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SIM UNIVERSITY

SCHOOL OF SCIENCE AND TECHNOLOGY

DEVELOPMENT OF MINIATURIZED

MULTI-BAND ANTENNAS FOR MOBILE

DEVICES

STUDENT NAME : ZHANG TAO

STUDENT PI : K0706404

SUPERVISOR : DR SHEN ZHONG XIANG

PROJECT CODE : JAN2009/BEHE/49

Submitted to the School of Science and Technology

in partial fulfilment of the requirements for the degree of

Bachelor of Engineering in Electronics

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November 2009

ABSTRACT

All of today's wireless communication systems contain one key element, an antenna of someform. This antenna serves as the transducer between the controlled energy residing within the

system and the radiated energy existing in free space. In designing wireless systems,

engineers must choose an antenna that meets the system's requirements to firmly close the

link between the remote points of the communications system.

This project is to develop of miniaturized multi-band antennas for mobile devices

mainly design of square microstrip patch antenna. Basically the square microstrip patch

antennas are analyzed and detailed exploration is conducted to determine the antenna's

properties. The current distributions, bandwidth, radiation patterns and gain of the antenna

are discussed.

In addition, the time domain performance of the proposed antenna is also evaluated in

simulations. The research results show that this kind of square microstrip patch antenna can

radiate and receive short pulse signals without distortion.

The result of study indicates that the improved antenna can realize good bandwidth

performance as the square microstrip patch antenna, and it has low-cost, simple structural

characteristics. The miniature square microstrip patch antenna and the improved type are

suitable for the wireless communication systems, satellite communication systems and

mobile communications systems with good prospects.

I will summarise the accomplishment, performances of the design and the problemsencountered during the whole project. Further improvements and recommendations to the

project were also proposed.

ENG499 CAPSTONE PROJECT REPORT 2

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TABLE OF CONTENTS

1.

Introduction 9

1.1 Overview of Microstrip Antenna .................................................................. 101.2 Project Objective ......................................................................................... 11

1.3 Proposed Approach .................................................................................... 11

1.4 Organization of the Thesis .......................................................................... 11

Literature Review 12

2.1 Introduction Microstrip Patch Antenna .......................................................12

2.2 Advantages and Disadvantages ................................................................. 13

2.3 Feeding Methods ........................................................................................ 14

2.3.1 Microstrip Line Feed ............................................................................. 14

2.3.2 Coaxial Feed ......................................................................................... 15

2.3.3 Aperture Coupled Feed ......................................................................... 16

2.3.4 Proximity Coupled Feed ....................................................................... 16

2.4 Method of Analysis ...................................................................................... 17

2.4.1 Transmission Line Model...................................................................... 17

2.4.2 Cavity Model......................................................................................... 20

2.5 Multi-Band Antenna .................................................................................... 212.5.1 Definition of Multi-Band Antenna .......................................................... 21

2.5.2 Design of Multi-Band Antenna ............................................................. 22

2.6 Antenna Miniaturization Techniques ........................................................... 23

Square Microstrip Patch Antenna 26

3.1 Introduction ................................................................................................ 26

3.2 Design Specifications ................................................................................. 26

3.3 Design of Square Microstrip Antenna Using Theory Calculation .................26

3.3.1 Design Procedure ................................................................................ 27

3.4 Design of Square Microstrip Antenna using IE3D Simulator .......................29

3.4.1 Results of Simulation ............................................................................ 30

Miniaturization Antenna Design 34

4.1 Introduction ............................................................................................... 34

4.2 Design Description ...................................................................................... 34

4.2.1 Reduce dielectric constant technique .................................................34

4.2.2 Square patch with shorting GND technique ........................................344.2.3 Increase of substrate thickness technique ...........................................35


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4.2.4 Double layer half wave patch technique .............................................. 35

4.2.5 Combination of shorting GND and increase substrate thickness

technique ...................................................................................................... 35

4.3 Results of Simulation using IE3D Simulator ................................................36

Conclusions 51

5.1 Thesis Contributions ................................................................................... 51

5.2 Future Work ................................................................................................ 52

Reflections 53

Acknowledgements 55

References 56


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List of Figures

2-1 Structure of a microstrip patch antenna 11

2-2 Common shapes of microstrip patch elements 11

2-3 Microstrip line feed 13

2-4 Probes fed rectangular microstrip patch antenna 142-5 Aperture-coupled feed 15

2-6 Proximity-coupled feed 16

2-7 Microstrip line 16

2-8 Electric field lines 16

2-9 Microstrip patch antennas 17

2-10 Top view of antenna 18

2-11 Side view of antenna 182-12 Charge distribution and current density creation on the microstrip patch 19

2-13 Patch with slots yields longer patch length 22

2-14 Circular patch with slots and high dielectric constant substrate 22

2-15 Folding of a half- wave path 23

2-16 Folding of a quarter-wave patch 23

2-17 Inverted-F patch antenna post 23

2-18 Circular patch with shorting 232-19 Circular polarized wire antenna 24

2-20 Antenna height reduction utilizing photonic hand-gap material 24

3-1 (a) Top view of microstrip patch antenna (b) Side view of microstrip

patch antenna (c) Overall design of microstrip patch antenna 27

3-2 Patch designed in IE3D software 29

3-3 S-parameter display for S (1, 1) 29

3-4 S-parameter displays for S (2, 2) 29

3-5 Smith Chart display for S (1, 1) 30

3-6 Smith Chart display for S (2, 2) 30

3-7 VSWR for port 1 30

3-8 VSWR for port 2 30

3-9 3D current distribution 31

3-10 Antenna and radiationefficiency vs frequency 31

3-11 Gain vs frequency 32

3-12 Total field directivity vs. frequency 32


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4-1 Shorted GND patch drawing 33

4-2 Shorted GND patch Omit substrate view 33

4-3 Double layer or folded patch drawing 34

4-4 S-parameters for S (1, 1) comparison: (a) Original patch (b) Reduce dielectric

constant patch (c) Shorting GND patch (d) Increase substrate thickness patch

(e) Double layer half-wave patch (f) Combine methods patch 35

4-5 S-parameters for S (2, 2) comparison: (a) Original patch (b) Reduce dielectric

constant patch (c) Shorting GND patch (d) Increase substrate thickness patch

(e) Double layer half-wave patch (f) Combine methods patch 36

4-6 VSWR for port 1 comparison: (a) Original patch (b) Reduce dielectric

constant patch (c) Shorting GND patch (d) Increase substrate thickness

patch (e) Double layer half-wave patch (f) Combine methods patch

38

39

4-7 VSWR for port 2 comparison: (a) Original patch (b) Reduce dielectric



39

4-8 Smith Chart S (1, 1) comparison: (a) Original patch (b) Reduce dielectric



40

4-9 Smith Chart S (2, 2) comparison: (a) Original patch (b) Reduce dielectric




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41

4-10 Total field gain vs frequency comparison: (a) Original patch (b) Reduce

dielectric constant patch (c) Shorting GND patch (d) Increase substrate

thickness patch (e) Double layer half-wave patch (f) Combine methods

patch

43

44

4-11 Total voltage field gain vs frquency comparison: (a) Original patch (b)

Reduce dielectric constant patch (c) Shorting GND patch (d) Increase

substrate thickness patch (e) Double layer half-wave patch (f) Combine

methods patch

45

4-12 Total field directivity vs frequency comparison: (a) Original patch (b)

Reduce dielectric constant patch (c) Shorting GND patch (d) Increase

substrate thickness patch (e) Double layer half-wave patch (f) Combine

methods patch

464-13 Antenna and radiation efficiency vs frequency comparison: (a) Original

patch (b) Reduce dielectric constant patch (c) Shorting GND patch (d)

Increase substrate thickness patch (e) Double layer half-wave patch (f)

Combine methods patch

48


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List of Tables

4.1 Comparison result of S-parameter 35

4.2 Comparison result of VSWR 38

4.3 Comparison result of total field gain 43


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4.4 Comparison result of total voltage field gain 44

4.5 Comparison result of total field directivity 46

4.6 Comparison result of antenna and radiation efficiency 47

4.7 Comparison of each technique overall performance 49

Chapter 1

Introduction

Modern and future wireless systems are placing greater demands on antenna designs. Many

systems now operate in two or more frequency bands, requiring dual or triple band operation


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of fundamentally narrow band antennas. These include, satellite navigation systems, cellular

systems, wireless LAN and combination of these systems.

One of the most popular antennas employed in mobile communication systems is the

monopole antenna and its family. The monopole antennas are convenient to match to 50

ohms, and are unbalanced. The square microstrip patch antenna reported for multi-bands for

handsets is only about 0.05 times the wavelength of the lowest operating frequency.

This antenna is not only capable of multiband operations, but also possesses

omnidirectional radiation patterns for all operation bands. The impedance BW covers almost

all the present wireless systems of GSM (880-960MHz), including Digital Communication

Systems (DCS, 1720-1880MHz), Personal Communication Systems (PCS, 1850-1990MHz)

Universal Mobile communication systems (UMTS, 1920-2170MHz) and Industrial Science

Band (ISM, 2400-2484MHz). Its desired characteristics, such as low cost, ease of

manufacture, compact size, very wide BW, acceptable radiation efficiency, and

omnidirectional radiation patterns, makes the proposed antenna very attractive for mobile

communications.

1.1 Overview of Microstrip Antenna

A microstrip antenna consists of conducting patch on a ground plane separated by

dielectric substrate. This concept was undeveloped until the revolution in electronic

circuit miniaturization and large-scale integration in 1970[1]. After that many authors have

described the radiation from the ground plane by a dielectric substrate for different

configurations. The early work of Munson on micro strip antennas for use as a low profile

flush mounted antennas on rockets and missiles showed that this was a practical concept for

use in many antenna system problems. Various mathematical models were developed for this

antenna and its applications were extended to many other fields. The number of papers,

articles published in the journals for the last ten years, on these antennas shows the

importance gained by them. The micro strip antennas are the present day antenna designerschoice. Low dielectric constant substrates are generally preferred for maximum radiation.

The conducting patch can take any shape but rectangular and circular configurations are the

most commonly used configuration. Other configurations are complex to analyze and require

heavy numerical computations. A microstrip antenna is characterized by its length, width,

input impedance, and gain and radiation patterns.

Various parameters of the microstrip antenna and its design considerations were

discussed in the subsequent chapters. The length of the antenna is nearly half wavelength in


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the dielectric; it is a very critical parameter, which governs the resonant frequency of the

antenna. There are no hard and fast rules to find the width of the patch .

1.2 Project Objective

The project objective is to develop a miniaturized multi-band antenna with a smaller

dimension and get better performance. Not only desired for GSM 900, 1800, 1900, UMTS

and WLAN applications to contribute effectively to standards for 3 rd generation mobile

devices but also required in modern personal wireless communication devices.

1.3 Proposed Approach

The main approach would be to conduct at the SIM University Electronics laboratory. The

course required to re-design a smaller multi-band antenna. Existing miniaturization multi-

band antennas technique will be analyzed and see their performances from data.

The requirements of this project will be from literature review, and the guidance from

the project supervisor. The project will involve software which is available in the internet. A

systematic procedure of tests and measurement will have to be carrying out to ensure

accuracy of the test result. Assistant and guidance will be provided by Nanyang

Technological University. This project is scheduled for one year.

1.4 Organization of the Thesis

An introduction to microstrip antennas was given in Chapter 2.Apart from the advantages and

disadvantages, the various feeding techniques and models of analysis were listed.

Chapter 3 deals with design of square microstrip patch antenna and provides

Information about ID3E Software for simulation ofsquare microstrip patch antenna

which will be used for cross verification of results for designed antennas.

Chapter 4 provides the design and development of miniaturization square microstrip

patch antenna and verification of the results fordesigned antennas.Finally, Chapter 5 summarizes the contribution of this thesis and suggests areas for

future work.

Chapter 2


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Literature Review

2.1 Introduction Microstrip Patch Antenna

Fundamentally, a microstrip patch antenna consists of a radiating patch on one side of a

dielectric substrate, and a ground plane on the other side as shown in Figure 2-1. The patch is

generally made of high conducting material such as copper or gold and no restriction on theshape. The radiating patch and the feed lines are usually photo etched on the dielectric

substrate.

Figure 2-1 Structure of a microstrip patch antenna

In order to simplify analysis and performance prediction, the patch is generally

square, rectangular, circular, triangular, and elliptical or some other common shape as shown

in Figure 2-2. For a rectangular patch, the length L of the patch is usually 0.3333o

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Microstrip patch antennas radiate primarily because of the fringing fields between the patch

edge and the ground plane. For good antenna performance, a thick dielectric substrate having

a low dielectric constant is desirable since this provides better efficiency, larger bandwidth

and better radiation. However, such a configuration leads to a larger antenna size. In order to

design a compact Microstrip patch antenna, substrates with higher dielectric constants must

be used which are less efficient and result in narrower bandwidth. Hence a trade-off must be

realized between the antenna dimensions and antenna performance.

2.2 Advantages and Disadvantages

Microstrip patch antennas are increasing in popularity for use in wireless applications due to

their low-profile structure. Therefore they are extremely compatible for embedded antennas

in handheld wireless devices such as cellular phones, pagers etc.

The telemetry and communication antennas on missiles need to be thin and conformal and are

often in the form of microstrip patch antennas. Another area where they have been used

successfully is in Satellite communication. Some of their principal advantages discussed by

Kumar and Ray are given below:

Light weight and low volume.

Low profile planar configuration which can be easily made conformal to

host surface.

Low fabrication cost, hence can be manufactured in large quantities.

Supports both, linear as well as circular polarization.

Can be easily integrated with microwave integrated circuits (MICs).

Capable of dual and triple frequency operations.

Mechanically robust when mounted on rigid surfaces.

Microstrip patch antennas suffer from more drawbacks as compared to conventional

antennas. Some of their major disadvantages discussed by and Garg et al are given below:

Narrow bandwidth. Low efficiency.

Low Gain.

Extraneous radiation from feeds and junctions.

Poor end fire radiator except tapered slot antennas.

Low power handling capacity.

Surface wave excitation.

Microstrip patch antennas have a very high antenna quality factor (Q). It represents the lossesassociated with the antenna where a large Q leads to narrow bandwidth and low efficiency. Q


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can be reduced by increasing the thickness of the dielectric substrate. However, as the

thickness increases, an increasing fraction of the total power delivered by the source goes into

a surface wave. This surface wave contribution can be counted as an unwanted power loss

because it is ultimately scattered at the dielectric bends. That causes degradation of the

antenna characteristics. Other problems like lower gain and lower power handling capacity

can be overcome by using an array configuration for the elements.

2.3 Feeding Methods

Feeding of the microstrip patch antennas can be used by a variety of methods. These methods

can be classified into two categories- contacting and non-contacting. In the contacting

method, the RF power is fed directly to the radiating patch using a connecting element such

as a microstrip line. In the non-contacting scheme, electromagnetic field coupling is done to

transfer power between the microstrip line and the radiating patch. The four most popular

feed techniques used are the microstrip line, coaxial probe; both contacting schemes; aperture

coupling and proximity coupling; both non-contacting schemes.

2.3.1 Microstrip Line Feed

In this type of feed technique, a conducting strip is connected directly to the edge of the

Microstrip patch as shown in Figure 2-3. The conducting strip is smaller in width compared

to the patch. This kind of arrangement has the advantage of the feed can be etched on the

same substrate to provide a planar structure.

Figure 2-3 Microstrip line feed

The purpose of the inset cut in the patch is to match the impedance of the feed line to the

patch without the need for any additional matching element. This can be achieved byproperly controlling the inset position. Hence this is an easy feeding scheme, since it provides


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ease of fabrication and simplicity in modeling as well as impedance matching. However as

the thickness of the dielectric substrate being used, increases, surface waves and spurious

feed radiation also increases, which hampers the bandwidth of the antenna. The feed radiation

also leads to undesired cross polarized radiation.

2.3.2 Coaxial Feed

The Coaxial feed or probe feed is a very common technique used for feeding microstrip patch

antennas. As seen from Figure 2-4, the inner conductor of the coaxial connector extends

through the dielectric and is soldered to the radiating patch, while the outer conductor is

connected to the ground plane.

Figure 2-4 Probe fed rectangular microstrip patch antenna

The main advantage of this type of feeding scheme is that the feed can be placed at any

desired location inside the patch in order to match with its input impedance. This feed method

is easy to fabricate and has low spurious radiation. However, a major disadvantage is that it

provides narrow bandwidth and is difficult to model since a hole has to be drilled in thesubstrate and the connector protrudes outside the ground plane, thus not making it completely

planar for thick substrates (h > 0.02o). Also, for thicker substrates, the increased probe

length makes the input impedance more inductive, leading to matching problems. It is seen

above that for a thick dielectric substrate, which provides broad bandwidth, the microstrip

line feed and the coaxial feed suffer from numerous disadvantages. The non-contacting feed

techniques which have been discussed below, solve these issues.


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2.3.3 Aperture Coupled Feed

In this type of feed technique, the radiating patch and the microstrip feed line are separated

by the ground plane as shown in Figure 2-5. Coupling between the patch and the feed line is

made through a slot or an aperture in the ground plane.

Figure 2-5 Aperture-coupled feed

The coupling aperture is usually centered under the patch, leading to lower cross

polarization due to symmetry of the configuration. The amount of coupling from the feed line

to the patch is determined by the shape, size and location of the aperture. Since the ground

plane separates the patch and the feed line, spurious radiation is minimized. Generally, a high

dielectric material is used for bottom substrate and a thick, low dielectric constant material is

used for the top substrate to optimize radiation from the patch. The major disadvantage of thisfeed technique is that it is difficult to fabricate due to multiple layers, which also increases

the antenna thickness. This feeding scheme also provides narrow bandwidth.

2.3.4 Proximity Coupled Feed

This type of feed technique is also called as the electromagnetic coupling scheme. As shown

in Figure 2-6, two dielectric substrates are used such that the feed line is between the two

substrates and the radiating patch is on top of the upper substrate. The main advantage of thisfeed technique is that it eliminates spurious feed radiation and provides very high bandwidth

(as high as 13%), due to overall increase in the thickness of the microstrip patch antenna.

This scheme also provides choices between two different dielectric media, one for the patch

and one for the feed line to optimize the individual performances.


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Figure 2-6 Proximity-coupled Feed

Matching can be achieved by controlling the length of the feed line and the width to-

line ratio of the patch. The major disadvantage of this feed scheme is that it is difficult to

fabricate because of the two dielectric layers which need proper alignment. Also, there is an

increase in the overall thickness of the antenna.

2.4 Method of Analysis

The preferred models for the analysis of microstrip patch antennas are the transmission line

model, cavity model, and full wave model, which include primarily integral equations,

Moment Method. The transmission line model is the simplest of all and it gives good physical

insight but it is less accurate. The cavity model is more accurate and gives good physical

insight but is complex in nature. The full wave models are extremely accurate, versatile and

can treat single elements, finite and infinite arrays, stacked elements, arbitrary shaped

elements and coupling. These give less insight as compared to the two models mentioned

above and are far more complex in nature.

2.4.1 Transmission Line Model

This model represents the microstrip antenna by two slots of width Wand height h, separated

by a transmission line of length L. The microstrip is essentially a non-homogeneous line of

two dielectrics, typically the substrate and air.

Figure 2-7 Microstrip Line Figure 2-8 Electric Field Lines


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Hence, as seen from Figure 2-7, most of the electric field lines reside in the substrate and

parts of some lines in air. As a result, this transmission line cannot support pure transverse-

electric-magnetic (TEM) mode of transmission, since the phase velocities would be different

in the air and the substrate. Instead, the dominant mode of propagation would be the quasi-

TEM mode. Hence, an effective dielectric constant ( reff ) must be obtained in order to

account for the fringing and the wave propagation in the line. The value of reff is slightly

less than r because the fringing fields around the periphery of the patch are not confined in

the dielectric substrate but are also spread in the air as shown in Figure 2-8 above. The

expression for reff is given by Balanis [2] as:

(2.1)Where reff = Effective dielectric constant

r = Dielectric constant of substrate

h= Height of dielectric substrate

W= Width of the patch

Consider Figure 2-9 below, which shows a rectangular microstrip patch antenna of

lengthL, width Wresting on a substrate of height h. The co-ordinate axis is selected such that

the length is along the x direction, width is along the y direction and the height is along thezdirection.

Figure 2-9 Microstrip Patch Antennas

In order to operate in the fundamental TM10 mode, the length of the patch must be slightly

less than /2 where is the wavelength in the dielectric medium and is equal to o/ reff

where ois the free space wavelength. The TM10 mode implies that the field varies one /2


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cycle along the length, and there is no variation along the width of the patch. In the Figure 2-

10 shown below, the microstrip patch antenna is represented by two slots, separated by a

transmission line of length L and open circuited at both the ends. Along the width of the

patch, the voltage is maximum and current is minimum due to the open ends. The fields at the

edges can be resolved into normal and tangential components with respect to the ground

plane.

Figure 2-10 Top View of Antenna Figure 2-11 Side View of Antenna

It is seen from Figure 2-11 that the normal components of the electric field at the two

edges along the width are in opposite directions and thus out of phase since the patch is /2

long and hence they cancel each other in the broadside direction. The tangential components

(seen in Figure 2-11), which are in phase, means that the resulting fields combine to give

maximum radiated field normal to the surface of the structure. Hence the edges along the

width can be represented as two radiating slots, which are /2 apart and excited in phase and

radiating in the half space above the ground plane. The fringing fields along the width can be

modeled as radiating slots and electrically the patch of the microstrip antenna looks greater

than its physical dimensions. The dimensions of the patch along its length have now been

extended on each end by a distance L, which is given empirically by Hammers tad [3] as:

(2.2)

The effective length of the patch effL now becomes:

(2.3)


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For a given resonance frequency 0f , the effective length is given by:

(2.4)

For a rectangular microstrip patch antenna. The resonance frequency for any TM mode is

given by James and Hall [4] as:

(2.5)

Where m and n are modes alongL and Wrespectively.

For efficient radiation, the width Wis given by Bahl and Bhartia [4].

(2.6)

2.4.2 Cavity Model

Although the transmission line model discussed in the previous section is easy to use, it has

some inherent disadvantages. Specifically, it is useful for patches of rectangular design and it

ignores field variations along the radiating edges. These disadvantages can be overcome by

using the cavity model. A brief overview of this model is given below.

In this model, the interior region of the dielectric substrate is modeled as a cavitybounded by electric walls on the top and bottom. The basis for this assumption is the

following observations for thin substrates (h

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Consider Figure 2-12 shown above. When the microstrip patch is provided power, a charge

distribution is seen on the upper and lower surfaces of the patch and at the bottom of the

ground plane. This charge distribution is controlled by two mechanisms-an attractive

mechanism and a repulsive mechanism as discussed by Richards. The attractive mechanism

is between the opposite charges on the bottom side of the patch and the ground plane, which

helps in keeping the charge concentration intact at the bottom of the patch. The repulsive

mechanism is between the like charges on the bottom surface of the patch, which causes

pushing of some charges from the bottom, to the top of the patch. As a result of this charge

movement, currents flow at the top and bottom surface of the patch. The cavity model

assumes that the height to width ratio (i.e. height of substrate and width of the patch) is very

small and as a result of this the attractive mechanism dominates and causes most of the

charge concentration and the current to be below the patch surface. Much less current would

flow on the top surface of the patch and as the height to width ratio further decreases, the

current on the top surface of the patch would be almost equal to zero, which would not allow

the creation of any tangential magnetic field components to the patch edges. Hence, the four

sidewalls could be modeled as perfectly magnetic conducting surfaces. This implies that the

magnetic fields and the electric field distribution beneath the patch would not be disturbed.

However, in practice, a finite width to height ratio would be there and this would not make

the tangential magnetic fields to be completely zero, but they being very small, the side walls

could be approximated to be perfectly magnetic conducting.

2.5 Multi-Band Antenna

2.5.1 Definition of Multi-Band Antenna

An antenna designed to operate on several bands. It is used design one part of the antenna is

active for one band, and another part is active for a different band. A multi-band antenna may

have lower than average gain or may be physically larger in compensation.

A multi-band antenna adapted to a portable electrical device capable of operating invarious wireless communication bands includes a first radiating conductor having opposite

elongated sides, a second radiating conductor extending from one end of the first radiating

conductor, a third radiating conductor arranging about a central area of the first radiating.

Both the second radiating conductor and the third radiating conductor extend from the same

elongated side of the first radiating conductor. A feeding body is curved from the third

radiating conductor. According to a position that the feeding body connecting to the third

radiating conductor and designed the feeding body, operation of the multi-band antenna has apreferred range of a low frequency bandwidth and a high frequency harmonic bandwidth.

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2.5.2 Design of Multi-Band Antenna

Compact antenna

To efficiently radiate an electromagnetic wave into the free space, the size of an antenna

should be something in the order of the wavelength radiated, which is inversely proportional

to the frequency.

Complete built-in antenna

As the handsets saturate in their proliferation and they diversify in functions, the design has

emerged as a major element of driving the customers to buy; In contrast to whip antennas that

protrude from the casing, built-in antennas that are installed within the casing for proper

operation can give a high degree of freedom of design. Not only because of this, but also

from the standpoints of reinforcing shock resistance, improvement of specific absorption rate

on the human body, reduction of manufacturing costs, the requirement for complete built-in

antennas for handsets is always growing.

Multi-band Operation

The application of multi-band systems with a variety of frequency band combinations is

accelerating, whereby the international roaming is progressing globally, the communications

capacity is increasing and new functions are being added including GPS and Bluetooth. It s

expected, therefore, that all the handsets will probably become compatible with multi-band in

the near further.

Isolation Characteristics

The isolation characteristics of an antenna indicate whether its performance is stabilized or

not against the environmental changes. Much importance has been placed on the isolation

characteristics of a mobile phone antenna from the two viewpoints as show below.

The first relates to the foldable casing consisting of the main circuit board and

display. More specifically, whether or not the same level of communication sensitivity can be

maintained between the two conditions where the casing is folded or unfolded.

The second is concerned with the performance stability against the influence of the

human hand and head. This is a problem specific to handsets such that the equipment is used

near the head while being held by the hand. Since human body is a lousy dielectric, the

electromagnetic waves radiated during the communication are absorbed by the human body

thus considerably degrading the radiation efficiency.


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2.6 Antenna Miniaturization Techniques

Below is several miniaturization techniques have been identified:

The use of high dielectric-constant material

The most popular technique in reducing the size of a printed antenna is to use high-dielectric-

constant material for its substrate. In doing so, the guided-wavelength underneath the patch is

reduced and, hence the resonating patch size is also reduced. To further reduce the size, slot

can be introduced onto the resonating patch. In doing so, the current on the patch or the filed

underneath the patch will resonate from one edge as illustrated in Fig 2-13.

Slots on the resonating patch

For the longer path, reduces the resonant frequency or the physical size of the antenna.

Depending on the length of the slots, a 10% to 20% size reduction can be achieved. Show in

Fig 2-14.

The folding of a single-layer patch into a two-layer structure

This technique is to fold the complete single-layer patch antenna (including substrate and

ground plane) to form a two-layer structure and hence reduce the planar dimension by half.The configuration of the folded half-wave patch is illustrated in Fig 2-15 and the folding of a

quarter-wave patch is shown in Fig 2-16.


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The inverted-F configuration

This technique is to use the planar inverted-F configuration as shown in Fig 2-17. Where the

width dimension of the short-circuited plate is significantly smaller than L1 and the

dimensions L1 and L2 are each on the order of 1/8. The use of a shorting post

This technique is very similar to the inverted-F method, is the use of a circular patch with a

shorting post as illustrated in Fig 2-18.

The quarter-wave-patch approach

The antenna operates as a quarter wave patch antenna and is constructed from a rectangular

metal patch separated from a larger metallic plane. This metallic plane serves as the reference

ground plane for a circuit attached to the antenna, with a direct short between the patch and

the ground plane along one edge of the patch.

The genetic algorithm

This technique is used to minimize the size of wire type or printed antennas, while optimize

their RF performance. This antenna optimization is very similar to humans biological


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genetic evolution where biological configurations adapt to optimal fitness to the natural

environment by a huge number of chromosome sets with binary type of genetic decisions.

For example, by using this technique, an odd-shaped small wire antenna as shown in Fig 2-

19, achieved circular polarization with hemispherical radiation coverage.

The use of photonic band-gap material

This emerging techniques show the photonic band-gap material. In the case of

electromagnetic application, it is also best called the electromagnetic band gap material. It

acts very similar to a frequency selective surface, will reflect or transmit through only a

certain band of electromagnetic energy. This material comes in various forms. One uses a

thin slab of dielectric material with many equally spaced holes as shown in Fig 2-20.


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Chapter 3

Square Microstrip Patch Antenna

3.1 Introduction

In this chapter, the procedure for designing a square microstrip patch will be discussed. By

using theory to calculate design antenna, the dimension of the antenna is achieved. Follow by

the simulation of the design using IE3D application. The results obtained from the

simulations are demonstrated and analyzed.

3.2 Design Specifications

The three essential parameters for the design of a square microstrip patch antenna are:

Frequency of operation ( 0f ): The resonant frequency of the antenna must be

selected appropriately. The Mobile Communication Systems uses the frequency range from

850-3000 MHz Hence the antenna designed must be able to operate in this frequency range.

The resonant frequency selected for my design is 3.0 GHz.

Dielectric constant of the substrate ( r ): The dielectric material selected for my

design is silicon with a constant of 2.5. A substrate with a high dielectric constant has been

selected since it reduces the dimensions of the antenna.

Height of dielectric substrate (h): For the square microstrip patch antenna to be used

in cellular phones, it is essential that the antenna is not bulky. Hence, the height of thedielectric substrate is selected as 1.5 mm.

Hence, the essential parameters for the design are:

0f = 3.0 GHz

r = 2.5

h = 1.5 mm

3.3 Design of Square Microstrip Antenna Using Theory Calculation

The propagation of the electromagnetic field is usually considered in free space, where it

travels at the speed of light. smvo /1038

= ., lambda is the wavelength, expressed in

meters.

Wavelength of the GSM band

In GSM band, the following expression is used:

)(GHz

o

f

v=

(3.1)


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Hence, the wavelength of the antenna when operating at 3 GHz is 0.1 m.

3.3.1 Design Procedure

From the above, the essential parameters for the design are:

a. of = 3 GHz,b. r = 2.5,c. h = 1.5 mm

a) Calculation of the Width (W):

The width of the microstrip patch antenna is given by equation:

1

2

2 +=

ro

o

f

vW

(3.2)

Substituting ov =3x10 8 m/s, r =2.5 and of =3 GHz,W= 38 mm

b) Calculation of Effective dielectric constant ( reff ):2

1

1212

1

2

1

+

+

+=

W

hrrreff

(3.3)Substituting r =2.5, W= 38 mm and h= 1.5 mm, reff =2.36

c) Calculation of the Effective length ( effL ):

reffo

oeff

f

vL

2

= (3.4)

Substituting ov =3x10 8 m/s, reff =2.36 and of =3 GHzeffL =32.5 mm

d) Calculation of the length extension (L):

)8.0)(258.0(

)264.0)(3.0(412.0

+

++

=

h

Wh

W

hL

reff

reff

(3.5)Substituting ov =3x10 8 m/s, reff =2.36 and of =3 GHz

L =1.24 mm

e) Calculation of actual length of patch (L):

LLL eff = 2 (3.6)Substituting effL =33.95 mm, L =1.24 mm

=L 30.01mm

f) Calculation of the ground plane dimensions (Lg and Wg):


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The transmission line model is applicable to infinite ground planes only. However, for

practical considerations, it is essential to have a finite ground plane. The finite ground can be

obtained if the size of the ground plane is greater than the patch dimensions by approximately

six times the substrate thickness all around the periphery. Hence, for this design, the ground

plane dimensions would be given as:

Lg= 6h + L, Wg= 6h + W (3.7)

Hence, the calculatedLgand Wgare 39 mm and 47 mmrespectively.

g Microstrip Patch Antenna Dimensions

Figure 3-1 (a) Top view of microstrip patch antenna

Figure 3-1 (b) Side view of microstrip patch antenna


Figure 3-1 (c)Overalldesign of microstrip patch antenna.

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Based on the calculation above, the L and Wderived are 30 mm and 38 mm .The design of

the microstrip antenna array starts from microstrip antenna. The microstrip antenna is feed

using microstrip feed line, the design dimensions for this project is as follows:

Frequency, of = 3GHz

Dielectric constant, r = 2.5

Substrate thickness, h = 1.5 mm

Metallic strip thickness, t= 0.02 mm

Conductivity of ground plane (Copper),g= 5.8 x 10 7 S/m

Effective dielectric constant, reff = 2.3

Resonant input impedance, Rin = 50

h) Using bandwidth equation:

BW=3.77 ( ) ( ) ( ) ///1 2 hLWrr

(3.8)

Substituting r = 2.5, W= 38mm, h = 1.5 mm L= 30 mm

BW=0.167 GHz

3.4 Design of Square Microstrip Antenna using IE3D Simulator

Given specifications were,

1. Dielectric constant ( r ) = 2.5

2. Frequency ( rf ) = 3.0 GHz.

3. Height (h) = 1/16 Inch = 1.59 mm.

4. Velocity of light (c) = 310 8 ms1 .

5. Practical width (W) W = 38 mm.

6. Loss Tangent (tan ) = 0.001.

7. Practical Length (L) L = 30 mm.

8. Metallic strip thickness, t= 0.02 mm


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3.4.1 Results of Simulation

The Figure 3-2 shown the square microstrip patch design shape using

IE3D simulator.

Figure 3-2 Patch designed in IE3D software

S-Parameters

S-parameters are mostly used for networks operating at radio frequency and microwave

frequencies where signal power and energy considerations are more easily quantified than

currents and voltages. Below Figure 3-3, 3-4 show that S-Parameter Displays for S (1.1) and

S (2.2). From the graphs, the bandwidth is about 0.16 GHz and closed to the calculation

result.0.167 GHz at frequency 3 GHz.

Figure 3-3 S-Parameter display for S (1, 1) Figure 3-4 S-Parameter displays for S (2, 2)

http://en.wikipedia.org/wiki/Microwavehttp://en.wikipedia.org/wiki/Microwave

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Smith Charts

From the graph Figure 3-5, 3-6 as shown that the system impedance R1 is 50.

Figure 3-5Smith Chart display for S (1, 1) Figure 3-6 Smith Chart display for S (2,

2)

Voltage Standing Wave Ratio (VSWR)

From the graph Figure 3-7, 3-8 shown that the ratio of the amplitude of a partial standing

wave at an antinodes (maximum) to the amplitude at an adjacent node (minimum) for thedesign patch antenna. Therefore VSWR estimate is 3 at frequency 3 GHz.

Figure 3-7 VSWR for Port 1 Figure 3-8 VSWR for Port 2

3D Current Distribution

From Figure 3-9 graph is shown the design patch current distribution condition.

http://en.wikipedia.org/wiki/Ratiohttp://en.wikipedia.org/wiki/Amplitudehttp://en.wikipedia.org/wiki/Standing_wavehttp://en.wikipedia.org/wiki/Standing_wavehttp://en.wikipedia.org/wiki/Node_(physics)http://en.wikipedia.org/wiki/Ratiohttp://en.wikipedia.org/wiki/Amplitudehttp://en.wikipedia.org/wiki/Standing_wavehttp://en.wikipedia.org/wiki/Standing_wavehttp://en.wikipedia.org/wiki/Node_(physics)

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Figure 3-9 3D Current distribution

Antenna and Radiation Efficiency Display

From Figure 3-10 shown that the design of square microstrip patch antenna has 80% antenna

efficiency and 85% radiation efficiency at frequency 3 GHz.

Figure 3-10 Antenna and radiationefficiency vs frequency

Total Gain vs. Frequency Graph

The Figure 3-11 is shown that the total field gain is about 6.5 dBi at frequency 3 GHz.


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Figure 3-11 Gain vs frequency

Total Field Directivity vs. Frequency Graph

The Figure 3-12 is shown that total field directivity has 7.2 dBi at frequency 3 GHz.

Figure 3-12 Total field directivity vs. frequency


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Chapter 4

Miniaturization Antenna Design

4.1 Introduction

In this chapter, 5 types of miniaturization antenna techniques are analyzed and simulated

using IE3D application and the each type of results are compared. Consequence of

miniaturization the physical dimension can be result in undesirable changes of bandwidth,

efficiency and so on. Applying of technique could cover back such condition, depend on the

techniques that applied, there may be different outcome. In this Section, these techniques or

of miniaturization are tested out by applying on the original antenna patch and follow by,

analyzed how much the antenna simulated results are different.

4.2 Design Description

4.2.1 Reduce dielectric constant technique

Changing the dielectric constant could vary the antenna performance. In this design, the

dielectric constant is lowed and specifications are as follows:

Dielectric constant ( r ) = 1.5

Height of substrate (h) = 1/16 Inch = 1.5 mm.

Thickness of patch = 0.002 mm

Loss Tangent (tan ) = 0.001.Practical width (W) W = 38 mm.

Practical Length (L) L = 30 mm.

The specification is same as the original design. The only change is on reducing of dielectric

constant 2.5mm to 1.5mm.

4.2.2 Square patch with shorting GND technique

This method is widely used in some of the monopole planar antenna. Antenna patch andground will be shorted directly near the feeding probe. Finite ground have used for this

design. Design is as follows:


Figure 4-1 Shorted GND patch drawing Figure 4-2 Shorted GND patch omit substrate view

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4.2.3 Increase of substrate thickness technique

In the microstrip antenna type, the thickness and dielectric constant of the substrate are

playing a major role. Changing those will result in alteration of the original design. Any

techniques could have advantages and disadvantages. In this part, the substrate thickness will

be doubled compare to the original design.

Dielectric constant ( r ) = 2.5

Height of substrate (h) = 1/16 Inch = 3.0 mm.

Thickness of patch = 0.002 mm

Loss Tangent (tan ) = 0.001.

Practical width (W) W = 38 mm.

Practical Length (L) L = 30 mm.

4.2.4 Double layer half wave patch technique

Normally, when one is thinking of miniaturization on the object, example an A4 paper sheet,

folding it would be a first instinct idea. Folding the object into smaller part is the most

obvious in physical appearance in smaller. Therefore, the experiment on folding the square

patch is carried out in this section and the specification is as follows:

4.2.5 Combination of shorting GND and increase substrate thickness technique

After trying out the above techniques and analyzing the data from the simulation, combining

the two techniques into one is considered. From the result, shorting the GND and increasing

the substrate is desirable.


Figure 4-3 Double layer or folded patch drawing

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4.3 Results of Simulation using IE3D Simulator

4.3.1 S-parameter- S (1, 1)

After analyses the S-parameter simulation result from Table 4.1.the result has shown that:

a) Reduce dielectric constant technique will be get more than 50% bandwidth compare the

original design bandwidth.

b) Square patch with shorting GND technique get more than 112% bandwidth compare the


c) Double sizes of thickness substrate technique get same bandwidth result compare the


d) Half wave square patch technique get more than 400% bandwidth compare the original

design bandwidth.

e) Combination of square patch with shorting GND and increase substrate thickness

technique get more than 180% bandwidth compare the original design bandwidth.

S-parameter Comparison Results (Bandwidth(dBi)1.Original Design 0.16 GHZ2.Dielectric Constant Reduce 1.5 mm 0.24 GHZ3.Square Patch With Shorting GND 0.34 GHZ4.Thickness Substrate Increase from 1.5 to 3mm 0.15 GHZ5.Half Wave Square Patch (double layer substrate) 0.78 GHz6.Square Patch with Shorting GND + Increase Substrate Thickness 0.31 GHZ

Table 4.1 Comparison results of S-parameter

Below Figure 4-4 and Figure 4-5 are each technique simulation result graph for S-parameter

using IE3D simulator.


Figure 4-4 (a) Original patch Figure 4-4 (b) Reduce dielectric constant patch

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4.3.2 S-parameter s( 2,2 )


Figure 4-4 (c) Shorting GND patch Figure 4-4 (d) Increase substrate thickness patch

Figure 4-4 (e) Double layer half-wave patch Figure 4-4 (f) Combine methods patch

Figure 4-5(a) Original patch Figure 4-5(b) Reduce dielectric constant patch

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4.3.3 VSWR Port 1

After analyses the VSWR simulation result from Table 4.2.the result has shown that:

a) Reduce dielectric constant technique will be get 71.3. It is more worst than original

design VSWR.

b) Square patch with shorting GND technique get same result compare the original design

patch.

c) Double size of thickness substrate technique get slightly larger VSWR than the original

design patch.

d) Half wave square patch technique get 2 times larger VSWR than the original design

patch.


technique get more than 2 times larger VSWR than the original design patch antenna.


Figure 4-5 (c) Shorting GND patch

Figure 4-5(e) Double layer half-wave patch

Figure 4-5 (d) Increase substrate thickness patch

Figure 4-5 (f) Combine methods patch

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VSWR Comparison Results VSWR

1.Original Design 32.Dielectric Constant Reduce 1.5 mm 71.33.Square Patch With Shorting GND 3.14.Thickness Substrate Increase from 1.5 to 3mm 4.85

5.Half Wave Square Patch (double layer substrate) 66. Square Patch with Shorting GND + Increase Substrate Thickness 6.32 Table 4.2Comparison results of VSWR

Below Figure 4-6 and Figure 4-7 are each technique simulation result graph for VSWR using

IE3D simulator.




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4.3.4 VSWR Port 2


Figure 4-6(e) Double layer half-wave patch Figure 4-6 (f) Combine methods patch



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4.3.5 Smith Chart S( 1,1 )

After analyses the Smith Chart simulation result from graph. I can say that only the increase

substrate thickness patch technique given same result and the rest techniques are worse thanthe original patch antenna design. Below Figure 4-8 and Figure 4-9 are each technique

simulation result graph for Smith Chart using IE3D simulator.




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4.3.6 Smith Chart S( 2,2 )





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4.3.7 Total Field Gain Vs Frequency

After analyses the total field gain simulation result from Table 4.3. The result has shown that:

a) Reduce dielectric constant technique will be get -9.47 dBi. It is more worst than original

design gain.

b) Square patch with shorting GND technique get lower gain compare the original design

patch.c) Double sizes of thickness substrate technique get slightly higher than shorting GND

technique but still not good enough than the original design patch.

d) Half wave square patch technique get -7.6 dBi. It is better than reduce dielectric constant

technique but it is worst than original design gain.


technique only get 2.07 dBi power gains. It is not better than original design patch

antenna.




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Total Field Gain Comparison Results Power Gain(dBi)

1.Original Design 6.5

2.Dielectric Constant Reduce 1.5 mm -9.47

3.Square Patch With Shorting GND 2.92

4.Thickness Substrate Increase from 1.5 to 3mm 3.77

5.Half Wave Square Patch (double layer substrate) -7.66. Square Patch with Shorting GND + Increase Substrate Thickness 2.07

Table 4.3 Comparison results of total field gain

Below Figure 4-10 are each technique simulation result graph for total field gain vs frequency





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4.3.8 Total Voltage Field Gain Vs Frquency

After analyses the total voltage field gain simulation result from Table 4.4. The result has

shown that:

a) Reduce dielectric constant technique will be get -15 dBi. It is more worst than original

design gain.

b) Square patch with shorting GND technique get lower gain compare the original design

patch.

c) Double sizes of thickness substrate technique get slightly higher than shorting GND

technique but still not good enough than the original design patch.d) Half wave square patch technique get -12.56 dBi. It is better than reduce dielectric

constant technique but it is worst than original design gain.


technique get -0.64 dBi power gain. It is not better than original design patch antenna.

Total Voltage Field Gain Comparison Results Voltage Field Gain(dBi)

1.Original Design 3.85

2.Dielectric Constant Reduce 1.5 mm -153.Square Patch With Shorting GND -1.13

4.Thickness Substrate Increase from 1.5 to 3mm -1.11

5.Half Wave Square Patch (double layer substrate) -12.56

6. Square Patch with Shorting GND + Increase Substrate Thickness -0.64

Table 4.4 Comparison results of total voltage field gain

Below Figure 4-11 are each technique simulation result graph for total field gain vs frequency




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4.3.9 Total Field Directivity Vs Frequency

After analyses the total voltage field directivity simulation result from Table 4.5. The result

has shown that:

a) Reduce dielectric constant technique will be get 5.24 dBi. It is lower than original design

gain.

b) Square patch with shorting GND technique get slightly lower compare the original design

patch.





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c) Double sizes of thickness substrate technique get slightly higher than the original design

patch.

d) Half wave square patch techniques get 6.4 dBi and lower than original design gain.


technique get 7.05 dBi. It is not better than original design patch antenna.

Total Field Directivity Comparison Results Directivity(dBi)1.Original Design 7.202.Dielectric Constant Reduce 1.5 mm 5.24

3.Square Patch With Shorting GND 6.86

4.Thickness Substrate Increase from 1.5 to 3mm 7.4

5.Half Wave Square Patch (double layer substrate) 6.4

6. Square Patch with Shorting GND + Increase Substrate Thickness 7.05Table 4.5 Comparison results of total field directivity

Below Figure 4-12 are each technique simulation result graph for total field directivity vs

frequency using IE3D simulator.




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4.3.10 Antenna and Radiation Efficiency Vs Frequency

After analyses the antenna and radiation efficiency simulation result from Table 4.6. The

results have shown that:a) Reduce dielectric constant technique is given 68.3% lower radiation efficiency and only

4.93% antenna efficiency compare the original patch antenna result.

b) Square patch with shorting GND technique get slightly higher radiation efficiency and

only 40.5 % antenna efficiency compare the original patch antenna result.

c) Double size of thickness substrate technique get slightly lower radiation efficiency and

50% antenna efficiency compare the original patch antenna result.

d) Half wave square patch technique get only 20.27% radiation efficiency and only 4.34%antenna efficiency compare the original patch antenna result.


technique given same radiation efficiency but the antenna efficiency result is not better

than original patch antenna result.



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Table 4.6 Comparison result of antenna and radiation efficiency

Below Figure 4-13 are each technique simulation result graph for antenna and radiation

efficiency using IE3D simulator.


Antenna and Radiation Efficiency Comparison ResultsRadiation

Efficiency

Antenna

Efficiency

1.Original Design 84.80% 78%

2.Dielectric Constant Reduce 1.5 mm 68.30% 4.93%

3.Square Patch With Shorting GND 85.50% 40.50%

4.Thickness Substrate Increase from 1.5 to 3mm 75.59% 50%

5.Half Wave Square Patch (double layer substrate) 20.27% 4.34%

6. Square Patch with Shorting GND + IncreaseSubstrate Thickness

84.50% 33.30%



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4.3.11 Each Technique Overall Performance

From above data come out the overall simulation performance. The Table 4.7 is shown that

original design is still the best overall performance. The rest miniaturization techniques can

only achieved individual best performance.

Overall Performance

Results

Bandwidth

(dBi)

Power

Gain

(dBi)

VSWRRadiation

Efficiency

Antenna

Efficiency

Voltage Field

Gain(dBi)Directivity(dBi)

1. Original Design 0.16 GHz 6.5 3 84.80% 78.00% 3.85 7.2

2. Dielectric Constant

Reduce to 1.5mm0.24GHz -9.47 71.3 68.30% 4.93% -15 5.24

3. Square Patch with

Shorting GND0.34 GHz 2.92 3.1 85.50% 40.50% -1.13 6.86

4. Thickness Substrate

Increase from 1.5 to 3

mm

0.15 GHz 3.77 4.85 75.59% 50.00% -1.11 7.4

5. Half Wave Square

Patch0.78 GHz -7.6 6 20.27% 4.34% -12.56 6.4

6. Square Patch with

Shorting GND +

Increase Substrate

Thickness

0.31 GHz 2.07 6.32 84.50% 33.30% -0.64 7.05

Table 4.7 Comparison of each technique overall performance



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Chapter 5

Conclusions

5.1 Thesis Contributions

The design of square microstrip patch antenna for mobile device has been completed using

IE3D software. The simulation results are good enough to satisfy our requirements to

fabricate it on hardware which can be used wherever needed, especially for the frequency

3GHz. Although the simulation was carried out for the frequency of 3GHz, the design can be

adjusted to the desired frequency according to the formulae state in the section 3, since the

result have been proof that formula is reliable to be used.

Each simulation results have stated in the section 4 is for the techniques of miniature

for the square microstrip patch antenna. Difference techniques have given different

advantages. The idea of the section 4 is to show clear statement between the original patch

and the patch that have applied the miniature techniques. From them, one can choose whichmethod is suitable for the application. Although, the results are good enough, the size

adjustment should be carried out in the future work.

Above all, this report can be a good starting point for the person, who is planning to

use the square type microstrip antenna. Formulae are given, and good enough to design.

However, one must be take note that investigation in this report has been limited, mostly to

theoretical studies and simulations due to lack of fabrication facilities.


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5.2 Future Work

Firstly, since this project is mainly reference on the theory and research paper. All the results

that have been collected are based on the simulation, which is nearly closer to the actual

result. In order to use it in the real time system, actually hardware should be fabricated and

tested out, which can be given accurate and reliable answer.Detailed experimental studies can

be taken up at a later stage to fabricate the antenna. Before going for fabrication we can

optimize the parameters of antenna using one of the soft computing techniques known as

Particle Swarm Optimization (PSO).

Secondly, during the software simulation, using the origin design, there are some

difference in simulation result, when the probe feed different position on the patch will given

out the different answer. Importance of the probe position doesnt explain much in the book

that referred. Therefore, different probe location on the same patch and number of probe

using may differ. This should be carried out in the future work and find out the best location

for the probe feed.

Thirdly, dielectric constant for the substrate has been simulated using 1.5 which is less

than the original design. Constant of material greater than original design are worth for trying.

It can be given different answer.

Finally, miniatures techniques that have mention in this report are individual result of

adjusting the original design, without changing the original dimension. Actual size should be

changed to smaller dimension from the original and applying all the methods on the newly

designed patch. The result of the same methods original and new design should be compared

and analyzed. This can lead to importance of the technique.


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Reflections

Finally, come to the end of the report. I have put all my effort on this. All my energy and

strength are putting in for the completion the report before deadline. Moreover, final year

report is the core of the degree course it is like a turning point of my life. Struggling such

important thing is not an easy job indeed. Any mistake or any wrong choice can end up my

afford in vain. As the saying state that Think before you leap, I have to put an extra care onevery steps that I moved.

Only with the foundation courses like Wireless Communication Systems (ENG315)

and Electronic Material (ENG323) taught in SIM University, there is a lot of knowledge and

skills require having a deeper understanding in miniature microstrip patch antenna theories,

and its mathematical relations. Therefore, the first step was to find the relevant papers and

books on this microstrip patch antenna.

Not to my surprise, there are a lot of researches done in this area, and this did not helpat all as I have somehow lost focus on what is desired, this is the typical information overload

during the literature survey. During the meet up with Dr Shen, he provides me with the

relevant comments and valuable inputs with regards to my progress. Without the help of my

dedicated tutor to guide me and to align the ideas, this project would not be completed.

When I started on this project, I have an initial idea on fabricating it and tested out in

the anechoic chamber. This can be given a reliable product. However, such facilities are

pretty expensive and difficult for a part-time student like me to make a time arrangement to


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carry out. Therefore, I have decided to use the simulation software, which is specialized in

designing the antenna.

When I do the pre planning on the project, it seems to be going smoothly. Initial report

is seamlessly done. Timeline is drawn out according to my schedule. Planar antenna design is

chosen. However, when it come to part for the simulation and miniaturization, I start to

realize that substrate is playing an important role for the antenna. It can make a difference

putting the substrate in between ground and patch. Therefore, I have to modify my initial

design into microstrip type antenna, which is quite a well built up design. Substrate layer is

added between patch and ground layer. This can be solved for one of the miniature

techniques.

On the other hand, simulation applications are quite hard to get within in my research.

Reliable and availability of software are main concerns for me. Some applications are

provided with evaluation version. It didnt turn out to be reliable and easy to use. Results are

turn out to be limited to certain expectation.

The first application that I have tried out is Antenna Magus from CST MICROWAVE

STUDIO. This application is user friendly, but, since it provide evaluation version, I can only

able to use some of the designs. Simulation for the microstrip antenna is easily carried out,

because the antenna design are pre defined and user only need to put in the dimension of the

antenna patch and dielectric constant of the substrate. However, the simulation results are not

in detail. Graphs are pretty general. Moreover, pre defined design cannot be able to use for the

section 4, where I am going to deal with the changing of the design.

Next application that I have used is HFSS from ANSOFT. This application is like

professional software for designing the antenna design. It is quite powerful, user can draw his

own design and simulate. When I used this application, I found out that this software is too

powerful to be used on my notebook. It needs a high performance machine to handle the

simulation. For the first time, I have seen that my notebook have to keep on running for two

days in order to do the simulation, yet it didnt complete. Therefore, I have to give up on thisapplication.

At the end, I found out the IE3D from ZELAND, which I have borrowed from one of

my close friend, is a good software for designing the antenna. Although it is not a user

friendly, it can be drawn my own design and do the simulation, which can give a satisfy result.

Day and night, trying and learning the tutorial on IE3D, finally, I have got my expected result

which has been stated in this report.

Putting so much effort on this report, it is not in vain at all. I have leant a lot. Such alesson cannot be able to find in the class room. We must go and try it, experience it. Learning


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in the class room may not be giving me a same experience or lesson as I do the project. This

is a very good opportunity to use what we have leant in the class.

Work out such important thing with a full concentration would not be a problem, but it

doesnt turn out in that way for me. I have to work full time in the morning and going for the

lesson in the evening. Life will not be easy if there is need of playing multiple roles. Job,

study and family are the only vocabulary to define my life for the past few years. Of course, I

am aware of that these are pains that I am giving or should I say investing. Nothing is free in

this world, No Pain No Gain, in order to achieve what I want. I have to cross this journey.

Acknowledgements

I would like to express my sincere gratitude and appreciation to my advisor Dr Shen Zhong

Xiang for his guidance and instruction during my years at SIM University made my graduate

career challenging, exciting and rewarding. I am indebted to them for their time, patience,

and support.

I would like to thank to Sean not only for his help and valuable suggestions for

this thesis, but also for his advice and taking the time to read my thesis.

I am especially indebted to my faithful colleague Lim Eng Ann, for her friendship,

support and encouragement. Without her help this work would have been a lot harder.

I would like to thank Hong Bo and Liu Pan for sharing with me his optimism andintelligence. There are always willing to help anyone.

Acknowledgements are also due to Bao Chen, Chen Hua, Yen, Zhi Wei, for their

support and friendship.

I would like to thank my parents for their continued support and encouragement and

my family stood behind me for which I am thankful for them forever.


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Finally, I would like to thank my wife Chen Qi for her patience, understanding and

unlimited encouragement.Without her support, I would not have made it.

References

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