Rfid Library Management System Project Report Doc

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					                                                         ENG499 Capstone Project
                                                           Yit Shu Ling B0605400

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               SIM UNIVERSITY
     SCHOOL OF SCIENCE AND TECHNOLOGY




    CHALLENGES IN IMPLEMENTING RFID TAG
                    IN A
          CONVENTIONAL LIBRARY




           STUDENT      : YIT SHU LING (B0605400)
           SUPERVISOR   : DR LUM KUM MENG
           PROJECT CODE : JAN2009/BEHE/46




            A project report submitted to SIM University
     in partial fulfillment of the requirements for the degree of
                 Bachelor of Electronics Engineering
                             Nov 2009
                                                                    ENG499 Capstone Project
                                                                      Yit Shu Ling B0605400



ACKNOWLEDGEMENT

I would like to express my deep and sincere appreciation to my project supervisor, Dr. Lum
Kum Meng for his understanding, encouragement and personal guidance throughout the
whole year. His extensive knowledge in RF and his sharing of knowledge has been of great
value for me. Dr Lum held frequent meet ups to check on my progress to ensure that I can
manage the project and clarified my technical doubts.




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ABSTRACT

Library operation involves tracking a large number of resources such as books and
magazines. Radio Frequency Identification (RFID) is widely used in libraries to improve
asset management. High-frequency RFID tags are used in library books or bookstore
tracking, pallet tracking, building access control, airline baggage tracking, and apparel and
pharmaceutical items tracking.

Among the many uses of RFID technology, RFID has slowly begun to replace the traditional
barcodes on library items such as books, CDs and video tapes. This kind of RFID tag can
contain identifying information, such as a book's title or material type. The National Library
of Singapore is the first to introduce RFID in libraries.

The aim of this project is to implement RFID into a Library Management System. This
project explores the challenges in implementing RFID in a library.

The primary objective of this project is to design a RFID tag antenna for tracking of books in
a convectional library. The operating frequency is at ISO 144443, 13.56 MHz. A rectangular
spiral design was chosen for this project.

The usage of this RFID tag antenna is to detect signals from an RFID reader or scanner and
then returns a signal that includes a unique serial number or other customized information.

This allows library users or library stuff to have easier access to certain data of a book such
as location and facilitate library functions like borrowing and returning of books without a
line-of sight instrument.




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                                        TABLE OF CONTENTS
ACKNOWLEDGEMENT ....................................................................................................... i
ABSTRACT ............................................................................................................................. ii
1.          INTRODUCTION....................................................................................................... 1
     1.1.       Background of Project .............................................................................................. 1
     1.2.       Project Objectives ..................................................................................................... 1
     1.3.       Overall Objectives .................................................................................................... 2
     1.4.       Proposed Approach ................................................................................................... 2
     1.4.1. Project Scope ............................................................................................................. 3
     1.4.2. Skills Review ............................................................................................................. 4
     1.4.3. Project Management .................................................................................................. 4
     1.5.       Outline of Thesis ....................................................................................................... 4
2.          LITERATURE REVIEW .......................................................................................... 6
     2.1.       What is RFID ............................................................................................................ 6
     2.2.       How RFID works ...................................................................................................... 6
     2.3.       RFID Applications .................................................................................................... 8
     2.4.       Overview of Library RFID Management System ..................................................... 9
     2.4.1. Working Principle of RFID in Library ...................................................................... 9
     2.4.2. Advantages of RFID in Library ............................................................................... 10
     2.5.      Types of RFID Tags ................................................................................................ 10
     2.5.1. Active Tags .............................................................................................................. 10
     2.5.2. Passive Tags ............................................................................................................. 11
     2.5.3. Semi-Passive Tags ................................................................................................... 12
     2.6.       Types of Antennas .................................................................................................. 13
     2.7.       RFID Radio Frequencies Range ............................................................................. 13
     2.8.       Micro-strip Antenna ................................................................................................ 15
     2.8.1. Rectangular Micro-strip Antenna ............................................................................ 16
               - Substrate Selection ................................................................................................ 16
               - Antenna Length and Width Determination ........................................................... 17
               - Micro-strip Antenna Feeding Techniques ............................................................. 18
               - Coaxial Probe Feed (CPF) ..................................................................................... 18
               - Micro-strip Transmission Line Feed (TLF)........................................................... 18
               - Proximity Coupled Feed (PCF) ............................................................................. 19



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               - Aperture Coupled Feed (ACF) .............................................................................. 19
     2.8.2. Antenna Properties ................................................................................................... 20
               - Radiated Power ...................................................................................................... 20
               - Effective Angle ...................................................................................................... 20
               - Directivity .............................................................................................................. 20
               - Gain ....................................................................................................................... 20
               - Polarization ............................................................................................................ 21
               - Radiation Pattern ................................................................................................... 21
               - Voltage Standing Wave Ratio (VSWR) ................................................................ 22
               - Return Loss & Insertion Loss ................................................................................ 22
               - S-Parameters .......................................................................................................... 22
     2.8.3. Classifications of Antenna Operations..................................................................... 24
               - Near-Field .............................................................................................................. 24
               - Far-Field ................................................................................................................ 24
     2.9.       Advanced Design System Software & Maxwell’s Equation .................................. 25
3.          Proposed Design and Concepts ................................................................................ 27
     3.1.       Project Definition .................................................................................................... 27
     3.2.       Project Specifications.............................................................................................. 27
     3.3.       Proposed Design Concepts ..................................................................................... 28
     3.4.       Proposed Design Method ........................................................................................ 29
     3.4.1 Initial Design A: ....................................................................................................... 31
     3.4.2 Initial Design A1: ..................................................................................................... 34
     3.4.3 Final Design A2: ...................................................................................................... 36
     3.4.4 Final Design A3 ....................................................................................................... 37
     3.4.5 Final Design A4 ....................................................................................................... 38
     3.4.6 Final Design A5 ....................................................................................................... 39
     3.4.7 Final Design B1 ....................................................................................................... 40
     3.4.8 Final Design B2 ....................................................................................................... 42
     3.4.9 Final Design B3 ....................................................................................................... 43
     3.5.       Proposed Feeding Techniques ................................................................................ 44
4.          Simulation Results .................................................................................................... 44
     4.1        Final Design A ........................................................................................................ 44
     4.2        Final Design A1 ...................................................................................................... 47
     4.3        Final Design A2 ...................................................................................................... 49


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     4.4       Final Design A3 ...................................................................................................... 51
     4.5       Final Design A4 ...................................................................................................... 53
     4.6       Final Design A5 ...................................................................................................... 55
     4.7       Final Design A Result Comparison ........................................................................ 57
     4.8       Final Design B1 ...................................................................................................... 58
     4.9       Final Design B2 ...................................................................................................... 60
     4.10      Final Design B3 ...................................................................................................... 62
     4.11      Final Design B Result Comparison......................................................................... 64
     4.12      Results Conclusion.................................................................................................. 64
5.          Further Works & Recommendations...................................................................... 65
6.          Conclusion ................................................................................................................. 65
7.          Critical Reviews & Reflections ................................................................................ 65
References .............................................................................................................................. 66
Appendix I ............................................................................................................................. 69
Appendix I ............................................................................................................................. 70
Appendix I ............................................................................................................................. 71
Appendix I ............................................................................................................................. 72
Appendix II ............................................................................................................................ 73
Appendix III .......................................................................................................................... 74
Appendix IV .......................................................................................................................... 75
Appendix V ............................................................................................................................ 76
Appendix VI .......................................................................................................................... 86




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                                           LIST OF FIGURES
Figure 1.1: A Typical Library RFID Management System ...................................................... 1
Figure 1.2: A typical Smart Shelve ........................................................................................... 1
Figure 1.3: A typical RFID tag ................................................................................................. 2
Figure 2.1: A typical RFID system ........................................................................................... 6
Figure 2.2: A typical RFID system in a logistic ....................................................................... 7
Figure 2.3: How RFID anti-theft works .................................................................................... 7
Figure 2.4: RFID vs Barcode .................................................................................................... 8
Figure 2.5: A model for using RFID tags in a Library ............................................................. 9
Figure 2.6: RFID Library System Block diagram .................................................................. 10
Figure 2.7: An Active RFID ................................................................................................... 10
Figure 2.8: A Passive RFID Tag ............................................................................................. 11
Figure 2.9: Block diagram of how passive tags works ........................................................... 12
Figure 2.10: A Semi-passive RFID tag ................................................................................... 12
Figure 2.11: Typical Frequencies and Tag Type .................................................................... 14
Figure 2.12: A typical micro-strip antenna ............................................................................. 15
Figure 2.13: Common shapes of patch antennas .................................................................... 15
Figure 2.14: Rectangular Micro-strip Antenna ....................................................................... 16
Figure 2.15: Dielectric Constant for common substrate ......................................................... 17
Figure 2.16: Coaxial Probe Feed ............................................................................................ 18
Figure 2.17: Micro-strip Transmission Line Feed .................................................................. 18
Figure 2.18: Proximity Coupled Feed ..................................................................................... 19
Figure 2.19: Aperture Coupled Feed ...................................................................................... 19
Figure 2.20: Different types of polarizations .......................................................................... 21
Figure 2.21: Typical rectangular plot of and polar plot of radiation ...................................... 21
Figure 2.22: Methods of Moments (Microwave) .................................................................... 25
Figure 2.23: Maxwell’s Equations .......................................................................................... 26
Figure 3.1: RFID Tags compliant to ISO 144443 .................................................................. 27
Figure 3.2: A diagram explaining how current flows through magnetic field........................ 29
Figure 3.3: A diagram explaining how voltage flows through magnetic field ....................... 29
Figure 3.4: Equivalent Tag Antenna RLC circuit ................................................................... 30
Figure 3.5: Initial Design A .................................................................................................... 31
Figure 3.6: Equivalent Schematic for proposed design ....................................................... 32
Figure 3.7: Configuration of MRIND (Left) and Substrate properties 1 (Right) ................... 32

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Figure 3.8: Substrate properties 2 (Left) and Substrate properties 3 (Right).......................... 33
Figure 3.9: Substrate properties 4 (Left) and Final Design A1 (Right) .................................. 33
Figure 3.10: Final Design A1.................................................................................................. 34
Figure 3.11: Design parameters of Final Design A1 .............................................................. 35
Figure 3.12: Final Design A2.................................................................................................. 36
Figure 3.13: Design parameters of Final Design A2 .............................................................. 36
Figure 3.14: Final Design A3.................................................................................................. 37
Figure 3.15: Design parameters of Final Design A3 .............................................................. 37
Figure 3.16: Final Design A4.................................................................................................. 38
Figure 3.17: Design parameters of Final Design A4 .............................................................. 38
Figure 3.18: Final Design A5.................................................................................................. 39
Figure 3.19: Design parameters of Final Design A5 .............................................................. 39
Figure 3.20: A rectangular micro-strip antenna with multilayered dielectric substrate ......... 40
Figure 3.21: Final Design B1 .................................................................................................. 40
Figure 3.22: Substrate properties of Final Design B1............................................................. 41
Figure 3.23: Design parameters of Final Design B1............................................................... 41
Figure 3.24: Final Design B2 .................................................................................................. 42
Figure 3.25: Design parameters of Final Design B2............................................................... 42
Figure 3.26: Final Design B3 .................................................................................................. 43
Figure 3.27: Design parameters of Final Design B3............................................................... 43
Figure 4.1: S- parameters of Final Design A .......................................................................... 44
Figure 4.2: Radiation pattern of Final Design A..................................................................... 45
Figure 4.3: Planar (Vertical) Cut ............................................................................................ 45
Figure 4.4: Antenna Parameters of Final Design A ................................................................ 46
Figure 4.5: S- parameters of Final Design A1 ........................................................................ 47
Figure 4.6: Radiation pattern of Final Design A1................................................................... 48
Figure 4.7: Antenna Parameters of Final Design A1 .............................................................. 48
Figure 4.8: S- parameters of Final Design A2 ........................................................................ 49
Figure 4.9: Radiation pattern of Final Design A2................................................................... 50
Figure 4.10: Antenna Parameters of Final Design A2 ............................................................ 50
Figure 4.11: S- parameters of Final Design A3 ...................................................................... 51
Figure 4.12: Radiation pattern of Final Design A3................................................................. 51
Figure 4.13: Antenna Parameters of Final Design A3 ............................................................ 52
Figure 4.14: S- parameters of Final Design A4 ...................................................................... 53
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Figure 4.15: Radiation pattern of Final Design A4................................................................. 53
Figure 4.16: Antenna Parameters of Final Design A4 ............................................................ 54
Figure 4.17: S- parameters of Final Design A5 ...................................................................... 55
Figure 4.18: Radiation pattern of Final Design A5................................................................. 55
Figure 4.19: Antenna Parameters of Final Design A5 ............................................................ 56
Figure 4.20: S- parameters of Final Design B1 ...................................................................... 58
Figure 4.21: Radiation pattern of Final Design B1 ................................................................. 58
Figure 4.22: Antenna Parameters of Final Design B1 ............................................................ 59
Figure 4.23: S- parameters of Final Design B2 ...................................................................... 60
Figure 4.24: Radiation pattern of Final Design B2 ................................................................. 60
Figure 4.25: Antenna Parameters of Final Design B2 ............................................................ 61
Figure 4.26: S- parameters of Final Design B3 ...................................................................... 62
Figure 4.27: Radiation pattern of Final Design B3 ................................................................. 62
Figure 4.28: Antenna Parameters of Final Design B3 ............................................................ 63




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1. INTRODUCTION

1.1.   Background of Project

As technologies improve over the years, Radio Frequency Identification (RFID) has become
more popular for asset management. There are many advantages in RFID as compared to
traditional barcode system. One key advantage is the improvement of efficiency in asset
management. Furthermore, RFID can transfer data through a non-contact method between a
tag and a reader through air. It is also designed to read many items at a time without any
line-of-sight instruments [1]; unlike in a barcode system whereby each item must be scanned
individually. RFID is used in supply chain, production lines and library. This project explores
the challenges in implementing RFID in a library. One key challenge is the RFID tag design.




                       Figure 1.1: A Typical Library RFID Management System

1.2.   Project Objectives

The National Library Board of Singapore introduced the RFID system in March 2008. The
Smart Shelves system allows library users and library staffs to have real-time book location
on shelf, to track readership patterns, allowing real-time inventory checks to assist library
staff in performing quick and accurate shelving. RFID tags are used to replace barcode for
identification and anti-theft detection.




                                 Figure 1.2: A typical Smart Shelve




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The main objective of this project is to design and analyze a micro-strip tag antenna. The
proposed approach and method for this project are as follows:

     To study the challenges faced when implementing RFID into a Library Management
      System.

     To design and model of a RFID tag antenna

     To study the usage of Agilent-ADS software to design and analyze a micro-strip tag
      antenna.                                                               Microchip
                                                          Antenna




                                                                                            Inlay




                                   Figure 1.3: A typical RFID tag




1.3.   Overall Objectives

There are a number of challenges faced, such as the need to establish a common
communication platform within the subsystems such as loaning and returning of books and
the data capture of books into the RFID tags. This RFID tag contains data of a book and the
electronic article surveillance (EAS) [2]. The overall objective of this project is to discuss the
challenges faced in implementing a RFID tag in a library.


1.4.   Proposed Approach

For this project to succeed, it must have a well planned schedule and execution procedures.
A suitable tag antenna must have low cost and small size.




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1.4.1. Project Scope

There are 5 main stages in this project:

   1.   Project initiation stage
   2.   Project planning or design stage
   3.   Project execution or production stage
   4.   Project monitoring and controlling systems
   5.   Project completion stage

In order to complete this project, the following resources are required:

       High speed processing PC as ADS software requires a lot of RAM
       Searching online for journals, articles and findings
       Reference books from libraries
       Agilent Advanced Design System Software (ADS)
       Measurement/Analysis tools for tag antenna(if applicable)

                                           Project Initiation Stage
                                              Feasibility Study


                                    Project Planning/Design Stage
                                  Requirement Specifications/Analysis




                                                 System
                                                 Design
                                              Specifications




                                  Project Execution/Production Stage
                                    Realisation of Physical Design



                                 Project Monitoring/Controlling Stage
                                           Meet Schedule


                                       Project Completion Stage
                                  Final Product and Project Closeout




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1.4.2. Skills Review

To able to achieve the project goals requires the following skills:

      RFID background and technologies
      RFID design technologies
      Micro-strip Antenna design concepts
      Knowledge of Advanced Design System(ADS)
      Project Management


1.4.3. Project Management

The table below shows the project schedule:




1.5.     Outline of Thesis

This thesis consists of 7 chapters. The below shows a summary of the thesis:

Chapter 1:
This chapter provides an introduction on the conditions of project, the objectives of the
project and proposed approach in completing the project.

Chapter 2:
Literature review of RFID system, RFID technology and micro-strip patch antenna, are
describes in this chapter.

This chapter is further broken down in details of working principle of RFID in Library, types
of RFID tags, types of antennas, RFID frequencies, substrate selection, and types of feeding
techniques, return/insertion loss and Advanced Design System.

Chapter 3:
This chapter describes the proposed designs and concepts




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Chapter 4:
It demonstrates the simulation results obtained from the proposed designs. The results
between single substrate layer micro-strip antenna and double substrate layer micro-strip are
compared.

Chapter 5:
Some further works for the future are discussed.

Chapter 6:
Final conclusions is made in chapter 6 based on the conclusion of the project.

Chapter 7:
Critical review and reflections are discussed in Chapter 7.




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2. LITERATURE REVIEW

2.1.   What is RFID

Radio Frequency Identification (RFID) system is a system that transmits identification in a
form of numbers wirelessly, using radio waves. There are 4 common bands of RFID
applications. They are Low Frequency Band (LFB, less than 135 kHz), High Frequency Band
(HFB, 13.56MHz), the Ultra-High Frequency Band (UHFB, 860MHz-960MHz) and the
Microwave Band (MWB, 2.45GHz) [3]. This reduces processing time and labour required to
input data manually and to improve data accuracy.


2.2.   How RFID works

In a RFID system, a RFID tag is used to transmit data. The tag is read by a tag reader and
transmits the information and process according to the particular application’s needs. The
transmitted data may consist of identification or location of an item or any purchase
information such as price or color.




                               Figure 2.1: A typical RFID system




A typical RFID system consists of 4 major components:

     A microchip attached to a radio antenna mounted on a substrate. There are 2 types of
      tags, active and passive. Active tags are powered by battery while passive tags are
      powered by reader.
     A computing device.
     An antenna
     Server/Host computer on which the software that interfaces with the integrated
      software is loaded.




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                                                                                     Passive tags




                                                                                       External Antenna




                           Figure 2.2: A typical RFID system in a logistic

There are many advantages in using RFID in asset management as compared to a traditional
barcode system:

    RFID tags are available in different sizes and shapes to suit different needs for each
     industry (Flexibility).
    Tags are readable through different mediums such as rain or dirt (Reliability).
    No line-of-sight equipments are required to read tags (Contactless).
    Detectable within active readable range (Portability).

One of the major advantages is RFID can provide anti-theft capability. RFID system has the
ability to read data from the tag and transmit signals wireless to the main database. Radio
waves from a transmitter at the exit/entrance generate a current to activate an IC chip in the
tag antenna. The receiver picks up the signal and sounds the alarm. Upon checking out, a
librarian will pass the item through a deactivating device to destroy the electronic
components in the RFID, disallowing it to transmit any signal [5].




                              Figure 2.3: How RFID anti-theft works



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The main disadvantage of using a bar-code system is it requires manually scanning of a label
or tag to capture data. RFID is to enable readers to capture data on tags and transmit it to a
computer system wirelessly. The table below shows the differences between RFID and
Barcode.




                                   Figure 2.4: RFID vs Barcode



2.3.     RFID Applications

The table below shows examples of the different type of RFID available in the market [6].

       Areas of RFID
                                                        Description
        Applications
                        Track product location after manufactured and shipped to hospitals.
 Health Care            Hospital employees utilize the system for inventory management,
                        billing & product recalls and expirations.
                        Enables company to view temperature of the strawberries packed at
 Logistics              its processing facility and record of temperature during
                        transportation.
                        Track library books location, allows librarians to extract book
 Libraries
                        information easily
                        Track tools at power-generation facilities. Tools often go missing or
                        are not returned in a timely way & are thus unavailable for others
 Manufacturing
                        who need them. To reduce production delays and additional
                        expenses.
 Packaging              Track reusable pallets, to store them in a specific location.
 Retail                 Track retail items, better asset management and anti-theft protection.

                          Table 1: Summary of different RFID applications




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2.4.   Overview of Library RFID Management System

                                            In RFID, special readers are used to identify a
                                            unique representation of an item using radio
                                            waves. The reader communicates with an RFID
                                            tag, which holds digital information stored on a
                                            microchip. In a library, each book has an RFID
                                            tag attached to it [45].



                                            Figure 2.5: A model for using RFID tags in a Library



The RFID tag is programmed with the specified book data. Antennas are attached to a library
staff workstation at the borrowing, return and other parts of the library, which allow
identification of an item without a library staff physically to handle them.

The system is designed to read many items at one go and no line-of-sight instruments are
required; unlike in a barcode system whereby each item needs be scanned individually.


2.4.1. Working Principle of RFID in Library

This system is designed to provide real time tracking and locating of tagged items on shelves.
The RFID system components consist of:

     RFID tags that transmit data to a reader
     RFID readers which include antenna to read or write data to the RFID tags
     Communication system whereby defined radio frequency and a protocol to transmit
      and receive data from tags
Tag readers communicate with tag by broadcasting an RF signal. The tags reply by
transmitting back with data. There must be sufficient memory in the tag to hold the data. The
common memory storage size is 64 bits. The reader needs to read multiple tags within a
closed range.
There are 3 types of RFID tags; “Read only”, “Write once read many” and “Read/write”.
“Read only” are tags which data are encoded during manufacturing time and are not
rewritable. “Write once read many” tags are programmable at user end and do not have the
ability to rewrite. “Read/write” tags have the ability to read and rewrite data. [9]. The most
common type used in Library RFID is “Read/write”.
RFID is a combination of radio frequency technology and microchip technology. The
information contained on microchips in the tags is glued to library materials are read by
using radio frequency regardless of item direction or position.
When a RFID tag is passed through a reader, the information stored on the chip is read by the
reader and sent integrated library system. If the material is not checked out properly, the
system will turns on the alarm. Readers can be used at the circulation station, for the issue
and return of books and library items [9].



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                          Figure 2.6: RFID Library System Block diagram


2.4.2. Advantages of RFID in Library

The use of RFID reduces the amount of time required to perform circulation operations as
information can be read from RFID tags at a faster speed than from barcodes. When books
are stacked, the tags are still readable.

Another unique advantage of RFID systems is their ability to scan books on the shelves
without removing them. As compare with Electro-Mechanical (EM) and Radio Frequency
(RF) systems, RFID systems can track materials throughout the library. A hand-held
inventory reader can be moved rapidly across a shelf of books to read all of the unique
identification information. This helps to update inventory and also identify which items are
out of proper order.

2.5.   Types of RFID Tags

There are 3 main types of RFID tags; active, passive and semi-passive tags. Active RFID
tags have a built-in power supply, such as a battery. Passive RFID tags do not have a power
supply and must rely on the power emitted by an RFID reader to transmit data [10].


2.5.1. Active Tags

Active tags consist of a microchip and an antenna. They
have their own on-board power supply and on-board
circuitries. The power supply can be battery or solar
powered. The built-in power supply allows the tag to
transmit data to a reader on its own, without the need to
draw power from the reader as compared to passive tags.


                                                                 Figure 2.7: An Active RFID

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Active tags’ reading distances are of 100 feet or more. They use ultra-high frequency ranges
from 860 MHz to 960MHz. Active tags are bigger in size as compared to passive tags due to
the on-board power supply and circuitries.

On-board circuitries can consist of sensors, microprocessors, and input/output ports, all of
which are powered by the tag's on-board power source. These circuitries allow the active
RFID tags to be used in a wider range of applications than passive tags.

For example, perishable food products can be tagged with sensors to collect data that can be
used to determine expiry dates and warn the end user that the item may be spoiled. An RFID
tag equipped with a temperature sensor might be able to predict the actual expiration date of
a carton of milk, for example, which may be very different from the printed date.


2.5.2. Passive Tags

                                                Passive tags consist of 3 parts: an integrated
                                                circuit or chip, an antenna and a substrate.

                                                The RFID chip stores data and performs
                                                specific tasks. The chip may be design for
                                                Read-Only (RO), Write-Once, Read-Many
                                                (WORM), or Read-Write (RW).


       Figure 2.8: A Passive RFID Tag

The antenna transmits the radio waves after receiving from the reader. The performance of a
passive RFID tag is strongly dependent on the antenna's size and shape. The antennas are
usually in coils shapes to utilize the magnetic field. With a larger antenna, the passive tag can
store more energy. Passive tags are powered from electromagnetic field generated by reader
antenna. Reader antenna has to transmit enough power to provide enough energy to the tag so
it could to transmit back data.

The third component of a passive RFID tag is called a substrate, which is commonly a plastic
film. Both the antenna and the chip are attached to the substrate, which may be thought of as
the "glue" that holds all of the tag's pieces together. Passive tags are usually smaller and less
expensive than active RFID tags.

In a library RFID system, passive tags are commonly used as it is cheaper and smaller in
size. The nature of its small size allows the tag to be able to conveniently attach to a book.
The figure below shows how a typical passive tag works.




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                        Figure 2.9: Block diagram of how passive tags works


2.5.3. Semi-Passive Tags
Semi-passive tags use internal power source to power the microchip. They use a process to
generate a tag response similar to that of passive tags. Semi-passive tags are different from
passive as semi-passive tags possess an internal power source (battery) for the tag's circuitry
which allows the tag to complete other functions such as monitoring of environmental
conditions (temperature, shock) and which may extend the tag signal range.




                               Figure 2.10: A Semi-passive RFID tag




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2.6.   Types of Antennas
In RFID applications, an antenna coil is used for 2 main reasons:
          To transmit the RF carrier signal to power up the tag
          To receive data signals from the tag
Tag antenna works by making use of field magnetic induction coupling between transmitting
and receiving antennas. When the time-varying magnetic field is passed through a coil
antenna, it induces a voltage across the coil terminal and powers the passive tag device. A
typical number for turns of the coil is about 100 turns for 125kHz and 3-5 turns for
13.56MHz devices. As the number of turn’s increases, the operating frequency decreases
[11].
The operating frequencies and the application of a RFID system determine the type of
antenna used. In a low frequency application, such as passive tags, many antenna coils are
required to power the tag circuit. This is because the voltage induced is proportional to
frequency.
In a high frequency application, tag antennas that have a few planar spiral coils of 4-5 turns
can provide a readable range of a few meters. Typically in high frequency antennas, the
design requires 2 metal layers and 1 insulator for crossover connection from the outer most
layers to the inner layer of the spiral.

In an ultra-high frequency application, the design requires 1 metal sheet. Dipole antennas are
used in these designs. Typical dipole antenna consists of 2 quarter wavelength conductors
placed back to back. They have a poorer performance as the input impedance is high.


2.7.   RFID Radio Frequencies Range

In RFID, 3 types of frequencies are commonly used. They are low frequency (LF) ranging
from 125 kHz to 124 kHz, high frequency (HF) ranging from 3MHz to 30MHz and ultra high
frequency (UHF) ranging from 300MHz to 1GHz.
A typical LF RFID system operates at 125 kHz or 134.2 kHz. It is commonly used in passive
tags, has low data-transfer rates between the tag and the reader and performs well in an
environment containing metals, liquids, dirt, snow, or mud.
In a typical HF RFID system, 13.56 MHz is the common frequency used. Commonly used in
passive tags, the data transfer rate is slow from the tag to a reader and performance is fair in
the presence of metals and liquids.
A UHF system is used in both active and passive tags. It has a fast data-transfer rate between
the tag and the reader. However its performance is poor in the presence of metals and liquids.
In a typical passive UHF RFID system, the operating frequency is 915 MHz in the United
States and 868 MHz in Europe. In a typical active UHF RFID system operates at frequency
315 MHz and 433 MHz. [12]
In this project, the resonance frequency used is 13.56MHz.
The table below shows the common frequencies, readable range and the tag type used.


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                                                 Passive
                                                 Tag
                    125-134 kHz
                                                                  RFID
                                                                  Wristband

      P                13.56 MHz
                                                            Meds -          Passive                Pum
                                                 HF           Bottle        Tag                       p
      as                                         Tag

      si                                                                              Meds -
                                                                                        Case
      ve
      Ta           902-928 MHz
      gs

                        2.45 GHz
                                                                                                    Active
                                                                                                      Tag
          Active Tags 433 MHz                                                                      20’ – 300’
                 (Wi-Fi) 2.4 GHz
                  (UWB) 6.1 GHz
                             etc.
                        Tag Size
                                       2’   4’         6’  108’                    20
                                                           ’                       ’
                                     Figure 2.11: Typical Frequencies and Tag Type



The table below shows the common International frequencies [13].

 Country          LF                HF                      UHF                                Microwave
                                    13.56 MHz10
                                                            902-928 MHz, 1 watt ERP
                                    watts                                                      2400–2483.5 MHz, 4 watts,
 United           125–134                                   or 4 watts ERP with a
                                    effective                                                  ERP 5725–5850 MHz, 4
 States           KHz                                       directional antenna with at
                                    radiated                                                   watts ERP
                                                            least 50-channel hopping.
                                    power(ERP)
                                                            865–865.5 MHz, 0.1 watts
                                                            ERP, Listen Before Talk
                  125–134                                   (LBT). 865.6–867.6 MHz,
 Europe                             13.56 MHz                                                  2.45 GHz
                  KHz                                       2 watts ERP, LBT.
                                                            867.6–868 MHz, 0.5 watts
                                                            ERP, LBT.
                                                            Not allowed. MPHPT
                                                            (Ministry of Public
                                                            Management, Home
                  125–134
 Japan                              13.56 MHz               Affairs, Posts and                 2.45 GHz
                  KHz
                                                            Telecommunications) has
                                                            opened up 950–956 MHz
                                                            band for experimentation.
                  125–134                                   923–925 MHz. 2 watts
 Singapore                          13.56 MHz                                                  2.45 GHz
                  KHz                                       ERP.
                                                            Not allowed. Future
                                                            possibility: 840–843 MHz
                                                            and/or 917-925 MHz.
                  125–134                                                                      2446–2454 MHz, 0.5 watts
 China                              13.56 MHz               SAC (Standardization
                  KHz                                                                          ERP
                                                            Administration of China) is
                                                            entrusted to formulate the
                                                            RFID regulations.

                                            Table 2: International Frequencies




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2.8.   Micro-strip Antenna

Micro-strip antenna consists of a patch of metallization on a grounded substrate as shown in
Fig 2.12. It consists of a radiating patch on one side of the dielectric substrate and a grounded
plane on the other side. The patch conductors are usually made of copper and gold [14].




                              Figure 2.12: A typical micro-strip antenna



 The advantages of micro-strip antennas are:
         Light weight, low volume and thin profile configurations
         Low fabrication cost
         Simple feed with linear and circular polarizations
         Dual frequency and polarizations can be easily made

 The disadvantages of micro-strip antenna are:
          Narrow bandwidth and have tolerance problem
          Lower gain
          Difficult to achieve polarization purity
          Use of high dielectric substrate cause poor efficiency and narrow bandwidth

 Rectangular and circular patch antennas are commonly used. A patch antenna has a gain
 between 5-6dB and a 3dB beam width of between 70° to 90°. The figure below shows the
 shapes of commonly used patch antennas. [14]




                           Figure 2.13: Common shapes of patch antennas



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2.8.1. Rectangular Micro-strip Antenna

In this project, a rectangular shape micro-strip antenna is chosen. The advantage of using
rectangular is the simplicity. The figure below shows a basic rectangular antenna which
consists of a strip conductor of dimensions L x W on a substrate with a dielectric constant,
r and thickness, h backed by a ground plate.




                            Figure 2.14: Rectangular Micro-strip Antenna

When the patch is excited by a feed, a magnetic charge is formed beneath the patch metal and
the ground plate. There are positive charges on the underside of the patch and negative
charges on the ground plate. The attraction forces between the patch and ground plate cause a
large charge to form between these two surfaces [14].


- Substrate Selection

For a successful antenna design, a suitable dielectric substrate of suitable thickness and loss
tangent is required. As the thickness of a substrate increases, the radiated power also
increase, which also reduce conductor loss and improve on the impedance bandwidth. A
rectangular patch antenna will stop resonating once substrate thickness is greater than
0.11  0 . An ideal substrate dielectric constant would be  2.5 . The table below shows the
dielectric constant for common substrate used [14].




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                         Figure 2.15: Dielectric Constant for common substrate


- Antenna Length and Width Determination

The width of a patch antenna affects the resonant frequency and radiation pattern of the
antenna. A larger patch antenna width increases the radiated power, giving decreased
resonant resistance, increased bandwidth, and increased radiation efficiency. The patch
antenna width also affects the cross-polarization characteristics. The patch width should be
chosen to obtain good radiation. The patch length determines the resonant frequency, and is a
critical parameter in design because of the intrinsic narrow bandwidth of the patch.

The length of the antenna can be calculated by [14]:

                                                       c
                                            L
                                                 2 f r er

whereby c is the speed of light, fr is the operating frequency and εr is the dielectric constant
of the substrate.

The width of the antenna can by calculated by [14]:

                                               d  
                                     W  hd ln    1
                                               h  
                 0           c
whereby d          ,  0  ; c is the speed of light, f is the operating frequency and εr is
                  er          f
the dielectric constant of the substrate.



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- Micro-strip Antenna Feeding Techniques

There are several feeding techniques for micro-strip patch antennas:

      coaxial probe feed (CPF)
      micro-strip transmission line feed (TLF)
      proximity coupled feed (PCF)
      aperture coupled feed (ACF)

In direct contacting feeds, power is fed into the micro-strip patch antenna directly via a
conducting feed line connected to the patch conductor. In non-contacting feeds, the laminates
are separated by a ground plane and coupling between the micro-strip feed line, and the patch
antenna is achieved either electromagnetically or via a small slot on the ground plane [15].

- Coaxial Probe Feed (CPF)

A coaxial probe fed micro-strip patch antenna is fed using a coaxial probe whereby the outer
conductor is connected to the bottom ground plane. Its inner conductor is connected upwards
through the substrate to connect to the patch. Probe position is to control the impedance level.
It produces small bandwidth and generates high polarized fields when electrically thick
substrates are used.




                                 Figure 2.16: Coaxial Probe Feed


- Micro-strip Transmission Line Feed (TLF)

A micro-strip transmission line-fed patch antenna is made up feed line of a certain width and
length and is connected to a specific matching stub of corresponding width and length. The
stub is vital to match the high value of antenna’s characteristic impedance to the 50Ω
connector, especially when it is fed along on one of the radiating edges of the patch.
Impedance control is at the feed position of the edge. The disadvantages are narrow
bandwidth and gain.




                          Figure 2.17: Micro-strip Transmission Line Feed


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- Proximity Coupled Feed (PCF)

The proximity coupled fed micro-strip patch antenna consists of two layers on top of each
other. A grounded substrate at the bottom layer consists of a micro-strip feed line. Above this
material is another dielectric layer with a patch etched on its top surface. Power from the feed
network is coupled in between layers, up to the patch electromagnetically.




                                Figure 2.18: Proximity Coupled Feed



- Aperture Coupled Feed (ACF)

In aperture coupled-fed micro-strip patch antenna, separate dielectric laminates are used for
the feed network and the patch antenna. The alignment between layers and correct selection
of aperture size and position controls the antenna’s impedance. The natural existence of small
gaps in between the layers of dielectric laminates can affect the input impedance values. The
solution is to use conformal adhesives. The dielectric properties of the used chemical will
also affect the anticipated performance. This feed technique is more popular as it
significantly enhances the impedance bandwidth of the antenna.




                                Figure 2.19: Aperture Coupled Feed




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2.8.2. Antenna Properties

- Radiated Power

For micro-strip antennas, the electric field within the patch is normal to the strip conductor
and the ground plate. It can be calculated by integrating Poynting vector [16] over the
radiating aperture. The radiating aperture is the area of the circle constructed to the incoming
radiation whereby the entire radiation within the circle is delivered by the antenna to the
matched load. Antenna gain is directly proportional to aperture. An antenna with a gain of G
                    G2                              1                  
has an aperture of       . [17] Radiated Pwr, Pr  Re  (  H *).d S
                     4                              2


- Effective Angle

Effective angle is the angle whereby all the power emanating from the antenna would flow if
the maximum radiation intensity is constant for all angles over the beam area [18].


- Directivity
The directivity of the antenna is the antenna ability to focus energy in a particular direction
during transmits of data, or to receive energy from a particular direction [19]. Directivity can
be calculated as the ratio of the maximum value of transmitted power over the average power
transmitted. With poor directivity, the RFID reader might read a tag outside its operation
zone.


- Gain
The gain of the antenna is the antenna ability to radiate in a specific direction. It is measured
as a ratio of the energy radiated from a point of maximum radiation to energy radiated at the
same point by reference antenna [20].
                                                 P
                                           Ag  out
                                                 Pref

The reference antenna can be isotropic antenna as it radiates power uniformly in all
directions. Thus, the power radiated by a reference antenna can be taken as the input power,
assuming ideal case which is the antenna has no loss. Therefore, the gain of the antenna
becomes
                                                P
                                          Ag  out
                                                Pin

The antenna gain is usually expressed in decibel

                                                      Pout
                                      Ag(dB)  10 
                                                      Pin

High-gain antennas have the advantage of longer range and better signal quality.


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- Polarization
The polarization of the antenna is the orientation of the electric field of the radio waves.
Linear and circular polarizations are the common types of polarization.

In linear polarization, antenna radiates in one plane containing the direction of propagation
Horizontal and vertical polarizations are commonly used.Vertical polarization is used to
radiate a radio signal in all directions over a short to medium range. Horizontal polarization
is used over longer distances to reduce interference by vertically polarized equipment
radiating other radio noise [21].

In circular polarization, the plane of polarization rotates in a circle making one complete
revolution during one period of the wave. If the rotation is clockwise looking in the direction
of propagation, the sense is called right-hand-circular. If the rotation is counter clockwise, the
sense is called left-hand-circular.




                                 Figure 2.20: Different types of polarizations


- Radiation Pattern

The radiation pattern is a graphical representation of the relative field strength transmitted
from or received by the antenna. Radiation patterns are taken at one frequency, one
polarization, and one plane cut. The patterns are usually presented in polar or rectilinear form
with a dB strength scale. Radiation pattern is usually defined in the far-field area [22].




                      Figure 2.21: Typical rectangular plot of and polar plot of radiation

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- Voltage Standing Wave Ratio (VSWR)

When a transmission line cable is terminated by impedance that does not match the
characteristic impedance of the transmission line, not all of the power is absorbed by the
termination. Part of the power is reflected back down the transmission line. The incident
signal mixes with the reflected signal to cause a voltage standing wave pattern on the
transmission line. The ratio of the maximum to minimum voltage is known as Voltage
Standing Wave Ratio (VSWR) [23].

The ideal case of VSWR is a ratio of 1:1 whereby no power is being reflected back to the
source. In actual system, a ratio of 1.2:1 is considering good performance. The two first
numbers relate the ratio of impedance mismatch against a perfect impedance match and the
second number is always 1, representing the perfect match.


- Return Loss & Insertion Loss

Return loss is the reflection of signal power resulting from the insertion of a device in a
transmission line, usually expressed in dB [24].
                    P 
 RL(dB)  10 log 10  T  whereby PT is the transmitted power and PR is the reflected power.
                    P 
                     R
The value of return loss is desired to be as high as possible as there is lesser reflected power
which is good and has a large return loss number. A low return loss value shows a high
reflected power which is bad and has a small return loss number.

Insertion loss is the loss of signal power resulting from the insertion of a device in a
transmission line, commonly known as attenuation. It is relatively proportional to transmitted
                                 P 
signal power. IL(dB)  10 log 10  R  whereby PR is the received power and PT is the
                                 P 
                                  T
transmitted power by the source.


- S-Parameters

The S-parameters describe the response of an N-port network to voltage signals at each port.
The first number in the subscript refers to the responding port, while the second number
refers to the incident port. For example, S11 means the response at port 1 due to a signal at
port 1. S11 is also the input reflection coefficient of a 50Ω terminator output. S22 is the
output reflection coefficient of a 50Ω terminator input. S12 is the reverse transmission
coefficient of a 50Ω terminator input. S21 is the forward transmission coefficient of a 50Ω
terminator input. The value of S11 is expected to be as low as possible. In an ideal antenna
operation, the frequency needs to propagate as far as possible. In ideal case, there will be
some losses. This loss is S11, thus this value has to be low as possible as this means the
performance of the antenna is at its maximum performance [25].




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The figure below represents the signal wave in a 2 port electrical-element [26].




a 1 is the input wave of port 1 and b 1 is the output wave of port 1.
a 2 is the input wave of port 2 and b 2 is the output wave of port 2.


b 1 = a 1 s 11 + a 2 s 12
b 2 = a 1 s 21 + a 2 s 22
whereby
s 11 is the port-1 reflection coefficient: s 11 = b 1 /a 1 ; a 2 = 0
s 22 is the port-2 reflection coefficient: s 22 = b2 /a 2 ; a 1 = 0
s 21 is the forward transmission coefficient: s 21 = b 2 /a 1 ; a 2 = 0
s 12 is the reverse transmission coefficient: s 12 = b 1 /a 2 ; a 1 = 0

These equations can be solved for b 1 and a 1 in terms of a 2 and b 2 to yield the transmission
(T) parameters as follows:
b 1 = a 2 t 11 + b 2 t 12
a 1 = a 2 t 21 + b 2 t 22


The T-parameters are related to the S-parameters as follows:




S-parameters are defined with respect to reference impedance that is typically 50 ohms. For
50-ohm S-parameters-with the 2-port element terminated with 50 ohms at each port – the s 21
parameter represents the voltage gain of the element from port 1 to port 2.




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2.8.3. Classifications of Antenna Operations

Antenna operation can be categorized as near-field and far-field in terms of the method of
transmitting power from the reader to the tag.


- Near-Field

In near-field systems, the power transfer from a reader to a tag as well as the communication
between the reader and the tag can be achieved by inductive coupling through the interaction
with magnetic fields, or by capacitive coupling through the interaction with electric fields.

The disadvantages of the near-field RFID system is the limited reading distance of less than
1.5 meters. The intensity of the magnetic field component perpendicular to the coil antenna
plane is strong along the sight of the reader coil antenna, whereas the magnetic field
component parallel to the coil antenna plane is very weak or even zero. Therefore, if the tag
is positioned parallel to the magnetic field from the reader coil antenna, the tag cannot be
detected as no magnetic flux goes through the tag. In this project, the design is to be
near-field to meet the requirement of ISO 144443 [27].


- Far-Field

In far-field systems, the power transfer from reader to tag as well as the communication
between reader and tag are achieved by transmitting and receiving EM waves. The reader
emits energy through a reader antenna, and some of the energy is then reflected from the tag
and detected by the reader.

Far-field systems operate at frequencies greater than 100 MHz, typically in an ultra
high-frequency (UHF) band such as 868 MHz, 915MHz or 955MHz or a microwave
frequency band such as 2.4 GHz or 5.8 GHz. The reading distance is determined by the
intensity of energy received by the tag and the sensitivity of the reader’s receiver to the
reflected signals from the tag. A typical far-field reader can successfully interrogate tags 3–5
meters away. The maximum reading distance can be up to 10m or more.




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2.9.   Advanced Design System Software & Maxwell’s Equation

In this project, Advanced Design System by Agilent Technologies is chosen to be the
designing and simulation platform. Advanced Design System (ADS) is a powerful electronic
design automation software system. It offers complete design integration to designers of
products such as cellular and portable phones, pagers, wireless networks, and radar and
satellite communications systems.

In ADS, momentum is used to run the simulation for this project. Momentum provides the
function of:

              2.5D (vias) simulation tool for passive circuits
              Method of Moments technique as planar solver
              Unlimited substrate database for computation
              Full microwave or RF mode S-Parameter solutions
              Layout look-alike components for ADS simulation
              Co-simulation with ADS and optimization
              Visualization of current and far-field patterns

It uses Methods of Moments (Microwave) to solve.




                           Figure 2.22: Methods of Moments (Microwave)


The Methods of Moments (Microwave) uses the Full-wave approach. It uses electric and
magnetic of Greens function [41] incorporating along with the Maxwell’s equation to solve
the functions. Further details of how momentum works can be found in Appendix II.

Maxwell's equations are a set of four partial differential equations that describe the properties
of the electric and magnetic fields and relate them to their sources, charge density and current
density. Individually, the equations are Gauss's law, Gauss's law for magnetism, Faraday's
law of induction, and Ampère's law with Maxwell's correction [28].

        Gauss's law relates electric charge contained within a closed surface to the
         surrounding electric field. It describes how the divergence of an electrical field is
         affected by charges (electric field lines diverge from positive charges and are
         drawn towards negative charges). It also states that the total electric flux through a
         Gaussian surface is unrelated to the shape and size of that surface.

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 Gauss's law for magnetism states that the total magnetic flux through a Gaussian
  surface is zero. This is due to real world magnetic charges coming in pairs
  (referred to as dipoles), with the two charges giving rise to opposite magnetic
  field divergences which cancel each other out. The theoretical single magnetic
  charge is referred to as a magnetic monopole.
 Faraday's law of induction describes how a changing magnetic field can create an
  electric field
 Ampère's law with Maxwell's correction states that magnetic fields can be
  generated in two ways: By electrical current and by changing electric fields. The
  idea that a magnetic field can be induced by a changing electric field follows from
  the modern concept of displacement current which was introduced to maintain the
  solenoid nature of Ampere’s law in a vacuum capacitor circuit. This modern
  displacement current concept has the same mathematical form as Maxwell's
  original displacement current. Maxwell's current applies to the polarization
  current in a dielectric medium, and it sits adjacent to the modern displacement
  current in Ampere’s law.




                        Figure 2.23: Maxwell’s Equations




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3. Proposed Design and Concepts

3.1.   Project Definition

In this project, a RFID tag antenna is to be design for tracking of books in a convectional
library. The operating frequency is at ISO 144443, 13.56 MHz. A rectangular spiral design
was chosen for this project to be compliant with ISO 14443 [27].

Micro-strip line is an electrical transmission line which can be fabricated using printed circuit
board (PCB), and is used to convey microwave-frequency signals. It consists of a conducting
strip separated from a ground plane by a dielectric layer known as the substrate.

Micro-strip devices built on an ordinary FR4 (standard PCB) substrate can be achieve at a
very low cost. However the dielectric losses in FR4 are too high at microwave frequencies,
and that the dielectric constant is not easily controlled. Thus, an alumina substrate is chosen
for this project.


3.2.   Project Specifications

The designed tag is to be ISO 144443 compliant and the required operating frequency is
13.56MHz.
Near Field Communication (NFC) is a short-range radio frequency communication
technology that enables data exchange between devices a few centimetres apart. This
technology follows the ISO 144443 proximity standard. An NFC device is able to
communicate with existing ISO 144443 RFID tags and readers and other NFC devices [29].

The size of tag has to within 45mm x 76mm, which is similar to a credit card size.




                           Figure 3.1: RFID Tags compliant to ISO 144443




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The preferred values of the antenna are as follows:

                       Shape of Antenna                Rectangular
                       Operating Freq.                 13.56MHz
                       Dielectric constant of
                       substrate (PET)                     3.2
                       Height of substrate                38um
                       Ideal Return Loss, S11         -20dB to -40dB
                       Ideal Gain                       5dB to 7dB

S11 is the input reflection coefficient of port 1 being reflected back to source. An ideal S11
should be as low as possible. With a lower value, the reflected coefficient back to the source
is lesser; the output signal will be stronger.


3.3.   Proposed Design Concepts

A suitable tag antenna must have low cost and small size. The use of 13.56MHz frequency is
commonly used in a library RFID system. It offers many advantages over other bands such
as:

            Excellent immunity to environmental noise and electrical interference
            Good data transfer rate
            On-chip capacitors for tuning tag coil can be easily obtained
            Cost effective antenna coil manufacturing
            Low RF power transmission

In most 13.56MHz RFID systems, it works by using the near field inductive coupling of the
RFID tag with the reactive energy circulating around the reader antenna [46]. A RF signal
can be radiated effectively if the linear dimension of antenna is comparable with the wave
length of the operating frequency.
                                                            c
The wave length of a 13.56MHz is 22.12 meters, using   . Thus, it is impossible to form
                                                            f
a true antenna. Therefore, a magnetic dipole antenna is used. In such cases, highly inductive
printed spiral coils are used for 13.56MHz in RFID tag antennas [11].

For 13.56MHz passive tag applications, a few micro henries of inductance and a few hundred
pF of resonant capacitor are commonly used. When a time-varying magnetic field is passed
through a coil antenna, it produced a voltage across the coil terminal. This voltage is used to
activate the passive tag device.

The antenna coil of a RFID tag is usually made of thin wire. A typical number of turns are
100 for a 125 kHz application and 3-5 turns for 13.56MHz applications. When there is a
limited space, the design requires a multi-layer winding to reduce the number of turns.

In the initial design, the number of turns is set as 4 as the application is used on library
books, thus the space allowed is not restrictive. This coil will be printed on top of a low-cost
and easily found material such as polyethylene terephalate (PET) and adhesive dielectric
layer [42]. In this project, Advanced Design Solution (ADS) software is used to design and
simulate the tag antenna.

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3.4.   Proposed Design Method

Maxwell’s equations are used for RFID tag antenna design. As mentioned in Chap 2.9,
Maxwell’s equations consist of Faraday's law of induction, and Ampere's law with Maxwell's
correction.

Current and Magnetic Fields

The magnetic field produced by a current element on a round conductor, which in this
project, is a wire with a finite length is given by [11] :

                  o I
           B         cos 2  cos 1      (Weber / m 2 )
                  4r
           whereby :      I  current
                          r  dis tan ce from center of wire
                           0  permeability of free space, 4  10 7 (henry / meter)




              Figure 3.2: A diagram explaining how current flows through magnetic field


Induced Voltage

Faraday’s law states that a time-varying magnetic field through a surface bounded by a
closed path induces a voltage around the loop. The figure below shows how it works [11].




              Figure 3.3: A diagram explaining how voltage flows through magnetic field




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The induced voltage on the tag antenna coil is equal to the time rate of change of magnetic
flux, .

                              d
                       V  N
                               dt
                       whereby : N  number of turns in antenna coil
                                  magnetic flux through each turn

The negative sign shows that the induced voltage is opposing the produced magnetic flux.
This is also known as Lenz’s Law. It emphasizes the direction of current flow in the circuit is
such that the magnetic field produced by the induced current will oppose the original
magnetic field.

RFID tags extract their power from a reader’s field. The tags’ and readers’ antennas form a
system of coupled inductances. The efficient transfer of energy from the reader to the tag
depends on the precision of the parallel resonant RLC loop antenna tuned to the operating
frequency of 13.56MHz. The tag antenna can be symbolized using their equivalent electrical
circuit. The figure below shows the equivalent electrical circuit of the antenna.




                           Figure 3.4: Equivalent Tag Antenna RLC circuit




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3.4.1 Initial Design A:

For Initial Design A, the size of the antenna was 7500um x 4500um. It was designed using
MRIND (Micro-strip Rectangle Inductor) of the ADS software. It is formed by defining the
number of turns (N) in the inductor, length of second outermost segment (L1) and length of
outermost segment (L1). The wire width (W) and wire spacing (S) are also specified. The
figure below shows how MRIND can be configured.




Further details of how MRIND is configured can be found on Appendix III.

The figure below shows the antenna design for the tag:




                                  Figure 3.5: Initial Design A




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 The figure below shows the schematic equivalent for the proposed design:

                          RFID Antenna

                                                                    Cp = capacitive coupling due to electrical field
                                Cp           Rp

                                                                    Rp = resistance in series with Cp

        Input Port                                                  Ls = series inductance of square spiral
                                Ls           Rs
                                                                    Rs = ohm loss on metal traces of spiral
                   Cadh

                                                                    Cadh = adhesive material capacitance between
                                                                    coil & PET substrate
            Rsub             Csub

                                                                    Rsub = resistive loss in PET substrate

                                                                    Csub = PET substrate capacitance




                          Figure 3.6:   Equivalent Schematic for proposed design




The design parameters of Initial Design A are as follows:




               Figure 3.7: Configuration of MRIND (Left) and Substrate properties 1 (Right)




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Figure 3.8: Substrate properties 2 (Left) and Substrate properties 3 (Right)




  Figure 3.9: Substrate properties 4 (Left) and Final Design A1 (Right)




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3.4.2 Initial Design A1:

For Final Design A1, the size of the antenna was 50mm x 30mm. It was designed using
MRIND of the ADS software. It is modified from Initial Design A as that design was too
small for fabrication.

The substrate properties are the same as of Initial Design A. PET is used as substrate because
of its low-cost, ease of manufacturability and its low loss and permittivity. FR4 is not used in
this project as it is commonly used for low frequency. Alumina was used as the dielectric
constant is 1. For a high frequency design (13.56MHz) requires low dielectric constant
materials. The figure below shows the antenna design for the tag.

The length of the antenna can be calculated by:
                                                 c
                                        L            [14]
                                            2 f r r
whereby c is the speed of light, fr is the operating frequency and εr is the dielectric constant
of the substrate which gives a value of around 6cm (60mm). With some slight modifications,
the length is reduced to 5cm (50mm).

The width of the antenna can by calculated by:
                                             d  
                                W  hd ln    1 [14]
                                             h  
                           c
whereby d  0 ,  0  ; c is the speed of light, f is the operating frequency and εr is
                  er        f
the dielectric constant of the substrate which gives a value of around 3cm (30mm). The
number of turns for a typical 13.56MHz application is between 3-5 turns. In this project, 4
turns was chosen. The wire size is 0.5mm and the spacing between each wire is 0.5mm.




                                   Figure 3.10: Final Design A1

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The design parameters are as follows:




                       Figure 3.11: Design parameters of Final Design A1




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3.4.3 Final Design A2:

For Final Design A2, the size of the antenna was 50mm x 30mm with a wire size of 0.6mm
and the spacing between each wire is 0.4mm. The substrate properties are same as of Final
Design A1. The figure below shows the antenna design for the tag.




                                   Figure 3.12: Final Design A2


The design parameters are as follows:




                         Figure 3.13: Design parameters of Final Design A2

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 3.4.4 Final Design A3

 For Final Design A3, the size of the antenna was 50mum x 30mm with a wire size of 0.7mm
 and the spacing between each wire is 0.5mm. The substrate properties and wire spacing are
 same as of Final Design A1. The purpose of this design is to compare how different wire size
 will affect the overall performance of the antenna. The figure below shows the antenna
 design for the tag.




                                    Figure 3.14: Final Design A3

The design parameters are as follows:




                          Figure 3.15: Design parameters of Final Design A3
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 3.4.5 Final Design A4

 For Final Design A4, the size of the antenna was 50mum x 30mm with a wire size of 0.5mm
 and the spacing between each wire is 1mm. The substrate properties are same as of Final
 Design A1. The purpose of this design is to compare how different wire spacing will affect
 the overall performance of the antenna. The figure below shows the antenna design for the
 tag.




                                    Figure 3.16: Final Design A4

The design parameters are as follows:




                          Figure 3.17: Design parameters of Final Design A4


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3.4.6 Final Design A5

For Final Design A5, the size of the antenna was 50mum x 30mm with a wire size of 0.5mm
and the spacing between each wire is 0.7mm. The substrate properties are same as of Final
Design A1. The purpose of this design is to compare how different wire spacing will affect
the overall performance of the antenna. The figure below shows the antenna design for the
tag.




                                  Figure 3.18: Final Design A5


The design parameters are as follows:




                        Figure 3.19: Design parameters of Final Design A5

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3.4.7 Final Design B1

For Final Design B1, the size of the antenna was 40mum x 27mm with a wire size of 1.4mm
and the spacing between each wire is 0.5mm. It was designed using MRIND of the ADS
software. The substrate properties are modified to a 2 layer substrate. The purpose of this
design is to compare how different substrate properties will affect the overall performance of
the antenna.
                                                                        2re  1  A
The equivalent relative permittivity εr’ is given by: r '                           whereby
                                                                           1 A
                    1
                
     12h12        2
A  1                [14].
        w 




           Figure 3.20: A rectangular micro-strip antenna with multilayered dielectric substrate



The figure below shows the antenna design for the tag.




                                      Figure 3.21: Final Design B1




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The substrate properties are as follows:




                        Figure 3.22: Substrate properties of Final Design B1


The design parameters are as follows:




                        Figure 3.23: Design parameters of Final Design B1




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3.4.8 Final Design B2

For Final Design B2, the size of the antenna was 40mum x 27mm with a wire size of 1.6mm
and the spacing between each wire is 0.4mm. The substrate properties are same as of design
B1. The figure below shows the antenna design for the tag.




                                  Figure 3.24: Final Design B2



The design parameters are as follows:




                        Figure 3.25: Design parameters of Final Design B2

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3.4.9 Final Design B3

For Final Design B3, the size of the antenna was 40mum x 27mm with a wire size of 2mm
and the spacing between each wire is 0.5mm. The substrate properties are same as of design
B1. The figure below shows the antenna design for the tag.




                                  Figure 3.26: Final Design B3



The design parameters are as follows:




                        Figure 3.27: Design parameters of Final Design B3


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3.5.   Proposed Feeding Techniques

In this project, coplanar micro-strip transmission line feeding technique is used to simulate
the designs. The simulation results can be found in Chap 4.


4. Simulation Results

4.1 Final Design A
This design is simulated with a sweep frequency from 5MHz to 20MHz.The S-parameters
are as follows:




                            Figure 4.1: S- parameters of Final Design A

The return loss (S11, S22) of the antenna are at an acceptable range of -46.54dB and
-58.94dB at resonance frequency of 13.75MHz. It is noticed there is a shift of 0.19 MHz. No
account is taken into consideration to look into the mismatch of the reactance. Thus there is a
resonant shift in the frequency. The insertion loss (S12, S21) are around -0.001dB. The
definition of S-parameters of the antenna can be found on Chap 2.8.2 Antenna Properties.




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                            Figure 4.2: Radiation pattern of Final Design A

The above figure shows the 3D radiation pattern of the antenna in the far-field plot option of
ADS. It is computed using E-Theta option. This is the swept parameter of a planar cut. When
THETA is swept, PHI is at a fixed angle specified in the Cut Angle field and is not returned
to the dataset. For the planar cut, the angle phi, which is relative to the x-axis, is kept
constant. The angle theta, which is relative to the z-axis, is swept to create a planar cut. Theta
is swept from 0 to 360 degrees. This produces a view that is perpendicular to the circuit
layout plane. This shows the coverage of the RF field is well distributed. It should be easily
detected by the reader [18].




                                   Figure 4.3: Planar (Vertical) Cut




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                         Figure 4.4: Antenna Parameters of Final Design A

The above figure shows the gain and directivity parameters of the antenna. The overall gain
of the antenna is -27.13dB and directivity is 5.93dB. This implies that the signal is heavily
attenuated. The effective angle is 183.7° whereby all the power radiate from the antenna
would flow if the maximum radiation intensity is constant for all angles over the beam area.
The radiated power is extremely low of 1.07  10 12 W. The parameters of the antenna can be
found on Chap 2.8.2 Antenna Properties.




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4.2   Final Design A1

This design is simulated with a sweep frequency from 3.56MHz to 23.56MHz.The
S-parameters are as follows:




                          Figure 4.5: S- parameters of Final Design A1

The return loss (S11, S22) of the antenna are -33.15dB and -21.32dB which is considered as
acceptable. The insertion loss (S12, S21) are around 0.032dB. The S-parameters of the
antenna can be found on Chap 2.8.2 Antenna Properties.




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                           Figure 4.6: Radiation pattern of Final Design A1

The above figure shows the 3D radiation pattern of the antenna. The coverage of the RF field
is well distributed. It should be easily detected by the reader.




                         Figure 4.7: Antenna Parameters of Final Design A1

The above figure shows the gain and directivity parameters of the antenna. The overall gain
of the antenna is 7.74dB and directivity is 7.72dB. This implies that the signal is intensified.
The effective angle is 121° whereby all the power radiate from the antenna would flow if the
maximum radiation intensity is constant for all angles over the beam area. The radiated
power is low of 2.44  1011 W. This is lower than Final Design A. The parameters of the
antenna can be found on Chap 2.8.2 Antenna Properties.

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4.3   Final Design A2

This design is simulated with a sweep frequency from 3.56MHz to 23.56MHz.The
S-parameters are as follows:




                          Figure 4.8: S- parameters of Final Design A2

The return loss (S11, S22) of the antenna are -32.80dB and -37.61dB which is considered as
acceptable. The insertion loss (S12, S21) are around -0.020dB. The S-parameters of the
antenna can be found on Chap 2.8.2 Antenna Properties.




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                           Figure 4.9: Radiation pattern of Final Design A2

The above figure shows the 3D radiation pattern of the antenna. The coverage of the RF field
is well distributed. It should be easily detected by the reader.




                         Figure 4.10: Antenna Parameters of Final Design A2

The above figure shows the gain and directivity parameters of the antenna. The overall gain
of the antenna is 7.74dB and directivity is 7.75dB. This implies that the signal is intensified.
The effective angle is 120° whereby all the power radiate from the antenna would flow if the
maximum radiation intensity is constant for all angles over the beam area. The radiated
power is low of 2.22  1011 W. The parameters of the antenna can be found on Chap 2.8.2
Antenna Properties.

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4.4   Final Design A3

This design is simulated with a sweep frequency from 3.56MHz to 23.56MHz.The
S-parameters are as follows:




                          Figure 4.11: S- parameters of Final Design A3

The return loss (S11, S22) of the antenna are -59.36dB and -16.99dB which is considered as
acceptable. The insertion loss (S12, S21) are around 0.028dB. The S-parameters of the
antenna can be found on Chap 2.8.2 Antenna Properties.




                        Figure 4.12: Radiation pattern of Final Design A3

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The above figure shows the 3D radiation pattern of the antenna. The coverage of the RF field
is well distributed. It should be easily detected by the reader.




                        Figure 4.13: Antenna Parameters of Final Design A3

The above figure shows the gain and directivity parameters of the antenna. The overall gain
of the antenna is -13.87dB and directivity is 7.74dB. This implies that the signal is
attenuated. The effective angle is 121° whereby all the power radiate from the antenna would
flow if the maximum radiation intensity is constant for all angles over the beam area. The
radiated power is low of 2.27  1011 W. This shows that this design is not very good as
signal is being attenuated. A good antenna should have a gain of around 5 to 7dB.

This concluded that as the wire size increased with same wire spacing, the antenna
performance will drop. The parameters of the antenna can be found on Chap 2.8.2 Antenna
Properties.




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4.5   Final Design A4

This design is simulated with a sweep frequency from 3.56MHz to 23.56MHz.The
S-parameters are as follows:




                         Figure 4.14: : S- parameters of Final Design A4

The return loss (S11, S22) of the antenna are -43.23dB and -43.46dB which is considered as
acceptable. The insertion loss (S12, S21) are around -0.043dB. The S-parameters of the
antenna can be found on Chap 2.8.2 Antenna Properties.




                        Figure 4.15: Radiation pattern of Final Design A4

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The above figure shows the 3D radiation pattern of the antenna. The coverage of the RF field
is well distributed. It should be easily detected by the reader.




                        Figure 4.16: Antenna Parameters of Final Design A4

The above figure shows the gain and directivity parameters of the antenna. The overall gain
of the antenna is -15.47dB and directivity is 7.75dB. This implies that the signal is
attenuated. The effective angle is 121° whereby all the power radiate from the antenna would
flow if the maximum radiation intensity is constant for all angles over the beam area.

The radiated power is low of 2.46  1011 W. Thus, this result shows that this design is not
very good as signal is being attenuated. A good antenna should have a gain of around 5 to
7dB. This concluded that as the wire spacing size increased, the antenna performance will be
decreased. The parameters of the antenna can be found on Chap 2.8.2 Antenna Properties.




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4.6   Final Design A5

This design is simulated with a sweep frequency from 3.56MHz to 23.56MHz.The
S-parameters are as follows:




                          Figure 4.17: S- parameters of Final Design A5

The return loss (S11, S22) of the antenna are -33.94dB and -38.89dB which is considered as
acceptable. The insertion loss (S12, S21) are around 0.037dB. The S-parameters of the
antenna can be found on Chap 2.8.2 Antenna Properties.




                        Figure 4.18: Radiation pattern of Final Design A5

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The above figure shows the 3D radiation pattern of the antenna. The coverage of the RF field
is well distributed. It should be easily detected by the reader.




                        Figure 4.19: Antenna Parameters of Final Design A5

The above figure shows the gain & directivity parameters of the antenna. The overall gain of
the antenna is -14.87dB and directivity is 7.73dB. This implies that the signal is attenuated.
The effective angle is 121° whereby all the power radiate from the antenna would flow if the
maximum radiation intensity is constant for all angles over the beam area. The radiated
power is low of 2.46  1011 W. Thus, this result shows that this design is not very good as
signal is being attenuated.

A good antenna should have a gain of around 5 to 7dB. This concluded that as the wire
spacing size increased, the antenna performance will be decreased. The parameters of the
antenna can be found on Chap 2.8.2 Antenna Properties.




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4.7    Final Design A Result Comparison

The following table summarizes the results obtained:

                           Return                                                              Wire     Wire
  Design     Resonant                                Directivity   Radiated   Length   Width                     N (No of
                          Loss (S11)     Gain(dB)                                              Width   Spacing
  Name       Freq. (Hz)                                 (dB)       Pwr (W)     (mm)    (mm)                       turns)
                            (dB)                                                               (mm)     (mm)

   Final                                                            1.07 x
             13.56MHz     -41.54dB        -27.13dB    5.93dB                   7.5      4.5     0.1     0.18        5
 Design A                                                           10-12
   Final                                                            2.44 x
             13.56MHz     -33.15dB        7.74dB      7.72dB                   50       30      0.5      0.5        4
 Design A1                                                          10-11
   Final                                                            2.22 x
             13.56MHz     -32.80dB        7.74dB      7.75dB                   50       30      0.6      0.4        4
 Design A2                                                          10-11
   Final                                                            2.27 x
             13.56MHz     -59.36dB        -13.87dB    7.74dB                   50       30      0.7      0.5        4
 Design A3                                                          10-11
   Final                                                            2.46 x
             13.56MHz     -43.23dB        -15.47dB    7.75dB                   50       30      0.5       1         4
 Design A4                                                          10-11
   Final                                                            2.46 x
             13.56MHz     -33.94dB        -14.87dB    7.73dB                   50       30      0.5      0.7        4
 Design A5                                                          10-11

                                       Table 3: Final Design A Result Summary

Conclusion:

After comparing Final Design A, A1, A2, A3, A4 and A5 simulation results, Final Design A1
has the most optimum result. From the results, it is noticed that the gain is same as Final
Design A2, the return loss is less than of Final Design A1.This concluded that there is less
power being radiated back to the source in Final Design A1 thus the transmitted signal is
stronger than Final Design A2. Final Design A3, A4 and A5 failed to meet the requirement of
positive gain. This concluded that for a well antenna design with a good positive gain, the
wire width and spacing has to be equally sized and spaced out.




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4.8   Final Design B1

This design is simulated with a sweep frequency from 3.56MHz to 23.56MHz.The
S-parameters are as follows:




                          Figure 4.20: S- parameters of Final Design B1

The return loss (S11, S22) of the antenna are -40.61dB and -43.01dB which is considered as
acceptable. The insertion loss (S12, S21) are around -0.009dB. The S-parameters of the
antenna can be found on Chap 2.8.2 Antenna Properties.




                         Figure 4.21: Radiation pattern of Final Design B1
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The above figure shows the 3D radiation pattern of the antenna. The coverage of the RF field
is well covered.




                        Figure 4.22: Antenna Parameters of Final Design B1

The above figure shows the gain and directivity parameters of the antenna. The overall gain
of the antenna is 8.18dB and directivity is 8.16dB. This shows that the signal is intensified.

The effective angle is 109° whereby all the power radiate from the antenna would flow if the
maximum radiation intensity is constant for all angles over the beam area. The radiated
power is lower than of A1.

Thus, this result shows that this design is very good as signal is being intensified. A good
antenna should have a gain of around 5 to 7dB. The gain of this design has exceeded. This
concluded that as the change from a single layer substrate to a double layer substrate has an
effect of the antenna performance. The parameters of the antenna can be found on Chap 2.8.2
Antenna Properties.




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4.9   Final Design B2

This design is simulated with a sweep frequency from 3.56MHz to 23.56MHz.The
S-parameters are as follows:




                          Figure 4.23: S- parameters of Final Design B2

The return loss (S11, S22) of the antenna are -31.59dB and -21.28dB which is considered as
acceptable. The insertion loss (S12, S21) are around -0.033dB. The S-parameters of the
antenna can be found on Chap 2.8.2 Antenna Properties.




                         Figure 4.24: Radiation pattern of Final Design B2

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The above figure shows the 3D radiation pattern of the antenna. The coverage of the RF field
is well covered.




                        Figure 4.25: Antenna Parameters of Final Design B2

The above figure shows the gain and directivity parameters of the antenna. The overall gain
of the antenna is 8.03dB and directivity is 8.02dB. This shows that the signal is intensified.
The effective angle is 113° whereby all the power radiate from the antenna would flow if the
maximum radiation intensity is constant for all angles over the beam area.

The radiated power is lower than of B1. The parameters of the antenna can be found on Chap
2.8.2 Antenna Properties.




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4.10 Final Design B3

This design is simulated with a sweep frequency from 3.56MHz to 23.56MHz.The
S-parameters are as follows:




                          Figure 4.26: S- parameters of Final Design B3

The return loss (S11, S22) of the antenna are -15.53dB and -47.17dB which is considered as
acceptable. The insertion loss (S12, S21) are around -0.018dB. The S-parameters of the
antenna can be found on Chap 2.8.2 Antenna Properties.




                         Figure 4.27: Radiation pattern of Final Design B3

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The above figure shows the 3D radiation pattern of the antenna. The coverage of the RF field
is well covered.




                        Figure 4.28: Antenna Parameters of Final Design B3

The above figure shows the gain & directivity parameters of the antenna. The overall gain of
the antenna is 7.87dB and directivity is 7.86dB. This shows that the signal is intensified.

The effective angle is 117° whereby all the power radiate from the antenna would flow if the
maximum radiation intensity is constant for all angles over the beam area. The radiated
power is lower than of B1. The parameters of the antenna can be found on Chap 2.8.2
Antenna Properties.




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4.11 Final Design B Result Comparison

The following table summarizes the results obtained:

                          Return
                                                                                                      Wire          Wire
  Design     Resonant      Loss        Gain      Directivit     Radiated       Length      Width                                 N (No of
                                                                                                      Width        Spacing
  Name       Freq. (Hz)    (S11)       (dB)        y(dB)        Pwr (W)         (mm)       (mm)                                   turns)
                                                                                                      (mm)          (mm)
                            (dB)
   Final
             13.56MHz     -40.61dB    8.18dB      8.16dB        1.63x10-11       40         27         1.4           0.4            4
 Design B1
   Final
             13.56MHz     -31.59dB    8.03dB      8.03dB        1.52x10-11       40         27         1.6           0.4            4
 Design B2
   Final
             13.56MHz     -15.53dB    7.87dB      7.86dB        1.57x10-11       40         27         2             0.5            4
 Design B3

                                     Table 4: Final Design B Result Summary


Conclusion:

After comparing Final Design B1, B2 and B3 simulation results, Final Design B1 will be 2nd
chosen design for this capstone project. From the results, it is noticed that the gain of B1 is
the highest and the return loss is the least. This concluded that there is less power being
radiated back to the source in Final Design B1 thus the transmitted signal is strongest in Final
Design B1.


4.12 Results Conclusion

The following table summaries the results obtained:

                          Return
                                                                                                        Wire            Wire
  Design     Resonant      Loss                   Directivity      Radiated      Length      Width                                   N (No of
                                      Gain(dB)                                                          Width(        Spacing(
  Name       Freq. (Hz)    (S11)                     (dB)          Pwr (W)        (mm)       (mm)                                     turns)
                                                                                                         mm)            mm)
                            (dB)
   Final                                                            2.44 x
             13.56MHz     -33.15dB     7.74dB       7.72dB                            50         30          0.5           0.5          4
 Design A1                                                          10-11
   Final
             13.56MHz     -40.61dB     8.18dB       8.16dB        1.63x10-11          40         27          1.4           0.4          4
 Design B1

                          Table 5: Comparison between Final Design A & B Results

Conclusion:

After comparing the results of A1 and B1, it is decided that Final Design A1 will be chosen
design for this project. This concluded that having a double layer of substrate will improve
return loss and gain of the antenna. There is less power being radiated back to the source and
the radiated power is lesser. The disadvantage of using PET as it will limit the efficiency of
the coil antenna due to the dielectric loss ( tan   0.017 ). Furthermore, a double layer
substrate will cause more power leakage as compared to a single layer. Even though the
efficiency of the antenna is increased, the readable range of the double layer tag drops.




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5. Further Works & Recommendations

Due to the time limitation, this project is not able to proceed with the fabrication and
measurements. Actual measurements are required to ensure the designs specifications are
met. The antenna then can be fully commercialized.

There are still some mismatches in the designs as there are no dips in the S-11 plots.
Further works should be carried out the substrate designs such as thickness, type and
different dielectric constant.

6. Conclusion

The objective of this project is to design and analyze a micro-strip tag antenna has been
fulfilled. The overall results and performances of the designs are satisfactory.

The fabrication of the antenna designs is possible if more time is allocated for this project.
There will be a possibility of doing a measurement if the testing equipment is made available.

The antenna designs have the properties of small size, high gain and single sided radiation
pattern. The advantage of the single substrate design with balanced feed eliminates the need
for any cross–layered structures thus reduce the manufacturing complexity and cost.

With double layer substrate design, the gain and return loss of the antenna has improved
although it might increase the manufacturing complexity and cost. The other advantage of
using a double layer design is the smaller size compared to single layer.


7. Critical Reviews & Reflections

There are quite number setbacks throughout the project process. My working experiences as
a Project Engineer have helped me to resolve the problems. The following list reviews the
phases and the process I have gone through.

Literature review and research:
This is the initial stage of the project, where reference books from the library and information
from the internet are being gathered. I also have to read through IEEE journals and articles.

Design and Simulation:
After reviewing the basic parameters of the antenna, I have to read through different designs
and made comparisons to propose an ideal design. There are numerous of ways and methods
available to design the antenna. Many simulations were carried out to improve on the design
of the antenna. This is a phase where I have to review every design and understand where to
improve on the design to achieve a better gain. I also faced problems using the ADS software
as I have never use before. I managed to resolve the problem with the help of my tutor and
studying the momentum manual and the ADS manual to understand and utilize the usage. I
also found out that there are some design mistakes probably due to the wrong size and
substrate selection. I had tried changing the substrate properties, the results are negative. Due
to time constraints, I am not able to make changes to the wire size and spacing.



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References

 [1]   Anthony Furness, "Understanding RFID -A Guide to Radio Frequency Identification
       Technologies and Applications", Vicarage Publication Ltd, 2000

 [2]   http://en.wikipedia.org/wiki/Electronic_article_surveillance

 [3]   Kin Seong Leong, Mun Leng Ng, PeterH.Cole, "A Simple Dual-frequency Antenna
       Design for RFID Tag", AutoID Labs White Paper

 [4]   http://www.rfidjournal.com/article/articleview/1339/1/129/

 [5]   http://www.explainthatstuff.com/rfid.html

 [6]   http://www.rfidjournal.com/

 [7]   http://www.activewaveinc.com/applications_hospitals.php

 [8]   http://www.activewaveinc.com/applications_manufacturing_line.php

 [9]   V. NagaLakshmi, I.Rameshbabu, D. Lalitha Bhaskari, "A Security Mechanism for
       library management system using low cost RFID tags", Department of Computer
       Science, Gandhi Institute of Technology and Management, Visakhapatnam, Andhra
       Pradesh, India

 [10] http://www.scienceprog.com/how-does-rfid-tag-technology-works/

 [11] Youbok Lee , "RFID Coil Design" , Microchip Application Notes, 1998

 [12] RFID Technical Institute, "The Evaluation of RFID – Next Wave Principles,
      Challenges & Solutions ", 2007

 [13] http://www.gitthailand.com/Product/RFIDs/RFID_Frequency.htm

 [14] Ramesh Garg, Prakash Bhartia, "Microstrip Antenna Design Handbook", Artech
      House, 2001

 [15] P. J. SOH1, M. K. A. RAHIM2, "Design, Modelling and Performance Comparsion of
      Feeding Techniques for a Microstrip Patch Antenna", University Teknologi Malaysia,
      2007

 [16] http://ocw.kfupm.edu.sa/user062/EE34004/Lecture-31.doc

 [17] http://en.wikipedia.org/wiki/Antenna_aperture

 [18] Agilent, "Momentum Manual", Agilent Technologies, September 2004

 [19] http://www.larsen-antennas.com/techref_antbasicconcepts.shtml

 [20] http://en.wikipedia.org/wiki/Antenna_(radio)

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[21] http://www.air-stream.org.au/Polarization

[22] http://www.vias.org/wirelessnetw/wndw_06_05_05.html

[23] http://emc.toprudder.com/vswr.pdf

[24] http://en.wikipedia.org/wiki/Return_loss

[25] HP, "S-Parameter Techniques, Hewlett Packard", 1996-1997

[26] http://cp.literature.agilent.com/litweb/pdf/ads2008/cktsimsp/ads2008/S-Parameter_Si
     mulation_Description.html#S-ParameterSimulationDescription-SParameterFrequency
     Conversion

[27] http://en.wikipedia.org/wiki/ISO/IEC_14443

[28] http://en.wikipedia.org/wiki/Maxwell_equation

[29] http://www.autepra.lt/en/rfid_tag.html

[30] Sandip Lahiri, "RFID Sourcebook", IBM Press/Pearson pic, 2006

[31] K.C Gupta, Ramesh Garg, "Mircostrip Lines and Slotlines", Artech House, 1996

[32] http://www.articlesbase.com/technology-articles/passive-rfid-tags-vs-active-rfid-tags-
     217838.html

[33] http://www.apaxcn.com/eng/solution_rfid.htm

[34] http://www.ibmpressbooks.com/articles/article.asp?p=413662

[35] http://www.scienceprog.com/how-does-rfid-tag-technology-works/

[36] http://www.microwaves101.com/encyclopedia/sparameters.cfm

[37] http://cp.literature.agilent.com/litweb/pdf/ads2008/emds/ads2008/Radiation_Patterns
     _and_Antenna_Characteristics.html

[38] http://wireless.agilent.com/vcentral/viewvideo.aspx?vid=479

[39] http://www.technovelgy.com/ct/Technology-Article.asp?ArtNum=50

[40] http://fuxm.org/rfid/tech.html

[41] http://en.wikipedia.org/wiki/Green's_function




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IEEE Journals

[42] Greg s. Pope, Michael Y. Loukine, "Innovative Systems Design for 13.56MHz
     RFID", Integrated Silicon Design pty .Ltd.
[43] Xianming Qing, Zhi Ning Chen, Ailia Cai, "Multi-loop Antenna for High Frequency
     RFID Smart Shelf Application", Institute for Infocomm Research, Singapore
[44] Madhuri Eunni, Mutharasu Sivakumar, Daniel D. Deavours, "A Novel Planar
     Microstrip Antenna Design for UHF RFID", Information and Telecommunications
     Technology Centre, University of Kansas
[45] V.Nagalakshmi, I.Rameshbabu, D.Lalitha Bhaskari, "A Security Mechanism for
     library management system using low cost RFID tags", Department of Comuter
     Science, Gandhi Institute of Technology and Management, India
[46] Lukas W. Mayer, Arpad L. Scholtz, "A Dual-band HF/UHF Antenna for RFID tags",
     Vienna University of Technology, Insitute of Communications and Radio-Frequency
     Engineering, Austria
[47] Kyiaki Fotopoulou, Brain W Fylnn, "Optimum Antenna Coil Structure for Inductive
     Powering of Passive RFID tags", Institute for Micro and Nano Systems, School of
     Engineering and Electronics, University of Edinburgh, UK
[48] K.V.Seshagiri Rao, Pavel V. Nikitin, Sander F.Lam, "Antenna Design for UHF RFID
     Tags: A Review and a Practical Approach", RFID Intellitag Engineering Department,
     Intermec Technologies.
[49] L.H. Guo, A.P.Popov, H.Y.Li,Y.H.Wang, "A Small OCA on a 1 x 0.5mm2 2.45GHz
     RFID Tag – Design and Integration Based on a CMOS Compatible Manufacturing
     Technology", Institute of Microelectronics, Singapore




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Appendix I

Due to the fact that, there is no dip in shown in S-parameters shown earlier, the designs are
further simulated with a sweep frequency from 12.2MHz to 14.6MHz. The following
diagrams shows how S-parameters look like when the designs are simulated with a sweep
frequency from 12.2MHz to 14.6MHz.

Final Design A1 :




Final Design A2 :




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Appendix I

Final Design A3 :




Final Design A4 :




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Appendix I

Final Design A5 :




Final Design B1 :




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Appendix I

Final Design B2 :




Final Design B3 :




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Appendix II




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Appendix III




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Appendix IV




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Appendix V


                                  Meeting Log #01

Date: 31 Jan 2009
Time: 4.30pm- 6.00pm
Title: 1st FYP briefing

Matter discussed:

1. Definition of individual project role & objectives
2. Discussion of project background
3. Required skill-sets for completion of FYP
4. Discuss of TMA01 requirement




Consensus/ Decision taken:

1. Explaining theory and settings
2. Meet-up date decided
3. Expected to see new design and show literature research progress on next meetup.




                                                                                Written on:
                                                                               01 Feb 2009




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                                Meeting Log #02

Date: 14 Feb 2009
Time: 4.30pm- 6.00pm
Title: 2nd FYP briefing

Matter discussed:

1. Update on TMA01
2. Demo use of Agilent - Advanced Design System (ADS) software
3. Detailed discuss of TMA01 write-up




Consensus/ Decision taken:

1. Finalised on TMA01 initial design
2. Expected to design & simulation progress on next meetup




                                                                            Written on:
                                                                           15 Feb 2009




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                                 Meeting Log #03

Date: 28 Feb 2009
Time: 4.30pm- 6.00pm
Title: 3rd FYP briefing

Matter discussed:

1. Review of initial proposed design and simulation progress
2. Discussion on modification of proposed initial design
3. Update of project status to supervisor




Consensus/ Decision taken:

-




                                                                          Written on:
                                                                         01 Mar 2009




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                              Meeting Log #04

Date: 14 Mar 2009
Time: 4.30pm- 6.00pm
Title: 3rd FYP briefing

Matter discussed:

1. Further discussion of modified design simulation settings
2. Discussion of actual design
3. Discussion of Thesis format
4. Second demo use of Agilent - Advanced Design System (ADS) software
5. Explaining electromagnetic theory




Consensus/ Decision taken:

1. Prepare interim report
2. Meet-up date decided




                                                                           Written on:
                                                                          15 Mar 2009




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                              Meeting Log #05

Date: 28 Mar 2009
Time: 4.30pm- 6.00pm
Title: 4th FYP briefing

Matter discussed:

1. Discussion of project fabrication
2. Q&A session for Agilent - Advanced Design System (ADS) software




Consensus/ Decision taken:

-




                                                                           Written on:
                                                                          29 Mar 2009




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                                Meeting Log #06

Date: 11 Apr 2009
Time: 4.30pm- 6.00pm
Title: 6th FYP briefing

Matter discussed:

1. Review of project simulations done
2. Assess of project progress
3. Q&A session for project design, problems faced during designing & simulation
4. Discussion of interim report write-up




Consensus/ Decision taken:

1. Expected to see more simulation results on next meetup.
2. Prepare interim report




                                                                               Written on:
                                                                              12 Apr 2009




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                                Meeting Log #07

Date: 31 May 2009
Time: 10.00am- 12.00pm
Title: 7th FYP briefing

Matter discussed:

1. Project Progress
2. Briefing/explanation on FYP presentation that held on 30 May 09.
3. Q&A session for project design, problems faced during designing & simulation




Consensus/ Decision taken:

1. Expected to see more improved simulation results on next meetup.




                                                                                  Written on:
                                                                                 01 Jun 2009




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                                Meeting Log #08

Date: 25 Jul 2009
Time: 3.00pm - 4.00pm
Title: 8th FYP briefing

Matter discussed:

1. Project Progress
2. Expectation of upcoming presentation
3. Q&A session for project design, problems faced during designing & simulation
4. Thesis write up - requirements




Consensus/ Decision taken:

1. Expected to see more improved simulation results on next meetup.




                                                                                  Written on:
                                                                                  27 Jul 2009




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                                 Meeting Log #09

Date: 3 Oct 2009
Time: 2.00pm - 4.00pm
Title: 9th FYP briefing

Matter discussed:

1. Project Progress
2. Expectation of upcoming presentation
3. Q&A session for project simulation results
4. Thesis write up – more details were discussed, including presentation poster




Consensus/ Decision taken:

1. To complete thesis writing




                                                                                   Written on:
                                                                                  04 Oct 2009




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                                 Meeting Log #10

Date: 15 Oct 2009
Time: 7.00pm - 9.00pm
Title: 10th FYP briefing

Matter discussed:

1. Thesis Progress
2. Expectation of upcoming presentation
3. Q&A session for project simulation results




Consensus/ Decision taken:

1. To complete thesis writing & poster design




                                                                Written on:
                                                               16 Oct 2009




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Appendix VI


 H:\UniSIM\ENG 499
TMA01\Thesis\ENG499 Poster Yit Shu Ling B060540.ppt




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