna

at 2.45GHz is analyzed between [23], [24], [25]. In [23], researcher proposed four planar

dipole elements placed in two parallel lines whereas in [24], a compact wideband

microstrip thinned array antenna using EBG substrate is designed. Then, researcher in

[25] proposed 2x1 linear antenna array , 4-element microstrip linear array antenna with

Butler matrix beamforming network is designed, analyzed and implemented using

microstrip technology in completely planar structure. The gain of antenna design by

researcher in [23], [24], and [25] is 7.5dBi, 8.2dBi, 9.186dBi for 2x1 linear antenna array.