Example of Final Project Thesis

BEng (Hons) in Electrical & Electronics Engineering 3+0in collaboration with UNIVERSITY OF EAST LONDON.

LOOP PATCH ANTENNA DESIGN

BY ABUBAKAR MAHDI ALHAJI 1

900MHz CIRCULAR LOOP PATCH ANTENNADESIGN AND IMPLEMENTATION

FINAL YEAR PROJECT REPORT

XXX

BACHELOR OF ENGINEERING (HONS)ELECTRICAL & ELECTRONIC

ENGINEERING (COMMUNICATION)

UNIVERSITY OF EAST LONDON

JANUARY 2012




900MHz CIRCULAR LOOP PATCH ANTENNA DESIGN ANDIMPLEMENTATION

XXXXX

A project report submitted in partial fulfillment of the requirements for the award ofdegree of Bachelor of Engineering (Hons) in Electrical & Electronic Engineering

(Communication)

UNIVERSITY OF EAST LONDON

JANUARY 2012

DECLARATION




I hereby declare that this project entitled " 900MHz CIRCULAR LOOP PATCH

ANTENNA DESIGN AND IMPLEMENTATION" has been done by myself under the

supervision of Mr. ALI ZUHAIR, and no portion of the work contained in this report has

been submitted in support of any application for any other degree of qualification of this

or any other university or institute of higher learning.

I declare that this project is entirely my own work except where due references are

made.

Signature: _______________

Name:

UEL ID:

Date:

Supervisor's Signature: _____________________

Supervisor's name

Date:




iiACKNOWLEDGEMENT

Initially, I thank Almighty Allah for making this project a success. This project

mainly was achieved with the help of hard-working people that guide me throughout my

final year project and will also say thanks to those important people who spend time and

being patient while doing this project.

Special appreciation to my project supervisor, Mr. ALI ZUHAIR for his guidance

and advice. He inspired me, used human management skills in order to encourage me,

and shared his ideas during the course of this project. I completed my project and also

got the opportunity to learn and develop skills for myself in the future.

The rest of engineering staffs in Stamford college were very helpful and many of the

expert in antenna research. Next I would like to thank my parents who give financial

support throughout my course.




iiiABSTRACT

This project is about the circular loop patch antenna design that operates in 900MHz

frequency. The antenna is a single loop patch which lies on the surface of the dielectric

substances, FR4. A 50 SMA RF port is attached at the end tip of the antenna for 50

coaxial cable connection.

The antenna is designed and simulated using ADS software. The concerned

parameters of the antenna are, S11, Gain and impedance. Apart from these, other concern

parameters are radiation pattern and power also will be take into consideration when

simulate antenna.

At the end of the project, a working loop patch antenna will be demonstrated and

operate at 900MHz. If network analyzer is not available, a television will be used to test

the working of the antenna. By connecting the loop patch antenna to the television, one

channel or more can be received and see clearly.




iv

.

TABLE OF CONTENTS

Page

Declaration .......................................................................................................................ii

Acknowledgements...........................................................................................................iii

Abstract.............................................................................................................................iv

Table of Contents..............................................................................................................vi

List of Figures..................................................................................................................vii

List of Abbreviations.......................................................................................................viii

CHAPTER 1: INTRODUCTION.................................................................................1

1.1 Background.........................................................................................................1

1.2 Statement of The Problems.................................................................................2

1.3 Objectives...........................................................................................................3

1.4 Scope of the Project............................................................................................3

1.5 Expected Outcome of the Project.......................................................................4

1.6 Technical proposed block diagram to implement the project.............................5

1.7 Overview of the report........................................................................................6

CHAPTER 2: REVIEW OF LITERATURE..............................................................8




2.1 The Theory of Loop Antenna.............................................................................8

2.2 Radiated Fields...................................................................................................10

2.3 Power Density of the Loop Antenna..................................................................13

2.4 Loop Patch Antenna Design...............................................................................13

CHAPTER 3: SYSTEM DESIGN................................................................................16

3.1 Design requirements.............................................................................................19

3.2 Loop Patch Antenna Design.................................................................................19

CHAPTER 4: HARDWARE & SOFTWARE IMPLEMENTATION.....................24

4.1 Hardware Requirement for the making of Loop Patch Antenna.........................24

4.1.1 FR4 PCB Copper Board................................................................................24

4.1.2 SMA Port.......................................................................................................25

4.1.3 SO239 Port.....................................................................................................26

4.1.4 50 Coaxial Cable.........................................................................................27

4.1.5 75 Coaxial cable..........................................................................................28

4.1.6 Soldering Gun................................................................................................29

4.1.7 Soldering Lead ..............................................................................................30

4.2 Software Requirement to design the Loop Patch Antenna..................................31

4.3 Loop Patch Antenna Design using ADS..............................................................31

4.4 The Making of Loop Patch Antenna....................................................................40

CHAPTER 5: RESULTS & DISCUSSIONS..............................................................50

5.1 Simulation Results................................................................................................50

5.2 Experimental Test of Loop Patch Antenna...........................................................64

5.3 Apply and test the Loop Patch Antenna using Television....................................71

5.3.1 The performance of commercial type of loop antenna...................................71

5.3.2 The performance loop patch antenna developed in this project.....................72




CHAPTER 6: CONCLUSIONS AND RECOMMENDATIONS..............................75

6.1 Conclusion............................................................................................................75

6.2 Problem Facings...................................................................................................76

6.3 Recommendation.................................................................................................76

REFERENCES..............................................................................................................77

APPENDIX A: RADIO FREQUENCY SPECTRUMS.............................................79

APPENDIX B: INPUT IMPEDANCE OF LOOP ANTENNA GRAPHS...............80

APPENDIX C: LAYOUT OF LOOP PATCH ANTENNA......................................81

APPENDIX D: PRICE LIST.......................................................................................82

APPENDIX E: GANTT CHART................................................................................83




LIST OF FIGURES

Page

Figure 1.1: Application of loop antenna in metal detector................................................2

Figure 1.2: Application of loop antenna in VHF/UHF frequency....................................2

Figure 1.3: The scope of the project..................................................................................3

Figure 1.4: Expected outcome of the project.....................................................................4

Figure 1.5: Technical block diagram to implement the project.........................................5

Figure 2.1: Loop antennas.................................................................................................9

Figure 2.2: Geometry of circular loop..............................................................................10

Figure 2.3: Resistance versus the directivity ................................................................14

Figure 2.4: Reactance versus the directivity .................................................................15

Figure 3.1: A process to build a 900MHz loop patch antenna.........................................16

Figure 3.2: Determine the 50 resistance from the graph..............................................21

Figure 3.3: The physical appearance of the loop patch antenna......................................23

Figure 4.1: FR4 PCB copper board.................................................................................24

Figure 4.2: SMA Port......................................................................................................25

Figure 4.3: SO239 Female port.......................................................................................26

Figure 4.4: 50 Coaxial cable........................................................................................27

Figure 4.5: 75 TV coaxial cable...................................................................................28

Figure 4.6: Soldering gun................................................................................................29

Figure 4.7: Soldering lead...............................................................................................30

Figure 4.8: ADS starting window...................................................................................31


LOOP PATCH ANTENNA DESIGNBY ABUBAKAR MAHDI ALHAJI

10

Figure 4.9: Creating new project.....................................................................................32

Figure 4.10: New project template window....................................................................32

Figure 4.11: Schematic window......................................................................................33

Figure 4.12: The window for patch antenna design.........................................................34

Figure 4.13: Dimension of the measurement in 2D coordinates system..........................35

Figure 4.14: Important functions to sketch the path loop antenna...................................35

Figure 4.15: Draw a circle in the ADS software..............................................................36

Figure 4.16: Draw a second circle and overlap it.............................................................36

Figure 4.17: Creating a single loop on the circle..............................................................37

Figure 4.18: A ring or a single turn of loop patch antenna...............................................37

Figure 4.19: Strip of conductor joint with the ring...........................................................38

Figure 4.20: Joining the strip and loop together...............................................................39

Figure 4.21: The complete loop patch antenna design.....................................................40

Figure 4.22: Print out the loop patch antenna layout from ADS software.......................41

Figure 4.23: Material prepared for ironing process..........................................................42

Figure 4.24: Use sticker to hold the print out and put on the PCB board........................42

Figure 4.25: Ironing in progress.......................................................................................43

Figure 4.26: The ironing process time phases..................................................................44

Figure 4.27: Result after ironing process and darken the image......................................45

Figure 4.28: Prepare for etching.......................................................................................45

Figure 4.29: Etching in progress......................................................................................47

Figure 4.30: Process of making the loop patch antenna after etching.............................48

Figure 4.31: The final outlook of the circular loop patch antenna...................................49

Figure 4.31: The final outlook of the circular loop patch antenna...................................49

Figure 5.1: Window that allow user key in the antenna parameters.................................50

Figure 5.2: Simulation control window............................................................................51

Figure 5.3: S11 and S22 simulation results of loop patch antenna shown in Figure 4.21..52

Figure 5.4: The meaning of S11 and S22 on the loop patch antenna..................................53

Figure 5.5: The Smith charts plot for S11 and S22.............................................................55



11

Figure 5.6: Impedance plot of the loop patch antenna.....................................................56

Figure 5.7: VSWR plot of loop patch antenna.................................................................58

Figure 5.8: Ready to plot the radiation pattern.................................................................59

Figure 5.9: Circular polarization radiation pattern...........................................................60

Figure 5.10: The gain and directivity radiation pattern....................................................61

Figure 5.11: Efficiency of the loop patch antenna............................................................61

Figure 5.12: 3D view of loop patch antenna....................................................................62

Figure 5.13: Three 3D radiation pattern of the loop patch antenna.................................63

Figure 5.14: Network analyzer.........................................................................................64

Figure 5.15: Network analyze test on loop patch antenna................................................65

Figure 5.16: The S11 plot of the loop patch antenna.........................................................66

Figure 5.17: The Smith Chart plot of loop patch antenna................................................68

Figure 5.18: Impedance plot of loop patch antenna.........................................................69

Figure 5.19: The VSWR plot............................................................................................70

Figure 5.20: Using commercial type of loop antenna to receive the TV channels...........71

Figure 5.21: Using loop patch antenna to receive the TV channels.................................72

Figure 5.22: Analysis on how loop patch antenna works to receive the TV channel......73



12

LIST OF ABBREVIATIONS

RF - Radio Frequency

PCB - Printed Circuit Board

SMA - Subminiature Version A

UHF - Ultra High Frequency

VHF - Very High Frequency

HF - High Frequency

VSWR - Voltage Standing Wave Ratio

TV - Television

S11 - Input reflection coefficient

S22 - Output reflection coefficient



13

LIST OF TABLES

Table 3.1 - The technical parameters and design requirement of the antenna.................19

Table 5.1 - Technical features of the network analyzer...................................................65

Table 5.2 - The performance of commercial type of loop antenna..................................72

Table 5.3 - The performance of loop patch antenna on the TV channels reception.........73

Table 6.1 - Summarized the comparison results between simulation and practical.........75



14

CHAPTER 1: INTRODUCTION

1.1 Background

Antenna plays an important role to receive and transmit the RF signal in wireless

communication. The size of antenna varies from one to another and depends on the

operating frequency. The size of antenna usually determine by wavelength.

Today a variety of antennas can be seen everywhere. Generally the antennas can be

classified under three types: elemental antennas, dish antennas and patch antennas.

Elemental types of antennas are the simple type of wires antenna. The design can be a

simple conductor to a complex structure. Dish antennas are using a reflector to reflect

the RF signal and focus the signal at one point. Patch however is a flat antenna or

conductor which can be many shapes and lie on a piece of dielectric material. Many

small wireless electronic communication devices such as cell phones are using patch

antennas.

In this project, a circular loop patch antenna operates at 900MHz frequency is

designed and implemented. The loop patch antenna in this project consists of single loop

of copper conductor lies on FR4 material which having a relative permeability of 4. A

50 SMA port is attached at the end point of the antenna for coaxial cable connection.

At the end of construction of the antenna, the antenna will be send for testing in the RF

lab using network analyzer.

To implement or apply the antenna into real time, the antenna may be tested using

television to observe the channels received.

1.2 Statement of the problems



15

Loop patch antenna is not concerned by many RF researchers. This is because its

dimension usually big in size and difficult to implement. In the past ten years [1], many

metal detectors are using loop antennas, but not in patch format, to detect the land mine

or any metal objects burry under the ground. This kind of loop antenna made from many

turns of wires and heavy in weight. Besides that, the operating frequency of the loop

antenna used by the metal detectors are low in frequency. This can be easily distorted by

noise. Figure 1.1 shows typical metal detector [2]:

Figure 1.1 - Application of loop antenna in metal detector [2].

Figure 1.2 - Application of loop antenna in VHF/UHF frequency [3].

Figure 1.2 shows the loop antenna also used for indoor TV channels reception. As

seen in the diagram, the loop is very big in size and inconvenient to install.



16

1.3 Objectives

The objective of this project is to:

Design and implement a loop patch antenna that operates at 900MHz.

The gain of the antenna must be greater than 2dBi.

The antenna has to resonance at 900MHz.

The input impedance of the antenna must be 50.

The antenna must at least receive one television channel.

1.4 Scope of the project

The scope of the project is shown in Figure 1.1:

Figure 1.3 - The scope of the project.

As seen in Figure 1.3, the scope of the project covers the design and construction of

the loop path antenna. After design, the parameters will be keyed into antenna

Scope of the project

Design aloop pathantenna

Fabricate theantenna

Simulate theantenna usingADS

Test and analyze theresults



17

simulation software (ADS) to compute and optimize the gain as well as the resonance

frequency.

If the result of the simulation is satisfied, next proceed to the fabrication stage. In this

stage, the PCB board which also called FR4 board will be used to make a loop antenna.

Finally, the antenna is sends for testing using network analyzer and applies it to detect

the television channels.

1.5 Expected Outcome of the Project

Figure 1.4 shows the expected outcome of the project:

Figure 1.4 - Expected outcome of the project.

The parts, name and functions of the antenna is summarized into table 1.1.

Parts Name Functions



18

56 Loop antenna A copper conductor used to receive the signals34 FR4 dielectric material To support the loop antenna12 50 SMA port Connect to coaxial cable

Table 1.1 - Summarized the parts, name and functions of the loop antenna

1.6 Technical proposed block diagram to implement the project

Figure 1.5 - Technical block diagram to implement the project.

Figure 1.5 shows general view of project components. As seen in the block diagram, the

loop patch antenna developed consists of SMA connector or SO239 connector. The

SMA connector is only used when the antenna tested under network analyzer whereas

the SO239 is used when the antenna is tested using television.

Loop patch antennaSMA or SO239 port

TV/RF signal generator(Optional)

Network analyzer



19

In other words, the SMA or SO239 are the ports to fetch the RF signal. Since antenna

is a reciprocal device, it can be work for both transmitting and receiving. As a matter of

fact, to view the transmitting signal and receiving signal, a network analyzer is used. In

this network analyzer, the RF signal is generated internally and transmit to the loop

patch antenna via 50 coaxial cables. The signal is then returned back to network

analyzer using the same cables. From transmit and receive signal, the network analyzer

can determine S11 (input impedance), VSWR and return loss of the antenna.

RF signal generator is an optional source to connect to the antenna for testing. If the

network analyzer does not has RF source function, then RF signal generator is needed.

Television is connected to see whether the loop patch antenna can be used to receive the

VHF/UHF signal or not. This will be shown later in this report.

1.7 Overview of the report

Chapter 1 of this report is an introduction. This chapter introduces overview of the

project and its objectives. The chapter also explains the technical content of the project

in terms of block diagram. Apart from that, chapter 1 highlights the overview of the

report chapters.

Chapter 2 is a literature review. This chapter discusses theory of loop antenna and

design issues. Reviewing the current loop patch antenna research also fall into this

chapter.

Chapter 3 is about the methodology. This chapter will show systematic way to

implement the project. A flow chart is used to summarize the entire work and a detail

explanation on the method used to design the antenna.



20

Chapter 4 is hardware and software implementation. This chapter discusses the

components used in the project, how the components combined to made a loop patch

antenna and software used to design and simulate the antenna.

Chapter 5 is a results display and analysis. This chapter mainly discusses the data

collected from the experimental works. The chapter also explains technical issues on the

design of hardware as well as the problem facing.

Chapter 6 is a conclusion chapter. This chapter concludes the project outcomes and

its limitation. Advantages and disadvantages also will be stated in this chapter. Future

improvement on the project will be briefly described in this chapter too.

CHAPTER 2: REVIEW OF LITERATURE



21

2.1 The Theory of Loop Antenna

Loop antennas take many different forms such as rectangle, square, triangle, ellipse,

circle and many other configurations. Because of the simplicity in analysis and

construction, the circular loop is the most popular and has received the widest attention.

It will be shown that a small loop is equivalent to an infinitesimal magnetic dipole

whose axis is perpendicular to the plane of the loop. That is, the fields radiated by an

electrically small circular loop are of the same mathematical form as those radiated by

an infinitesimal magnetic dipole [1].

Loop antennas are usually classified into two categories, electrically small and

electrically large. Electrically small antennas are those whose overall length (number of

turns times circumference) is usually less than about one tenth of the a wavelength (NC

< /10). However, electrically large loops are those whose circumference is about a free

space wavelength (C ~ ). Most of the applications of loop antennas are in HF (3 -

30MHz), VHF (30 - 300MHz) and UHF (300 - 3000MHz) bands. When used as field

probes, they find applications even in the microwave frequency range [2].

Loop antennas with electrically small circumference or perimeters have small

radiation resistances that are usually smaller than their loss resistances. Thus they are

very poor radiators, and they are seldom employed for transmission in radio

communication. When they are used in any such application, it is usually in the

receiving mode, such as in portable radios and pagers, where antenna efficiency is not as

important as the signal to noise ratio. They are also used as probes for field

measurements and as directional antennas for radio wave navigation. Figure 2.1 shows

few examples of existing loop antennas.



22

Figure 2.1 - Loop antennas [3].

The field pattern of electrically small loop antennas is similar to that of an infinitesimal

dipole with a null perpendicular to the plane of the loop and with its maximum along the

plane of the loop. As the overall length of the loop increases and its circumference

approaches one free space wavelength, the maximum of the pattern shifts from the plane

of the loop to the axis of the loop which is perpendicular to its plane [4].

The radiation resistance of the loop can be increased and made comparable to the

characteristic impedance of practical transmission lines, by increasing its perimeter or

the number of turns. Another way to increase the radiation resistance of the loop is to

insert within its circumference or perimeter, a ferrite core of very high permeability

which will raise the magnetic field intensity and hence the radiation resistance. This

forms so called ferrite loop.



23

2.2 Radiated Fields

To find the fields radiated by the loop, we need to consider the potential function in

three dimensional spaces. This is given by [5]:

4)z,y,x(A

C

This equation can be derived by referring to Figure 2.2 [6]:

From Figure 2.2, R is the distance from any point on the loop to the observation

point and dl' is an infinitesimal section of the loop antenna. In general, the current

distribution Ie(x', y', z') can be writte

Electrical & Electronics Engineering 3+0in collaboration with UNIVERSITY OF EAST LONDON.

LOOP PATCH ANTENNA DESIGNMAHDI ALHAJI


three dimensional spaces. This is given by [5]:

'dR

e)'z,'y,'x(I

jkR

C

e

This equation can be derived by referring to Figure 2.2 [6]:

Figure 2.2 - Geometry of circular loop [6].


is an infinitesimal section of the loop antenna. In general, the current

(x', y', z') can be written as:


(1)

eometry of circular loop [6].


is an infinitesimal section of the loop antenna. In general, the current



24

Ie(x', y', z') = ax Ix(x', y', z') + ay Iy(x', y', z') + azIz(x', y', z')

(2)

For the circular loop antenna shown in Figure 2.2, it would be more convenient to write

the rectangular current components in terms of the cylindrical components using matrix

as [7]:

zz

y

x

I

I

I

100

0'cos'sin

0'sin'cos

I

I

I

(3)

For the circular loop, the current is flowing in the direction so that [8]:

Ie = arIsinsin(-') + aIcos sin(-') + aI cos(-')

(4)

The distance R, from any point on the loop to the observation point, can be written as

[9]:

222 )'zz()'yy()'xx(R

(5)

Since

x = r sincos

y = r sinsin

z = r cos

x' = a cos'



25

y' = a sin'

z' = 0

The equation 5 can be reduced to [10]:

)'cos(sinar2arR 22 (6)

The differential element length is given by [10]:

dl' = a d' (7)

Hence equation 1 can be simplified to [10]:

'd'cossinar2ar

e'cos

4

IaA

22

'cossinar2arjk2

0

0

22

(8)

Using Maclaurin series to simplify the integration and introducing H and E as magnetic

field and electric field components, the magnetic field reduced to [11]:

jkr

2

02

r ejkr

11

r2

cosIkajH

(9)

jkr

2

02

e)kr(

1

jkr

11

r4

sinI)ka(H

(10)

The electric fields correspond to [12]:



26

Er = E = 0

E = jkr02

ejkr

11

r4

sinI)ka(

(11)

2.3 Power Density of the Loop Antenna

The fields radiated by a small loop are valid every where except at the origin. The

power in the region very close to the antenna is predominantly reactive and in the far

field is predominantly real. To illustrate this, the complex power density is defined as

[13]:

)HE(2

1W (12)

When equation 12 is integrated over a closed sphere, only its radial component given by:

32

22

0

4

r)kr(

1j1

r

sin|I|

32

)ka(W (13)

Which contribute to the complex power Pr. Thus [13]:

ddsin)kr(

1j1|I|

32

)ka(dsWP 3

2

0

2

03

20

4

r (14)

Which reduces to:

3

20

4r

)kr(

1j1|I|)ka(

12P (15)

2.4 Loop Patch Antenna Design

The loop patch antenna design is begin by considering the size. This can be done

using the equation shown below [14]:



27

f

c (16)

Where is a wavelength express in meter.

Once the size of the loop is determined, it is then proceed to calculate radius of the loop.

This can be obtained using equation 17 [15].

2r a

3

2120R

(17)

Where Rr is a characteristic impedance 50 and "a" is a radius of the loop antenna.

The gain and directivity of the antennas can be obtained from the chart as shown in

Figure 2.3 and 2.4.



28

Figure 2.3 - Resistance versus the directivity [16].



29

Figure 2.4 - Reactance versus the directivity [16].

The conductor length connected to the loop antenna and the port is normally given by

/4 long. If there is a spacing happen due to two conductors lengths are used, then the

spacing equation is given by [17]:

1

2

f2

cS

r (18)

Where S = Spacing

f = frequency

c = speed of light

r = dielectric constant



30

CHAPTER 3: SYSTEM DESIGN

Project design steps are very important to achieve the objectives. A successful project

is because of proper planning and implementation. This chapter will shows a detail of

system design of the project. The general design of the loop patch antenna can be

summarized as shown in Figure 3.1.

Yes No

Figure 3.1 - A process to build a 900MHz loop patch antenna.

Study the looppatch antennaparameters

Highlight the designrequirements

Manually design the antenna todetermine its dimension based on thefrequency and gain requirement.

Put all the design parameters into antennasimulation software

Test and analyze the results

Fabricate the antenna

Changeparameters

Is the simulationresult correct?

Simulate the antenna



31

The first step of designing the project is to identify the parameters of the loop patch

antenna and the antenna features. The study of loop patch antenna or the information

regarding the antennas can be obtained from the following resources:

Internet

Journals

Conference papers

Antenna textbooks

Among all the resources, textbooks will be widely used compared to others. The antenna

books provide sufficient information on the design of loop patch antenna. Not only that,

the book also contents the detail design of the antenna.

Journal and conference papers are used as a guideline in implementing the loop patch

antenna. Journal and conference papers do not provide clear or detail in the system

design of the antenna. As a matter of fact, these two resources normally used to

determine the similar works or research that has been done by some one else. They also

used for comparison purposes.

Internet is a huge library. Internet can provide information on the loop patch antenna

designs. However, this does not mean that the text in the literature review is copy from

internet. In this project, the use of internet is to fetch some picture information, not the

text information. Lecturers and examiners are welcome to upload this document to

"Turn-It-In" plagiarism checker to check for plagiarism.

After getting enough information on the loop patch antennas. It is then perform

manual design on the antenna. Of course, the design requirement must be highlighted

before the simulation. The design requirement will be shown in next section.



32

Once the antenna has been manually design on a piece of paper, the parameters are

then keyed into the antenna simulation software. Although there are many antenna

simulation software available in the market, however, the ADS (Advanced Design

System) antenna simulation software will be used. This software is developed by Agilent

company in 2002. A pirated version of this software can get from many computer shops.

The advantages of using ADS are:

1. Automatic scale the antenna size once the parameter such as permeability and

dielectric constant as well as the frequency values has been keyed in.

2. Fast computation using mesh integration and green theorem.

3. The results can be optimized until desire results are obtained.

4. For the antenna design, the simulation results will show: radiation pattern in 2D/3D,

power transmit/receive, S-parameters, Smith chart, gain, impedance and directivity

plots.

Simulation usually will take longer times because of optimization to get a better

result. For example, the loop patch antenna in this project is operates in 900MHz.

However, this does not mean that after manually design and key in those parameters into

the ADS software, the result will directly show resonance at 900MHz. In the real time,

the results get from the first simulation will be different from the expected results. As a

matter of fact, optimization is needed.

When the antenna simulation results are all correctly, the next step is proceed to the

antenna fabrication. Fabrication of antenna will be shown detail later in this chapter.

Finally the antenna will be tested in the lab using network analyzer and television.

The results are then compared to the simulation results.



33

3.1 Design requirements

This section will shows the loop patch antenna technical design requirements. The

requirements are listed and stated in table 3.1.

Parameters RequirementsFrequency 900MHzGain > 2dBiRadiation pattern CircularInput impedance, S11 50VSWR 1 - 3No. of turns of the loop 1Shape of the loop Circular

Table 3.1 - The technical parameters and design requirement of the antenna.

3.2 Loop Patch Antenna Design

Step1: Determine the overall size of the antenna

To determine the overall size of the antenna, the design must begin with frequency and

calculate the wavelength. Wavelength is the only parameter that can tell the overall size

of the antenna. Hence, for the loop patch antenna operate in 900MHz,

Size of antenna:6

8

10900

103

f

c

= 33.3cm



34

Step 2: Find the radius of the loop

Since the RF source having is 50 of output impedance, we are expecting radiation

resistance to be 50 as well as so that maximum power can be transfer. With that, we

can find out the radius of the loop.

2r a

3

2120R

2a3

212050

a = 0.25m or 25cm

Hence, the radius of the loop is 25cm.

The circumference is = 2r = 20.25 = 1.57m or 157cm

Step 3: Find the circumference of the loop

To find out the circumference of the circular loop, it is important to refer the graph

shown in Figure 3.2 (resistance graph). Since only = 8 can give lower resistance

which is nearly 50, then from the graph in Figure 3.2, ka = c/ is 0.3.



35

Figure 3.2 - Determine the 50 resistance from the graph.

So, the second loop which has circumference of:

0.30.333 = 0.0999m or 9.99cm



36

Step 4: Determine the length which strip conductor that connect to the loop.

The length connecting loop in the form of patch is determine using /4. So, the length is:

/4 = 33.3/4 = 8.235cm

Step 5: Calculate the width of the strip conductor.

The width of the conductor that connects to the loop is then given by:

W = L/10 = 8.235cm./10

= 0.8235cm

Step 6: Calculate the conductor separation.

Since two equal size of conductors are used and connected to the loop, then a suitable

spacing is:

1

2

f2

cS

r

Where r dielectric constant of the material to build the loop antenna.

C is speed of light.

So, the spacing is:

144

2

109002

103S

6

8

= 0.035m = 3.5cm



37

Where 44 is a dielectric constant of FR4 board which is used to make the loop antenna.

Step 7: Sketch the diagram of the design.

Based on the calculated parameters, the outcome or physical appearances of the loop is

then sketch and shows in Figure 3.3.

Figure 3.3 - The physical appearance of the loop patch antenna.



38

CHAPTER 4: HARDWARE & SOFTWARE IMPLEMENTATION

This chapter shows the hardware and software implementation of the project. The

chapter will begin by introducing the hardware components needed to build the loop

patch antenna and then followed by software ADS.

4.1 Hardware Requirement for the making of Loop Patch Antenna

The hardware requires used to build antenna is FR4 PCB copper board, SMA port,

SO239 port, 50 coaxial cable, soldering gun and soldering lead. Each of the

components will be briefly describe in this section.

4.1.1 FR4 PCB Copper Board

Figure 4.1 - FR4 PCB copper board.



39

FR4 copper board also known as PCB and is a common board to make a circuit for

electronic and electrical. This board can support the signal up to 3GHz. As a result, it is

suitable used to make a patch antenna or printed circuit board antenna. The FR4 is in

single layer of copper. Although double layer also exist, but it cannot be used for the

project because if both sides are conductor, a leak of electromagnetic wave may occurs.

4.1.2 SMA Port

Figure 4.2 - SMA Port.

It is an RF female port which supports the coaxial cable. This port has characteristic

impedance of 50. The port offer excellent electrical performance from DC to 18GHz.



40

4.1.3 SO239 Port

This port supports UHF and VHF signals. Typical port is suitable for TV connection.

The port exists in male and female type. The characteristic impedance of the port is 75

As a result, when using this port for loop pat

must be 75 types.

Electrical & Electronics Engineering 3+0in collaboration with UNIVERSITY OF EAST LONDON.

LOOP PATCH ANTENNA DESIGNMAHDI ALHAJI

Figure 4.3 - SO239 Female port.


The port exists in male and female type. The characteristic impedance of the port is 75

As a result, when using this port for loop patch antenna connection, typical coaxial cable


The port exists in male and female type. The characteristic impedance of the port is 75.

ch antenna connection, typical coaxial cable



41

4.1.4 50 Coaxial Cable

Figure 4.4 - 50 Coaxial cable.

The cable is suitable for most of the lab equipments connection such as network

analyzer, function generator or even the spectrum analyzer. The impedance of the cable

would not change as the frequency is change. As a result, this type of cable is very

suitable used for connection between loop patch antenna and the network analyzer for

testing.



42

4.1.5 75 Coaxial cable

Figure 4.5 - 75 TV coaxial cable.

The 75 coaxial can be seen every where for those who have television at home. The

cable is only suitable for television to aerial connection. This kind of cable is very

flexible and can stand for weather changed. The cable is also tough and not easy to cut.

As seen in Figure 4.5, the cable has two conductors. One at the center is called core

conductor, which usually connect to positive terminal where as the one at the size is

called secondary conductor for ground connection. The cable only supports VHF to

UHF signals. The impedance of 75 would not change over the range from VHF to

UHF.



43

4.1.6 Soldering Gun

Figure 4.6 - Soldering gun.

Soldering gun comes in variety power output. The smallest output power is 18W. The

highest output power is 200W. Soldering gun is used to melt the soldering lead so that

the lead can make connection between SMA port or SO239 port with the loop patch

antenna. Most of the soldering gun works for more than 1A of current with 240V AC

input voltage.



44

4.1.7 Soldering Lead

Figure 4.7 - Soldering lead.

Soldering lead melt when expose to high temperature. About 75C, the lead can melt and

becomes solid again when the heat is release. The lead can form of conductor and

usually used for soldering purposes. In the project, the soldering lead is used joint the RF

connector and the loop patch antenna.



45

4.2 Software Requirement to design the Loop Patch Antenna

As mentioned before, ADS is a software used to design and simulate the loop patch

antenna. This section will briefly introduce the Agilent ADS software.

4.3 Loop Patch Antenna Design using ADS

The ADS stand for Advance Design System. It is a fasts and accurate patch antenna

simulation software. Figure 4.8 shows the window template to begin the ADS when a

copy of ADS software is available in the computer.

Figure 4.8 - ADS starting window.



46

To use the software design any patch antenna, it is always begins with new project.

Figure 4.9 shows the way to click on "New Project".

Figure 4.9 - Creating new project.

Figure 4.10 - New project template window.



47

When click on the "New Project", the template window shown in Figure 4.10 will pop

out. In this window, user is asked to key in the project name and unit. The default unit is

in mm. Click "Ok" and the window of Figure 4.11 will appear.

Figure 4.11 - Schematic window.

Note that, the window appears is not the window for the patch antenna design. The

window shows in Figure 4.11 is to design the antenna schematic diagram and it will not

be used in the project.

To go to the window for patch loop antenna design, from Figure 4.11, click

"Window" "Layout" and immediately the window of Figure 4.12 will appear.



48

Figure 4.12 - The window for patch antenna design.

There are few important functions in the window of Figure 4.12 to design the loop parch

antenna. Just before shows the functions, user has to take note on the dimension and its

units. Figure 4.13 shows the dimensions in x and y coordinates. Moving the mouse

pointer around will change the dimension values.



49

Figure 4.13 - Dimension of the measurement in 2D coordinates system.

To begin design the loop patch antenna, user has to use the function as shown in Figure

4.14:

Figure 4.14 - Important functions to sketch the path loop antenna.

The circle shape shown in Figure 4.14 is used to sketch the circle in order to form a loop.

By following the calculation, the radius of the circle is, 250mm or 25cm, then a click on

the circle shown in Figure 4.14 to draw a circle with radius of 250mm. This is shown in

Figure 4.15.



50

Figure 4.15 - Draw a circle in the ADS software.

To create a loop, user has to create another circle which is smaller the one show in

Figure 4.15 then overlap it. This is shown in Figure 4.16.

Figure 4.16 - Draw a second circle and overlap it.



51

Now, go to "Edit" "Merge" "Union Minus Intersection" and click on it as seen in

Figure 4.17, the result of circle is then loop like the one show in Figure 4.18.

Figure 4.17 - Creating a single loop on the circle.

Figure 4.18 - A ring or a single turn of loop patch antenna.



52

Now, the loop shown in Figure 4.18 needs to connect to the strip of conductor for RF

port insertion. To do that, use the rectangular function shows in Figure 4.14 and create a

connection between strip and the loop. The length should follow the calculated value.

Figure 4.19 shows this.

Figure 4.19 - Strip of conductor joint with the ring.

Notice that when user tries to joint the strip and the loop together, it does not mean that

it is actually jointed together. ADS will not have this automatic jointing the path. As a

matter of fact, to joint the loop and the strip of the conductor, user has to highlight the

two components as shown in Figure 4.20.



53

Figure 4.20 - Joining the strip and loop together.

After highlight the two components, then go to "Edit" "Merge" and click on "Union"

to finish the job on joining the components.

The loop patch antenna shown in Figure 4.20 needs to be trimmed and corrected

before doing the simulation. Figure 4.21 shows the final outlook or actual loop patch

antenna that will be used in the project.



54

Figure 4.21 - The complete loop patch antenna design.

4.4 The Making of Loop Patch Antenna

This section will show the how the prototype of the loop patch antenna will be made.

The loop patch antenna only can be made when the simulation results are confirmed

correct. If not, it will affect the practical results and hence affect the television channel

receptions.

To build the prototype of loop patch antenna, it important to prepare the materials:

Laser printer, PCB pen, Ironing, A4 size transparent paper, sticker, Iron (III) Chloride,

alcohol solution and clean water.



55

The first step of doing the loop patch antenna is print out the antenna layout using

laser printer and A4 size transparent paper as shown in Figure 4.22:

Figure 4.22 - Print out the loop patch antenna layout from ADS software.

After print out, the next step is prepares the FR4 PCB board, PCB pen, sticker and

ironing. This is shown in Figure 4.23. The process of ironing will begin and it is a

process to transfer the image of print out on to the PCB FR4 board. Figure 4.24 shows

the image put on the PCB FR4 board and ready to do the ironing process.



56

Figure 4.23 - Material prepared for ironing process.

Figure 4.24 - Use sticker to hold the print out and put on the PCB board.



57

The ironing process now begins and it is shown in Figure 4.25.

Figure 4.25 - Ironing in progress.

In the ironing process, heat plays an important role to determine the yield or quality of

image transfer. For good ironing process, the time spends should in between within 10

seconds for temperature of 80C. Figure 4.26 shows the time recorded graph while

ironing is in progress.



58

Figure 4.26 - The ironing process time phases.

As seen from the graph shown in Figure 4.26, the total time taken is 80 seconds to do

the whole ironing process. When temperature reaches 80C, the toner transfer will be

started. This takes about 10 seconds.

Figure 4.27 shows the results of image after ironing. Notice that the image of loop

patch antenna has been printed on the FR4 PCB board. If the image printed on FR4

material is not clear. It can be make clearer by using the PCB pen. This is shown in

Figure 4.27 (b).



59

(a) Layout printed on FR4 PCB. (b) Darken the image using PCB pen.

Figure 4.27 - Result after ironing process and darken the image.

Figure 4.28 - Prepare for etching.



60

Figure 4.28 shows the materials prepare for etching after darken the antenna on the

FR4. Etching is a process that removes materials from such us unwanted copper from

the PCB surface to achieve circuit design requirements. The etching process used in this

project is called chemical etch or pattern etch.

The most important thing about etching is the etch rate. Etch rate will determine the

quality of PCB. Too much etching will remove part of the wanted copper area whereas

little etched will take long time end the process. Hence, etch rate is defined as:

TimeEtch

etchaftercopperofThickness-etchbeforecopperofThichnessrateEtch

The etch time usually affected by few factors as shown below:

The concentration of iron (III) chloride

The temperature

Disturbance of solution

The concentration of iron (III) chloride will determine rate of chemical reaction. In

this etching process, the chemical reaction involve in the etch process is:

FeCl3 + Cu FeCl2 + CuCl

Where FeCl3 is the iron (III) chloride, Cu is copper, FeCl2 is iron (II) chloride and CuCl

is a copper chloride. The rate of reaction is given by:

TakenTime

reactedPCBoncopperofmassTotalreactionofRate



61

Figure 4.29 shows the etching in progress and Figure 4.30 shows process of cleaning the

loop patch antenna after etching and attaching the RF port on it.

Figure 4.29 - Etching in progress.



62

(a) Clean the antenna after etching. (b) Clean the antenna using alcohol.

(c) Result of loop patch antenna after clean. (d) Solder the SMA port on the tip of the

antenna.

Figure 4.30 - Process of making the loop patch antenna after etching.



63

Figure 4.31 - The final outlook of the circular loop patch antenna.

Figure 4.31 shows the complete outlook of the circular loop patch antenna and ready to

go for testing.



64

CHAPTER 5: RESULTS & DISCUSSIONS

This section will present the results from the experimental test and practical application

of the loop patch antenna. The discussion will begin with the simulation results followed

by lab test on the loop patch antenna and finally apply the loop patch antenna to receive

the TV channels.

5.1 Simulation Results

To simulate the antenna shown in Figure 4.21, one must go to "Momentum"

"Substrate" and click on "Create/Modify", the window of Figure 5.1 will pop out:

Figure 5.1 - Window that allow user key in the antenna parameters.



65

Note that the important parameters that can affect the results of S11, radiation pattern,

input impedance and gain of the antenna are thickness, permittivity and real.

Some parameters cannot changes because it has to follow the practical value. The

parameters such as real and permittivity cannot changes. In real time, the permittivity

and real has to put 40 because the FR4 material used to make the antenna has a

permittivity of 40. The only parameter can change is the thickness of the substrate. In the

market, there are many types of thickness of the substrates. As a result, to tune the

antenna so that it produces desire result, the thickness is one of the concerned parameter

besides side of the antenna or the radius of the antenna.

After key in the antenna parameters, user now has to insert the port at the tip of the

antenna. This port can be clicked from . Without the port, ADS cannot do the

simulation because port is a RF source where it determine the input power.

After inserting the port, user now can go to "Momentum" "Simulation" and click

on "S-parameters". The window of Figure 5.2 will come out.

Figure 5.2 - Simulation control window.



66

Figure 5.2 is a simulation control window. As seen in the window, it asks the user to

enter the start frequency and stop frequency. Since the loop patch antenna is operates in

900MHz, a wide range frequency should be entered. From the window, 500MHz to

2GHz is sufficient ranges.

The sample point limit is the amount of iteration. It determines the number of samples

so that a graph can be plotted. The higher the sample point limits, the more accurate the

results but computation will become slow.

After determine the sample point limits and enter the start and stop frequency, it is

then click on "Update" "Apply" "Simulate". The simulation should begin and the

results of S-parameters will automatically plot in the graphs.

Figure 5.3 - S11 and S22 simulation results of loop patch antenna shown in Figure 4.21.

52



67

Analysis: Figure 5.4 shows the input reflection coefficient (S11) and output reflection

coefficient (S22) plots of the loop patch antenna. The meaning of S11 and S22 are shown in

Figure 5.4 based on the loop patch antenna design.

Figure 5.4 - The meaning of S11 and S22 on the loop patch antenna.

From Figure 5.3, the S11 is -27.071dB resonance at almost 900MHz. Here the resonance

frequency is 957MHz. The exact 900MHz would not give an expected magnitude of S11.

Basically, the lower the S11 values toward more negative, the better the result is. This is

because it approaches 50 which can match with the impedance of the RF generator.

From Figure 5.3 the S11 = -27.071dB, the input impedance is [18]:

NB: The most important parameters are S11 and S22, because both can transmit and

receive. As for the S12 and S21 they can only receive without transmitting and

transmitting without receiving respectively. Since the antenna is a reciprocal antenna,

then we can only focus on parameters that have reciprocal functions (i.e transmitting

and receiving).



68

-27.071dB = 20log10 S11

20

071.27

10

= S11

S11 = 0.0443

50Z

50ZS

in

in11

0.0443 (Zin + 50) = Zin - 50

0.0443Zin + 500.0443 = Zin - 50

0.0443Zin + 2.215 = Zin - 50

2.215 + 50 = Zin - 0.0443Zin

52.215 = 0.9557Zin

9557.0

215.52Z in

= 54.64

Which is very near to 50. Since the ADS using 1Vrms RF signal as a source to obtain

the S11 and S22 parameters, then the transmit power at the output of the RF source is:

Pin(Source) = I2R

= 12 50

= 50W

Since the input and out of the antenna is having the same impedance as 54.64, then the

power that will be radiated by the antenna is:

POut(radiate) = 1254.64

= 54.64W



69

The loss of power due to impedance mismatch is:

Power loss = 54.64W - 50W

= 4.64W

Apart from the S11 and S22 graphs plotted, The Smith charts results also shown for S11

and S22. The two Smith charts results are shown in Figure 5.5.

Figure 5.5 - The Smith charts plot for S11 and S22.

Analysis: Looking into the Smith chart and identify the frequency of 957MHz, it is seen

that the loop patch antenna having a complex impedance of 1.045 + j0.01. The actual

impedance is then:

Zactual = 50 (1.045 + j0.01)

= 52.25 + j0.5



70

Since the both the circles are toward left, that means the impedance of the loop patch

antenna from 500MHz to 2GHz would be small and typical values is less than 60. The

circles are covered the semi circle of Smith chart on top and bottom. As a result, this can

conclude that the loop patch antenna is having equal inductive reactance and capacitive

reactance. Hence it will be easy to tune to the resonance when construct it in the

practical.

Figure 5.6 shows the impedance plot of the loop patch antenna from 500MHz to

900MHz. Putting the market at near to 900MHz, it shows the impedance is 0.906

normalizes impedance.

Figure 5.6 - Impedance plot of the loop patch antenna.



71

Analysis: The graph shows in Figure 5.6 is an impedance plot for the loop patch

antenna from 500MHz to 2GHz. The impedance is given by:

Z = (R jX)

Where Z = Impedance

R = Resistance in real

X = Reactance either capacitance or inductance

We know that X is given by [19]:

fL2XL

fC2

1XC

Hence the Xc or XL are varies with the frequency. That is why we get difference

impedance at difference frequency. Since our concerned frequency is 900MHz, from the

graph, it gives 0.906 normalize impedance. 0.906 is not actual impedance. It is called

normalized impedance by characteristic impedance which is 50. To calculate the

actual impedance, we have to multiply by 50. Hence, actual impedance at 898.4MHz

is:

Zactual = 500.906

= 45.3



72

Figure 5.7 shows the VSWR plot of loop patch antenna from the simulation result.

Figure 5.7 - VSWR plot of loop patch antenna.

Analysis: VSWR is a measure of how much the wave is returned to the source when

impedance is mismatched. The practical excepted range of value is from 0 to 2. When

VSWR is more than 2, the antenna is lost its impedance mismatched and it might not be

able to receive any channel. There is a relationship between VSWR and the S11. The

relationship between them can be expressed mathematically as shown below:

11

11

S1

S1VSWR

Since the VSWR = 1.16 at 900MHz,



73

1.16 (1 - S11) = 1 + S11

1.16 - 1.16S11 = 1 + S11

1.16 - 1 = S11 + 1.16S11

0.16 = 2.16S11

S11 = 0.074

Convert to dB, we have:

S11(dB) = 20log100.074

= -22.615dB

To plot the radiation pattern of the antenna, user can co go to "Momentum" "Post

Processing" and click on "Radiation pattern". The following window will pop out:

Figure 5.8 - Ready to plot the radiation pattern.



74

Analysis: Figure 5.8 shows the window which ready to plot the radiation pattern of the

loop patch antenna. Before plot the radiation pattern, the window request user to select

which types of radiation to be plotted, 2D or 3D? Before looking the 3D, we would like

to see the 2D plot. As a result, use mouse to click on "2D data display". The window also

asks for port excitations, user can choose either one because they are the same. Once

complete setting, click on "Apply" then "Compute". The 2D radiation plot is shown in

Figure 5.9 and 5.10.

Figure 5.9 - Circular polarization radiation pattern.



75

Figure 5.10 - The gain and directivity radiation pattern.

Figure 5.11 - Efficiency of the loop patch antenna.



76

Although there are many graphs plotted in the radiation 2D radiation patterns. Only

three graphs like circular polarization, gain & directivity and efficiency of the antenna

are useful to describe the performance of loop patch antenna.

From Figure 5.9, it is seen that the radiation pattern of the loop patch antenna is

circular. The red colour represent magnetic field whereas the blue colour is electric

field. Note that both are radiate in the same direction with the same power. As a result,

it can be predict that these fields must be a near field radiation.

Figure 5.10 shows gain and directivity of the loop patch antenna. Notice that the gain

and directivity are having the peak value of 5dB at the angle of 0. Figure 5.11 shows

the efficiency of the antenna. The efficiency of the loop patch antenna is very high which

is about 85%. This shows that only 15% of the power has been loss when operate at

957MHz of frequency.

To view the radiation plot in 3D as well as the prototype of the loop patch antenna in

3D, user has to go back to Figure 5.6 and click on "3D Visualization". The windows of

Figure 5.12 and 5.13 immediately will come out.

Figure 5.12 - 3D view of loop patch antenna.



77

Figure 5.13 - Three 3D radiation pattern of the loop patch antenna.

Analysis: Figure 5.12 shows the 3D view of the loop patch antenna with the current

distribution along the loop antenna. The current represented by blue colour and excited

from the port with a little green colour. This indicates the source is from the port.

Figure 5.13 shows the 3D radiation pattern of the loop patch antenna. The radiation

is plotted in the polar coordinate which circulates in 360. The radiation is in circular

polarization as shown.



78

5.2 Experimental Test of Loop Patch Antenna

This section presents an experimental test of loop patch antenna in the lab using

network analyzer. Figure 5.14 shows the typical network analyzer used to test the loop

patch antenna:

Figure 5.14 - Network analyzer.



79

Table 5.1 shows the technical features of the network analyzer.

Technical Features RequirementPower supply 240V, 50HzMaximum current 20Aone Keypad 4x3No. of ports 2No. of USB port 1Frequency sweep 9kHz - 13.6GHzWindow XpNo. Markers 3Functions Measures S-parameters, Smith chart, impedance, VSWR,

and power transmit/receiveFrequency entered Start, Centre and stopAttenuation 0dB - 50dB

Table 5.1 - Technical features of the network analyzer.

Figure 5.15 shows the loop patch antenna is connected to network analyzer for testing.

Figure 5.15 - Network analyze test on loop patch antenna.



80

Figure 5.16, 5.17, 5.18 and 5.19 shows the S11 measurement, Smith chart plot,

impedance plot and VSWR plot

Figure 5.16 - The S11 plot of the loop patch antenna.

Analysis: Figure 5.16 shows the S11 results obtained from the real time network

analyzer machine. Notice that there are quite a number of resonance points happen at

different frequency. However, the most concerned frequency is the one near to 900MHz

because the antenna is operates at 900MHz. From Figure 5.14, the highest peak of S11 is

-24.622dB which happens at 840.16392MHz frequency. This is the only frequency very

to 900MHz. The exact 900MHz would not get resonance due to following factors:



81

1. The soldering point between antenna and the port causes resonance point shifted.

2. The N-connector which converts from SMA to network analyzer port causes about -

3dB loss of signal. As a result, this also affects the resonance point of frequency.

From Figure 5.16, the input reflection coefficient S11 at 840.16392MHz is:

- 24.622dB = 20log10S11

20

622.24

11 10S

= 0.0587

0.0587 (Zin + 50) = Zin - 50

0.0587Zin + 2.94 = Zin - 50

2.94 + 50 = Zin - 0.0587Zin

52.94 = 0.9413Zin

9413.0

94.52Z in

= 56.24

Compare to simulation result, we have 54.64. As a matter of fact, the simulation is of

S11 is almost match with the practical result of S11 with almost the same impedance.



82

Figure 5.17 - The Smith Chart plot of loop patch antenna.

Analysis: Figure 5.17 shows the Smith chart plot of loop patch antenna. Note that from

the marker point, the impedance shows 57.440 + j15.552 at 841.12671MHz. Compare

to simulation result, it shows 52.25 + j0.5. That means, the practical of loop patch

antenna is more inductive.



83

Figure 5.18 - Impedance plot of loop patch antenna.

Analysis: Figure 5.18 shows the impedance plot of loop patch antenna. The impedance

varies with the frequency. At 837.38MHz which is very near to 900MHz, the impedance

is 63.346. Basically the impedance should be the same with calculated which is

56.24. This is because the marker of the network analyzer did not allow positioned to

the frequency of 840.16392MHz. It is too narrow, as a result, the marker only stop at

837.38MHz. Compare with simulation result, the impedance at near the 900MHz is

45.3.



84

Figure 5.19 - The VSWR plot.

Analysis: Figure 5.19 shows the VSWR plot of the loop patch antenna tested with

network analyzer. Looking into the graph, the VSWR is 1.385 at the frequency of

839.44MHz. The S11 can be calculated:

11

11

S1

S1VSWR

1.385 (1 - S11) = 1 + S11

1.385 - 1.385S11 = 1 + S11

0.385 = 2.385S11

S11 = 0.1614



85

5.3 Apply and test the Loop Patch Antenna using Television

This section will present the application of loop patch antenna to test the TV signal

reception. Since the 900MHz is under the range of VHF/UHF, the antenna should be

able to receive some channels from the Television broadcast station. A comparison

between commercial types of loop antenna with loop patch antenna developed in this

project will be shown.

5.3.1 The performance of commercial type of loop antenna

Figure 5.20 - Using commercial type of loop antenna to receive the TV channels.

Analysis: The commercial type of loop antenna is an elemental type of loop antenna

which using wires to form a loop antenna. In the picture of Figure 5.20, the loop

antenna has two turns. As seen in the pictures, the loop antenna tried to receive the TV

channels from the TV broadcast station. The location of doing the experimental is in

Sunway, Condominium, 5th floor face to North direction and the time is 8pm.



86

Table 5.2 shows the results recorded when using the commercial type of loop antenna to

the detect the TV channels in Malaysia.

Available Free TV Channels in Malaysia Detected by commercial type of loopantenna

TV1 TV2 Not clearTV3 NTV7 Not clearTV8 TV9

Legend:

= Able to receive with clear pictures and voice

= Not able to receive and no voice at all

Table 5.2 - The performance of commercial type of loop antenna.

5.3.2 The performance loop patch antenna developed in this project

Figure 5.21 - Using loop patch antenna to receive the TV channels.



87

Analysis: Figure 5.21 shows the pictures of using the loop patch antenna receive some

TV channels. As seen in the pictures, by using the loop patch antenna, a much clearly

channels can be received compared to the commercial type of loop antenna. Table 5.3

shows the performance of loop patch antenna on the detection of the TV channels.

Available Free TV Channels in Malaysia Detected by the developed type of loopantenna

TV1 TV2 TV3 Not clearNTV7 TV8 TV9

Table 5.3 - The performance of loop patch antenna on the TV channels reception.

To understand how the loop patch antenna works on receiving the TV channel, one have

to refer to the Gauss's law and Amperes law on current induce when a conductor is

immersed in the electric field.

Figure 5.22 shows the loop patch antenna immersed in the electric field E which

represent the TV channels.

Figure 5.22 - Analysis on how loop patch antenna works to receive the TV channel.



88

Using Ampere's law [20],

dt

di E

0

Which state that the rate of change of electric fields produces the current in a conductor.

From the Gauss's law,

E = EdA, E = Eds, or E = EdV

Where dA is a small element of area

ds is a small element of distance

dV is a small element of vollume

From Figure 5.22, E = Eds, is the most suitable express to analyze the voltage

induced in the loop antenna. Hence from Gauss's law again,

Vp = Eds

Showing potential across the point P is an integration of electric fields. From Figure

5.22,

20

Pr

dq

4

1V (From Gauss Law)

220

p

zR

q

4

1V

At the loop center where z = 0,

R4

qV

0

p

So, it is clearly since that the radius of loop plays an important role to determine the

potential difference across the terminal!



89

CHAPTER 6: CONCLUSIONS AND RECOMMENDATIONS

6.1 Conclusion

This project has achieved the objectives requirement. As seen in the results, the

antenna can operate at 900MHz or near to 900MHz. The gain is more than 2dBi shown

in the simulation result. At the frequency of 900MHz, the antenna gets resonance and

has lower magnitude of input reflection coefficient, S11. The input impedance of the

antenna also approach 50 and the antenna can receive more than one channel of the

television programme.

The comparison between the simulation results and the practical results on the loop

patch antenna is summarized in table 6.1.

Simulation results Practical resultsS11 = -27.071dB @ 957MHz S11 = -24.622dB@ 840.16392MHz

Zactual = 52.25 + 0.5 @ 957MHz Zactual = 57.440 + j15.552 @ 841.1267MHz

ZL = 45.3 @ 900MHz ZL = 63.346 @ 837.38MHzVSWR = 1.16 @ 900MHz VSWR = 1.385 @ 839.44 MHzGain = 4.8dBi -Directivity = 5dB -

= 85% -

Radiation pattern = Circular -

Table 6.1 - Summarized the comparison results between simulation and practical.



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From the testing of antenna with television channels reception, it is seen that the loop

patch antenna has better performance compared to the commercial type of loop antenna.

6.2 Problem Facings

There are few problems faces while doing the project. These problems are

highlighted as show below:

1. Soldering lead does affect the performance of antenna.

Solution: Tune the antenna by adjust the position so that it resonance at 900MHz.

2. The markers point in the simulation and network analyzer can located at the exact

frequency of 900MHz.

Solution: Use approximation frequency to justify its parameters.

3. The radiation pattern cannot be tested practically.

Solution: Depends on the simulation results.

6.3 Recommendation

In future, the project can be improved to detect the satellite TV signals which operate

at KU band and above. It is also interesting to improve the antenna so that it can receive

the WiFi signal.

Apart from the improvement, an auto searching of the channels also can be added it

into the antenna so that searching of strong signal is done automatically



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REFERENCES

[1] Baker, D.E. (1) and C.A. Van der Neut: “A Compact, Broadband, BalancedTransmission line Patch Antenna from Loops”, IEEE Ant. Prop. Soc. Symp., pp. 568– 570. Albuquerque, 1982.

[2] Kerr, J.L. (1): “Short Loop Axial Length Broad Band Antenna,” IEEE Tans. Ants.Prop., AP-21, 710 – 714, September 1973.

[3] Shin, J.(1) and D.H. Schaubert: “A parametric Study of Loop Patch Antenna,” IEEETrans. Ant. Prop., 47, 879 – 886, May 1999.

[4] Kraus, J.D. (4): “Characteristic of Antennas with Closely-Spaced Elements,” Radio,no.236, 9-19, February 1939.

[5] Kraus, J.D. (6):” W8JK Loop Array Beam Antenna,” QST, 54, 11-14, July 1970.

[6] Bagby, C.K. “A Theoretical Investigation of Electromagnetic Wave propagation onthe Loop Antenna,” Master’s thesis, Electrical Engineering Department,Ohio State University. 1948.

[7] DuHamel, R.H. and A.R. Mahmad: Chap. 28 in R.C. Johnson (ed.), RadioEngineering Handbook, 3rd ed., McGraw-Hill, New York, 1993.

[8] Lindenblad, N.E. “Antennas and Transmission Lines at the Empire State TelevisionStation,” Communications, 21, 10-14, 24-26, April 1941.

[9] Yagi, H. “Loop Patch Antenna Design,” Proc. IRE., 16, 715 – 740, June1998.

[10] RRL(1), Radio Research Laboratory staff, Very High Frequency Techniques,McGraw-Hill, 1974, Chap.4.

[11] Jordan, E.C., G.A. Deschamps, J.D. Dyson and P.E. Mayes, “Developments inBroadband Antennas,” IEEE Spectrum, 1, 58-71, April 1964.

[12] Ballantine, Stuart. “Reciprocity in Loop Patch Antenna”, Proc. IRE, 17, 929 – 951,June 1997.



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[13] Garson, J.R. “Reciprocal Theorems in Antenna Communication,” Proc. IRE, 17,952 – 956, June 1929.

[14] Cox, C.R. “Mutual Impedance between Loop and the Ports,” Proc. IRE, 35, 1367 –1370, November 2000.

[15] Labus, J., “Recherische Ermittlung der Impedanz von Antenna,”Honchfrequenztechink und Electroakustik, 17, January 2001.

[16] Brown, G.H. and O.M. Woodward, “Experimentally Determined ImpedanceCharacteristics of Loop Antennas,” Proc. IRE, 33, 257-262, April 2001.

[17] King, H.E., “Mutual Impedance of Two Loop Antennas in Echelon,” IEEETrans. Ants. Prop., AP-5, 306 – 313, July 2002.

[18] King, Ronold and C.W. Harrison, Jr., “The Distribution of Current along aSymmetrical Loop Antenna,” Proc. IRE, 31, 548 – 567, October 2002.

[19] Lindenblad, N.E.. “Antennas and Transmission Lines at the Empire StateTelevision Station,” Communications, Vol.20, p. 13, May 2003.

[20] E.F. Collin, "Electromagnetic Field Theory", McGraw-Hill Book Co., New York,

2004.



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APPENDIX A: RADIO FREQUENCY SPECTRUM



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APPENDIX B: INPUT IMPEDANCE OF LOOP ANTENNA GRAPHS



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APPENDIX C: LAYOUT OF LOOP PATCH ANTENNA



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APPENDIX D: PRICE LIST

ITEMS PRICE

1. FR4 (20cm x 20cm) RM 12

2. Soldering gun x 1 RM 78

3. Soldering lead x 1 RM 17

4. PCB stand x 4 RM 2.80

5. Transparent plastic board (30cm x 30cm) RM 59

6. Travelling RM 300

7. Iron Chloride RM 46

8. Drill RM 500

9. RF port/SO 239 RM 34

10. TV antenna RM 30

Total RM 1078.80



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APPENDIX E: GANTT CHART

Example of Final Project Thesis

Documents

Transcript of Example of Final Project Thesis