FREQUENCY RECONFIGURABLE LOG-PERIODIC ANTENNA DESIGNeprints.utm.my/id/eprint/28250/5/MuhammadFaizalIsmailMFKE2011.pdfKemudian, Antena Boleh-Ubah Log-Periodik direkabentuk dengan meletakan

FREQUENCY RECONFIGURABLE LOG-PERIODIC

ANTENNA DESIGN

MUHAMMAD FAIZAL BIN ISMAIL

UNIVERSITI TEKNOLOGI MALAYSIA

FREQUENCY RECONFIGURABLE LOG-PERIODIC ANTENNA DESIGN

MUHAMMAD FAIZAL BIN ISMAIL

A thesis submitted in fulfilment of the

requirements for the award of the degree of

Master of Engineering (Electrical)

Faculty of Electrical Engineering

Universiti Teknologi Malaysia

NOVEMBER 2011

iii

Specially dedicated to my beloved mom and dad,

Hjh Arapah bte Osman and Hj Ismail bin Baba,

my siblings and family, for their encouragement and support;

as well as my lovely fiancé, Noraini Khalil and all my friends who always inspired

and motivated me along my excellent journey of education

iv

ACKNOWLEDGEMENT

In the name of Allah, Most Gracious, Most Merciful. Praise be to Allah, the

Cherisher and Sustainer of the Worlds. With His permission I have completed my

Master Degree of Electrical Engineering and hopefully this thesis will benefit the

development of the Ummah all over the world.

Special thanks as well to my project supervisor, Associate Professor Dr.

Mohamad Kamal A. Rahim, for his guidance, motivations, support and constructive

comments in accomplishing 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. I would also like

to thank the wonderful members of P18; Mr. Huda A. Majid, Mr. Mohd Nazri A.

Karim, Mr. Osman Ayop, Mr. Farid Zubir, Mr. Amiruddeen Wahid, Mrs. Maisarah

Abu, Mrs. Kamilia, Mrs. Mai Abdul Rahman and Mr. Mohsen Khalily, who have

been extremely kind and helpful throughout my stay. “We don’t remember days, but

we remember moments” and I had a great time and moments with all these guys

during my study in UTM.

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. A million thanks for all.

v

ABSTRACT

The concept of reconfigurable antenna is widely used as additional features of

reconfigurable ability for future wireless communication system. There are various

configurations of reconfigurable antenna such as monopole, dipole and log-periodic

wideband antenna. The integrations of reconfigurable antennas with radio frequency

(RF) switches are needed to perform the switchable ability. In this research, a log-

periodic antenna (LPA) has been designed to perform a wideband frequency

operation by connecting thirteen square-patch antennas using inset feed line

technique. Then, the reconfigurable log-periodic antenna (RLPA) is designed by

connecting positive-intrinsic-negative (PIN) diodes at every transmission lines with a

quarter-wave length radial stub biasing. The representation of real PIN diodes and

the locations of biasing circuits in simulation are also included. Three different sub-

band frequencies with a bandwidth of 20% (3 - 4, 3.7 - 5, and 4.8 - 6 GHz for each

band) are configured from the total of 73% bandwidth (3 to 6 GHz) of the wideband

operations by switching ON and OFF of the PIN diode. Other sub-bands or narrow

band can also be configured by selecting other group of patches. Validation for the

LPA and RLPA is achieved by comparing the simulated and measured radiation

patterns. The measured half-power beamwidth (HPBW) for LPA are 62°, 58° and

72° at frequency 3.4 GHz, 4.0 GHz and 5.8 GHz, respectively, while 73°, 67° and

72° for RLPA at the same frequency band. The simulated gain for LPA and RLPA

are around 4.9 dB and 5.0 dB respectively, while the measured gain is around 5.5 dBi

for LPA and 5.7 dBi for RLPA within a frequency range of 3 – 6 GHz. All the

structures have been fabricated and the measurement results show accuracies of

97.5% for return loss, 80.2% for gain and 98.4% for HPBW with the simulation

results.

vi

ABSTRAK

Konsep antena boleh-ubah telah digunakan secara meluas sebagai

penambahan ciri dalam keupayaan boleh-ubah untuk sistem perhubungan tanpa

wayar di masa hadapan. Terdapat pelbagai konfigurasi antena boleh-ubah

menggunakan antena jenis jalur lebar seperti antena satu-polar, dwipolar dan log-

periodik. Penyepaduan antena dan suis RF diperlukan untuk melaksanakan

keupayaan boleh-ubah. Dalam penyelidikan ini sebuah antena log-periodik telah

direkabentuk untuk operasi jalur lebar dengan menyambung sebanyak tiga belas

antena tampalan segi empat dengan menggunakan teknik kemasukan jalur suapan.

Kemudian, Antena Boleh-Ubah Log-Periodik direkabentuk dengan meletakan diod

PIN pada setiap jalur penghantaran antena bersama dengan pincangan suku

gelombang puntung berjejari. Perwakilan diod PIN yang sebenar dan lokasi litar

pincangan dalam proses simulasi juga disertakan dalam projek ini. Tiga sub jalur

frekuensi yang berlainan dengan lebar jalur sebanyak 20% (3-4, 3.7-5 dan 4.8-6 GHz

bagi setiap jalur) telah dikonfigurasikan dari operasi jalur lebar yang mempunyai 73

% (3 hingga 6 GHz) lebar jalur dengan menukar diod PIN kepada keadaan ON dan

OFF. Sub jalur atau jalur sempit yang lain juga boleh diubah dengan memilih

kumpulan antena tampalan yang lain. Pengesahan untuk LPA dan RLPA tercapai

dengan membandingkan corak sinaran dari hasil simulasi dan pengukuran. Separuh-

Kuasa Lebaralur (HPBW) bagi LPA adalah 62°, 58° dan 72° pada frekuensi 3.4

GHz, 4.0 GHz dan 5.8 GHz manakala sebanyak 73°, 67° and 72° bagi RLPA pada

julat frekuensi yang sama. Gandaan simulasi untuk LPA dan RLPA adalah masing-

masing sekitar 4.9 dB dan 5.0 dB, manakala bagi gandaan pengukuran adalah sekitar

5.5 dBi bagi LPA dan 5.7 dBi bagi RLPA pada julat frekuensi 3-6 GHz. Kesemua

struktur telah difabrikasi dan keputusan pengujian mempunyai ketepatan 97.5% bagi

kehilangan balikan, 80.2% bagi gandaan dan 98.4% bagi HPBW berbanding

keputusan simulasi.

vii

TABLE OF CONTENT

CHAPTER TITLE PAGE

DECLARATION ii

DEDICATION iii

ACKNOWLEGMENT iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENTS vii

LIST OF TABLES xi

LIST OF FIGURES xiii

LIST OF SYMBOLS xviii

LIST OF ABBREVIATIONS xix

1 INTRODUCTION 1

1.1 Introductions 1

1.2 Project Background 2

1.3 Problem Statement 3

1.4 Objective 4

1.5 Scope and Limitation of the Project 4

1.6 Organization of the Thesis 5

2 LITERATURE REVIEW 7

2.1 Introductions 7

2.2 Antenna Properties 8

2.2.1 Return Loss 8

viii

2.2.2 Bandwidth 9

2.2.3 Radiation Pattern 10

2.2.4 Half-Power Beamwidth 11

2.2.6 Gain 11

2.3 Wideband Antenna 12

2.3.1 Log-Periodic Antenna 13

2.4 Reconfigurable Antenna 14

2.5 RF Switching 17

2.5.1 PIN Diode Switch 18

2.5.2 PIN Diode Equivalent Circuit Modeling 19

2.5.2 Biasing Circuit 20

2.6 Previous Related Research 23

2.6.1 The Log-Periodic Antenna Development 23

2.6.2 Reconfigurable Using Log-Periodic Antenna 27

2.6.3 Others Reconfigurable Antenna 30

2.7 Summary 37

3 LOG-PERIODIC ANTENNA DESIGN 38

3.1 Introductions 38

3.2 Project Methodology and Flow Chart of Log

Periodic Antenna

41

3.3 Single Patch Antenna Design 43

3.4 The Design of Log-Periodic Wideband Antenna 48

3.5 Parametric Study of Log-Periodic Antenna 51

3.5.1 Simulation on Distance of Adjacent Patch 51

3.5.2 Simulation on Different Length of Inset Feed

Line

53

3.5.3 Simulation on Different Scaling Factor 54

3.5.4 Parametric Studies Conclusion 55

3.6 Summary 56

ix

4 RECONFIGURABLE LOG-PERIODIC ANTENNA

DESIGN

57


4.2 Project Methodology and Flow Chart 58

4.3 Analysis of PIN Diode Representation 60

4.3.1 PIN Diode Representation using Lumped

Element

61

4.3.2 PIN Diode Representation using PEC Pad 63

4.4 Analysis of Biasing Circuit Location 65

4.4.1 Biasing circuit at the transmission line of

patch

66

4.4.2 Biasing circuit at the middle of length patches 67

4.4.3 Biasing circuit at the back of antenna 69

4.4.4 Parametric Studies Conclusion 70

4.5 Reconfigurable Log-Periodic Antenna (RLPA)

Design

71

4.6 Fabrication Process 78

4.7 Measurement Process 80

4.7.1 Input Return Loss Measurement Setup 80

4.7.2 Radiation Pattern Measurement Setup 81

4.8 Summary 82

5 RESULT ANALYSIS AND DISCUSSION 83


5.2 Analysis Result and Discussion of Log-Periodic

Antenna

84

5.2.1 Input Return Loss 84

5.2.2 Current Distribution 86

5.2.3 Realized Gain and Power Received 87

5.2.4 Radiation Pattern and Half-Power

Beam- width

89

5.3 Analysis Result of Frequency Reconfigurable Log-

Periodic Antenna and Discussion

93

x

5.3.1 Return Loss (S11) 94

5.3.2 Current Distribution 96

5.3.3 Simulated Realized Gain and Power

Received Measurement

97

5.3.4 Radiation Pattern and Half-Power

Beam-width

100

5.4 Overall Discussion 104

5.5 Summary 105

6 CONCLUSION 106

6.1 Overall Conclusion 106

6.2 Key Contribution 108

6.3 Future Research 108

REFERENCES 109

Appendices A - C 116-135

xi

LIST OF TABLES

TABLE NO. TITLE PAGE

2.1 Parameters value of equivalent circuits for PIN

Diodes

20

2.2 Lumped element’s representation in low and high

frequency

21

2.3 The switches' states of U-Koch reconfigurable

microstrip antenna

32

2.4 Previous researches on reconfigurable antenna 35

3.1 Design description of log-periodic antenna 48

3.2 LPA dimension for each patch. 50

3.3 Result of varying the adjacent patch 52

3.4 Result of varying the length of inset feed line 54

3.5 Summaries result of varying the scaling factor. 55

4.1 The value of lumped elements as a PIN diode 62

4.2 Reconfigurable log-periodic antenna properties 77

4.3 The dimensions for each patches of RLPA. 72

4.4 Switches’ states for each case 75

4.5 Performances of antenna using different PIN

diode representation

77

4.6 Antenna Fabrication Process 78

5.1 Comparison return loss between simulation and

measurement for LPA

86

5.2 Simulated realized gain and efficiency of the LPA 88

5.3 Half-power beam-width for Log-Periodic Antenna 93

xii

5.4 Comparison of return loss between simulation

and measurement of RLPA

96

5.5 Half-power beam-width for Reconfigurable Log-

Periodic Antenna

104

5.6 Comparison of overall performances in term of

frequency, bandwidth, gain and HPBW between

LPA and RLPA

105

xiii

LIST OF FIGURES

FIGURE NO. TITLE PAGE

2.1 Coordinate system for radiation pattern measurement 10

2.2 Two-dimensional of power pattern 11

2.3 Reconfigurable Antenna Block Diagram 15

2.4 Cross section diagram of PIN diode 18

2.5 (a) Equivalent circuit for forward biased

(b) Equivalent circuit for reverse biased

19

2.6 Equivalent circuit for a PIN diode 20

2.7 Schematic design of Series SPST Switch 22

2.8 Bias network configuration using radial line stub 23

2.9 Log-Periodic Slot Antenna Array structure 24

2.10 VSWR of Log-Periodic Slot Antenna Array. (Line-

measured, dotted line - computed)

24

2.11 Log-periodic Dipole Fractal Koch Antenna design 25

2.12 Return loss of Log-periodic Dipole Fractal Koch

Antenna

25

2.13 The structure of Log-Periodic Terahertz Antenna 26

2.14 The simulated return loss of Log-Periodic Terahertz

Antenna

26

2.15 Proposed prototype antenna 27

2.16 Measured (a) S-parameter in dB of wideband log

periodic antenna and (b) Efficiency of reconfigurable

antenna

27

2.17 The structure of reconfigurable LPDA (a) the 28

xiv

schematic design and (b) fabricated proposed antenna

2.18 a) Simulated and b) measured return loss response of

the reconfigurable LPDA

28

2.19 Schematic design of reconfigurable log-periodic

dipole antenna with harmonic traps

29

2.20 Measured return loss of reconfigurable log-periodic

dipole antenna

30

2.21 The dimension of annular slot antenna design. The

feeding line with the matching stubs is on the bottom

and the annular slot antenna is on the top side of the

substrate

31

2.22 Simulated and measurement result of reconfigurable

annular slot antenna at three different frequency

31

2.23 Radiation pattern of the reconfigurable annular slot

antenna (a) Simulation (b) Measurement

32

2.24 The structure of U-Koch reconfigurable microstrip

antenna

33

2.25 The measured return loss of U-Koch reconfigurable

microstrip antenna

33

2.26 Geometry of the reconfigurable Vivaldi antenna: (a)

top view, (b) side view, and (c) bottom view.

34

2.27 Measured return loss of reconfigurable Vivaldi

antenna for wideband and sub-band operation

34

3.1 Flow chart of overall process including log-periodic

antenna and reconfigurable antenna

40

3.2 Flow chart of research methodology for LPA 42

3.3 Simulated design of square patch antennas 44

3.4 Return loss of single patch antenna 46

3.5 3-D view radiation pattern of single patch antenna at

3.0 GHz

46

3.6 (a) Polar plot of radiation pattern at 3.0 GHz in E-

plane and (b) Polar plot of radiation pattern at 3.0

GHz in H-plane for single patch antenna with theta

47

xv

and phi setup in simulation.

3.7 Layout of Log-Periodic Antenna 49

3.8 Dimension of Log-Periodic Antenna 50

3.9 Result of varying distance of adjacent patch (Sa) 52

3.10 Result of varying the length of inset feed line (lf) 53

3.11 Result of varying scaling factor (τ) 55

4.1 RLPA design flow chart 59

4.2 (a) PIN diode representation using lumped element in

single patch antenna. (b) Lumped element data in

CST.

61

4.3 Lumped element circuit that use in CST software (a)

RLC-Serial (b) RLC-Parallel.

62

4.4 Return loss of antenna (lumped element as a PIN

diode)

63

4.5 PIN Diode representation using PEC pad in (a) ON

state (b) OFF state.

63

4.6 Return loss of antenna. (PEC stripe as a PIN diode) 64

4.7 The structure of Antenna A1 66

4.8 Current distribution of Antenna A1 66

4.9 Return loss of Antenna A1 67

4.10 The structure of Antenna A2 67

4.11 Current distribution of Antenna A2 68

4.12 Return loss of Antenna A2 68

4.13 The structure of Antenna A3 (a) front view (b) back

view

69

4.14 Current distribution of Antenna 3 (a) front view (b)

back view

70

4.15 Return loss of Antenna 3 70

4.16 The geometrical structure of reconfigurable log-

periodic antenna

74

4.17 Design description of reconfigurable log-periodic

antenna

74

4.18 Reconfigurable log-periodic antenna design. (a) PEC 76

xvi

stripe as a PIN diode (b) Lumped element circuit as a

PIN diode

4.19 Comparison of PIN diode representation for RLPA in

wideband operation

76

4.20 Return loss measurement setup. (a) Network analyzer

(b) Calibration kit

81

4.21 Power received and radiation pattern measurement

set-up.

81

4.22 Anechoic chamber 82

5.1 Photo of fabricated LPA 84

5.2 Simulated and measured return loss for LPA 85

5.3 Simulated current distribution for LPA at: (a) 3 GHz

(b) 4 GHz (c) 5 GHz (d) 6 GHz.

87

5.4 Measured received of the LPA and the horn antenna 89

5.5 Simulated radiation pattern of LPA at 3.4 GHz (a) 3-

D view. (b) 2-D view in E-plane. (c) 2-D view in H-

plane

90

5.6 Measured radiation pattern of LPA at 3.4 GHz (a) E-

plane. (b) H-plane

90



plane

91


plane. (b) H-plane

91



plane

92


plane. (b) H-plane

92

5.11 Photo of Reconfigurable Log-Periodic Antenna 93

5.12 Simulation and measurement return loss of the

antenna when all switches are in ON state.

94

5.13 Return loss of simulated reconfigurable log-periodic 95

xvii

antenna for different band

5.14 Return loss of measured reconfigurable log-periodic

antenna for different band

95

5.15 Simulated current distribution for reconfigurable log-

periodic antenna at: (a) 3 GHz (b) 4 GHz (c) 5 GHz

(d) 6 GHz.

97

5.16 (a) Simulated realized gain, directivity and efficiency

of RLPA.

(b) Simulated realized gain of RLPA in different

sub-bands.

98

5.17 Power received for different types of antenna at

measurement set-up

99

5.18 Power received of reconfigurable log-periodic

antenna (a) E-Plane (b) H-Plane

99

5.19 Simulated radiation pattern of RLPA at 3.4 GHz (a)

3-D view. (b) 2-D view in E-plane. (c) 2-D view in H-

plane

101

5.20 Measured radiation pattern of RLPA at 3.4 GHz (a)

E-plane. (b) H-plane

101



plane

102



102



plane

103



103

xviii

LIST OF SYMBOLS

fl - Low frequency

fh - High frequency

τ - Scaling factor

E - Electric field.

H - Magnetic field.

h - Substrate thickness.

t - Copper thickness

wp - Width of patch

εr - Relative permittivity of material.

tan δ - Tangential loss of material.

dB - Decibel

lf - Length of inset fed

ltx - Length of transmission line

mm - millimeter

R - Resistor

L - Inductor

C - Capacitor

xix

LIST OF ABBREVIATIONS

LPA - Log-Periodic Antenna

RLPA - Reconfigurable Log-Periodic Antenna

WLAN - Wireless Local Area Network

WiMAX - Worldwide Interoperability for Microwave Access

UWB - Ultra Wide Band

CR - Cognitive Radio

VSWR - Voltage Standing Wave Ratio

RL - Return Loss

BW - Bandwidth

BW% - Bandwidth Percentage

HPBW - Half Power Bandwidth

FR-4 - Fire Retardant Type 4

mm - Millimeter

GHz - Gigahertz

THz - Terahertz

SMA - Sub-Miniature version A

UV - Ultra Violet

CST - Computer Simulation Technology

xx

LIST OF APPANDICES

APPENDIX TITLE PAGE

A List of publications 116

B Datasheet of PIN Diode Infineon BAR 64 117

C Datasheet of wideband horn antenna 134

CHAPTER 1

INTRODUCTION

1.1 Introductions

This thesis proposes the design and development of wideband antenna using

log-periodic technique. The integration of the antenna with PIN diode switches and

lumped elements forms the reconfigurable antenna that enables the antenna to select

several sub-bands from a wideband frequency. This work involves the design,

fabrication and measurement process of the antenna that has wideband frequency

operation with frequency reconfigurability for future wireless communication system

such as cognitive radio, radar system and wireless communication network.

This thesis describes the antenna’s development including the literature

review on the reconfigurable antenna, the simulation design until the fabrication and

measurement process. In this first chapter, the brief background of the project is

discussed, providing problem statements, objectives, methodology, and scope of

work in conducting the research including the project’s possible outcome and

contributions and also the thesis organization.

2

1.2 Project Background

The field of wireless communication nowadays has put more emphasis on the

field of antenna design. In the early years when radio frequency was discovered, an

antenna with a simple design was used as a device to transmit electrical energy or

radio wave through the air in all directions. This innovative way of communication

to replace wired technology to wireless technology was first introduced by Galileo

Marconi when he successfully initiated the first wireless telegraph transmission in

1895 [1]. After that, the development of wireless technology makes leaps and

bounds.

Antenna development play a key role in wireless technology since the rapidly

increasing number of users in broadcasting, telecommunications, navigation, radar,

sensors, military and perhaps for future wireless communication e.g. the cognitive

radio [2]. The increasing number of users may lead to congestion of existing

spectrum such as Wireless Local Area network (WLAN), Wireless Personal Area

Network (WPAN), mobile communication and radio spectrum. Therefore, the

development of a reconfigurable antenna is very interesting in the improvement of

modern wireless communication system because they enable users to provide a

single antenna to be used in many systems.

The advantage of the reconfigurable antenna is they can alter or change the

antenna parameters based on their field of operation. The development of a

reconfigurable antenna is usually related to the microstrip antenna and their

integration with switching circuit. Its advantages include a low fabrication cost, light

weight, low profile, conforming, and compatible with integrated circuits devices [3,

4]. Besides, it can be designed at a specific resonant mode to radiate the required

frequency bands for the applications of wireless communication systems. However,

the new era of wireless communication requires antenna to operate in a wideband

range, possesses good radiation and has switchable ability [5, 6].

3

1.3 Problem Statement

As modern wireless communication systems have developed rapidly in recent

years, an antenna as a front component is required to have a wide band, good

radiation performances and sometimes switchable ability. To obtain the switchable

ability of the antenna, the concept of a reconfigurable antenna was proposed to easily

select the frequency from wideband to narrowband. The reconfigurable

characteristics of antennas are very valuable for many modern wireless

communication and radar system applications, such as object detection, secure

communications, multi-frequency communications, vehicle speed tests and so on.

Besides, the reconfigurable antenna can also operate within multiple systems by just

using a single antenna. For example, a single antenna can be used for both WLAN

2.4 GHz and 5.8 GHz by reconfiguring their dual-band operation.

The RF switch is important parts in development of reconfigurable antenna as

selection devices to makes tunable ability. The modeling of the RF switch in

simulation tools with an antenna also important that can give better results when

comparing with the fabricated antenna. From the previous research on reconfigurable

antenna [7-11], the implementation of real RF switches into the proposed antenna are

limited and not included with the simulation of an antenna. Some researchers have

used an ideal case to simulate the reconfigurable antenna. This project has propose

the development of reconfigurable antenna with integration of real RF switch and its

modeling in simulation to give better results when comparing with fabricated

antenna.

The development of wideband antenna usually uses a monopole structure [7]

because of various advantages: it is low profile, thin and small, has the ability to

produce very wide frequencies and possesses an omni-directional pattern. However,

by using a monopole structure, there has a difficulty on selection of location to

configure from wideband to narrow bands. Therefore, the log-periodic concept is

used to perform a wideband operation since it has directional radiation pattern; it also

easily selects a narrow band frequency since the log-periodic antenna allows a single

patch to radiate at single frequency. The integration of log-periodic antenna with RF

switching circuit can make the reconfigurable antenna even better.

4

1.4 Objective

The main objectives of this project are as follows:

i. Design, simulate and fabricate frequency reconfigurable antenna from

wideband range to narrow band range with integration of real PIN diodes

and biasing circuits.

ii. Design, simulate and fabricate a wideband antenna using log-periodic

technique.

iii. To characterize the antenna parameters in term of input return loss,

radiation pattern, half power beam width and gain for both simulation and

measurement.

1.5 Scope and Limitation of the Project

The main scopes of this research are:

i. Literature review and previous research study on log-periodic antenna and

reconfigurable antenna.

ii. Design, simulate and analyze the log-periodic wideband antenna and

reconfigurable log-periodic antenna using CST Microwave Studio

Software.

iii. Fabricate and measure the log-periodic antenna and reconfigurable log-

periodic antenna. The fabrication part includes soldering the PIN diode

and lumped elements.

iv. Analyze and compare the results between simulation and measurement.

v. Journal and thesis documentation.

5

The limitations of this research are:

i. The range of frequency is limit to 6GHz due to available low cost RF PIN

diode from the manufacturers.

ii. There are multiple parameters can be tuned for reconfigurable antenna.

However, this research only focuses on frequency reconfigurable from

wideband, to narrowband.

iii. The measurements of the antenna are based on available facilities in this

university. The anechoic chamber for radiation pattern measurement can

only measure from 0° to 180° rotation. Hence, only front lobes of

radiation patterns are compared with the simulation.

iv. The switching mechanism of this antenna is using manually by DIP

switch to control the PIN diode.

1.6 Organization of the Thesis

This thesis is divided into six chapters that describe all the work done for this

project. The first chapter consists of the introduction, project background, problem

statement, objectives, scope of study and project contribution. Chapter 2 is literature

review that explains literature about the log-periodic antenna and the reconfigurable

antenna. The basics of the antenna properties such as radiation pattern, bandwidth,

gain and HPBW are presented. The log-periodic concept is introduced and explained

to get a wideband operation before integrated with the lumped elements and PIN

diodes. Besides, the circuit representation of PIN diode and its biasing circuit have

also been explained for reconfigurable purposes. Some overview of previous studies

is also presented.

The design process of Log-Periodic Wideband Antenna is presented in

Chapter 3. The initial result of single patch antenna and the designing process of the

log-periodic wideband antenna are also presented. In order to get an optimum result

in term of return loss and bandwidth, a parametric study by varying the adjacent

distance between the patches, the length of inset feed line and the scaling factor value

6

are presented. While Chapter 3 discusses the passive antenna, the active antenna that

integrated with lumped element is discussed in Chapter 4. In this chapter, the

research flow, design methodology and simulation setup of Reconfigurable Log-

Periodic Antenna is briefly described. The PIN diode representation and biasing

circuit location in RLPA are also presented. This chapter also presents the fabrication

and measurement process of the antenna.

The simulated and measured results of the Log-periodic Wideband Antenna

and Reconfigurable Log-Periodic Antenna are presented in Chapter 5. The simulated

result such as return loss, current distribution, realized gain and radiation pattern is

clearly presented. Then, the measurement process is done to validate the simulated

results and both results have been compared to each other in terms of return loss,

received power and radiation pattern. A discussion of the results is presented clearly.

Lastly, the conclusion of the project is presented in Chapter 6. This chapter concludes

the findings of the project, some key contribution and provides recommendations for

future work.

FREQUENCY RECONFIGURABLE LOG-PERIODIC ANTENNA DESIGNeprints.utm.my/id/eprint/28250/5/MuhammadFaizalIsmailMFKE2011.pdfKemudian, Antena Boleh-Ubah Log-Periodik direkabentuk dengan meletakan

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