FREQUENCY RECONFIGURABLE LOG-PERIODIC ANTENNA ...
Transcript of FREQUENCY RECONFIGURABLE LOG-PERIODIC ANTENNA ...
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
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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
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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.
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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.
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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.
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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
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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
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4 RECONFIGURABLE LOG-PERIODIC ANTENNA
DESIGN
57
4.1 Introductions 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
5.1 Introductions 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
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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
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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
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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
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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
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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
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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
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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
5.7 Simulated radiation pattern of LPA at 4.0 GHz (a) 3-
D view. (b) 2-D view in E-plane. (c) 2-D view in H-
plane
91
5.8 Measured radiation pattern of LPA at 4.0 GHz (a) E-
plane. (b) H-plane
91
5.9 Simulated radiation pattern of LPA at 5.8 GHz (a) 3-
D view. (b) 2-D view in E-plane. (c) 2-D view in H-
plane
92
5.10 Measured radiation pattern of LPA at 5.8 GHz (a) E-
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
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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
5.21 Simulated radiation pattern of RLPA at 4.0 GHz (a)
3-D view. (b) 2-D view in E-plane. (c) 2-D view in H-
plane
102
5.22 Measured radiation pattern of RLPA at 4.0 GHz (a)
E-plane. (b) H-plane
102
5.23 Simulated radiation pattern of RLPA at 5.8 GHz (a)
3-D view. (b) 2-D view in E-plane. (c) 2-D view in H-
plane
103
5.24 Measured radiation pattern of RLPA at 5.8 GHz (a)
E-plane. (b) H-plane
103
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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
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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
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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.
CHAPTER 2
LITERATURE REVIEW
2.1 Introduction
Since decades ago, the reconfigurable antenna received a lot of attention due
to its numerous applications and offers versatility in wireless communication system
such as radar system, cellular-radio system, smart weapons protections, and wireless
local area network system and for future applications including the cognitive radio
system. The reconfigurable antenna is capable of tuneable adjustment on various
antennas’ parameter such as operating frequency, polarization, radiation pattern or
more than one parameter.
In this project, the frequency reconfigurable antenna has been selected to
study the antenna properties before and after integration of the PIN diode. The
frequency reconfigurability needs wideband range to reconfigure to narrow bands.
Hence, to design a wideband antenna, a log-periodic structure has been chosen due to
ease of tuning the frequency. In this chapter, the literature study of the log-periodic
antenna and the reconfigurable antenna is discussed. The important antenna
parameters are also included and discussed in order to understand the antenna
concept before discussing the antennas’ results. This chapter also discusses previous
research on the log-periodic antenna and the reconfigurable antenna to review work
done by other researchers related to this project.
8
2.2 Antenna Properties
The parameters of the antenna play a major role in the performance of the
antenna. These parameters can be modified in the process of designing the antenna to
increase the performance and criteria which is needed for a dedicated application.
There are many parameters that can be measured from an antenna. In this work, only
certain parameters that will be discussed in details due to the lack of equipments and
facilities, but the parameters discussed in this work are sufficient enough to analyze
the performances of the prototype antenna.
2.2.1 Return Loss
The most important parameter to analyze the performance of antenna is the
input return loss. The efficiency of power transmitted to the load via transmission
line is a return loss. In an antenna measurement, the power transmitted of the antenna
can be represent as a Pin while Pref as a power reflection to the source. Ideally, a good
antenna performance is when the power is 100 percent transmitted to the antenna
while 0 percent is reflected back. However, losses in the antenna could reduce the
power transmitted. Hence, the ratio of Pin/Pref is expressed by a return loss using
equation 2.1 below or in term of as shown in equation 2.2 [12-13]. Most of the
journals related in this project [7-9] have defined -10 dB is minimum return loss to
describe the performance of the antenna.
(2.1)
(2.2)
9
2.2.2 Bandwidth
The range of operating frequency within the selected return loss or VSWR is
called the bandwidth of the antenna [1]. There are two ways to represent a bandwidth
which is for broadband antenna and narrowband antenna. For broadband antenna, the
bandwidth is defined as a ratio of the upper-to-lower frequencies of acceptable
operation. As an example, the ratio of 7:1 represents the upper frequencies is seven
times greater than the lower frequencies.
However, for a narrowband antenna, the percentages of the difference
between upper and lower frequency is used over the centre frequency. For the
narrowband application, a 5% bandwidth shows that the difference of the upper and
the lower frequency is about 5% of the centre frequency. It’s also can be calculated
by using these formulas [1]:
!"#$$%&#"' (2.3)
( !&$#&#"' (2.4)
In this project, the designed antenna is a broadband type of antenna. The
bandwidth percentage is calculated as shown in equation 2.5 [1].
( )%100% ×
×−
=lu
lu
ffff
BW (2.5)
where:
fu = upper frequency bandwidth
fl = lower frequency bandwidth
10
2.2.3 Radiation Pattern
The radiation of the antenna is defined as a representation of antenna
performances in term of mathematical and graphical function in free space
coordinates [1]. In other words, radiation pattern is about how an antenna focuses the
energy in space, which represents the coverage area of an antenna itself. The
standard spherical coordinate (r, φθ , ) system is usually used to represent field pattern
of the antenna as shown in Figure 2.4. Radiation pattern can be found in 3D and 2D
plot, but typically 3D pattern is provided by sophisticated simulation software.
However, in practical situation, to measured 3D radiation pattern need sophisticated
Anechoic Chamber and it is too expensive. Nevertheless, a 2D pattern is good
enough to analyze the pattern of the antenna.
Figure 2.1: Coordinate system for radiation pattern measurement [1]
2.2.4 Half-Power Beam
The half-power beam
value that is calculated between two angles from the main lobe [1]. In other words,
the HPBW is measured at the main beam, by calculating the angle of the gain which
has the value of the maximum value minus 3 dB
width is an important parameter for the antenna and
use it. The beam width is always used as a trade
analyze the antenna performance.
Figure 2.
2.2.5 Gain
The gain of the antenna
when the performances of
(AUT) is referred to an antenna which has a
be calculated compared to the reference antenna
antenna. The gain of an antenna
given direction between the AUT and the reference ant
Power Beam-width
power beam width (HPBW) can be defined as
that is calculated between two angles from the main lobe [1]. In other words,
he HPBW is measured at the main beam, by calculating the angle of the gain which
has the value of the maximum value minus 3 dB as shown in Figure 2.2
width is an important parameter for the antenna and is usually referred to when
The beam width is always used as a trade-off between the side lobe levels to
analyze the antenna performance.
Figure 2.2: Two-dimensional of power pattern.
of the antenna is an important parameter that will always be referred
the performances of an antenna is defined. When the antenna
(AUT) is referred to an antenna which has a certain gain value, the AUT’s gain can
be calculated compared to the reference antenna; but it depends on the reference
of an antenna can be defined as the ratio of the power gain in a
given direction between the AUT and the reference antenna with the power input for
11
half the maximum
that is calculated between two angles from the main lobe [1]. In other words,
he HPBW is measured at the main beam, by calculating the angle of the gain which
shown in Figure 2.2. The beam
is usually referred to when users
off between the side lobe levels to
dimensional of power pattern.
is an important parameter that will always be referred
the antenna is under test
certain gain value, the AUT’s gain can
pends on the reference
ratio of the power gain in a
enna with the power input for
12
both antennas are same [1]. The reference antenna could be a horn antenna, dipole
antenna or the others antenna whose the gain can be calculated. The calculation of
the gain is shown in equation 2.6 [1].
)()(
)()(
max
max antennareferenceGantennareferenceP
AUTPdBGGain ×== (2.6)
where;
Pmax (AUT) = Maximum power transmitted from the antenna
under test in watt (W)
Pmax (reference antenna) = Input power of the antenna in watt (W)
G(reference antenna) = Gain of the reference antenna
2.3 Wideband Antenna
Patch antennas suffer from narrow bandwidth which can limit their uses in
some modern wireless application; therefore there is an increasing demand for low
profile and wideband antenna for various future applications. A variety of studies
have come up with different techniques to achieve wideband operation for printed
antennas. Some of the techniques employed are changing the physical size of the
antenna, patch array technique [14], monopole [15], log-periodic technique [8],
adding the U-slot [16], shorting wall [17], folded shorting wall [18], Y-V slot [19],
and staked patch [20]. All these design have been proposed by others researchers to
achieve wide impedance bandwidths [21-25]. Since decade ago, the log periodic
antenna is a most uses by researcher to obtain wideband range referred to its
frequency independent or self-scaling of their dimensions. The log periodic antenna
also suitable for reconfigurable use since each elements of log-periodic antenna are
radiate for each frequency, so that the reconfigurable can be achieved by controlling
every single elements.
13
2.3.1 Log-Periodic Antenna
In the 1950s, antenna evolution advanced into a development of broadband
antennas that have bandwidths greater than 40:1. This antenna’s breakthrough was
referred to as frequency independent or self-scaling and they have geometries that are
specified by angles where the antennas were scaled to change their operating
frequency / bandwidth. In antenna scale modelling, the changing factor of operating
frequency or wavelength is inversely proportional with the physical size of antenna
while the characteristics of an antenna such as impedance, pattern and polarization
are invariant [26]. As an example, if the physical dimensions are reduced by a factor
of three, the performance of the antenna will remain the same if the operating
frequency is increased by a factor of three.
One of the criteria of self-scaling antenna is all the patches or radiator must
be connected with a transmission line and the signal power is connected at high-
frequency end to deliver the power to a lower frequency part. Log Periodic Antenna
is another type of a self-scaling antenna configuration, which closely parallels the
frequency independent concept introduced by DuHamel and Isbell [1, 26]. They
exhibit the same properties at frequencies f and τf. This is possible because the
structure becomes equal to itself by a scaling τ of its dimensions. The structure
works periodically and it would be frequency independent if the variation of the
electrical characteristics over a period is not too significant [3]. The limit of the
bandwidth (low-frequency and high-frequency) is determined by the largest and the
smallest dimension of the structure.
) *+,-*+,
./0,-./0, .,-.,
1,1,- (2.7)
where m = 1, 2, 3, ……
wp = width of patch
ltx = length of transmission line
lf = length of inset fed
F = frequency
14
One of the most important parameters that describe log periodic antennas in
general is the scaling factor. This scaling factor allows the antenna dimensions to
remain constant in terms of wavelength. The design principle of log-periodic
wideband antenna requires scaling the dimensions periodically so that the
performance is periodic with the logarithm of frequency. The patch length (lp), the
width (wp), the inset feed (lf) and the frequency (F) are related to the scaling factor
(τ) by equation 2.7 [26]. The condition is necessary to maintain the same impedance
and radiation characteristics over a wide range of frequencies.
2.4 Reconfigurable Antenna
Microstrip antennas have been closely investigated by researchers to explore
a new structure because of its advantages such as low fabrication cost, light weight,
low profile, conformal, and compatibility with integrated circuits devices [3, 4].
Besides that, it is 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 antenna technology needs the antenna to operate in wideband range,
has good radiation and has occasional switchable ability.
In the past few decades advance technology in microstrip antennas have been
increased especially in incorporating the active components. There has been a
dramatic increase in the awareness of reconfigurable antenna for the applications in
future wireless communication such as cognitive radio [27], ground penetrating radar
(GPR) applications [28], RFID application [29], vehicle speed test [30], secure
communication [31], smart weapon protection [32] and etc.
The advantage of frequency reconfigurable antenna is it can be reconfigured
into any frequency in wideband range and can change dynamically, either
transmitting or receiving on a single antenna instead of using multiple antennas as
usual. For radar application or smart weapon detection, it is advantageous to vary the
beam shaping functionality in that system. Besides that, the reconfigurable antenna
15
can also reduce any unfavorable effects from congested signals especially in ISM
Band (2.4 GHz and 5.8 GHz) and also caused by co-site interference and jamming
effect.
In addition, the development of reconfigurable antenna can reduce the
number or size of antenna used; hence it reduces the power usage and supports the
development of green technology. The most interesting about reconfigurable antenna
is it provides a tunable adjust of the single or more of antennas parameter such as
operating frequency as reported in [32-35], polarization [36-38], radiation pattern
[39-41], and/or two or more of parameters [42-44] in a single antenna. The block
diagram of the reconfigurable antenna is shown in Figure 2.3.
Figure 2.3: Reconfigurable antenna block diagram
Most researchers have designed the reconfigurable antenna for cognitive
radio applications. Hall P.S in [2] has reported that the cognitive radio is a wireless
transponder that has the ability to sense the environment in which it operates and can
adapt itself to optimize its operation. The system could continuously monitor the
spectrum usage in a process which runs parallel with the communication link or use a
single spectrum for spectrum sensing and communication. Therefore, the cognitive
radio system needs antenna that have wideband operation to sense a single spectrum
by reconfiguring the frequency. The reconfigurable antenna that is proposed by Hall
P.S is in one of three ways which is by (a) switching on or turning off parts of the
Antenna
Switch
RF Switch: MEMS
PIN Diode Varactor diode FET transistor
+
Operating frequency
Polarization Radiation Pattern
More than one parameter
16
antenna structures; (b) by changing the antenna geometry by mechanical/electrical
movement and (c) by adjusting the loading or matching of the antenna externally.
The first approach on designing the reconfigurable antenna may employ the
electronic, mechanical or optical switching [45]. However, the efficiency and the
reliability makes the electronic switching more frequently used compared to others.
The electronic switching includes the PIN diodes, FET transistor, varactor diodes or
RF MEMS switches. As reported in [7], the MEMS switches have advantages in
term of isolation and insertion loss compared to the PIN diodes and varactor diodes.
Meanwhile, the RF PIN diodes have low rate of loss and low cost to be employed
with reconfigurable antenna, but it needs to be connected with forward bias direct
current when in the ON state which will degrade the power efficiency and antenna’s
performance.
In [8], the frequency reconfigurability is achieved when the RF switches are
inserted with log periodic aperture fed microstrip antenna. The five bands are
selected from a wideband frequency by switching ON and OFF state at desired
patches. The polarization reconfigurable also has been presented in [36]. A square
patch with two cross-shaped diagonal slots has been designed with three types of
reconfigurable polarization which are a linear, right-handed and left handed. In [40]
the author has presented the pattern reconfigurable from a planar array microstrip
antenna with separated transmission line design.
Besides reconfiguring a single parameter of the antenna, many researchers
have designed an antenna that has more than one configurable parameter. In [42],
the author has designed an annular slot to configure two parameters which are
operating frequency and radiation pattern. By changing the matching stub, three
different frequencies can be reconfigured. The radiation pattern is reconfigured by
controlling the DC voltage of PIN diodes on the slot.
The monopole wideband antenna is also proposed for configuring purposes
[7] because of their advantages; low profile, thin and small, able to produce very
wide frequency and possessing an omni-directional pattern. The cognitive
communication system requires wideband antennas for spectrum sensing and narrow
17
band antennas for transmission which has directional radiation pattern to increase the
performance of signal detection. The development of wideband reconfigurable
antenna with directional radiation pattern has been reported in [8-9]. Furthermore,
the antenna should be well suited in terms of cost, radiation pattern, gain and ease to
integrate with switching circuits.
2.5 RF Switching
The leading technology for reconfigurable system is based on switchable
antenna elements. The reconfigurable antennas are usually equipped with switches
that are controlled by DC bias signals. The switches and the accompanying control
system are very often an integral part of the reconfigurable antenna. The switch
between on and off states of the switches the antenna can be reconfigured to support
a discrete set of operating parameters, e.g. frequency, polarization, radiation pattern.
Each reconfigurable antenna employs a distinct mechanism in order to achieve the
required reconfigurability. Electronic, mechanical or optical switching may be
employed with reconfigurable antennas. Nonetheless, electronic tunability is more
frequently used because of its efficiency and reliability especially in dynamic
bandwidth allocation.
There are various types of RF switches use for reconfigurable antenna such
as RF MEMS, PIN diode and FET transistor where all these types have their own
advantages and disadvantages. As reported in [7], RF MEMS switches have better
performance in terms of isolation, insertion loss, power consumption and linearity
compared to PIN diodes or FET transistors. However, the PIN diode has widely used
by reconfigurable researchers included for this research because of low cost and easy
to fabricate. Besides that, the circuit representations of PIN diodes in simulation also
has presented in [46] where that’s circuit can be used in CST software tools to
compare the antenna’s performances with measurement.
2.5.1 PIN Diode Switch
This research has used a RF PIN diode as a switch component to tune the
reconfigurable antenna because it is a low
This sub-chapter will discuss the overview of RF PIN diode switch and its equivalent
circuit modeling. A microwave PIN diode is a semiconductor device that operates as
a variable resistor at RF and microwave frequency while
component for opening and closing the connection of a circuit or for changing the
connection of a circuit device [47
resistance to current flow in ON state while infinite resistance
Figure 2.4 shows the cross section of a PIN diode which consist of p
semiconductor, n-type semiconductor and intrinsic layer at the middle while metal
pin and glass acts as jacket to cover the PIN diode. The operation of PIN diode ca
be imagined by filling up a water bucket with a hole on the side. The water will
begin pour out when it reaches the hole. Electrically speaking, once the number of
electrons and the number of hole in intrinsic region is equal, the current will be
conducted by the diode since the flooded electrons and holes reaches an equilibrium
point.
When the diode is forward biased, holes and electrons are injected into the I
region. This charge does not recombine ins
in the intrinsic layer. While
behaves like a Capacitance (C
diode in reverse biased [47
biased are discuss in sub
PIN Diode Switch
This research has used a RF PIN diode as a switch component to tune the
reconfigurable antenna because it is a low-cost component and easy
chapter will discuss the overview of RF PIN diode switch and its equivalent
circuit modeling. A microwave PIN diode is a semiconductor device that operates as
a variable resistor at RF and microwave frequency while the switch is an electrical
component for opening and closing the connection of a circuit or for changing the
nnection of a circuit device [47]. Ideally, the function of switch needs zero
resistance to current flow in ON state while infinite resistance in OFF state.
Figure 2.4 shows the cross section of a PIN diode which consist of p
type semiconductor and intrinsic layer at the middle while metal
pin and glass acts as jacket to cover the PIN diode. The operation of PIN diode ca
be imagined by filling up a water bucket with a hole on the side. The water will
begin pour out when it reaches the hole. Electrically speaking, once the number of
electrons and the number of hole in intrinsic region is equal, the current will be
ed by the diode since the flooded electrons and holes reaches an equilibrium
Figure 2.4: Cross section diagram of PIN diode
When the diode is forward biased, holes and electrons are injected into the I
region. This charge does not recombine instantaneously, but has a finite lifetime (
intrinsic layer. While there is no stored charge in the I-region and the device
behaves like a Capacitance (CT) shunted by a parallel resistance (R
diode in reverse biased [47]. The equivalent circuit based on forward and reverse
biased are discuss in sub-section below.
18
This research has used a RF PIN diode as a switch component to tune the
component and easy-to-fabricate.
chapter will discuss the overview of RF PIN diode switch and its equivalent
circuit modeling. A microwave PIN diode is a semiconductor device that operates as
the switch is an electrical
component for opening and closing the connection of a circuit or for changing the
]. Ideally, the function of switch needs zero
in OFF state.
Figure 2.4 shows the cross section of a PIN diode which consist of p-type
type semiconductor and intrinsic layer at the middle while metal
pin and glass acts as jacket to cover the PIN diode. The operation of PIN diode can
be imagined by filling up a water bucket with a hole on the side. The water will
begin pour out when it reaches the hole. Electrically speaking, once the number of
electrons and the number of hole in intrinsic region is equal, the current will be
ed by the diode since the flooded electrons and holes reaches an equilibrium
Cross section diagram of PIN diode
When the diode is forward biased, holes and electrons are injected into the I-
tantaneously, but has a finite lifetime ( τ )
region and the device
) shunted by a parallel resistance (RP) when the PIN
lent circuit based on forward and reverse
19
2.5.2 PIN Diode Equivalent Circuit Modeling
The equivalent circuit modeling for PIN diode based on Microsemi [47] is
shown in Figure 2.5. The equivalent circuit for forward biased consist of a series
combination of the series resistance (RS) and a small Inductance (LS) as shown in
Figure 2.5 (a). Series resistance is a function of the forward bias current (If) and this
function can be found in PIN diode datasheet in Appendix B while the small
inductance depends on the geometrical properties of the package such as metal pin
length and diameter. Figure 2.5 (b) shows the equivalent circuit for PIN diode when
reverse biased that consist of the PIN diode Capacitance (CT), a shunt loss element
(RP), and the parasitic inductance (LS).
(a) (b)
Figure 2.5: (a) Equivalent circuit for forward biased (b) Equivalent circuit for
reverse biased
The PIN diode equivalent circuit is an important part in simulation of
reconfigurable antenna to get a result similar to the measurement result. There are
many papers or journals that describe the parameter value of the equivalent circuit by
using appropriate software. In [46], the author has predicted the value of parameter
PIN diode equivalent circuit based on the through-delay-line de-embedding using
Agilent Advanced Design System (ADS) as shown in Figure 2.6 and Table 2.1. The
author has used a micro-semi MPP4203 PIN diode that can operate from 1 to 6 GHz
frequency.
20
Figure 2.6: Equivalent circuit for a PIN diode [46]
Table 2.1: Parameters value of equivalent circuits for PIN Diodes [46]
PIN Diode state Parameter
L (nH) R(ohm) C (pF)
ON 0.45 3.5 -
OFF 0.45 3K 0.08
A. Mikarmali in [9] also proposed that the equivalent circuit for PIN diode is
the same as Figure 2.5 for his proposed antenna. The values of parameters are: L=
0.6nH, RS = RP = 15Kohm and CT= 0.3 pF. After modeling the PIN diode in a
simulation process, the biasing network is designed to supply the specific bias
voltage and current to the PIN diode in fabrication process. The bias networks are
discussed in the following sub-section.
2.5.3 Biasing Circuit
Bias networks are important devices in any active microstrip circuit to supply
the specific bias voltage and current. The bias network can be realized in lumped
form with lumped inductances and capacitances as distributed network [48].
(a) Series Single Pole Single Throw Switches
An example of a simple circuit diagram of series single pole single throw
switches consists of two capacitors and two inductors as shown in Figure 2.7. The
input DC is connected at the positive terminal of PIN diode while the negative
terminal is connected with the ground. When the RF device is connected with direct
current (DC), the present low frequency from DC must be considered in order to
21
prevent signal from DC (low frequency) being interrupted by RF part (high
frequency). It needs the DC to be blocked to avoid DC signal going to RF signal and
RF chock to evade RF signal goes to DC signal. The estimation value of inductor (L)
as a RF chock and capacitor © as a DC block can be made by using equation 2.9 and
2.10 below [13].
23 45 (2.9)
26 76 (2.10)
Where ZL = Inductive resistance (ohm)
ZC = Capacitive resistance (ohm)
L = Inductor (H)
C = Capacitor (F)
f = frequency (Hz)
The DC source that is used in Figure 2.7 is 6 volts with 50 Hz frequency. The
value of inductive resistance (ZL) must be low to allow DC current to pass through
and activate the PIN diode. At point A, the DC signals cannot pass through the
capacitor since the capacitive resistance (ZC) is very high and it has become a DC
open circuit. By viewing from RF signal source that has high frequency, the value of
ZC must be low or become RF short circuit to allow RF signal to pass through the
capacitor from port 1 and forbid the DC signal from going through the Inductor since
it has very high ZL and looks like an open circuit. Table 2.2 shows the realization
about the circuit representation of inductor and capacitor for DC and RF signal.
Table 2.2: Lumped element’s representation in low and high frequency
Inductor (L) Capacitor (C)
DC (low frequency) Short Open
RF (high frequency) Open Short
22
Figure 2.7: Schematic design of Series SPST Switch
(b) Radial Line Stub
Bias networks are important devices in any active microstrip circuit and can
be found in amplifiers, oscillators and frequency multipliers. Radial stubs provide a
well-defined point for radial wave excitation due to their narrow coupling aperture
[48]. Figure 2.8 shows the example of radial line stub that be used as bias network
for biasing a PIN diode. In [49], the author has proposed the radial stubs that can be
operated on broadband to be applied to active devices that operates more than 100
MHz. A bias network consists of a capacitor that acts as a DC block and RF bias line
with radial stub to form a low pass filter in point A. At this point, only a low
frequency from DC source is passing through to activate the PIN diode while it is
blocked by capacitor from interrupting the RF source.
V_DCSRC1Vdc=6 V
LL1
R=L=0.6 nH
LL2
R=L=0.6 nH
CC2C=0.3 pF
CC1C=0.3 pF
PortP2Num=2
PortP1Num=1
DiodeDIODE1
Mode=nonlinearTrise=Temp=Region=Scale=Periph=Area=Model=
A
Figure 2.
2.6 Previous Related Research
The study on reconfigurable antennas has
year by many researchers. Many types and designs of reconfigurable antenna have
been achieved to improve their performance in diversity of frequency, polarization
and radiation pattern. This sub
reconfigurable antenna from a decade ago up until the latest development. Three
parts have been divided to clarify the related work that has been done by previous
researcher in the development of log
periodic antenna and other development of reconfigurable antenna using electronic
devices.
2.6.1 The Log-Periodic Antenna Development
The development of log
pioneered by some researchers in
that, the development of log
increased rapidly. In [51
element patches using log
antenna is designed using the finite
DC block
PIN diode
Figure 2.8: Bias network configuration using radial line stub
Previous Related Research
The study on reconfigurable antennas has received great attention in recent
year by many researchers. Many types and designs of reconfigurable antenna have
been achieved to improve their performance in diversity of frequency, polarization
and radiation pattern. This sub-topic has discussed about the development of the
reconfigurable antenna from a decade ago up until the latest development. Three
parts have been divided to clarify the related work that has been done by previous
researcher in the development of log-periodic antenna, the reconfigur
periodic antenna and other development of reconfigurable antenna using electronic
Periodic Antenna Development
The development of log-periodic antenna for broadband application has been
pioneered by some researchers in University of Illinois, USA in 1955 [50
that, the development of log-periodic antenna to improve the bandwid
increased rapidly. In [51], the author has designed a wideband antenna using nine
element patches using log-periodic slotted configuration as shown in Figure 2.9. This
antenna is designed using the finite- difference time domain method (FDTD) and
λ/4
λ/4
Bias DC source DC block
PIN diode
RF line Radial stub
A
RF source
23
Bias network configuration using radial line stub
received great attention in recent
year by many researchers. Many types and designs of reconfigurable antenna have
been achieved to improve their performance in diversity of frequency, polarization
the development of the
reconfigurable antenna from a decade ago up until the latest development. Three
parts have been divided to clarify the related work that has been done by previous
periodic antenna, the reconfigurable log-
periodic antenna and other development of reconfigurable antenna using electronic
periodic antenna for broadband application has been
in 1955 [50]. After
periodic antenna to improve the bandwidth has
has designed a wideband antenna using nine-
periodic slotted configuration as shown in Figure 2.9. This
difference time domain method (FDTD) and
24
compared with fabricated results. The result of VSWR between simulated and
measured is shown in Figure 2.10 below. The scaling factor for this antenna is 1.05
and it is designed for frequency range 8-12 GHz which suitable for Ku-band
application. Compared to the antenna design in this project which uses an inset fed
line, this antenna is used a slotted transmission line underneath a layer of substrate.
Figure 2.9: Log-Periodic Slot Antenna Array structure [51]
Figure 2.10: VSWR of Log-Periodic Slot Antenna Array. (Line - measured, dotted
line - computed) [51]
25
The development of log-periodic dipole antenna for UHF application has
been proposed by the authors in [52]. The fractal Koch design was introduced by the
authors to reduce the overall size of the antenna as shown in Figure 2.11. The
antenna was fabricated on FR-4 board where both arms were fabricated on both sides
of substrate. The same idea with the log-periodic patch antenna in this project was by
applying the log-periodic concept to provide the wideband operation. The scaling
factor of this antenna is 1.17 and this antenna can operates from 0.5 GHz to 4.0 GHz
as shown in Figure 2.12.
Figure 2.11: Log-periodic Dipole Fractal Koch Antenna design [52]
Figure 2.12: Return loss of Log-periodic Dipole Fractal Koch Antenna [52]
26
The development of log-periodic antenna for wideband operation is continued
by A. Scheuring in [53]. They have proposed the theoretical and analytical
calculation of log-periodic design in Terahertz operation as shown in Figure 2.13.
They have claimed that the Terahertz operation could be applied for radio astronomy,
spectroscopy and civil security. The proposed antenna composes of six arm log-
periodic dipole antenna that can operate from 2.0 THz until 4 THz as shown in
Figure 2.14. However, for measurement process the authors have developed a large-
scale antenna that operates at Gigahertz operation due to limitation of equipments.
Figure 2.13: The structure of Log-Periodic Terahertz Antenna [53]
Figure 2.14: The simulated return loss of Log-Periodic Terahertz Antenna [53]
27
2.6.2 The Reconfigurable Log-Periodic Antenna Development
A novel reconfigurable low profile log periodic patch array is proposed in [8].
The patches are fed with a modulated meander line through aperture slots. A
wideband mode from 7–10 GHz and three selected narrow band modes at 7.1, 8.2,
and 9.4 GHz are demonstrated. The wideband to narrow band reconfiguration is
realised by bridging the slot aperture, effectively deactivating the corresponding
radiating element. Potentially the proposed method offers a very fine control of a
narrow pass band. The configurability is done by switching off the patch by bridging
the aperture slot. An almost identical measured and simulated result is presented,
thus verifying the proposed concept.
Figure 2.15: Proposed prototype antenna [8]
(a) (b)
Figure 2.16: Measured (a) S-parameter in dB of wideband log periodic antenna and
(b) Efficiency of reconfigurable antenna [8]
28
In [10], the authors have designed a planar log-periodic dipole array that can
be operated from 1 GHz to 4 GHz. The prototype dipole antenna is fabricated on
R04003C substrate where an arm is located on both sides. The PIN diodes switch is
used at both arms for configuration purposes. So, for a single frequency to
reconfigure, two switches are needed for both arms. Hence, this design use a larger
number of PIN diodes for wideband reconfigurable antenna design compared to the
proposed antenna in this thesis.
(a) (b)
Figure 2.17: The structure of reconfigurable LPDA (a) the schematic design and (b)
fabricated proposed antenna [10]
(a) (b)
Figure 2.18: a) Simulated and b) measured return loss response of the reconfigurable
LPDA [10]
29
The authors in [9] proposed a reconfigurable wideband dipole antenna with
the harmonic trap as shown in Figure 2.19. The harmonic trap is used to eliminate
higher order frequency modes to obtain a smooth wideband frequency operation. The
wideband frequency operation is obtained when eight dipoles are arranged in log-
period array formation. Then, the PIN diodes are connected at every single arm and
harmonic traps tune the frequency from wideband to narrowband. Hence, the biggest
number of PIN diode is need for biggest number of dipole.
Figure 2.19: Schematic design of reconfigurable log-periodic dipole antenna with
harmonic trap [9].
The frequency reconfigurable is obtained by switching the PIN diode to ON
or OFF mode to allow certain desired dipole to radiate. The bandwidth of 1:3 is
achieved when all PIN diode is switched to ON mode and three sub bands are
achieved by selecting several groups oh PIN diodes. The measure return loss of the
antenna is shown in Figure 2.20. This design requires large number of PIN diode for
reconfigurable purposes compared to the RLPA design in this project. The largest
number of PIN diode will degrade the performances of antenna. However, a narrow
band could be obtained over a wideband frequency by selecting a group of radiating
elements which is the same idea with the RLPA.
30
Figure 2.20: Measured return loss of reconfigurable log-periodic dipole antenna [9].
2.6.3 Others Development of Reconfigurable Antenna
A pattern and frequency reconfigurable of annular slot antenna has been
proposed by the authors in [42]. The authors have fabricated the antenna on Duroid
substrate while the configurability has been done by using the PIN diode switch. The
antenna consist of a ring slot antenna acting as radiating element while the
transmission line, matching and biasing network was fabricated on another side of
substrate as shown in Figure 2.21. For this antenna, the radial stub and DC line was
used as the biasing network of PIN diode; same as to the RLPA design.
The matching stub was connected to the PIN diode to provide the frequency
reconfigurability by switching ON and OFF. The antenna can operates at 5.2 GHz,
5.8 GHz and 6.4 GHz as shown in Figure 2.22. In order to reconfigure the radiation
pattern, the PIN diode is used to short the annular slot antenna in preselected
positions along the circumference [42]. Hence, it will change the null at the pattern to
provide the tunable pattern.
31
Figure 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 [42]
Figure 2.22: Simulated and measurement result of reconfigurable annular slot
antenna at three different frequency [42].
32
(a) (b)
Figure 2.23: Radiation pattern of the reconfigurable annular slot antenna (a)
Simulation (b) Measurement [42].
The frequency reconfigurable using wideband monopole antenna has been
proposed in [7] as shown in Figure 2.24. The U-slot fractal Koch is located at the
middle of the antenna to increase the antenna's electrical length for operation at lower
frequency bands [7]. Without increasing the antenna dimension, this technique will
increase the resonance at a lower frequency. The partial ground plane at the back of
the antenna is function to obtain a wideband operation from 2.5 GHz until 6.7 GHz.
This antenna has used a metal bridge to operate as a RF switch in simulation process.
The frequency reconfigurability is obtained when the RF switch is connected at the
slot by switching ON and OFF state at certain group of RF switch as shown in Table
2.3 below.
Table 2.3: The switches' states of U-Koch reconfigurable microstrip antenna [7]
33
Figure 2.24: The structure of U-Koch reconfigurable microstrip antenna [7]
Figure 2.25: The measured return loss of U-Koch reconfigurable microstrip antenna
[7]
The vivaldi antenna was proposed by the authors in [11] to perform a
wideband operation from 2 GHz until 8 GHz. The antenna was fabricated on Taconic
TLY-5 substrate. The Vivaldi antenna that proposed by the authors have a dimension
of an elliptical shape of tappered slot with horizontal radius 20 mm and vertical
radius of 40 mm. The antenna also consist of 2.3mm radius of circular slot stubs
located at the centre of Vivaldi antenna as shown in Figure 2.26. The antenna was
34
fed by a transmission line and terminated with a quarter circle at the end of
transmission line.
(a) (b) (c)
Figure 2.26: Geometry of the reconfigurable Vivaldi antenna: (a) top view, (b) side
view, and (c) bottom view. [11]
In order to perform a frequency reconfigurability, the antenna is integrated
with ring slots to act as a band stop. Hence, several sub-band frequency could be
obtained from wide band operations by connected or disconnected all these ring
slots. The authors was selected three sub-bands which is high band (7.5 GHz), mid
band (5.0 GHz) and low band (2.5 GHz). The measured return loss can be referred to
in Figure 2.27. The similarities of this antenna with RLPA is the frequency selection
from a wideband operation to a narrow band operations. The authors also used a
metal bridge to perform as an ideal PIN diode in simulation process.
Figure 2.27: Measured return loss of reconfigurable Vivaldi antenna for wideband
and sub-band operation [11]
35
Tab
le 2.4
Pre
viou
s re
sear
ches
on
reco
nfig
urab
le a
nten
na
No
Title / Autho
rs
Recon
figu
rable
Typ
es of
Antenna
Ban
dwidth
Gain
Implem
entation
with real
switch
ing
1 Fr
eque
ncy
Rec
onfi
gura
ble
Log
Peri
odic
Pat
ch A
rray
[8]
Freq
uenc
y L
og-P
erio
dic
7-10
GH
z 9-
16 d
Bi
No/
Usi
ng id
eal
case
2 T
he D
esig
n of
Rec
onfi
gura
ble
Plan
ar L
og-P
erio
dic
Dip
ole
Arr
ay
Usi
ng S
witc
hing
Ele
men
ts [1
0]
Freq
uenc
y L
og-P
erio
dic
1-4
GH
z 7-
8 dB
i N
o/U
sing
idea
l
case
3 W
ideb
and
Freq
uenc
y
Rec
onfi
gura
tion
of a
Pri
nted
Log
-
Peri
odic
Dip
ole
Arr
ay [9
]
Freq
uenc
y L
og-P
erio
dic
0.7-
2.7
GH
z N
ot s
tate
d N
o/U
sing
idea
l
case
4 Pa
ttern
and
Fre
quen
cy
Rec
onfi
gura
ble
Ann
ular
Slo
t
Ant
enna
Usi
ng P
IN D
iode
s [4
2]
Freq
uenc
y an
d
Rad
iatio
n
patte
rn
Ann
ular
slo
t
ante
nna
5.2-
6.4
GH
z N
ot s
tate
d Y
es b
y us
ing
PIN
diod
es
5 A
Rec
onfi
gura
ble
U-K
och
Mic
rost
rip
Ant
enna
For
Wir
eles
s
App
licat
ions
[7]
Freq
uenc
y M
onop
ole
Ant
enna
2.4-
6.7
GH
z 5-
6 dB
i Y
es b
y us
ing
RF
ME
MS
36
6 R
econ
figu
rabl
e V
ival
di A
nten
na
[46]
Freq
uenc
y V
ival
di A
nten
na
2-8
GH
z 1.
14-6
.64
dBi
Usi
ng id
eal c
ase
7 Fr
eque
ncy
tuna
ble
mon
opol
e
coup
led
loop
ant
enna
with
broa
dsid
e ra
diat
ion
patte
rn [1
1]
Freq
uenc
y M
onop
ole
Ant
enna
470-
702
MH
z 2.
8 dB
i Y
es b
y us
ing
vara
ctor
dio
de
8 R
econ
figu
rabl
e W
ideb
and
Patc
h
Ant
enna
for C
ogni
tive
Rad
io [1
4]
Freq
uenc
y A
rray
Ant
enna
5-
7 G
Hz
5-8
dBi
Usi
ng P
IN d
iode
37
2.7 Summary
In conclusion, this chapter has explained literature regarding the log-periodic
antenna and the reconfigurable antenna. The basics of the antenna properties such as
radiation pattern, bandwidth, gain and HPBW have also been elaborated. 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. Finally, overviews of the previous works have been
presented and discussed in this chapter.
CHAPTER 3
LOG-PERIODIC ANTENNA DESIGN
3.1 Introductions
This chapter presents a project methodology, the steps of designing,
simulation and fabrication of Log-Periodic Wideband Antenna. The project
methodology of reconfigurable antenna is discussed at Chapter 4. The theory of log-
periodic antenna and wideband antenna design has been discussed in Chapter 2. The
antenna is designed from the development of single patch antenna by numerical
method and verified by simulation using Computer Simulation Technology (CST)
software. Then, the antenna is fabricated on FR-4 substrate using wet etching
technique. The parametric study on varying the parameters of antenna is also
discussed in this chapter. This chapter also included the overall designing process of
both log-periodic antenna and its reconfigurable antenna as Figure 3.1 shows the
flow chart of overall project.
39
Start
Literature review on
wideband and
reconfigurable antenna
Design wideband log-
periodic antenna using
CST Software
Desired
result?
Design a lumped element
circuit to represent RF
PIN Diode using CST
Software
Yes
No
A
Simulate RLPA
with PIN Diode
using CST software
Desired
result?
Yes
No
Theoretical calculation
on antenna design
Antenna fabrication
process
Return Loss
measurement
Radiation pattern and
gain measurement
Result analysis and
documentation
End
Yes
40
Figure 3.1 Flow chart of overall process including log-periodic antenna and
reconfigurable antenna
Return Loss
measurement
Radiation pattern and
gain measurement
Result analysis and
documentation
End
A
Antenna Fabrication
Process
Soldering PIN Diode
and lumped component
to the antenna
Testing the antenna
with switching board
and power supply
Antenna’s
working?
?
Yes
No
41
3.2 Project Methodology and Flow Chart of Log-Periodic Antenna Design
The methodology for this part focuses for log-periodic wideband antenna
(LPA) as shown in Figure 3.2. The design methodology for Reconfigurable Log-
Periodic Antenna (RLPA) will be discussed in the next chapter. The methodology of
this part begins with understanding the antenna parameter such as return loss,
radiation pattern, bandwidth and half-power beamwidth (HPBW). Besides, a
literature review of log-periodic antenna is also studied before proceeding to the next
step. After understanding the concept of log-periodic antenna, a single patch antenna
with inset feed technique is designed using Computer Simulation Technology (CST)
software.
The parameters of the antennas are calculated using appropriate equations
that can be obtained in [3-4]. From this single patch antenna, all the parameters are
scaled up with scaling factor (τ) to obtain wide band antenna. The antenna
parameters such as return loss, input impedance, current distribution and radiation
pattern are observed. For RLPA, the switching circuit for active components was
also designed and simulated. This step will be discussed in Chapter 4.
Then, the fabrication process is done using wet etching technique. The
antenna is fabricated on Flame Retardant 4 (FR4) laminate board with dielectric
constant, εr is 4.5 and loss tangent, tan δ is 0.019. Others equipment such as UV unit,
transparency, etching chemical and ferric chloride acid were used during the
fabrication process. In this situation, the etching room needs to be in a dark condition
to make sure that the laminated board is not exposed to UV light. After the
fabrication process, the SMA port is attached to the antenna.
The measurement process such as return loss, received gain and radiation
pattern was done using network analyzer and anechoic chamber. The network
analyser needs to be calibrated before measuring process is done to make sure that
the measured result is accurate. Finally, both simulated and measured results is
compared and analyzed for documentation.
42
Figure 3.2 Flow chart of research methodology for LPA
Start
Literature review on
log-periodic antenna
Design wideband
log-periodic antenna
using CST Software /
optimization
Desired
result?
Antenna fabrication
process
Return Loss
measurement
Radiation pattern and
gain measurement
Result analysis and
documentation
End
A
Yes
No
Design a single patch
using inset feed line
technique
A
43
3.3 Single Patch Antenna Design
The square patch antenna is the basic and the most commonly used for
microstrip antenna. This patch can be used for the simplest and the most demanding
applications. The sizes calculation of square patch is easier rather than other
dimension since the length and width of the antenna are same. The single patch
microstrip antenna as shown in Figure 3.3 has been designed using CST software.
The antenna is fabricated on FR4 board with the relative dielectric constant, r = 4.5,
substrate thickness of 1.6 mm with tangential loss of 0.019.
An inset feed technique is applied in this antenna design to obtain maximum
input impedance matching. The dimension of single patch after optimization is 23
mm and inset fed length is 8.2 mm with optimum area of substrate is 40x40 mm2
where operates at 3.0 GHz. The magnitude of the back lobe can be reduced while it
increased the gain of the antenna by increasing the sizes of ground plane. The
dimension of square patch can be calculated using equations 3.1 until 3.4 below [3-
4].
The type of feeding technique that will be used is the inset feed technique. It
is one of the easiest feeding techniques and it is also easy to control the input
impedance of the antenna. From figure 2.2 (b), the input impedance level of the patch
can be control by adjusting the length of the inset. The calculation of the inset fed is
shown in the equations 3.5 which show the resonant input resistance for the
microstrip patch. L is the length of the patch, lf is the length of the inset, G1 is the
conductance of the microstrip radiator and G12 is the mutual conductance between
the two slots. The conductance of the radiator is calculated using equation 3.6 and
3.7 while the current excited into the microstrip patch, I1 is calculated using equation
3.8. However, the simplest calculation for finding the inset length is proposed in [21]
as shown in the equation 3.9. This equation is valid for dielectric constant, εr from 2
to 10.
44
Figure 3.3 Simulated design of square patch antennas
𝑊 = 𝑐
2𝑓𝑟
2
𝜀𝑟 + 1 (3.1)
𝐿 =𝑐
2𝑓𝑟 𝜀𝑒𝑓𝑓− 2∆𝐿 (3.2)
𝜀𝑒𝑓𝑓 = 𝜀𝑟 + 1
2 +
𝜀𝑟 − 1
2 1 + 12
𝑊 −
12 (3.3)
∆𝐿 = 0.412 𝜀𝑒𝑓𝑓 + 0.3
𝑊
+ 0.264
𝜀𝑒𝑓𝑓 − 0.258 𝑊
+ 0.8 (3.4)
𝑅𝑖𝑛 𝑦 = 𝑙𝑓 =1
2(𝐺1±𝐺12 )𝑐𝑜𝑠2
𝜋
𝐿𝑙𝑓 (3.5)
𝐺1 =𝐼1
120𝜋2 (3.6)
L
L
lf
45
𝐼1 = sin
𝑘0
2 cos𝜃
cos 𝜃
2
𝑠𝑖𝑛3𝜋
0
𝜃 𝑑𝜃 (3.7)
𝐺12 =1
120𝜋2
sin 𝑘0𝑊
2 cos 𝜃
cos𝜃
2
𝐽0 𝑘0𝐿 sin𝜃 𝑠𝑖𝑛3𝜋
0
𝜃 𝑑𝜃 (3.8)
𝑙𝑓 = 10−4 0.001699𝜀𝑟7 + 0.13761𝜀𝑟
6 − 6.1783𝜀𝑟5 + 93.187𝜀𝑟
4 − 682.69𝜀𝑟3
+ 62561.9𝜀𝑟2 − 4043𝜀𝑟 + 6697
𝐿
2 (3.9)
Where:
c = speed of light =3x108 m/s
fr = operating frequency
𝜀𝑟 = permittivity of the dielectric
𝜀𝑒𝑓𝑓= effective permittivity
W = patch width
h = thickness of the dielectric
lf = inset fed length
Rin = input impedance
Figure 3.4 shows the input return loss (S11) for single patch antenna at 3.0
GHz. Input return loss requires the lowest value to make sure the maximum power
reflected back is only 10%. The graph reveals that the return loss for this antenna is -
28 dB or 0.2 % power is reflected back. The simple calculation for return loss
conversion is shown as below:
20 log𝛤 = −27 𝑑𝐵
𝛤 = 𝑎𝑛𝑡𝑖𝑙𝑜𝑔 −27
20 = 0.04467
𝑅𝑒𝑓𝑙𝑒𝑐𝑡𝑒𝑑 𝑃𝑜𝑤𝑒𝑟 𝑖𝑛 % = 0.044672 x 100%
𝑅𝑒𝑓𝑙𝑒𝑐𝑡𝑒𝑑 𝑃𝑜𝑤𝑒𝑟 𝑖𝑛 % = 0.2 %
46
Figure 3.4 Return loss of single patch antenna
The 3-D view of the radiation pattern of square patch antenna is shown in
Figure 3.5 where the value of realized gain is 3.139 dB and the total efficiency is -
3.022 dB or around 50 %. The high value of substrate’s tangential loss is possible
factor of degradation of directivity value. Figure 3.6 (a) shows the polar plot of the
radiation pattern in E-plane with 97.1O of 3 dB beam-width while Figure 3.6 (b)
shows the H-plane of the radiation pattern where the 3 dB beam-width approximately
similar value to the E-plane.
Figure 3.5 3-D view radiation pattern of single patch antenna at 3.0 GHz
47
a)
b)
Figure 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
and phi setup in simulation.
48
3.4 The Design of Log-Periodic Wideband Antenna
The design of LPA is based on a log-periodic structure that is elaborated in
Chapter 2.3. The geometrical structure and detail dimensions of the proposed LPA
structure is shown in Figure 3.7. There are thirteen square patches with inset fed line
which is connected with a log-periodic array formation to a 50 ohm transmission
line in a top layer of substrate. The antenna structure is constructed on a 1.6 mm
thickness of FR-4 substrate which has relative permittivity (εr) of 4.5 and loss
tangent (tan δ) of 0.019. This antenna structure is designed and the performances are
simulated by using Computer Simulation Technology (CST) software and compared
with measured results.
The antenna is designed for frequency reconfigurability and it needs a
wideband frequency range. However, the limitation of this project is the
performances of PIN diode that will be used. The PIN diode Infenion BAR64-02
only can operate with frequencies below 6 GHz. When that frequency is exceeded,
the isolation (S21) of PIN diode is very high and it will effect to the performance of
the antenna. Hence, the antenna is designed for frequency range up to 6 GHz and
the low frequency for the range is decided to limit the bandwidth of the antenna.
The broader bandwidth causes the increase of antenna size. The gain of the log-
periodic antenna is based on the gain of single patch antenna since the log-periodic
antenna allows a single patch radiated in a single frequency. Hence, the gain of the
log-periodic antenna is nearly same with a single antenna. The design descriptions
of this antenna are shown in Table 3.1.
Table 3.1: Design description of log-periodic antenna
Parameter Value
Operating frequency up to 6 GHz
Bandwidth > 70 %
Gain 6-8 dBi
Radiation pattern Directional
Polarization Linear
49
Figure 3.7: Layout of Log-Periodic Antenna
The design principle for log-periodic wideband antenna requires scaling of
dimensions from period to period so that the performance is periodic with the
logarithm of frequency. The patch length (lp), the width (wp) and the inset feed (I)
are related to the scaling factor (τ) by equation 2.6 in Chapter 2. The dimension of
the first patch (higher frequency) is 11.70 mm x 11.70 mm. The space between each
patch is half wavelength apart thus reducing mutual coupling effect. The dimensions
of proposed antenna are as follows: width of patch, wp =11.7mm, inset feed length, lf
=7.7 mm, distance between the patch, Sa = 11.5 mm (all dimension for smaller
patch), length of transmission line, ltx =208 mm, width of substrate, ws = 230 mm,
length of substrate ls =100 mm, thickness of substrate h = 1.6 mm. Figure 3.8 and
table 3.2 shows the dimensions of log-periodic antenna for each patches.
50
Figure 3.8: Dimension of Log-Periodic Antenna
Table 3.2 LPA dimension for each patch.
Patch Antenna Parameter
Patch Size (wp)
in millimeter
(mm)
Inset feed line
(lf) in millimeter
(mm)
Distance
between patch
(Sa) in mm
Frequency in
GigaHertz
(GHz)
1 11.7 4.17 11.5 6.00
2 12.37 4.41 12.85 5.68
3 13.07 4.66 13.58 5.37
4 13.82 4.93 14.35 5.08
5 14.60 5.21 15.17 4.81
6 15.44 5.50 16.04 4.55
7 16.32 5.81 16.95 4.30
8 17.25 6.15 17.92 4.07
9 18.23 6.50 18.94 3.85
10 19.27 6.87 20.02 3.64
11 20.37 7.26 21.16 3.45
12 21.53 7.67 22.37 3.26
13 22.76 8.11 23.64 3.05
51
3.5 Parametric Study of Log-Periodic Antenna
In this section, the parametric studies have been done by adjusting the value
of Tau factor (τ), distance adjacent patch (Sa) and the length of inset feed line (lf).
Even the calculation method has been done to obtain the dimensions of the antenna
(using equation 3.1- 3.9), the parametric study is also used to obtain optimum results
of wideband operation. The parametric studies have been done by using “Parameter
Sweep” function in CST simulation software.
3.5.1 Simulation on Different Distance of Adjacent Patch (Sa)
From the literature review, the distance between two adjacent patches is an
important criteria to obtain good antenna performance. The distance between the
patch will affect the radiation pattern due to the mutual coupling effect. For a normal
patch such as rectangular or square patch, the suitable distance between two patches
is larger than λ/2 of the patch to give a forward fire radiation pattern in addition to
reducing the mutual coupling effect. However, the trade-off of the larger distance is
the increasing size of the antenna.
In the log-periodic case, the sizes of the patches are different as the sizes of
patches are scaled up from the based patches. Therefore, the mutual coupling effect
is low compared to when using a same patch size. However, this situation does not
mean that the distance of adjacent patch can be ignored. The optimum distance could
give better performance in terms of return loss, efficiency and the radiation pattern.
Hence, for this antenna, the parametric study on varying the value of distance
between adjacent patch (Sa) is studied. The value varies from 10.5 mm until 12.5 mm
at the first two patches while the rest is scaled up by factor.
Figure 3.9 and Table 3.3 shows the result of return loss after varying the
parameters. From the result, it revealed that the distance of adjacent patches
significantly affects the input return loss and the bandwidth. The best bandwidth is
achieved when the distance of adjacent patch is 11.5 mm which is 63.14% or from
3.32 GHz to 6.18 GHz while the rest value gives a bandwidth below than 60%.
52
Further analysis shows that when the value of adjacent patch is increased, the total
length of transmission line and the size of the antenna also increased, leading to a
decrease in the efficiency of the antenna. Among the five values that have been
simulated, the distance 11.5 mm between adjacent patches is chosen to use as the
final simulation because it give a wider bandwidth.
Figure 3.9: Result of varying distance of adjacent patch (Sa)
Table 3.3: Result of varying the adjacent patch
Distance of
Adjacent Patch,
Sa (mm)
Low Frequency,
fL (GHz)
High Frequency,
fH (GHz)
Bandwidth (%)
10.5 3.76 5.1 30.60%
11.0 3.42 6.21 59.80%
11.5 3.32 6.18 63.14%
12.0 3.08 5.21 53.17%
12.5 3.07 5.13 51.91%
53
3.5.2 Simulation on Different Length of Inset Feed Line
The inset fed line is a feeding technique that is used in designing the antenna.
It is a simple technique rather than coaxial fed or aperture slot because the
transmission line is fed to the antenna on the same plane to obtain the maximum
matching network. The calculation of inset fed line using equation 3.5 has been done
to obtain the return loss for a single patch antenna. For log-periodic array antenna
that uses an inset feed line as a feeding technique, the optimization is used to get a
good return loss. The value of inset feed line varies from 4.0 mm to 4.3 mm on the
first patch while the other patches is scaled up by factor.
The result of return loss after varying the inset feed line is presented in Figure
3.10 and Table 3.4 shows the summarized result. After optimizing the value from 4.0
mm to 4.3 mm, the return loss and the bandwidth of the antenna does not change
significantly. The bandwidth of the antenna is about 63% after varying the parameter
value. However, a wider bandwidth below -10 dB return loss occurs when the length
of inset feed line is 4.17 mm which is equivalent to 64.11% or operates from 3.30
GHz until 6.20 Ghz.
Figure 3.10: Result of varying the length of inset feed line (lf)
54
Table 3.4: Result of varying the length of inset feed line
Length of inset
feed line (mm)
Low Frequency,
fL (GHz)
High Frequency,
fH (GHz)
Bandwidth (%)
4.00 3.35 6.25 63.38%
4.10 3.34 6.20 62.85%
4.17 3.30 6.20 64.11%
4.20 3.33 6.17 62.65%
4.30 3.32 6.13 62.29%
3.5.3 Simulation on Different Scaling Factor (τ)
After varying the parameters of adjacent distance between the patches and the
length of inset feed line, the last parameter that will be optimized it is the scaling
factor. The log-periodic design is much related to the scaling factor. Referring to the
equation 2.8 in Chapter 2, the dimensions of antenna’s parameter are scaled up based
on the value of scaling factor. Hence, the changing of the scaling factor could affect
the antenna’s performance. For this antenna design, the best performance is when the
return loss is below -10 dB at desired operating frequency. The scaling factor is
sweep from 1.05 until 1.07 to observe minimum return loss and maximum
bandwidth.
Table 3.5 and Figure 3.11 shows the return loss of the antenna after varying
the value of scaling factor. From the results, it revealed that changing the scaling
factor affects the return loss and the bandwidth of the antenna. All the parameters
that are used in designing the antenna are related to the scaling factor. From the
return loss result, it shows that the scaling factor of 1.055 gives a wider bandwidth
compared to other scaling factors which is 74.20%.
55
Table 3.5: Summaries result of varying the scaling factor.
Scaling Factor ,
τ
Low Frequency
(fL)
High Frequency
(fH)
Bandwidth (%)
1.05 3.20 6.17 66.80%
1.055 3.00 6.20 74.20%
1.06 3.28 6.14 63.73%
1.065 3.32 6.10 61.77%
1.07 3.33 6.18 62.82%
Figure 3.11: Result of varying scaling factor (τ)
3.5.4 Parametric Studies Conclusion
From observation, there are some parameters that have a very strong
influence to the resonant frequency and others are not significant. In conclusion, the
parameter of Sa, lf and τ has a very strong influence in the resonant frequency and the
input impedance of the antenna.
56
3.6 Summary
In this chapter, the research flow, design methodology and simulation setup
of Log-Periodic Wideband Antenna has been briefly described. The initial result of
single patch antenna and the design process of the log-periodic wideband antenna are
also presented. In order to get an optimum result in terms of return loss and
bandwidth, a parametric study of varying the adjacent distance between patches, the
length of inset feed line and the scaling factor value are also presented. The
integration of the antenna with the lumped element and PIN diode to perform a
reconfigurable antenna will be discussed in the next chapter.
CHAPTER 4
RECONFIGURABLE LOG-PERIODIC ANTENNA DESIGN
4.1 Introductions
This chapter discusses project methodology, the steps in designing,
simulating and fabrication of Reconfigurable Log-Periodic Antenna. Based on the
design of log-periodic wideband antenna that was discussed in Chapter 3, the antenna
is modified to integrate with PIN diode switch to perform frequency
reconfigurability. The design of biasing circuit is also discussed and was simulated
using Computer Simulation Technology (CST) software.
In the simulation process, the equivalent circuit modeling for PIN diode
switch is designed to predict the performance of PIN diode and reconfigurable
antenna. Hence, this chapter discusses the equivalent circuit modeling for PIN diode
and the biasing circuit that is used in the proposed antenna. Then, the antenna is
fabricated with FR-4 substrate using wet etching technique. The measurement setup
using network analyzer and anechoic chamber is also presented in the last part of this
chapter.
58
4.2 Project Methodology and Flow Chart
The design methodology for Reconfigurable Log-Periodic Antenna is the
same with the Log-Periodic Antenna. The methodology of this project is started by
understanding of the reconfigurable antenna, the RF switches and the effect of
combination between RF switch and the antenna. The revision on biasing circuit,
switching circuit, PIN diode and its equivalent circuit are deeply studied in order to
reveal its effect on the antenna’s performance. Then, the RLPA was designed and
simulated to study the antenna’s performance in terms of return loss, current
distribution, gain and radiation pattern.
When the simulation process shows a good result, the antenna was fabricated
using wet etching technique. The antenna is fabricated on Flame Retardant 4 (FR4)
laminate board with dielectric constant, εr is 4.5 and loss tangent, tan δ is 0.019.
Other equipment such as a UV unit, transparency, etching chemical and ferric
chloride acid were used during the fabrication process. Then, the drilling process is
continued by drilling the hole at transmission line to connect the biasing network at
the back of the antenna. A copper via is placed through each hole and punched using
puncher to ensure that the copper via is stable.
After that, the PIN diodes and capacitors were embedded into the antenna
using soldering tools. After soldering the components together, the multi-meter was
used to check the connectivity of the components and the antenna. After all
fabrication process is done, the measurement process is continued to get results such
as return loss, received gain and radiation pattern. Finally, both simulated and
measured results is compared and analyzed for documentation. The full flow chart on
designing the RLPA is shown in Figure 4.1.
59
Figure 4.1: RLPA design flow chart
Start
Literature review on
reconfigurable
antenna
Design wideband
log-periodic antenna
using CST Software /
optimization
Desired
result?
Design a lumped element
circuit to represent RF
PIN Diode using CST
Software
Return Loss
measurement
Radiation pattern and
gain measurement
Result analysis and
documentation
End
A
Yes
No
A
Simulate RLPA
with PIN Diode
using CST software
Desired
result?
Yes
No
Antenna Fabrication
Process
Soldering PIN Diode
and lumped component
to the antenna
Testing the antenna
with switching board
and power supply
Antenna’s
working?
?
Yes
No
60
4.3 Analysis of PIN Diode Representation
The PIN diode equivalent circuit is an important part in simulation of
reconfigurable antenna to support better results in measurement process which done
by using real PIN diode. The further explanations about PIN diode equivalent circuits
were discussed in Chapter 2. This part elaborates on the PIN diode that used in this
antenna design using Computer Simulation Technology (CST) software. Two types
of PIN diode representation are simulated and discussed which are:
i. PIN Diode Representation using Lumped Element
ii. PIN Diode Representation Using PEC Pad
A single patch antenna was used for simulation of PIN diode representation.
The antenna dimensions are taken from Chapter 3.3 where:
i. Resonant frequency : 3.0 GHz
ii. Patch width / length : 23 mm
iii. Length of transmission line : 19.7 mm
iv. Length of inset fed : 8.2 mm
v. Gap width : 0.7 mm
vi. Height of substrate : 1.6 mm
61
4.3.1 PIN Diode Representation using Lumped Element
Figure 4.2 shows simulation setting of square patch antenna
incorporated with lumped element data to represent a PIN diode in CST
simulation. The PIN diode equivalent circuit is based on Microsemi [47] that
was discussed in Chapter 2. The equivalent circuit of PIN diode for forward
bias consists of a series combination of the series resistance (RS) and a small
Inductance (LS). In CST simulation software, there are two types of circuit
which are RLC-Serial and RLC Parallel as shown in Figure 4.3. Hence, the
RLC-Series circuit has been chosen to be employed with the antenna. The
values of lumped elements in ON and OFF modes [31] are shown in Table
4.1.
(a) (b)
Figure 4.2: (a) PIN diode representation using lumped element in single
patch antenna. (b) Lumped element data in CST.
62
(a)
(b)
Figure 4.3: lumped element circuits that are developed in CST software (a)
RLC-Serial (b) RLC-Parallel.
Table 4.1: The value of lumped elements as a PIN diode
PIN Diode Modes Resistor (Ω) Inductor (H) Capacitor (F)
ON 2.1 4.5 x 10-12
0
OFF 3000 0 3 x 10-9
The return loss of antenna with lumped element as PIN diode
representation is shown in Figure 4.4. In ON mode, the series circuit of
lumped element consists of 3.5 Ω and inductor 4.5 pH is connected with the
transmission line of antenna. The return loss of -42 dB at 3.0 GHz shows that
the signal from Port 1 antenna has passed through the lumped element circuit
to the patch as a radiating element. While very high return loss (-0.5 dB at 3.0
GHz) is evident on OFF state that consists of series circuit of 3.0 kΩ resistor
and 3.0 nF capacitor. This shows that the series circuit has a very high
impedance to block the signal from going the radiating patch.
63
Figure 4.4: Return loss of antenna (lumped element as a PIN diode)
4.3.2 PIN Diode Representation Using PEC Pad
The other type of PIN diode representation in simulation process is
using a PEC pad. It is represented as an open or short of the transmission line
as shown in Figure 4.5. The ON state is represented by presenting the 3mm x
1mm metal stripe and the absence of the metal strip represents the OFF state.
This type is easier than the lumped element circuit because the simulation is
faster and more accurate. This principle of operation has also been used by
other researchers as reported in [7-9].
(a) (b)
Figure 4.5: PIN Diode representation using PEC pad in (a) ON state (b) OFF
state.
64
Figure 4.6 shows the return loss of the single antenna that use PEC
stripe as a PIN diode. The ON state is indicated by presenting the PEC stripe
to allow the signal from port 1 passed through to the radiating element and
the return loss is -28 dB at 3.0 GHz. While the OFF state is indicated by
removing the PEC stripes and the return loss is -0.6 dB at 3.0 GHz.
Figure 4.6: Return loss of antenna. (PEC stripe as a PIN diode)
65
4.4 Analysis of Biasing Circuit Location
Bias networks are important devices in any active microstrip circuit to supply
the specific bias voltage and current. In this project, the antenna uses the radial stub
and DC line as a biasing network for the PIN diode. Further discussion on radial stub
biasing circuit was discussed in Chapter 2. However, choosing a suitable location of
biasing network is a critical decision to make in order to maintain the antenna’s
performance [42]. Three locations of biasing circuit are discussed to activate the PIN
diode, which is:
i. The biasing circuit at the transmission line of patch (Antenna A1)
ii. The biasing circuit at the centre of length of patches (Antenna A2)
iii. The biasing circuit at the back of antenna (Antenna A3)
The single patch antenna was used for simulation of PIN diode
representation. The antenna dimensions are taken from Chapter 3.3 which are:
i. Resonant frequency : 3.0 GHz
ii. Patch width / length : 23 mm
iii. Length of transmission line : 19.7 mm
iv. Length of inset fed : 8.2 mm
v. Gap width : 0.7 mm
vi. Height of substrate : 1.6 mm
vii. Radial stub : 60°
viii. Length of radial stub : 14.0 mm
66
4.4.1 Biasing circuit at the transmission line of patch (Antenna A1)
Figure 4.7 shows the single patch antenna with biasing circuit
consisting of a quarter wave length radial stub and DC line. The biasing
circuit is located in the middle of transmission line in order to study the
effects of current distribution and return loss of antenna. The DC signal is
connected to the positive terminal of PIN diode via the biasing circuit.
Figure 4.7: The structure of Antenna A1
The simulated current distribution of the antenna was presented in
Figure 4.8. From that figure, it shows that the radial stub biasing circuit did
not disrupt the current flow at the transmission line. Hence, it can be
considered that the biasing circuit was not radiated since the maximum
current distribution was observed. Further analysis of the antenna showed that
the return loss is -17.5 dB as shown in Figure 4.9. It revealed that only low
signal transmitting power was reflected back.
Figure 4.8: Current distribution of Antenna A1
67
Figure 4.9: Return loss of Antenna A1
4.4.2 Biasing circuit at the middle of length patches (Antenna A2).
The second configuration of biasing circuit is shown in Figure 4.10
where the biasing circuit is located mid-length (L) of the patch. The theory
about the patch antenna shows that the radiating slot of the square/rectangular
patch is located at the edge width (W) of the patch. The maximum radiation
can be observed at this region while the minimum radiation is at the
lengthwise edge of patch. Hence, in order to reduce the disruption of the
current distribution, the biasing circuit is placed in the middle of patch’s
length.
Figure 4.10: The structure of Antenna A2
W
L
68
Figure 4.11 shows the simulated current distribution of the antenna.
From that figure, it shows that the current distribution at the patch was not
disrupted by the biasing circuit. Hence, it can be considered that the biasing
circuit was not radiated since the maximum current distribution was seen
along the width of patch. Further analysis of the antenna showed that the
return loss is very deep which -21 dB as shown in Figure 4.12 is. It revealed
that only minimum signal transmitting power was reflected back.
Figure 4.11: Current distribution of Antenna A2
Figure 4.12: Return loss of Antenna A2
69
4.4.3 Biasing circuit at the back of antenna (Antenna A3).
The structure on Figure 4.13 shows the third configuration of biasing
circuit on the single patch antenna. The biasing circuit was placed at the back
of the antenna on a different substrate plane and connected to the
transmission line through the copper via. The structure was constructed in
order to form a tidy design and to avoid destruction to the radiation pattern.
(a) (b)
Figure 4.13: The structure of Antenna A3 (a) front view (b) back view
Figure 4.14 (a) and (b) shows the current distribution of the antenna at
front and back view respectively. The maximum current density is shown at
the front radiating elements while very low current density is radiated at the
back of antenna. This radiation might be give effect to the back lobe of the
radiation pattern. However, the antenna still resonates at a frequency of 3.0
GHz with a return loss of -17 dB as shown in Figure 4.15.
70
(a) (b)
Figure 4.14: Current distribution of Antenna 3 (a) front view (b) back view
Figure 4.15: Return loss of Antenna 3
4.4.4 Parametric Studies Conclusion
The parametric studies on the locations of biasing circuit at the
antenna have been discussed. The biasing circuits are proposed to locate at
the transmission line, at the middle of patches and at the back of the antenna.
The return loss and the current distribution of each antenna also presented to
study the effect of the biasing circuit. The antenna with biasing circuit located
at the back has good current distribution compared the others since the
radiation from biasing circuit is not giving effect to the current distribution of
the antenna besides has return loss below that -10 dB. Hence, this
configuration will be use for full design of reconfigurable antenna.
71
4.5 Reconfigurable Log-Periodic Antenna (RLPA) Design
The wideband frequency reconfigurable based on log-periodic antenna has
been discussed in Chapter 2. The Computer Simulation Technology (CST) software
has been used to design the structure and simulate the performance of the antenna.
The geometrical structure and detail dimensions of the proposed RLPA structure are
shown in Figure 4.16 and Figure 4.17 respectively. There are thirteen square patches
with inset fed lines which are connected with a log-periodic array formation to a 50
ohm transmission line on a top layer of substrate. The antenna structure is
constructed on a FR-4 substrate with a thickness of 1.6 mm which has relative
permittivity (εr) of 4.5 and loss tangent (tan δ) of 0.019. The properties of RLPA are
shown in Table 4.2 while Table 4.3 shows the detailed antenna dimensions for each
patch. All the dimensions of the antenna are based on the dimensions of log-
periodic wideband antenna in Chapter 3.
Table 4.2: Reconfigurable log-periodic antenna properties
Parameter Value
Operating frequency up to 6 GHz
Bandwidth > 70 %
Gain 6-8 dBi
Radiation pattern Directional
Polarization Linear
Reconfigure Frequency
Switching RF PIN Diode
72
Table 4.3 The dimensions for each patches of RLPA.
Patch Antenna Parameter
Patch Size
(wp) in mm
Inset feed line
(lf) in mm
Distance
between
patch (Sa) in
mm
Frequency
in (GHz)
Radial
stub (rs)
in mm
1 11.7 4.17 11.5 6.00 7.23
2 12.37 4.41 12.85 5.68 7.64
3 13.07 4.66 13.58 5.37 8.07
4 13.82 4.93 14.35 5.08 8.53
5 14.60 5.21 15.17 4.81 9.02
6 15.44 5.50 16.04 4.55 9.54
7 16.32 5.81 16.95 4.30 10.08
8 17.25 6.15 17.92 4.07 10.66
9 18.23 6.50 18.94 3.85 11.27
10 19.27 6.87 20.02 3.64 11.91
11 20.37 7.26 21.16 3.45 12.59
12 21.53 7.67 22.37 3.26 13.30
13 22.76 8.11 23.64 3.05 14.06
The reconfigurabilty is achieved when the RF PIN diodes are incorporated
with the feeding line which acts as a switch and to control the ON/OFF mode. In
this project, the parametric study about PIN diode representation in simulation over
RLPA also discussed. The PIN diode representation for simulation process is
carried out by representing a PEC stripe and the lumped element circuit similarly as
discussed for single element before this. The antenna performances in term of return
loss and gain are discussed for both configurations. Using the same substrate
material, the biasing circuit consisting of a radial stubs as a bias network is located
underneath the antenna is connected to a power supply to bias the PIN diode.
73
The complete biasing circuitry controls the bias voltage consisting of high
impedance quarter wave lines, radial stubs, biasing pads, current limiting resistor,
and DC power supply. The quarter-wave length radial stub is located at the back of
antenna to connect from PIN diode to the DC and it operates as a RF choke. The
capacitor is also placed on the transmission line before being connected to the SMA
port to block the DC signal from going into the signal generator. The structure of
Antenna A3 is chosen because it is suitable for wideband antenna design which uses
a huge number of patch elements.
The design principle for log-periodic wideband antenna requires scaling of
dimensions from period to period so that the performance is periodic with the
logarithm of frequency. The patch length (lp), the width (wp) and the inset feed (I)
are related to the scaling factor (τ). The dimension of the first patch (higher
frequency) is 11.70 mm x 11.70 mm. The space between each patch is half a
wavelength apart thus giving a forward fire radiation pattern and reducing the
mutual coupling effect. A gap of 0.8 mm in the middle of patch’s transmission line
is where the PIN diode would be positioned. The dimensions of proposed antenna
are as follows: wp=11.7mm, lf=7.7 mm, rs= 7.23 mm (all dimension for smaller
patch), ltx=208 mm, ws= 230 mm, ls=100 mm, h= 3.305 mm, gap= 0.8 mm, and θ =
60°.
74
Figure 4.16: The geometrical structure of reconfigurable log-periodic antenna
Figure 4.17: Design description of reconfigurable log-periodic antenna
75
The proposed antenna has thirteen patches that require thirteen PIN diode
switches. The wideband operation is achieved when all switches are in ON state. By
controlling the switch at the transmission line of patch, the required frequency band
could be achieved. By controlling each patch using PIN diodes, this antenna is able
to tune from wideband range to narrowband based on required frequency. However,
a group of sub-bands are selected as represent a theory of reconfigurable frequency
selection from wideband range. Besides that, the results from group of sub-bands
are easily discussed and compared to each others. The PIN diode switch conditions
are shown in Table 4.4. In the first case, Band 1 is achieved when the diodes D1
until D5 are ON while the rest are in OFF state. Same as in the first case, the D5-D9
and D9-D13 are in ON states to achieve Band 2 and Band 3 respectively. The other
sub-bands might be achieved by controlling other groups of patches.
Table 4.4 Switches’ states at different bands for RLPA
Diode Band 1 Band 2 Band 3 Wideband
D1 – D5 OFF OFF ON ON
D5 – D9 OFF ON OFF ON
D9 – D13 ON OFF OFF ON
Figure 4.18 (a) and (b) shows two configuration of PIN diode representation
in simulation process which uses PEC stripes and lumped element circuit
respectively. For the first configuration, the switch in RF systems is represented by
an open or short of the transmission line. Therefore, a metal stripes with dimensions
of 3 mm x 0.8 mm is located at the transmission line of patch to represent a switch.
Hence, the ON state is represented by the metal stripe and the absence of the metal
stripe represents the OFF state. In the simulation process, the ohmic losses are
assumed to be zero by using the ideal substrate and perfect electric conductor. In
second configuration using lumped element circuit, the gaps at the transmission line
are connected with lumped component based on circuit in Table 4.1. For this
configuration, the simulation process becomes more difficult because it requires
higher mesh cells and longer simulation times. Hence, to reduce the simulation time,
the first configuration is use for other simulations.
76
(a)
(b)
Figure 4.18: Reconfigurable log-periodic antenna design. (a) PEC stripe as a PIN
diode (b) Lumped element circuit as a PIN diode
PEC
Stripe 3 mm
0.8 mm
77
Figure 4.19: Comparison of PIN diode representation for RLPA in wideband
operation
Table 4.5 Performances of antenna using different PIN diode representation
Parameter PEC Stripe Lumped Element
Low Frequency, fL (GHz) 3.07 GHz 2.95 GHz
High Frequency, fH (GHz) 6.2 GHz 6.3 GHz
Bandwidth (%) 71.7 % 77.7 %
Efficiency (%) /
Gain (dB)
at 3 GHz 31.6 % / 4 dB 25.0% / 2.7 dB
at 4 GHz 39.2 % / 4.8dB 37.2% / 4.5 dB
at 5 GHz 52.2 % / 6.9 dB 43.6% / 6.7 dB
at 6 GHz 38.1% / 3.8 dB 27.5% / 2.4 dB
78
4.6 Fabrication Process
The fabrication process is an intermediate process between the simulation and
measurement process. After obtaining such encouraging results in the simulation, the
antenna needs to be fabricated in order to measure the real antenna. The wet etching
technique was used in this process. The fabrication process consists of several steps
and these steps must be done carefully to get optimum results. Table 4.6 shows the
steps of fabrication process.
Table 4.6: Antenna Fabrication Process
No Picture Explanation
1
The design’s layout was carried out from
CST and was printed over transparency. The
substrate that will be used is FR-4 board with
photo resist layer.
2
Then, this layout will expose under ultra
violet (UV) light over FR-4 board. This step
is doing under lightless condition in order to
protect the photo resist layer.
3
After that, the structure is soaked and etched
about 30 seconds with the acid developer to
remove the positive photo resist layer. This
step also is doing under lightless condition.
4
Afterward, to remove the copper layer at
unused region, the structure was etched using
chemical acids. This is the last part of
fabrication processes.
79
5
Then, antenna will be fed using 50 Ohm
SMA connecter. This process involves the
soldering process using soldering tool. The
SMA connector must be connected to the
transmission line and the ground of antenna.
6
The drilling process is continued by drilled
the hole at transmission line to connect the
biasing network at the back of the antenna. A
copper via will be placed for each hole and
punched using puncher to ensure that the
copper via is sturdy in the hole.
7
After that, the PIN diodes and capacitors
were embedded with antenna using soldering
tools. The temperature of soldering must be
referred to datasheet in order to protect the
component was not over heat.
8
After soldering the components, the multi-
meter was use to checking the connectivity of
the components and the antenna.
9
Then, the antenna was connected with
switching circuit and power supply to
activate the PIN diode and enable the
reconfigurable antenna function. The multi-
meter also was used to check the continuity,
voltage, and current flow over PIN diode.
To activate the PIN diodes, +9 volts DC is
applied while 0 volt DC is applied to
deactivate the PIN diode.
80
10
Finally, the reconfigurable antenna is
measured in term of return loss, power
received and radiation pattern.
4.7 Measurement Process
After the fabrication process, the antenna is tested and measured to validate the
simulation results such as return loss, power received by antenna and the radiation
pattern. All measurement processes have been done in P18 and Wireless
Communication Centre, Universiti Teknologi Malaysia using appropriate
equipments.
4.7.1 Input Return Loss Measurement Setup
The equipment that was used in this measurement is Rohde & Schwarz
Network Analyzer that can measure from 9 kHz to 13 GHz. The equipment and the
calibration kit are shown in Figure 4.20. The first step to measure the input return
loss for those antennas is to setup the start and stop the frequency range. Next, the
equipment needs to be calibrated to ensure that the equipment gives precise results or
in other words can reduce uncertainties during the measurement process. The
calibration process is done by using the calibration kit by loading the open, short and
broadband terminator.
81
(a) (b)
Figure 4.20: Return loss measurement setup. (a) Network analyzer (b) Calibration
kit
4.7.2 Radiation Pattern Measurement Setup
The measurement of received gain of the antenna is conducted by comparing
the antenna with the horn antenna as a reference. The set-up in the anechoic chamber
is shown in Figure 4.21 while Figure 4.22 shows the actual picture of anechoic
chamber. The proposed antenna is placed as the antenna under test (AUT) to measure
the receiving power from the horn antenna. The antenna has been measured, and the
power will be received in dBm by varying the frequency range from 2 GHz to 7
GHz. The radiation pattern of the antenna was measured with a 180 degree rotator in
same anechoic chamber at the selected frequency bands in the E-plane and H-plane.
Figure 4.21: Power received and radiation pattern measurement set-up.
82
Figure 4.22: Anechoic chamber
4.8 Summary
In this chapter, the research flow, design methodology and simulation setup
of Reconfigurable Log-Periodic Antenna has been briefly described. Two types of
PIN diode representation in simulation and three locations of biasing circuit have
been studied and discussed. The simulated RLPA and detailed dimension also
presented. All configuration and design of RLPA have been analysed using CST
Microwave Studio software. The result of simulation and measurement will be
discussed and analysed in the next chapter.
CHAPTER 5
RESULT ANALYSIS AND DISCUSSION
5.1 Introductions
The measurement process is very important to validate the simulation result.
This process is conducted after the fabrication process has been completed. In this
chapter, the simulation result for both Log- Periodic Antenna and Reconfigurable
Log-Periodic Antenna is presented in terms of return loss, current distribution,
realized gain and radiation pattern. The measurement results are also presented in
terms of return loss, power received, and radiation pattern. After that, both
simulation and measurement results are compared, analyzed and discussed. The
comparisons between LPA and RLPA in terms of return loss and radiation pattern
are also presented. The measurement of return loss was conducted using network
analyzer within the range of 2 GHz until 7 GHz. The radiation pattern is plotted
based on measurement of power received by the antenna under test in anechoic
chamber room.
84
5.2 Analysis Result and Discussion of Log-Periodic Antenna
The parametric study of Log-Periodic Antenna has been done and presented
in Chapter 4 in term of varying the scaling factor, the distance between patches and
inset feed length to study the behavior of antenna performance so that a good result
in term of return loss and radiation pattern can be acheived. After simulation using
CST software is done, the antenna was fabricated using FR-4 board using wet
etching technique followed by measurement process. In this part, the simulated and
measured results of LPA are analyzed and compared. The photo of fabricated LPA is
shown in Figure 5.1. The overall size of the proposed antenna is 200mm x 100 mm
and thickness of 1.6mm. The measurement is carried out using Rohde and Schwarz
network analyzer while the radiation pattern is measured with 180 degree rotation in
anechoic chamber and plotted using appropriate software.
Figure 5.1: Photo of fabricated LPA
5.2.1 Input Return Loss
Based on simulation of the log-periodic antenna using CST software, the
input return loss of the antenna is below than -10 dB from 3.18 GHz to 6.23 GHz or
bandwidth of 68.52%. The simulation result then validated by comparing with the
measurement results. The measurement of return loss is conducted using Rohde and
Schwarz network analyzer. Figure 5.2 shows the comparison of the simulated and
measured return loss for log-periodic antenna. The measurement result shows a
good agreement between simulation results. The measurement shows that the
85
antenna can operate from 3.16 GHz to 6.3 GHz or 70.37% bandwidth with respect
to the -10dB.
The log-periodic antenna is an antenna that has periodical repetition of their
impedance and geometry with respect to the logarithm of frequency. Hence, each
element on LPA has their periodical impedance and operating frequencies. Figure
5.2 shows that the return loss of the proposed antenna has many ripples of return
loss. It revealed that every single element radiated for each operating frequency and
this situation is suitable for frequency reconfigurable. The desired frequency over
wideband operation can be selected by switching the PIN diode ON or OFF. The
comparison of the simulated and measured return loss for log-periodic wideband
antenna is shown in Table 5.1.
For simulated antenna bandwidth;
𝐵𝑊 = 𝑓ℎ−𝑓𝐿
𝑓ℎ 𝑓𝐿 × 100% =
6.23−3.18
6.23×3.18 × 100% = 68.52%
For measured antenna bandwidth;
𝐵𝑊 = 𝑓ℎ−𝑓𝐿
𝑓ℎ 𝑓𝐿 × 100% =
6.3−3.16
6.3×3.16 × 100% = 70.37%
Figure 5.2: Simulated and measured return loss for LPA
86
Table 5.1 Comparison of frequency bandwidth between simulation and
measurement for LPA.
Parameter Simulation Measurement
Lower Frequency (fL) 3.18 GHz / -10 dB 3.16 GHz / -10 dB
High Frequency (fH) 6.23 GHz / -10 dB 6.30 GHz / -10 dB
Bandwidth (MHz) 3050 MHz 3140 MHz
Bandwidth (%) 68.52 % 70.37 %
5.2.2 Current Distribution
The simulated current distributions of the log-periodic antenna at four
different resonant frequencies are shown in Figure 5.3. At a lower frequency, it can
be observed that the current propagates at the bigger element which confirms that
the antenna is resonating at the appropriate elements. Figure 5.3 (a) shows the
current distribution of the antenna at the bigger elements while Figure 5.3 (b) shows
the current propagating at the middle elements. The current propagation at 5 GHz
and 6 GHz are shown in Figure 5.3 (c) and 5.3 (d) respectively. The mutual
coupling effect at the antenna can be observed by monitoring the current
distribution or surface current. This effect can be reduced by adjusting the distance
between adjacent elements in the antenna design. However, the adjustment of the
distance may reduce the performance of the antenna especially the return loss and
radiation pattern.
87
(a) (b)
(c) (d)
Figure 5.3: Simulated current distribution for LPA at: (a) 3 GHz (b) 4 GHz (c) 5
GHz (d) 6 GHz.
5.2.3 Realized Gain and Power Received
Table 5.2 shows the simulated realized gain, antenna directivity and its
efficiency when operates over a wideband from 3.0 GHz to 6.0 GHz. From the
table, it revealed that the antenna has a high directivity, with an average of 9.0 dBi.
However, the antenna’s efficiency for the antenna is about 0.45 or 45 % on average
where high efficiency occurs at middle of wideband operations. The gain of the
antenna is affected by the efficiency of the antenna. The higher efficiency of the
antenna will result in higher gain. Since the log-periodic technique enables one
patch to radiate at a single frequency, the gain is approximately equal to the single
patch. Besides, the use of substrate FR-4 which has higher losses might lead to
lower efficiency.
88
Table 5.2: Simulated realized gain and efficiency of the LPA
Frequency Realized Gain (dB) Directivity (dBi) Efficiency
3.0 GHz 3.7454 9.34 0.32
3.5 GHz 4.2085 9.38 0.33
4.0 GHz 4.6103 8.95 0.39
4.5 GHz 4.8112 8.44 0.38
5.0 GHz 6.5542 9.64 0.51
5.5 GHz 5.9326 9.69 0.46
6.0 GHz 3.8230 7.57 0.44
The received measured power of LPA is shows in Figure 5.4. The
measurement process are conducted in an anechoic chamber by comparing the LPA
as an antenna under test (AUT) in receiving mode to the horn antenna as a reference
antenna in transmitting mode. The gain of the antenna was 15 dBi over the range of
0.7 GHz to 18 GHz as mention at Appendix C. The power that was received by the
LPA was plotted in the graph. The power received by the LPA is measured in dBm
by varying the frequency range from 2 GHz to 7 GHz. From the comparison of
power in Figure 5.4, the LPA has received power about 8 dB to 10 dB less than a
horn antenna. The gain of the LPA can be calculated by subtracting the horn
antenna’s gain with the LPA’s power received. Hence, the gain of LPA are 5 dB to
7 dB based on these calculation which also used in [52]. This range of gain is
similar to the simulated realized gain in Table 5.2. From the graph also, the received
power has a higher value at lower frequency compared to higher frequency, due to
the cable losses and free space losses.
89
Figure 5.4: Measured received of the LPA and the horn antenna
5.2.4 Radiation Pattern and Half-Power Beam-width
The simulated and measured radiation patterns for Log-Periodic Antenna are
presented in Figure 5.5 until Figure 5.10. The simulated radiation patterns are taken
from CST Microwave Studio while the measurement results are taken from a 180
degree rotator in an anechoic chamber. Three radiations patterns is selected, where
frequency bands are 3.4 GHz, 4.0 GHz, and 5.8 GHz were plotted using
appropriated software to view the pattern in E-plane (co-polar and cross-polar) and
H-plane (co-polar and cross-polar). Figure 5.5 and Figure 5.6 shows the radiation
pattern at 3.4 GHz for simulated and measured respectively. The simulated pattern
shows a low cross polarization with half power beam-width of 50° and 70.8° for E-
plane and H-plane respectively as shown in Table 5.3. The measured radiation
pattern in E-co and H-co plane at 3.4 GHz exhibit a similar pattern with the
simulation. The same pattern between simulated and measured also had shown at
frequencies of 4.0 GHz and 5.8 GHz.
8 dB 10 dB
90
(a)
(b) (c)
Figure 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 (solid line = Co-polar; dotted line = Cross-
polar)
(a) (b)
Figure 5.6: Measured radiation pattern of LPA at 3.4 GHz (a) E-plane. (b) H-plane
(solid line = measurement; dotted line = simulation)
91
(a)
(b) (c)
Figure 5.7: Simulated radiation pattern of LPA at 4.0 GHz (a) 3-D view. (b) 2-D
view in E-plane. (c) 2-D view in H-plane plane (solid line = Co-polar; dotted line =
Cross-polar)
(a) (b)
Figure 5.8: Measured radiation pattern of LPA at 4.0 GHz (a) E-plane. (b) H-plane
(solid line = measurement; dotted line = simulation)
92
(a)
(b) (c)
Figure 5.9: Simulated radiation pattern of LPA at 5.8 GHz (a) 3-D view. (b) 2-D
view in E-plane. (c) 2-D view in H-plane plane (solid line = Co-polar; dotted line =
Cross-polar)
(a) (b)
Figure 5.10: Measured radiation pattern of LPA at 5.8 GHz (a) E-plane. (b) H-plane
(solid line = measurement; dotted line = simulation)
93
Table 5.3 Half-power beamwidth for Log-Periodic Antenna
Frequency HPBW (E-plane) HPBW (H-plane)
Simulation Measurement Simulation Measurement
3.4 GHz 58° 62° 70.8° 67°
4.0 GHz 69.3° 58° 83° 65°
5.8 GHz 67.2° 72° 58.4° 68°
5.3 Analysis Result of Frequency Reconfigurable Log-Periodic Antenna and
Discussion
Similar to the LPA, the prototype of the RLPA has been fabricated using
conventional photolithography technique. Figure 5.11 shows a photograph of the
fabricated antenna structure with biasing circuit on FR-4 board. In order to validate
the simulation result, the antenna’s measurement and simulation results have been
compared. The result consists of radiation pattern, power received, realized gain and
radiation pattern. The measurement is carried out using Rohde and Schwarz
network analyzer while the radiation pattern is measured with 180 degree rotation in
anechoic chamber and plotted using appropriate software. The measurement result
shows good agreement between simulated results.
Figure 5.11: Photo of Reconfigurable Log-Periodic Antenna
Power supply
Switching circuit
Antenna
RF PIN Diode
94
5.3.1 Return Loss (S11)
Figure 5.12 to 5.14 show the simulated as well as measured return loss
characteristics of the antenna with different band frequencies. The simulated return
loss when ON state is plotted with measurement result is as shown in Figure 5.12. It
shows that the antenna has a good return loss from 3.17 GHz to 6.2 GHz with
bandwidths up to 71.7% and the result agrees with the measurement. The simulated
return loss for all band of RLPA is shown in Figure 5.13. It shows that the antennas
have a good return loss for band 1, band 2 and band 3 which is 27.2%, 27.3% and
26.6% bandwidth respectively. Figure 5.14 shows the measurement result of return
loss for all three bands. It shows that there are some different values of return loss
compared to simulated result but it has approximately the same bandwidth. For band
1 where diode 9 to 13 is switched ON while the rest is OFF, the return loss 4.65-6.1
GHz range is achieved for measurement results. Meanwhile, when the switching
condition is changed to band 2 and band 3, the return loss 3.28-4.5 GHz and 2.94-
3.71 GHz are achieved respectively. From the graph, it shows that the PIN diode
and radial stub’s effect is minimal upon the measurement result. The presence of a
metal pad in simulation is used to represent a PIN diode in measurement. The
complete result of return loss for proposed antenna is shown in Table 5.4.
Figure 5.12 Simulation and measurement return loss of the antenna when all
switches are in ON state.
95
Figure 5.13: Return loss of simulated reconfigurable log-periodic antenna for
different band
Figure 5.14: Return loss of measured reconfigurable log-periodic antenna for
different band
96
Table 5.4: Comparison of return loss between simulation and measurement of
RLPA
Band f1 (GHz) f2 (GHz) BW (MHz) BW
(%)
Band 1 Simulation 4.6 6.0 1400 27.2
Measurement 4.65 6.1 1450 27.2
Band 2 Simulation 3.73 4.9 1170 27.3
Measurement 3.28 4.5 1220 31.7
Band 3 Simulation 3.0 3.91 910 26.6
Measurement 2.94 3.71 770 23.3
Wide
Band
Simulation 3.17 6.2 3030 71.7
Measurement 3.05 6.27 3220 73.6
5.3.2 Current Distribution
Figure 5.15 shows the simulated current distribution of the proposed antenna
for four different resonant frequencies. The current distribution for RLPA was
similar to the current distribution of LPA. Figure 5.15 (a) shows that the current
propagates at bigger elements for low frequency while for mid frequency, the
current propagates at middle group of patches as shown in Figure 5.15 (b). The
current propagation at 5 GHz and 6 GHz are shown in Figure 5.15 (c) and 5.15 (d)
respectively. From the current distribution, the mutual coupling effect can be
controlled by monitoring the current distribution of two adjacent patches. This
effect can be reduced by adjusting the distance between adjacent elements of the
antenna. The larger distance between elements can reduce the mutual coupling
effect but it can also reduce the performance of the antenna in terms of return loss
and radiation pattern.
97
(a) (b)
(c) (d)
Figure 5.15: Simulated current distribution for reconfigurable log-periodic antenna
at: (a) 3 GHz (b) 4 GHz (c) 5 GHz (d) 6 GHz.
5.3.3 Simulated Realized Gain and Power Received Measurement
The simulated realized gain for reconfigurable log-periodic antenna in the
ON state, OFF state and all three cases of reconfigurable are plotted in Figure 5.16.
It is shown that the antenna has a good gain from 3.0 GHz to 6.0 GHz between 4 dB
to 6 dB for each bands. Since the log periodic technique enables one patch to radiate
at a single frequency, hence the gain is approximately equal to the single patch. It is
worth mentioning that the efficiency for this antenna is about 0.4 to 0.6 hence, the
directivity is about 8 dBi to 10 dBi.
98
(a) (b)
Figure 5.16 (a) Simulated realized gain, directivity and efficiency of RLPA. (b)
Simulated realized gain of RLPA in different sub-bands.
The measurement of received gain of RLPA is conducted by comparing the
RLPA antenna with the horn antenna as a reference. The measurement set-up in the
anechoic chamber is same as the radiation pattern setup as discussed in Chapter 4.
The RLPA is placed as the antenna under test (AUT) in ON and OFF mode to
measure its receiving power from the horn antenna as a reference antenna with gain
of 15 dBi over the range from 0.7 GHz until 18 GHz. The antenna has been
measured: the power received in dBm by varying the frequency range from 2 GHz
to 7 GHz.
Figure 5.17 shows the received power from the horn antenna and RLPA in
the ON and OFF mode versus frequency. From the graph, the RLPA received 8dBm
less than power received by a horn antenna. The gain of the RLPA can be calculated
by subtracting the horn antenna’s gain with the RLPA’s power received. Hence, the
gain of RLPA is about 7 dB based on these calculation which also used in [52]. This
range of gain is similar to the simulated realized gain as shown in Figure 5.17. The
same measurement set-up is also used to investigate the received power in different
planes, as shown in Figure 5.18. This shows that the proposed antenna has a higher
cross polarization, since the antenna was designed for linear polarization. From the
graph, the received power has a higher value at lower frequency compared to higher
frequency, due to the cable losses and free space losses.
99
Figure 5.17: Power received for different types of antenna at measurement set-up
(a) (b)
Figure 5.18: Power received of reconfigurable log-periodic antenna (a) E-Plane (b)
H-Plane
8 dBi
8 dBi
100
5.3.4 Radiation Pattern and Half-Power Beam-width
Figure 5.19 to Figure 5.24 shows the simulated and measured radiation
pattern in E-plane and H-plane. The pattern was plotted over a wideband in
frequency 3.4 GHz, 4.0 GHz and 5.8 GHz to study the polarization in co- and cross-
plane. The radiation patterns of the RLPA at the selected frequency bands in the E-
plane and H-plane were measured with a 180 degree rotator in an anechoic
chamber. The simulated radiation pattern at 3.4 GHz shows the HPBW for E-plane
and H-plane are 69.1° and 55.3° respectively. The small value of cross-polarization
revealed that the antenna is operating at linear polarization.
The comparison of a 180 degree radiation pattern between simulation and
measurement is shown in Figure 5.20. As observed, the measured radiation pattern
has a similar pattern with the simulated and has a directional radiation pattern. It
shows that the effect of integration PIN diode with the antenna have a minimal
effect and does not change the radiation pattern. There are limitations for full
measurement of radiation pattern to study the back lobe radition pattern due to lack
of facilities. The simulated and measured radiation pattern for 4.0 GHz and 5.8 GHz
are shown in Figure 5.21 until Figure 5.24 while the HPBW of the antenna is
demonstrated in Table 5.5. The main lobe of radiation patterns are slightly steered
from 0 degree, due to the difference in phase between the higher frequency and
lower frequency.
101
(a)
(b) (c)
Figure 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 (solid line = Co-polar; dotted line = Cross-
polar)
(a) (b)
Figure 5.20: Measured radiation pattern of RLPA at 3.4 GHz (a) E-plane. (b) H-
plane (solid line = measurement; dotted line = simulation)
102
(a)
(b) (c)
Figure 5.21: Simulated radiation pattern of RLPA at 4.0 GHz (a) 3-D view. (b) 2-D
view in E-plane. (c) 2-D view in H-plane (solid line = Co-polar; dotted line = Cross-
polar)
(a) (b)
Figure 5.22: Measured radiation pattern of RLPA at 4.0 GHz (a) E-plane. (b) H-
plane (solid line = measurement; dotted line = simulation)
103
(a)
(b) (c)
Figure 5.23: Simulated radiation pattern of RLPA at 5.8 GHz (a) 3-D view. (b) 2-D
view in E-plane. (c) 2-D view in H-plane (solid line = Co-polar; dotted line = Cross-
polar)
(a) (b)
Figure 5.24: Measured radiation pattern of RLPA at 5.8 GHz (a) E-plane. (b) H-
plane (solid line = measurement; dotted line = simulation)
104
Table 5.5 Half-power beamwidth for Reconfigurable Log-Periodic Antenna
Frequency HPBW (E-plane) HPBW (H-plane)
Simulation Measurement Simulation Measurement
3.5 GHz 69.1° 73° 55.3° 69°
4.0 GHz 73.0° 67° 51.8° 67°
5.8 GHz 66.6° 72° 60.2° 70°
5.4 Overall Discussion
The log-periodic and reconfigurable log-periodic antennas were simulated
with CST simulation tools and fabricated using wet etching technique on a FR-4
substrate. The entire antenna was measured to validate the simulation results in terms
of return loss, antenna gain, half-power beam width and the radiation pattern. The
comparison of overall performances in term of frequency, bandwidth, gain and
HPBW between LPA and RLPA are shown in Table 5.6. The development of
wideband antenna using log-periodic technique is achieved with bandwidth of 70.37
% and 73.6 % after the antenna is implementing with RF switch to perform
reconfigurability operations. Three sub bands are selected from reconfigurable
antenna by switching ON or OFF of RF switches to shows the operations of
reconfigurable antenna. However, the antenna could be configured into different sub-
bands or narrowband depending on its application.
The power received of both antennas also done by comparing the antenna to
the horn antenna as a reference antenna. The measured gain of antennas is the
compared to the simulated gain and it shows that good agreement between them. Due
to the facilities limitation, the measurement of radiation pattern is conducted by
taking a 180 degree radiation pattern while ignoring the back lobe of the antenna.
However, a good agreement between measurement and simulation results was
showed in term of return loss, antenna gain and radiation pattern. The results of the
antennas were discussed and plotted in the graph and tables for better viewing.
105
Table 5.6 Comparison of overall performances in term of frequency, bandwidth,
gain and HPBW between LPA and RLPA
Parameters
Log-Periodic Antenna Reconfigurable Log-
Periodic Antenna
Simulation Measurement Simulation Measurement
Frequency 3.18 GHz –
6.23 GHz
3.16 GHz –
6.30 GHz
3.17 GHz -
6.2 GHz
3.05 GHz -
6.27 GHz
Bandwidth 68.52 % 70.37 % 71.7 % 73.6 %
Gain
3.4 GHz 4.3 dB 6.0 dB 4.6 dB 6.0 dB
4.0 GHz 4.61 dB 5.0 dB 5.1 dB 7.0 dB
5.8 GHz 4.82 dB 6.0 dB 5.6 dB 6.0 dB
HPBW
(E-Plane)
3.4 GHz 58° 62° 69.1° 73°
4.0 GHz 69.3° 58° 73.0° 67°
5.8 GHz 67.2° 72° 66.6° 72°
5.5 Summary
The simulated and measured results of the Log-periodic Wideband Antenna
and Reconfigurable Log-Periodic Antenna have been presented and discussed. The
simulated result such as return loss, current distribution, realized gain and radiation
pattern has been clearly presented. Then, the measurement process has been 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. The simulation process
has been done using CST Microwave studio while the measurement process has been
done by using network analyzer and anechoic chamber. The results show a good
agreement between simulated and measurement values.
CHAPTER 6
CONCLUSION
6.1 Overall Conclusion
The development of a Log-Periodic Antenna (LPA) and Reconfigurable Log-
Periodic Antenna (RLPA) have been presented and discussed including the designing
process, fabrication process until measurement process. The introduction of RLPA
including a literature study on wideband antenna and reconfigurable antenna is also
presented in addition to the significance of the research works such as a recent
problem statement, the essential objectives and the research scopes. These were all
explained in detail.
The successful output from this research work is a result of plentiful literature
review in the particular field in order to have better understanding regarding the
RLPA development. In addition, the concept and the operating behavior of LPA and
RLPA were presented and discussed deeply with the assistance of appropriate figures
and tables. All the antennas have been design using Computer Simulation
Technology (CST) software which has many applications and bring benefits to the
researcher because the performance and characteristic of the antenna can be analyzed
before proceeding to the fabrication process besides reducing time wastage.
107
The design methodology and flow chart of LPA and RLPA were discussed
separately. The detailed dimension of LPA is included during simulation process
with some optimization of some parameter which are the scaling factor, the length of
inset feed line and the distance between adjacent patch, which are simulated in order
to produce a better result. The design of LPA was then integrated with lumped
elements and PIN diode switches to reconfigure the operating frequency from
wideband operation to narrow band operation which is represented by three sub-
bands (Band 1, Band 2 and Band 3). In the simulation process, three methods to
represent the PIN diode which are using lumped element and PEC pad were
discussed with some results. Then, the radial stub and DC line were use as biasing
circuits to bias the PIN diode with some parametric study on the location of biasing
circuit have been made.
The antennas were fabricated using wet etching technique on a FR-4 substrate
with presented details on the fabrication processes. The entire antenna was measured
to validate the simulation results in terms of return loss, antenna gain and the
radiation pattern. The wideband operation over 70% bandwidth and three sub-bands
with bandwidth around 20% has been measured after reconfigurable operation.
However, the antenna could be configured into different sub-bands or narrowband
depending on its application. Due to the limitation, the measurement of radiation
pattern is conducted by taking a 180 degree radiation pattern while ignoring the back
lobe of the antenna. However, a good agreement between measurement and
simulation results was showed in term of return loss, antenna gain and radiation
pattern. The results of the antennas were discussed and plotted in the graph and
tables for better viewing.
108
6.2 Key Contribution
The development of Log-Periodic Antenna and Reconfigurable Log-Periodic
Antenna has been studied and their performance is analyzed. After hard work on the
antenna’s development, three key contributions were verified:
1. The performance of wideband log-periodic antenna is improved by
integrating RF switch to have reconfigurability operation.
2. A reconfigurable antenna is design based on real circuit modeling of PIN
diode in simulation process using CST software tools. This contribution is
replacing the other method by using ideal case which the simulation results
are not similar to the measurement results.
3. The integration of wideband antenna with lumped elements and real PIN
diodes switches to develop a reconfigurable antenna with separated biasing
circuit is presented.
6.3 Future Research
The structure of Log-Periodic Antenna and Reconfigurable Log-Periodic
Antenna can be improved by the following:
1. One of the limitations of this project is that the PIN diode can be operated up
to a maximum of 6 GHz frequency. The use of high-frequency PIN diodes
could be applied for future research. Hence, the antenna can operate at a
very wideband operation.
2. Using a different substrate material that has a lower loss and higher
dielectric constant which can produce better performance.
3. Different technique of feeding such as aperture slots can be studied to reduce
the effect of PIN diode towards the antenna’s performance. Besides, it might
reduce the size of the antenna.
4. Employ different RF switches (besides PIN diode) without using the biasing
circuit that can disrupt the antenna’s performance.
5. The integration of reconfigurable antenna with FPGA or PIC controller to
automate the switching circuit (smart antenna) can also be studied.
109
REFERENCES
1. Balanis, C. A., (1997). Antenna Theory: Analysis and Design. (2nd
edition).
New York: John Wiley and Sons.
2. Hall, P.S., Gardner, P., Kelly, J., Ebrahimi, E., Hamid, M.R., Ghanem, F.,
―Reconfigurable Antenna Challenges for Future Radio Systems‖ 3rd
European Conference on Antennas and Propagation (EuCAP 2009), page(s):
949 – 955, 2009.
3. James, J. R. and P. S. Hall, (1989). Handbook of Microstrip Antennas,
London, UK: Peter Peregrenus.
4. Garg, R., P. Bhartia, I. Bahl, and A. Ittipiboon, (2001). Microstrip Antenna
Design Handbook, Norwood, MA: Artech House.
5. Denidni, T. A., Lee L., Lim Y., and Rao Q., ―Wideband High Efficiency
Printed Loop Antenna Design for Wireless Communication System‖, IEEE
Transaction on Vehicular Technology, Vol 54, 873-878, 2005.
6. Wong T. P., and Luk K. M., ―A Wide Bandwidth and a Wide Beamwidth
CDMA/GSM Base Station Antenna Array with low Backlobe Radiation‖,
IEEE Transaction on Vehicular Technology, Vol 54, 903-909, 2005.
7. A. H. Ramadan, K. Y. Kabalan, A. El-Hajj, S. Khoury, M. Al-Husseini, ―A
Reconfigurable U-Koch Microstrip Antenna For Wireless Applications‖
Progress In Electromagnetic Research, Vol. 93, 355-367, 2009.
110
8. M.R. Hamid, P. Gardner, P.S. Hall ―Frequency Reconfigurable Log Periodic
patch Array‖ Electronic Letters, Vol.46; No.25, 2010.
9. A. Mirkamali, P. S. Hall, ―Wideband Frequency Reconfiguration of a Printed
Log-Periodic Dipole Array‖ Microwave and Optical Technology Letters, Vol.
52, No. 4, April 2010.
10. A. A. Gheethan, and D. E. Anagnostou, ―The Design of Reconfigurable
Planar Log-Periodic Dipole Array (LPDA) Using Switching Elements‖ IEEE
Antennas and Propagation Soceity International Symposium, Page 1-4, 2009.
11. Mohamad R. Hamid, Peter Gardner, Peter S. Hall, and Farid Ghanem,
―Reconfigurable Vivaldi Antenna‖ Microwave and Optical Technology
Letters, Vol. 52, No. 4, April 2010.
12. Trevor S. Bird, ―Definition and Misuse of Return Loss‖ IEEE Antennas and
Propagation Magazine, Vol. 51, No.2, April 2009
13. D. M. Pozar, (1990), Microwave Engineering, New York: Addison Wesley.
14. H. F. Abu Tarboush, S. Khan, R. Nilavalan, H. S. Al-Raweshidy and D.
Budimir, ―Reconfigurable Wideband Patch Antenna for Cognitive Radio‖,
Loughborough Antennas & Propagation Conference, pp 141-144, 2009.
15. M. Abdallah, L. Le Coq, F. Colombel, G. Le Ray and M. Himdi ―Frequency
tunable monopole coupled loop antenna with broadside radiation pattern‖
Electronics Letter Vol. 45, No. 23, November 2009.
16. H. Wang, X. B. Huang and D. G. Fang, "A Single Layer Wideband U-Slot
Microstrip Patch Antenna Array", IEEE Antennas and Wireless Propagation
Letters, vol. 7, pp. 9-12, 2008.
17. C. Mak, R. Chair, K. Lee, K. Luk and A. Kishk, "Half U-slot patch antenna
with shorting wall", Elect. Letters, vol.39, pp.1779-1780, 2003.
111
18. Y. Li, R. Chair, K.M. Luk and K.F. Lee, "Broadband triangular patch antenna
with a folded shorting wall," IEEE Antennas and Wireless Propagation
Letters, vol. 3, pp. 189-192, 2004.
19. S. Qu and Q. Xue, "A Y-Shaped Stub Proximity Coupled V-Slot Microstrip
Patch Antenna", IEEE Antennas and Wireless Propagation Letters, vol. 6, pp.
40-42, 2007.
20. J. Anguera, C. Puente, C. Borja and J. Soler, "Dual-Frequency Broadband-
Stacked Microstrip Antenna Using a Reactive Loading and a Fractal-Shaped
Radiating Edge", IEEE Antennas and Wireless Propagation Letters, vol. 6,
pp. 309-312, 2007.
21. Azhari Asrokin (2007), Design and Developement of Dual Band Microstrip
Antenna Using Scaling Factor and Inset Feed for Wireless Local Area
Network Application. Master Thesis: Universiti Teknologi Malaysia.
22. M. K. A. Rahim, M. R. Ahmad, A. Asrokin, M. Z. A. A. Aziz, ―The design of
UWB antenna using log-periodic technique‖ Loughborough Antenna &
Propagation Conference, Loughborough, pp. 217-220, 2006.
23. H. Nouri, J. Nourinia, and Ch. Ghobadi, ―Multiband printed Dipole Antenna
with Log-Periodic Toothed Structure for WLAN/WIMAX Applications‖
Microwave and Optical Technology Letters, Vol. 53, No. 3, March 2011.
24. E. Avila-Navarro, J. M. Blanes, J. A. Carrasco, C. Reig, and E. A. Navarro,
―A New Bi-Faced Log-Periodic Antenna‖ Microwave and Optical
Technology Letters, Vol. 48, No. 2, February 2006.
25. Shau-Gang Mao, Shiou-Li Chen, and Jen-Chun Yeh, ―Broadband Series-fed
Printed Dipole Arrays with Mutual Coupling‖ Microwave and Optical
Technology Letters, Vol. 49, No. 5, May 2007.
112
26. Thomas A. Milligan, (2005) Modern Antenna Design: Second Edition, John
Wiley & Sons Publications.
27. Terence Wu, Rong Lin Li, Soon Young Eom, Seong Sik Myoung,―
Switchable Quad-Band Antennas for Cognitive Radio Base Station
Applications‖ IEEE Transactions on Antennas and Propagations, Vol. 58,
No. 5, May 2010.
28. N. Romano, G. Prisco, F. Soldovieri, ―Design of a Reconfigurable Antenna
for Ground Penetrating Radar Applications‖ Progress In Electromagnetics
Research, PIER 94, 1-18, 2009.
29. M. F. Jamlos, T. A. Rahman, and M. R. Kamarudin, ―Adaptive Beam
Steering of RLSA Antenna with RFID Technology‖ Progress In
Electromagnetics Research, Vol. 108, 65-80, 2010.
30. B.-Z. Wang, S. Xiao and J. Wang, ―Reconfigurable patch- antenna design for
wideband wireless communication systems‖ IET Microwave Antennas
Propagation, 1, (2), pp. 414–419, 2007.
31. Michael P. Daly, J. T. Bernhard, “Beamsteering in Pattern Reconfigurable
Arrays Using Directional Modulation” IEEE Transactions on Antennas and
Propagation, vol. 58, no. 7, July 2010.
32. Alkanhal, M. A. S. and A. F. Sheta, ―A novel dual-band reconfigurable
square-ring microstrip antenna," Progress In Electromagnetics Research,
PIER 70, 337-349, 2007.
33. M. F. Ismail, M. K. A. Rahim, F. Zubir and O. Ayop, ―Log-Periodic Patch
Antenna with Tunable Frequency‖ European Conference on Antennas and
Propagation (EuCAP), pp. 1-5, 2011.
113
34. Keng-Hsien Chen, Sung-Jung Wu, Cheng-Hung Kang, Chao-Kai Chan and
Jenn-Hwan Tarng, ―A Frequency Reconfigurable Slot Antenna Using PIN
Diodes‖ Asia Pacific Microwave Conference (APMC), pp. 1930-1933, 2009.
35. Xue-Song Yang, Bing-Zhong Wang, Weixia Wu, and Shaoqiu Xiao, “Yagi
Patch Antenna with Dual-Band and Pattern Reconfigurable Characteristics”
IEEE Antennas and Wireless Propagation Letters, vol. 6, 2007
36. G. Monti, L. Corchia, and L. TarriconeJ. ―Patch Antenna with
Reconfigurable Polarization‖ Progress In Electromagnetics Research C, Vol.
9, 13-23, 2009
37. W. B. Wei, Q. Z. Liu, Y. Z. Yin, and H. J. Zhou, ―Reconfigurable Microstrip
Patch Antenna with Switchable Polarization‖ Progress In Electromagnetics
Research, PIER 75, 63–68, 2007.
38. Parihar, M.S., Basu, A., Koul, S.K., ―Polarization reconfigurable microstrip
antenna‖ IEEE Asia Pacific Microwave Conference, Page(s): 1918 – 1921,
2009.
39. Y. Raedi, S. Nikmehr, and A. Poorziad, ―A Novel Bandwidth Enhancement
Technique for X-band RF MEMS Actuated Reconfigurable Reflectarray‖
Progress In Electromagnetics Research, Vol. 111, 179-196, 2011
40. M. T. Ali, T. A. Rahman, M. R. Kamarudin and M. N. Md Tan ―A Planar
Antenna Array With Separated Feed Line For Higher Gain and Sidelobe
Reduction‖ Progress In Electromagnetics Research C, Vol. 8, 69-82, 2009.
41. B.-H. Sun, S.-G. Zhou, Y.-F. Wei, and Q.Z. Liu, ―Modified Two-Element
Yagi-Uda Antenna with Tunable Beams‖ Progress In Electromagnetics
Research, Vol. 100, 175-187, 2010.
42. Symeon Nikolaou, B. Ramana, Cesar Lugo, C. Ileana, Dane C. Thompson,
E.Ponchak et al. ―Pattern and Frequency Reconfigurable Annular Slot
114
Antenna Using PIN Diodes.‖ IEEE Transactions on Antennas and
Propagation, Vol. 54, No. 2, February 2006: 439—448
43. Ouyang, J., F. Yang, S. W. Yang, Z. P. Nie, and Z. Q. Zhao, ―A novel
radiation pattern and frequency reconfigurable microstrip antenna on a thin
substrate for wide-band and wide-angle scanning application," Progress In
Electromagnetics Research, Vol. 4, 167-172, 2008.
44. G. H. Huff, J. Feng, S. Zhang, and J. T. Bernhard, ―A Novel Radiation
Pattern and Frequency Reconfigurable Single Turn Square Spiral Microstrip
Antenna‖ IEEE Microwave and Wireless Components Letters, Vol. 13, No. 2,
February 2003
45. Zhang, J., A. Wang, and P. Wang, ―A survey on reconfigurable antennas,"
Proceedings of the International Conference on Microwave and Millimeter
Wave Technology, Vol. 3, 1156-1159, April 21-24, 2008.
46. Jong-Hyuk Lim, Gyu-Tae Back, Young-Il Ko, Chang-Wook Song, and Tae-
Yeoul Yun, “A Reconfigurable PIFA Using a Switchable PIN-Diode and a
Fine-Tuning Varactor for USPCS/WCDMA/m-WiMAX/WLAN” IEEE
Transactions on Antennas and Propagation, Vol. 58, No. 7, July 2010.
47. W. E. Doherty Jr., R. D. Joos, (1998). The PIN Diode Circuit Designers’
Handbook, Watertown MA: Microsemi Corporation.
48. Gunter Kompa, (2005) Practical Microstrip Design and Application. Artech
House, Norwood.
49. B. A. Syrett, ―A Broad-Band Element for Microstrip Bias or Tuning Circuits‖
IEEE Transactions on Microwaves Theory and Techniques, Vol.MTT-28, No
8, August 1980.
50. R. DuHamel and D. Isbell, ―Broadband Logarithmically Periodic Antenna
Structures,‖ IRE International Convention Record, vol. 5, pp. 119–128, Mar
1957.
115
51. B. L. Ooi, K. Chew, and M. S. Leong ―Log-Periodic Slot Antenna Array‖,
Microwave and Optical Technology Letters, Vol. 25, No. 1, Page: 24-27,
April 5 2000.
52. M. N. A. Karim, M. K. A. Rahim, H. A. Majid, O. Ayop, M. Abu and F.
Zubir, ―Log-Periodic Fractal Koch Antenna for UHF Band Applications‖,
Progress In Electromagnetics Research, PIER 100, 201-218, 2010
53. A. Scheuring, A. Stockhausen, S. Wuensch, K. Ilin, M. Siegel, ―A new
analytical Model for log-periodic Terahertz Antennas‖ European Conference
on Antennas and Propagation (EuCAP), pp. 1-5, 2010
54. M. R. Kamarudin and P. S. Hall, ―Switched Beam Antenna Array with
Parasitic Elements‖ Progress In Electromagnetics Research B, Vol. 13, 187-
201, 2009.
116
APPENDIX A
Author’s Publication
Journal
1. M. F. Ismail, M. K. A. Rahim, H. A. Majid, F. Zubir and O. Ayop,
“Wideband Frequency Reconfiguration Using Switchable PIN Diode”
Microwave and Optical Technology Letters, 2011. – Submitted
2. M. F. Ismail, M. K. A. Rahim & H. A. Majid, “A Wideband Frequency
Reconfigurable Log-Periodic” Jurnal Teknologi, 2011. – Submitted.
Paper Conferences
1. M. F. Ismail, M.K.A. Rahim, S.H.S. Ariffin, S.K.S. Yusuf, M.R. Kamarudin,
“Simulation of Reconfigurable Log-Periodic Microstrip Antenna”
International Symposium on Antenna and Propagations (ISAP), Macao
China, 2010.
2. M. F. Ismail, M. K. A. Rahim, F. Zubir, O. Ayop, “Log-Periodic Patch
Antenna with Tunable Frequency” 5th
European Conference on Antenna and
Propagation (EuCAP), Rome Italy, 2011.
3. M. F. Ismail, M. K. A. Rahim, H. A. Majid, “The Investigation of PIN Diode
Switch on Reconfigurable Antenna” IEEE International RF and Microwave
Conference (RFM), Negeri Sembilan, 2011.
117
APPENDIX B
PIN Diode Datasheet – Infineon BAR64
2007-12-111
BAR64...
Silicon PIN Diode• High voltage current controlled RF resistor for RF attenuator and switches
• Frequency range above 1 MHz up to 6 GHz• Very low capacitance at zero volt reverse bias at frequencies above 1 GHz (typ. 0.17 pF)
• Low forward resistance (typ. 2.1 Ω @ 10 mA)• Very low signal distortion• Pb-free (RoHS compliant) package1)
• Qualified according AEC Q101
BAR64-02LRHBAR64-02VBAR64-03W
BAR64-05BAR64-05W
BAR64-06BAR64-06W
BAR64-07BAR64-04BAR64-04W
Type Package Configuration LS(nH) MarkingBAR64-02LRH BAR64-02V BAR64-03W BAR64-04 BAR64-04W BAR64-05 BAR64-05W BAR64-06 BAR64-06W BAR64-07
TSLP-2-7 SC79 SOD323 SOT23 SOT323 SOT23 SOT323 SOT23 SOT323 SOT143
single, leadless single single series series common cathode common cathode common anode common anode parallel pair
0.4 0.6 1.8 1.8 1.4 1.8 1.4 1.8 1.4 2
O O 2 blue PPs PPs PRs PRs PSs PSs PTs
1Pb-containing package may be available upon special request
2007-12-112
BAR64...
Maximum Ratings at TA = 25°C, unless otherwise specifiedParameter Symbol Value UnitDiode reverse voltage VR 150 V
Forward current IF 100 mA
Total power dissipation BAR64-02LRH, TS ≤ 135 °C BAR64-02V, TS ≤ 125 °C BAR64-03W, BAR64-07, TS ≤ 25 °C BAR64-04, -05, -06, TS ≤ 65 °C BAR64-04W, -05W, -06W, TS ≤ 115 °C
Ptot 250250250250250
mW
Junction temperature Tj 150 °C
Operating temperature range Top -55 ... 125
Storage temperature Tstg -55 ... 150
Thermal ResistanceParameter Symbol Value UnitJunction - soldering point1) BAR64-02LRH BAR64-02V, -04W, -05W, -06W BAR64-03W BAR64-04, -05, -06 BAR64-07
RthJS ≤ 60≤ 140≤ 370≤ 340≤ 290
Electrical Characteristics at TA = 25°C, unless otherwise specifiedParameter Symbol Values Unit
min. typ. max.DC CharacteristicsBreakdown voltage I(BR) = 5 µA
V(BR) 150 - - V
Forward voltage IF = 50 mA
VF - - 1.1
1For calculation of RthJA please refer to Application Note Thermal Resistance
2007-12-113
BAR64...
Electrical Characteristics at TA = 25°C, unless otherwise specifiedParameter Symbol Values Unit
min. typ. max.AC CharacteristicsDiode capacitance VR = 20 V, f = 1 MHz VR = 0 V, f = 100 MHz VR = 0 V, f = 1...1.8 GHz, BAR64-02LRH VR = 0 V, f = 1...1.8 GHz, all other
CT ----
0.230.3
0.130.17
0.35
---
pF
Reverse parallel resistance VR = 0 V, f = 100 MHz VR = 0 V, f = 1 GHz VR = 0 V, f = 1.8 GHz
RP ---
1043
---
kΩ
Forward resistance IF = 1 mA, f = 100 MHz IF = 10 mA, f = 100 MHz IF = 100 mA, f = 100 MHz
rf ---
12.52.1
0.85
202.8
1.35
Ω
Charge carrier life time IF = 10 mA, IR = 6 mA, measured at IR = 3 mA, RL = 100 Ω
τ rr - 1550 - ns
I-region width WI - 50 - µmInsertion loss1) IF = 3 mA, f = 1.8 GHz IF = 5 mA, f = 1.8 GHz IF = 10 mA, f = 1.8 GHz
IL ---
0.320.230.16
---
dB
Isolation1) VR = 0 V, f = 0.9 GHz VR = 0 V, f = 1.8 GHz VR = 0 V, f = 2.45 GHz VR = 0 V, f = 5.6 GHz
ISO ----
2217
14.58.5
----
1BAR64-02LRH in series configuration, Z = 50 Ω
2007-12-114
BAR64...
Diode capacitance CT = ƒ (VR)f = Parameter
0 2 4 6 8 10 12 14 16 V 20
VR
0.1
0.2
0.3
0.4
0.5
pF
0.7
CT
1 MHz100 MHz1 GHz1.8 GHz
Reverse parallel resistance RP = ƒ(VR)f = Parameter
0 5 10 15 20 25 30 V 40
VR
-1 10
0 10
1 10
2 10
3 10
4 10
KOhm
Rp
100 MHz1 GHz1.8 GHz
Forward resistance rf = ƒ (IF)f = 100MHz
10 -2 10 -1 10 0 10 1 10 2 mA
IF
-1 10
0 10
1 10
2 10
3 10
Ohm
RF
Forward current IF = ƒ (VF)TA = Parameter
0 0.2 0.4 0.6 0.8 V 1.2
VF
-6 10
-5 10
-4 10
-3 10
-2 10
-1 10
0 10 A
I F
-40 °C25 °C85 °C125 °C
2007-12-115
BAR64...
Intermodulation intercept pointIP3 = ƒ (IF); f = Parameter
10 -1 10 0 10 1 mA
IF
1 10
2 10
dBm
IP3
f=1800MHz f=900MHz
Forward current IF = ƒ (TS)BAR64-02LRH
0 30 60 90 120 °C 165
TS
0
10
20
30
40
50
60
70
80
90
100
mA120
I F
Forward current IF = ƒ (TS)BAR64-02V
0 15 30 45 60 75 90 105 120 °C 150
TS
0
10
20
30
40
50
60
70
80
90
100
mA120
I F
Forward current IF = ƒ (TS)BAR64-04, BAR64-05, BAR64-06
0 15 30 45 60 75 90 105 120 °C 150
TS
0
10
20
30
40
50
60
70
80
90
100
mA120
I F
2007-12-116
BAR64...
Forward current IF = ƒ (TS)BAR64-04W, BAR64-05W, BAR64-06W
0 15 30 45 60 75 90 105 120 °C 150
TS
0
10
20
30
40
50
60
70
80
90
100
mA120
I F
Permissible Puls Load RthJS = ƒ (tp)BAR64-02LRH
10 -6 10 -5 10 -4 10 -3 10 -2 10 0 s
tp
-1 10
0 10
1 10
2 10
K/W
Rth
JS
0.50.20.10.050.020.010.005D = 0
Permissible Pulse LoadIFmax/ IFDC = ƒ (tp) BAR64-02LRH
10 -6 10 -5 10 -4 10 -3 10 -2 10 0 s
tp
0 10
1 10
2 10
-
I Fm
ax/I F
DC
D = 00.0050.010.020.050.10.20.5
2007-12-117
BAR64...
Permissible Puls Load RthJS = ƒ (tp)BAR64-02V
10 -6 10 -5 10 -4 10 -3 10 -2 10 0 s
tp
-1 10
0 10
1 10
2 10
3 10
K/W
Rth
JS
0.50.20.10.050.020.010.005D = 0
Permissible Pulse LoadIFmax/ IFDC = ƒ (tp)BAR64-02V
10 -6 10 -5 10 -4 10 -3 10 -2 10 -1 10 1 s
tp
0 10
1 10
2 10
-
I Fm
ax /
I FD
C
D = 00.0050.010.020.050.10.20.5
Permissible Puls Load RthJS = ƒ (tp)BAR64-04, BAR64-05, BAR64-06
10 -6 10 -5 10 -4 10 -3 10 -2 10 0 s
tP
-1 10
0 10
1 10
2 10
3 10
K/W
Rth
JS
0.50.20.10.050.020.010.005D = 0
Permissible Pulse LoadIFmax/ IFDC = ƒ (tp)BAR64-04, BAR64-05, BAR64-06
10 -6 10 -5 10 -4 10 -3 10 -2 10 0 s
tP
0 10
1 10
2 10
-
I Fm
ax/I F
DC
D = 00.0050.010.020.050.10.20.5
2007-12-118
BAR64...
Permissible Puls Load RthJS = ƒ (tp)BAR64-04W, BAR64-05W, BAR64-06W
10 -6 10 -5 10 -4 10 -3 10 -2 10 0 s
tP
-1 10
0 10
1 10
2 10
3 10
K/W
Rth
JS
0.50.20.10.050.020.010.005D = 0
Permissible Pulse LoadIFmax/ IFDC = ƒ (tp)BAR64-04W, BAR64-05W, BAR64-06W
10 -6 10 -5 10 -4 10 -3 10 -2 10 -1 10 1 s
tP
0 10
1 10
2 10
-
I Fm
ax/I F
DC
D = 00.0050.010.020.050.10.20.5
Insertion loss IL = -|S21|2 = ƒ(f)IF = ParameterBAR64-02LRH in series configuration, Z = 50Ω
0 1 2 3 4 GHz 6
f
-0.4
-0.35
-0.3
-0.25
-0.2
-0.15
-0.1
dB
0
|S21
|2
3 mA
5 mA
10 mA
100 mA
Isolation ISO = -|S21|2 = ƒ(f)VR = ParameterBAR64-02LRH in series configuration, Z = 50Ω
0.5 1.5 2.5 3.5 4.5 GHz 6.5
f
-30
-25
-20
-15
-10
dB
0
|S21
|2
0 V1 V10 V
2007-12-119
BAR64...Package SC79
Package Out l ine
Foot Pr int
Marking Layout (Example)
Standard Packing
Reel ø180 mm = 3.000 Pieces/ReelReel ø180 mm = 8.000 Pieces/Reel (2 mm Pitch)Reel ø330 mm = 10.000 Pieces/Reel
±0.1
1.6
0.31
2
markingCathode
0.8 ±0.1
10˚M
AX.
±0.1
1.2
A
±0.05
10˚M
AX.
0.13
A0.2 M
+0.05-0.03
±0.040.55
±0.0
50.
20.35
0.35
1.35
BAR63-02VType code
Cathode markingLaser marking
2
0.66
0.93
0.4
1.33 1.96
8
0.2
Cathodemarking
4
Cathodemarking
Standard Reel with 2 mm Pitch
2005, JuneDate code
2007-12-1110
BAR64...
Date Code marking for discrete packages with one digi t (SCD80, SC79, SC751)) CES-Code
1) New Marking Layout for SC75, implemented at October 2005.
.
Month 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014
01 a p A P a p A P a p A P
02 b q B Q b q B Q b q B Q
03 c r C R c r C R c r C R
04 d s D S d s D S d s D S
05 e t E T e t E T e t E T
06 f u F U f u F U f u F U
07 g v G V g v G V g v G V
08 h x H X h x H X h x H X
09 j y J Y j y J Y j y J Y
10 k z K Z k z K Z k z K Z
11 l 2 L 4 l 2 L 4 l 2 L 4
12 n 3 N 5 n 3 N 5 n 3 N 5
2007-12-1111
BAR64...Package SOD323
Package Out l ine
Foot Pr int
Marking Layout (Example)
Standard Packing
Reel ø180 mm = 3.000 Pieces/ReelReel ø330 mm = 10.000 Pieces/Reel
BAR63-03WType code
Cathode markingLaser marking
0.8
0.8
0.6
1.7
markingCathode
±0.2
2.5
0.25
0.3
1
-0.05
M A
+0.1
+0.2
2
1.25-0.1
+0.05-0.2
1.7
0.3
0.15-0.06+0.1
0±0.05
+0.2
-0.1
A
0.9+0.2-0.1
±0.1
50.
45
0.24
82.
9
1
2
1.350.65Cathode
marking
2007-12-1112
BAR64...Package SOT143
Package Out l ine
Foot Pr int
Marking Layout (Example)
Standard Packing
Reel ø180 mm = 3.000 Pieces/ReelReel ø330 mm = 10.000 Pieces/Reel
RF s 2005, JuneDate code (YM)
BFP181Type code
56
Pin 1
0.8 0.81.20.
91.
10.
9
1.2
0.8
0.8
0.8 -0.05+0.1
1.9
1.7
±0.12.9
+0.1-0.050.4
0.1 MAX.
1 2
34
0.25 M B
±0.11
10˚ M
AX
.
0.15
MIN
.
0.2 AM
2.4
±0.1
5
0.2 10˚ M
AX
.
A
1.3
±0.1
0...8˚
0.08...0.15
2.6
4
3.15Pin 1
8
0.2
1.15
B
Manufacturer
2007-12-1113
BAR64...Package SOT23
Package Out l ine
Foot Pr int
Marking Layout (Example)
Standard Packing
Reel ø180 mm = 3.000 Pieces/ReelReel ø330 mm = 10.000 Pieces/Reel
EH sBCW66Type code
Pin 1
0.80.
90.
91.
3
0.8 1.2
0.25 M B C
1.9
-0.05+0.10.4
±0.12.9
0.95C
B
0...8˚
0.2 A
0.1 MAX.
10˚ M
AX
.
0.08...0.15
1.3
±0.1
10˚ M
AX
.
M
2.4
±0.1
5
±0.11
A
0.15
MIN
.
1)
1) Lead width can be 0.6 max. in dambar area
1 2
3
3.15
4
2.652.13
0.9
8
0.2
1.15Pin 1
Manufacturer
2005, JuneDate code (YM)
2007-12-1114
BAR64...Package SOT323
Package Out l ine
Foot Pr int
Marking Layout (Example)
Standard Packing
Reel ø180 mm = 3.000 Pieces/ReelReel ø330 mm = 10.000 Pieces/Reel
1.25
±0.1
0.1 MAX.
2.1±
0.1
0.15 +0.1-0.05
0.3+0.1
±0.10.9
1 2
3A
±0.22
-0.05
0.650.65
M
3x0.1
0.1
MIN
.
0.1
M0.2 A
0.24
2.15 1.1
8
2.3
Pin 1
Pin 1
2005, JuneDate code (YM)
BCR108WType code
0.6
0.8
1.6
0.65
0.65
Manufacturer
2007-12-1115
BAR64...Package TSLP-2-7
1
2
±0.050.6
1
2
±0.0
50.
65
±0.0
350.
251)
1±0.
05
0.05 MAX.
+0.010.39 -0.03
1) Dimension applies to plated terminal
Cathodemarking
1)±0.0350.5
Bottom viewTop view
Package Out l ine
Foot Pr int
Marking Layout (Example)
Standard Packing
Reel ø180 mm = 15.000 Pieces/ReelReel ø330 mm = 50.000 Pieces/Reel (optional)
For board assembly information please refer to Infineon website "Packages"
0.450.
275
0.27
50.
3750.
925
Copper Solder mask Stencil apertures
0.35
1
0.6
0.35
0.3
0.76
4
1.16
0.5
Cathodemarking
8
BAR90-02LRHType code
Cathode markingLaser marking
2007-12-1116
BAR64...
Edition 2006-02-01Published byInfineon Technologies AG81726 München, Germany© Infineon Technologies AG 2007.All Rights Reserved. Attention please! The information given in this dokument shall in no event be regarded as a guarantee of conditions or characteristics (Beschaffenheitsgarantie). With respect to anyexamples or hints given herein, any typical values stated herein and/or any informationregarding the application of the device, Infineon Technologies hereby disclaims anyand all warranties and liabilities of any kind, including without limitation warranties of non-infringement of intellectual property rights of any third party. Information For further information on technology, delivery terms and conditions and prices please contact your nearest Infineon Technologies Office (www.infineon.com). Warnings Due to technical requirements components may contain dangerous substances.For information on the types in question please contact your nearest Infineon Technologies Office.Infineon Technologies Components may only be used in life-support devices orsystems with the express written approval of Infineon Technologies, if a failure ofsuch components can reasonably be expected to cause the failure of that life-support device or system, or to affect the safety or effectiveness of that device or system. Life support devices or systems are intended to be implanted in the human body, or to support and/or maintain and sustain and/or protect human life. If they fail,it is reasonable to assume that the health of the user or other persons may be endangered.
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