Radio frequency identification by rfid project team . faculty of electronic engineering . communication department. menoufia university [combined and uploaded by a member of the team ( mohammed ali )]

-MenoufiaUniversity[Combinedanduploadedbyamemberoftheteam(MohammedAli)]
RadioFrequencyIdentificationByRFIDProjectTeam-FacultyofElectronicEngineering-Communicationdepartment

Menoufia University
Faculty Of Electronic Engineering
Department Of Electronics & Communication Engineering
Graduation Project
Supervised by
Dr. Hend Abd-El Azim Malhat
2013
Supervisors Head of the Department Dean
Radio Frequency
Identification Antennas

Preface
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Preface
The use of computerized systems to process information has changed lifestyles
around the world. Many automated systems have been developed for information
tracking and automated identification, simple decision response and control. Radio
frequency identification (RFID) is one of several types of automatic identification
(Auto-ID) procedures. Auto-ID procedures include barcode systems, contact-based
smart cards, and biometrics such as voice and fingerprint identification. RFID is an
emerging and leading technology in item identification. RFID is a wireless
communication technology that is used to uniquely identifying tagged objects or
people. The roots of RFID technology can be traced back to the World War II in
which, the Germans discovered that if pilots rolled their planes while they were
returning to base, the RFID tag changed the signal that was reflected back. This had
allowed the German base to identify the planes as friendly fighters or not and is
essentially a very basic RFID system.
In RFID systems, a reader communicates to a transponder with an attached
microchip that carries data and, in some systems, processes data. Data transfer
occurs between a tag and a reader through their antenna coupling. Thus, the RFID
tag and reader antennas play the major role in RFID system operation. In general,
RFID tags can be categorized as active and passive. The active tags get their energy
completely or partially from an integrated power supply, i.e., battery, while the
passive tags do not have any power supply and rely only on the power extracted from
the radio frequency signal received from the reader. The use of RFID depends on
the frequency bands licensed by governments. Operating frequencies include 135
kHz, 13.56 MHz, 868 MHz (Europe), 915 MHz (USA), 2.45 GHz, and 5.8 GHz
among others. The RFID tag and reader antennas play significant role in
determining the covered zone, range and accuracy of communication. Different

Preface
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types of antennas have been introduced for RFID tag. The antennas include printed
dipoles, folded dipoles, loop antennas, meander line printed antennas, and slot
antennas. The antenna impedance should be inductive in order to achieve conjugate
matching with the capacitive impedance of the IC-microchip. Adding an external
matching network with lumped elements is usually prohibitive in RFID tags due to
the cost and fabrication issues. Matching network has been added as an integral part
to the tag to provide a better match for the chip capacitive impedance. There are
several techniques to achieve complex impedance matching such as T-mach, the
proximity-loop, loading bar, and the nested-slot layouts. Most of the previous work
in the RFID tag antenna design does not include the effect of the object and the
surrounding environments. Also, some of these tag antennas are designed and
optimized for virtual IC-microchip, which is not practically available. Few RFID tag
parameters are calculated in the published work such as return loss (reflection
coefficient relative to 50 Ω), the input impedance, and the radiation pattern in free
space.

Contents
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P a g e | i
Contents
1 Automatic Identification Systems 1-1
1.1 Introduction 1-1
1.2 Barcode systems 1-2
1.2.1 One-dimensional
1.2.2 Two-dimensional
1.2.3 Advantages of Barcode systems
1.2.4 Disadvantages of Barcode systems
1.2.5 Bar-coding
1.2.6 Advantages of 2-D Barcode systems
1.3 Optical character recognition 1-6
1.4 Biometric procedures 1-6
1.4.1 Voice identification
1.4.2 Fingerprinting procedures
1.4.3 Applications of Biometric procedures
1.4.4 Advantages of Biometric procedures
1.4.5 Disadvantages of Biometric procedures
1.5 Magnetic stripe card 1-8
1.5.1 The magnetic stripe
1.5.2 Magnetic stripe coercivity
1.5.3 How does a magnetic stripe on the back of a
credit card work?
1.6 Smart cards 1-12
1.6.1 Memory cards
1.6.2 Microprocessor cards
1.7 Electronic Article Surveillance (EAS) 1-14
2 History of RFID 2-1
2.1 It All Started with IFF 2-1
2.2 RFID Technology 2-3
2.3 Components of an RFID System 2-4
2.4 Basic Operation 2-5
2.5 Different Types of RFID 2-5
2.5.1 Frequency bands are being used for RFID

Contents
P a g e | ii
2.5.2 RFID tags are further broken down into two
categories
2.5.3 There are two basic types of chips available on
RFID tags, Read-Only and Read-Write
2.6 Advantages of the Technology 2-7
2.6.1 Contactless
2.6.2 Writable Data
2.6.3 Absence of Line of Sight
2.6.4 Variety of Read Ranges
2.6.5 Wide Data-Capacity Range
2.6.6 Support for Multiple Tag Reads
2.6.7 Rugged
2.6.8 Perform Smart Tasks
2.6.9 Read Accuracy
2.7 Disadvantages of the technology 2-15
2.7.1 Poor Performance with RF-Opaque and RF-
Absorbent Objects
2.7.2 Impacted by Environmental Factors
2.7.3 Limitations on Actual Tag Reads
2.7.4 Impacted by Hardware Interference
2.7.5 Limited Penetrating Power of the RF Energy
2.7.6 Immature Technology
2.8 Applications 2-19
2.9 Security and Privacy Issues 2-21
2.9.1 Tag Data
2.9.1.1 Eavesdropping (or Skimming)
2.9.1.2 Traffic Analysis
2.9.1.3 Denial of Service Attack
2.9.2 RFID Reader Integrity
2.9.3 Personal Privacy
2.10 RFID Security Trends 2-22
2.10.1 Approaches for Tackling Security and
Privacy Issues
2.10.1.1 Solutions for Tag Data Protection
2.10.1.2 Solutions for RFID Reader Integrity
2.10.1.3 Solutions for Personal Privacy
2.11 “RSA” Selective Blocker Tag 2-25

Contents
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Conclusion 2-25
3 RFID Chip Tag 3-1
3.1 Definition 3-1
3.2 Tag Characteristics 3-1
3.2.1 Identifier Format
3.2.2 Power Source
3.2.2.1 A passive tag
3.2.2.2 An active tag
3.2.2.3 A semi-passive tag
3.2.2.4 A semi-active tag
3.2.3 Operating Frequencies
3.2.3.1 Low Frequency (LF)
3.2.3.2 High Frequency (HF)
3.2.3.3 Ultra High Frequency (UHF)
3.2.3.4 Microwave Frequency
3.2.4 Functionality
3.2.4.1 Memory
3.2.4.2 Read Only (RO)
3.2.4.3 Write Once, Read Many (WORM)
3.2.4.4 Read Write (RW)
3.2.4.5 Environmental sensors
3.2.4.6 Security functionality, such as password
protection & cryptography
3.2.4.7 Privacy protection mechanisms
3.2.5 Form Factor
3.3 Antennas 3-16
3.4 Basic Concepts 3-17
3.4.1 Tag Collision
3.4.2 Tag Readability
3.4.3 Information, Modulation, and Multiplexing
3.4.4 Backscatter Radio Links
3.4.5 Link Budgets
3.4.6 Reader Transmit Power
3.4.7 Path Loss
3.4.8 Tag Power Requirement
3.4.9 Factors which affect read range for RFID
3.4.9.1 Passive, BAP, NFC or Active RFID?
3.4.9.2 RFID Frequency
3.4.9.3 Surrounding materials

Contents
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3.4.9.4 Tag Type
3.4.9.5 Type of reader
3.4.9.6 Orientation
3.4.9.7 Time to read
3.4.9.8 Number of tags being read
3.4.9.9 Density of Tags
Conclusion 3-32
Simulation & Results A-1
A. Half wave dipole antenna A-2
A.1 Radiation Pattern in different planes
B. Printed Dipole antenna A-4
B.1 Radiation pattern in different planes
RFID Chip Tag Analysis B-1
Numerical Results B-3
UHF tag models
A. First model
B. Second model
Microwave tag models B-13
A. First model
B. Second model
4 RFID Chip-less Tag 4-1
4.2 Difficulties of achieving low cost RFID 4-1
4.3 Definition of Chip less RFID tag 4-1
4.4 Specifications for chip less RFID tag 4-1
4.4.1 Electrical specifications
4.4.2 Mechanical specifications
4.4.3 Commercial
4.5 Operation of the chip less RFID 4-2
4.6 Types of Chip less RFID tag 4-3
4.6.1 TDR-based chip less RFID tags
4.6.1.1 Non-Printable TDR-based
4.6.1.2 Printable TDR-based
4.6.1.2.1 Delay-line-based
4.6.2 Spectral signature-based chip less tags
4.6.2.1 Chemical tags

Contents
P a g e | v
4.6.2.1.1 Nano-metric materials
4.6.2.1.2 Ink-tattoo chip less tags
4.6.2.2 Planar circuit chip less RFID
4.6.2.2.1 Capacitive tuned dipoles
4.6.2.2.2 Space-filling curves
4.6.2.2.3 LC Resonant
4.6.2.2.4
4.7 Chip less RFID tag 4-5
4.8 Spiral Resonators 4-6
4.9 Theoretical Modeling of Spiral Resonator 4-6
4.10 Spiral Resonator Modeling Using Distributed
Components 4-7
4.11 Ultra Wideband Antennas 4-8
Simulation & Results C-1
A. Chip-less Tag (Rectangular) C-2
A.1 Variation of Frequency with length
B. Chip-less Tag (Ellipse) C-4
B.1 Variation of Frequency with length
5 Modern RFID Readers 5-1
5.2 RFID Reader Architecture 5-1
5.3 Review of RFID Readers 5-3
5.4 Towards Universal Reader Design 5-6
5.5 Proposed Chip-less RFID System 5-6
5.6 Review of Chip-less RFID Transponders 5-8
5.7 Chip-less RFID Transponders 5-10
5.8 Chip-less RFID Reader 5-12
5.9 Differences Between Chipped and Chip-less Tag
Readers 5-13
5.10 Transceiver Specifications for Chip-less Tag
Reader 5-14
5.11 Gen-1 Transceiver 5-16
5.12 Gen-2 Transceiver 5-19
5.13 UWB Transceiver 5-20

Contents
P a g e | vi
5.14 Chip-less RFID Tag-Reader System Components
5-23
5.15 RFID Reader Digital Control Section 5-24
5.16 Chip-less RFID Reader Tag Interrogation/Detec-
tion Algorithm 5-25
5.17 Application Software for Chip-less RFID System
5-27
Conclusion 5-27
Simulation & Results D-1
A.1.1 Folded Dipole Antenna
A.1.2 Simulated return losses of the proposed
antenna
A.1.3 Impedance
A.1.4 Measured gain of the proposed antenna
A.2 Measured radiation patterns at 922MHz for the
proposed antenna
References 1

Chapter 1Auto-ID systems
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1
Automatic Identification Systems
1.1 Introduction
In recent years, automatic identification procedures (Auto-ID) have become
very popular in many service industries, purchasing and distribution logistics,
industry, manufacturing companies and material flow systems. Automatic
identification procedures exist to provide information about people, animals,
goods and products in transit.
The barcode labels that triggered a revolution in identification systems some
considerable time ago are being found to be inadequate in an increasing
number of cases. Barcodes may be extremely cheap, but their stumbling block
is their low storage capacity and the fact that they cannot be reprogrammed.
The technically optimal solution would be the storage of data in a silicon chip.
The most common form of electronic data-carrying device in use in everyday
life is the smart card based upon a contact field (telephone smart card, bank
cards). However, the mechanical contact used in the smart card is often
impractical. A contactless transfer of data between the data-carrying device and
its reader is far more flexible. In the ideal case, the power required to operate
the electronic data-carrying device would also be transferred from the reader
using contactless technology. Because of the procedures used for the transfer of
power and data, contactless ID systems are called RFID systems (Radio
Frequency Identification).
Figure 1.1: Overview of the most important auto-ID procedures.
Auto -
ID
Barcode
s
1-D 2-D
OCR
Biometri
cs
Voice
identificatio
n
Fingerprinti
ng
procedures
Magneti
c stripe
card
Smart
cards
Memory
cards
Microprocess
or cards
EAS RFID

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1.2 Barcode systems
1.2.1 One-dimensional
Barcodes have successfully held their own
against other identification systems over the
past 20 years. The barcode is a binary code comprising a field of bars and gaps
arranged in a parallel configuration. They are arranged according to a
predetermined pattern and represent data elements that refer to an associated
symbol. The sequence, made up of wide and narrow bars and gaps, can be
interpreted numerically and alphanumerically.
It is read by optical laser scanning, i.e. by the different reflection of a laser
beam from the black bars and white gaps, as shown below.
However, despite being identical in their
physical design, there are considerable
differences between the code layouts in the
approximately ten different barcode types
currently in use.
Barcode systems require three elements:
1. Origin: You must have a source of barcodes. These can be preprinted or
printed on demand.
2. Reader: You must have a reader to read the barcodes into the computer.
The reader includes and input device to scan the barcode, a decoder to
convert the symbology to ASCII text, and a cable to connect the device
to your computer.
3. Computer system: You must have a system to process the barcode input.
These can be single-user, multi-user, or network systems.
The most popular barcode by some margin is the EAN code (European Article
Number), which was designed specifically to fulfill the requirements of the
grocery industry in 1976.
Figure 1.2: Example of the structure of a barcode in EAN coding.

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The EAN code represents a development of the UPC (Universal Product Code)
from the USA, which was introduced in the USA as early as 1973. Today, the
UPC represents a subset of the EAN code, and is therefore compatible with it.
The EAN code is made up of 13 digits: the country identifier, the company
identifier, the manufacturer’s item number and a check digit (Figure 1.2).
In addition to the EAN code, the following barcodes are popular in other
industrial fields:
• Code Coda bar: medical/clinical applications, fields with high safety
requirements.
• Code 2/5 interleaved: automotive industry, goods storage, pallets, shipping
containers and heavy industry.
• Code 39: processing industry, logistics, universities and libraries.
1.2.2 Two-dimensional
Within the Auto-ID family, a new two-dimensional
system of bar-coding has evolved which allows
barcodes to hold more data than the traditional method.
Data is encoded in both horizontal and vertical
dimensions and, as more data is encoded, the size of the
barcode can be increased in both the horizontal and
vertical directions.
Two-dimensional barcodes (Matrix Codes) are already being used for concert
tickets by sending a barcode to a mobile
phone and then scanning the message at
the door by a laser gun.
Bar codes and readers are most often seen
in supermarkets and retail stores, but a
large number of different uses have been
found for them.
1.2.3 Advantages of Barcode systems
 Fast and Reliable Data Collection.
 10,000 Times better Accuracy.
 Faster Access to Information.
1.2.4 Disadvantages of Barcode systems
 Require line of sight to be read.
 Can only be read individually (Can only be read one at a time).
 Cannot be read if damaged or dirty.
 Can only identify the type of item.

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 Cannot be updated (Cannot be written to or reprogrammed).
 Require manual tracking and therefore,
 Susceptible to human error.
 Low storage capacity, low read range.
 They only represent a series of items and not an individual or unique
item.
 Durability (as mostly printed paper).
1.2.5 Bar-coding
Barcodes are part of every product that we buy and has become the “ubiquitous
standard for identifying and tracking products”, Traditional bar-coding is
coupled with the Universal Product Code (UPC) and every day accounts for
billions of scans all over the world. According to a survey conducted by Zebra
Technologies in 2006, over 96% of European companies cited improved
efficiency as the main benefit of using bar-coding. Other reasons that
European companies gave for using barcodes were: increasing the accuracy of
ordering and in-voicing (32%), cost reduction (26%), and the fact that newer
technology isn’t ready yet (16%).
Within the Auto-ID family, a new two-dimensional system of bar-coding has
evolved which allows barcodes to hold more data than the traditional method.
Figures show the differences between one- and two-dimensional barcodes.
Product data is encoded in both horizontal and vertical dimensions and, as
more data is encoded, the size of the barcode can be increased in both the
horizontal and vertical directions thus maintaining a manageable shape for easy
scanning and product packaging specifications.
Two-dimensional code systems have become more feasible with the increased
use of moving beam laser scanners, and Charge Coupled Device (CCD)
scanners. The 2-D symbol can be read with hand held moving beam scanners
by sweeping the horizontal beam down the symbol. However, this way of
reading such a symbol brings us full circle back to the way 1D bar code was
read by sweeping a contact wand across the symbol. The speed of sweep,
resolution of the scanner, and symbol/reader distance take on the same
criticality as with contact readers and one-dimensional bar code.

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Two-dimensional barcodes are already being used for concert tickets by
sending a barcode to a mobile phone and then scanning the message at the door
by a laser gun. In Japan, mobile phones are being adapted to scan two-
dimensional barcodes placed in magazines adverts. The barcode is scanned
and connects the mobile to the internet and shows the user the film clip or plays
the ring tones. Further developments in the lasers used to scan barcodes help
improve the efficiency and speed in which barcodes can be scanned.
Barcodes can be printed on durable materials and are not affected by substrate
materials or electromagnetic emissions, all of which lend them a competitive
edge in some industries and environments. Improvements in how barcodes are
printed are evolving all the time as manufacturers strengthen the barcode
system. Two-dimensional barcodes can be read even when damaged, so this
further shortens the gap between the two technologies. Developments in the
range at which barcodes can be scanned similarly reduce the apparent
performance gap between RFID and bar-coding.
It is questionable why there has been no significant research around these
developments that can purportedly improve the quality and performance of
existing systems.
1.2.6 Advantages of 2-DBarcode systems
2-D codes can store up to 7,089 characters (the 20-character capacity of a one-
dimensional barcode).

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1.3 Optical character recognition
Optical character recognition (OCR) was
first used in the 1960s. Special fonts were
developed for this application that stylized
characters so that they could be read both
in the normal way by people and
automatically by machines. The most important advantage of OCR systems is
the high density of information and the possibility of reading data visually in an
emergency (or simply for checking). Today, OCR is used in production, service
and administrative fields, and also in banks for the registration of cheques
(personal data, such as name and account number, is printed on the bottom line
of a cheque in OCR type). However, OCR systems have failed to become
universally applicable because of their high price and the complicated readers
that they require in comparison with other ID procedures.
1.4 Biometric procedures
Biometrics is defined as the science of
counting and (body) measurement procedures
involving living beings. In the context of
identification systems, biometry is the general
term for all procedures that identify people by
comparing unmistakable and individual
physical characteristics. In practice, these are
fingerprinting and hand printing procedures,
voice identification, less commonly, retina (or
iris) identification and, DNA. In order to being
able to recognize a person on base of its biometric features, these features first
have to be captured, processed and stored as reference sample.
The reference template such way formed of the biometric features is stored in a
data-base.
Figure 1.3: Course of the verification.

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1.4.1 Voice identification
Recently, specialized systems have
become available to identify
individuals using speaker
verification (speaker recognition).
In such systems, the user talks into
a micro-phone linked to a
computer. This equipment converts
the spoken words into digital
signals, which are evaluated by the
identification software. The
objective of speaker verification is to
check the supposed identity of the person based upon their voice. This is
achieved by checking the speech characteristics of the speaker against an
existing reference pattern. If they correspond, then a reaction can be initiated
(e.g. ‘open door’).
1.4.2 Fingerprinting procedures
Criminology has been using fingerprinting procedures for the identification of
criminals since the early twentieth century. This process is based upon the
comparison of papillae and dermal ridges of the fingertips, which can be
obtained not only from the finger itself, but also from objects that the
individual in question has touched.
When fingerprinting procedures are used for personal identification, usually for
entrance procedures, the fingertip is placed upon a special reader. The system
calculates a data record from the pattern it has read and compares this with a
stored reference pattern. Modern fingerprint ID systems require less than half a
second to recognize and check a fingerprint. In order to prevent violent frauds,
fingerprint ID systems have even been developed that can detect whether the
finger placed on the reader is that of a living person.
1.4.3 Applications of Biometric procedures
Biometric-based solutions are able to provide for confidential financial
transactions and personal data privacy. The need for biometrics can be found in
federal, state and local governments, in the military, and in commercial
applications.
Enterprise-wide network security infrastructures, government IDs, secure
electronic banking, investing and other financial transactions, retail sales, law
enforcement, and health and social services are already benefiting from these
technologies.

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An example of the
reverse side of a
typical credit card:
Green circle #1 labels
the Magnetic stripe
1.4.4 Advantages of Biometric procedures
Can provide extremely accurate, secured access to information; fingerprints,
retinal and iris scans produce absolutely unique data sets when done.
Automated biometric identification can be done very rapidly and uniformly,
with a minimum of training.
Your identity can be verified without resort to documents that may be stolen,
lost or altered.
1.4.5 Disadvantages of Biometric procedures
The finger prints of those people working in Chemical industries are often
affected. Therefore these companies should not use the finger print mode of
authentication.
It is found that with age, the voice of a person differs. Also when the person
has flu or throat infection the voice changes or if there are too much noise in
the environment this method may not authenticate correctly. Therefore this
method of verification is not workable all the time.
For people affected with diabetes, the eyes get affected resulting in differences.
Biometrics is an expensive security solution.
1.5 Magnetic stripe card
A magnetic stripe card is a type of card capable of
storing data by modifying the magnetism of tiny iron-
based magnetic particles on a band of magnetic
material on the card. The magnetic stripe, sometimes
called swipe card or magstripe, is read by swiping past
a magnetic reading head.
Magnetic recording on steel tape and wire was invented
during World War II for recording audio. In the 1950s,
magnetic recording of digital computer data on plastic
tape coated with iron oxide was invented. In 1960 IBM
used the magnetic tape idea to develop a reliable way
of securing magnetic stripes to plastic cards, under a
contract with the US government for a security system.
A number of International Organization for Standardization standards, ISO/IEC
7810, ISO/IEC 7811, ISO/IEC 7812, ISO/IEC 7813, ISO 8583, and ISO/IEC
4909, now define the physical properties of the card, including size, flexibility,
location of the magstripe, magnetic characteristics, and data formats. They also
provide the standards for financial cards, including the allocation of card
number ranges to different card issuing institutions.

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Figure 1.4: Visualization of magnetically stored information on a magnetic
stripe card (Recorded with CMOS-MagView).
1.5.1 The magnetic stripe
Initially IBM considered and rejected using bar
codes and perforations, because these methods
did not offer sufficient density of information
storage required for the credit cards. Magnetic
storage was already known from World War II
and computer data storage in the 1950s.
The process of attaching a magnetic stripe to a
plastic card was invented at IBM in 1960 under
a contract with the US government for a
security system.
There were a number of steps required to
convert the magnetic striped media into an industry acceptable device. These
steps included:
1) Creating the international standards for stripe record content, including
which information, in what format, and using which defining codes.
2) Field testing the proposed device and standards for market acceptance.
3) Developing the manufacturing steps needed to mass produce the large
number of cards required.
4) Adding stripe issue and acceptance capabilities to available equipment.
These steps were initially managed by Jerome Svigals of the Advanced
Systems Division of IBM, Los Gatos, California from 1966 to 1975.
In most magnetic stripe cards, the magnetic stripe is contained in a plastic-like
film. The magnetic stripe is located 0.223 inches (5.66 mm) from the edge of
the card, and is 0.375 inches (9.52 mm) wide. The magnetic stripe contains
The first prototype of
magnetic stripe card created
in IBM in 1960'. A stripe of
cellophane magnetic tape is
fixed to a piece of cardboard
with clear adhesive tape

P a g e | 1 - 10
three tracks, each 0.110 inches (2.79 mm) wide. Tracks one and three are
typically recorded at 210 bits per inch (8.27 bits per mm), while track two
typically has a recording density of 75 bits per inch (2.95 bits per mm). Each
track can either contain 7-bit alphanumeric characters, or 5-bit numeric
characters. Track 1 standards were created by the airlines industry (IATA).
Track 2 standards were created by the banking industry (ABA). Track 3
standards were created by the Thrift-Savings industry.
Magstripe following these specifications can typically be read by most point-
of-sale hardware, which are simply general-purpose computers that can be
programmed to perform specific tasks. Examples of cards adhering to these
standards include ATM cards, bank cards (credit and debit cards including
VISA and MasterCard), gift cards, loyalty cards, driver's licenses, telephone
cards, membership cards, electronic benefit transfer cards (e.g. food stamps),
and nearly any application in which value or secure information is not stored
on the card itself. Many video game and amusement centers now use debit card
systems based on magnetic stripe cards.
Magnetic stripe cloning can be detected by the implementation of magnetic
card reader heads and firmware that can read a signature of magnetic noise
permanently embedded in all magnetic stripes during the card production
process. This signature can be used in conjunction with common two factor
authentication schemes utilized in ATM, debit/retail point-of-sale and prepaid
card applications.
Counterexamples of cards which intentionally ignore ISO standards include
hotel key cards, most subway and bus cards, and some national prepaid calling
cards (such as for the country of Cyprus) in which the balance is stored and
maintained directly on the stripe and not retrieved from a remote database.
1.5.2 Magnetic stripe coercivity
Figure 1.5: Detailed visualization of magnetically stored
information on a magnetic stripe card (Recorded with CMOS-
MagView).

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Magstripes come in two main varieties: high-coercivity (HiCo) at 4000 Oersted
and low-coercivity (LoCo) at 300 Oersted but it is not infrequent to have
intermediate values at 2750 Oersted. High-coercivity Magstripes are harder to
erase, and therefore are appropriate for cards that are frequently used or that
need to have a long life. Low-coercivity Magstripes require a lower amount of
magnetic energy to record, and hence the card writers are much cheaper than
machines which are capable of recording high-coercivity Magstripes. A card
reader can read either type of magstripe, and a high-coercivity card writer may
write both high and low-coercivity cards (most have two settings, but writing a
LoCo card in HiCo may sometimes work), while a low-coercivity card writer
may write only low-coercivity cards.
In practical terms, usually low coercivity magnetic stripes are a light brown
color, and high coercivity stripes are nearly black; exceptions include a
proprietary silver-colored formulation on transparent American Express cards.
High coercivity stripes are resistant to damage from most magnets likely to be
owned by consumers. Low coercivity stripes are easily damaged by even a
brief contact with a magnetic purse strap or fastener. Because of this, virtually
all bank cards today are encoded on high coercivity stripes despite a slightly
higher per-unit cost.
Magnetic stripe cards are used in very high volumes in the mass transit sector,
replacing paper based tickets with either a directly applied magnetic slurry or
hot foil stripe. Slurry applied stripes are generally less expensive to produce
and are less resilient but are suitable for cards meant to be disposed after a few
uses.
1.5.3 How does a magnetic stripe on the back of a
credit card work?
The stripe on the back of a credit card is a
magnetic stripe, often called a magstripe. The
magstripe is made up of tiny iron-based magnetic
particles in a plastic-like film. Each particle is
really a very tiny bar magnet about 20 millionths
of an inch long.
The magstripe can be "written" because the tiny bar magnets can be
magnetized in either a north or South Pole direction. The magstripe on the back
of the card is very similar to a piece of cassette tape fastened to the back of a
card.
Instead of motors moving the tape so it can be read, your hands provides the
motion as you "swipe" a credit card through a reader or insert it in a reader at
the gas station pump.
Your card also has a magstripe
on the back and a place for your
all-important signature.

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1.6 Smart cards
A smart card is an electronic data storage
system, possibly with additional
computing capacity (microprocessor
card), which for convenience is
incorporated into a plastic card the size of
a credit card. The first smart cards in the
form of prepaid telephone smart cards
were launched in 1984. Smart cards are
placed in a reader, which makes a
galvanic connection to the contact surfaces of the smart card using contact
springs. The smart card is supplied with energy and a clock pulse from the
reader via the contact surfaces. Data transfer between the reader and the card
takes place using a bidirectional serial interface (I/O port). It is possible to
differentiate between two basic types of smart card based upon their internal
functionality: the memory card and the microprocessor card.
One of the primary advantages of the
smart card is the fact that the data
stored on it can be protected against
undesired (read) access and
manipulation. Smart cards make all
services that relate to information or
financial transactions simpler, safer
and cheaper. For this reason, 200
million smart cards were issued
worldwide in 1992. In1995 this figure
had risen to 600 million, of which 500
million were memory cards and100 million were microprocessor cards. The
smart card market therefore represents one of the fastest growing subsectors of
the microelectronics industry.
One disadvantage of contact-based
smart cards is the vulnerability of
the contacts to wear, corrosion and
dirt. Readers that are used
frequently are expensive to maintain
due to their tendency to
malfunction. In addition, readers
that are accessible to the public
(telephone boxes) cannot be
protected against vandalism.

P a g e | 1 - 13
1.6.1 Memory cards
In memory cards the
memory, usually an
EEPROM, is accessed using
a sequential logic (state
machine). It is also possible
to incorporate simple
security algorithms,
e.g. stream ciphering, using
this system. The
functionality of the memory
card in question is usually
optimized for a specific
application. Flexibility of
application is highly limited but, on the positive side, memory cards are very
cost effective. For this reason, memory cards are predominantly used in price
sensitive, large-scale applications. One example of this is the national insurance
card used by the state pension system in Germany.
1.6.2 Microprocessor cards
As the name suggests, microprocessor cards contain a microprocessor, which is
connected to a segmented memory (ROM, RAM and EEPROM segments).
The mask programmed ROM incorporates an operating system (higher
program code) for the microprocessor and is inserted during chip manufacture.
The contents of the ROM are determined during manufacturing, are identical
for all microchips from the same production batch, and cannot be overwritten.
The chip’s EEPROM contains application data and application-related program
code. Reading from or writing to this memory area is controlled by the
operating system.
The RAM is the
microprocessor’s temporary
working memory. Data stored in
the RAM are lost when the
supply voltage is disconnected
(Figure 1.6).
Microprocessor cards are very
flexible. In modern smart card
systems it is also possible to
integrate different applications in
a single card (multi-application).

P a g e | 1 - 14
The application-specific parts of the program are not loaded into the EEPROM
until after manufacture and can be initiated via the operating system.
Microprocessor cards are primarily used insecurity sensitive applications.
Examples are smart cards for GSM mobile phones and the new EC (electronic
cash) cards. The option of programming the microprocessor cards also
facilitates rapid adaptation to new applications.
1.7 Electronic Article Surveillance (EAS)
EAS are typically a one bit system used to sense the presence/absence of an
item. The large use for this technology is in retail stores where each item is
tagged and large antenna readers are placed at each exit of the store to detect
unauthorized removal of the item (theft).
These systems were the first form of RFID to be commercially available and
have been in use since the 1960’s.
Figure 1.6: Operating principle of the EAS radio frequency procedure.

P a g e | 1 - 15

HISTORY OF RFID Chapter 2
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2
HISTORY OF RFID
2.1 It All Started with IFF
By the 1930s, the primitive biplanes of fabric and wood that had populated the
skies above the battlefields of World War I had become all-metal monoplanes
capable of carrying thousands of kilograms of explosives and traveling at
hundreds of kilometers per hour: by the time observers could visually identify
an incoming flight, it was too late to respond. Detection of airplanes beyond
visual range was the task of microwave radar, also under rapid development in
the 30s, but mere detection of the presence of aircraft begged the key question:
whose side were they on? It was exactly this inability to identify aircraft that
enabled the mistaken assignment of incoming Japanese aircraft to an unrelated
United States bomber flight and so ensured surprise at Pearl Harbor in 1941.
The problem of identifying as well as detecting potentially hostile aircraft
challenged all combatants during World War II.
The Luftwaffe, the German air force, solved this problem initially using an
ingeniously simplemaneuver1. During engagements with German pilots at the
beginning of the war, the British noted that squadrons of fighters would
suddenly and simultaneously execute a roll for no apparent reason.
This curious behavior was eventually correlated with the interception of radio
signals from the ground. It became apparent that the Luftwaffe pilots, when
they received indication that they were being illuminated by their radar, would
roll in order to change the backscattered signal reflected from their airplanes
(Figure 2.1). The consequent modulation of the blips on the radar screen
allowed the German radar operators to identify these blips as friendly targets.
This is the first known example of the use of a passive backscatter radio link
for identification, a major topic of the remainder of this book. Passive refers to
the lack of a radio transmitter on the object being identified; the signal used to
communicate is a radio signal transmitted by the radar station and scattered
back to it by the object to be identified (in this case an airplane). As a means of
separating friend from foe, rolling an airplane was of limited utility: aircraft
can be rolled and no specific identifying information is provided. That is, the
system has problems with security and the size of the ID space (1 bit in this
case). More capable means of establishing the identity of radar targets were the
subject of active investigation during the 1930s.
The United States and Britain tested simple IFF systems using an active beacon
on the airplane (the XAE and Mark I, respectively) in 1937/1938. The Mark III
system, widely used by the Britain, the United States, and the Soviet Union

P a g e |2-2
during the war, used a mechanically tunable receiver and transmitter with six
possible identifying codes(i.e., the ID space had grown to 2.5 bits). By the mid-
1950s, the radar transponder still in general use in aviation today had arisen.
Modern transponders are interrogated by a pair of pulses at 1030 MHz, in the
ultra-high frequency (UHF) band about which we will have a lot more to say
shortly. The transponder replies at 1090 MHz with 12 pulses each containing1
bit of information, providing an ID space of 4096 possible codes. A mode C
transponders connected to the aircraft altimeter and also returns the current
altitude of the aircraft.
A mode-S transponder also allows messages to be sent to the transponder and
displayed for the pilot. Finally, the typical distance between the aircraft and the
radar is on the order of one to a few kilometers. Since it takes light about 3μs to
travel 1 km, the radar reflection from a target is substantially delayed relative to
the transmitted pulse, and that delay can be used to estimate the distance of the
object.
An aircraft transponder thus provides a number of functions of considerable
relevance to all our discussions in this book:
• Identification of an object using a radio signal without visual contact or clear
line of sight: radio-frequency identification.
• An ID space big enough to allow unique identification of the object.
• Linkage to a sensor to provide information about the state of the object
identified (in this case, the altitude above ground).
• Location of each object identified (angle and distance from the antenna).
• Transmission of relevant information from the interrogator to the transponder.
These functions encompass the basic requirements of most RFID systems
today: RFID has been around for a long time. However, for many years, wider
application of these ideas beyond aircraft IFF was limited by the cost and size
of the equipment required. The early military transponders barely fit into the
confined cabins of fighter airplanes, and even modern general aviation
transponders cost US$1000–5000.
In order to use radio signals to identify smaller, less-expensive objects than
airplanes, it was necessary to reduce the size, complexity, and cost of the
mechanism providing the identification.
The number of companies actively involved in the development and sale of
RFID systems indicates that this is a market that should be taken seriously.

P a g e |2-3
Whereas global sales of RFID systems were approximately 900 million $US in
the year 2000 it is estimated that this figure will reach 2650 million $US in
2005 (Krebs, n.d.).
Figure 2.1: The Use of Backscattered Radiation to Communicate with a Radar
Operator (not to scale!).
Furthermore, in recent years contactless identification has been developing into
an independent interdisciplinary field, which no longer fits into any of the
conventional pigeon holes. It brings together elements from extremely varied
fields: HF technology and EMC, semiconductor technology, data protection
and cryptography, telecommunications, manufacturing technology and many
related areas.
2.2 RFID TECHNOLOGY
Radio frequency identification (RFID) tags are poised to replace barcodes as
the tags of choice, but the replacement has been slow because of the inability to
bring tag cost down to 5 cent (US). While silicon die costs have been lowered
via die reduction, assembly cost for small dies need to be lowered
concomitantly. Although large-scale low cost tag assembly solutions have been
developed, they are not suited for adoption by conventional packaging house
because of their high capital investment. In this thesis, a low cost hybrid self-
alignment die assembly method suited for evolutionary migration was
developed. In this approach, small dies are firstly placed onto the substrate
using low cost robotic pick and place and fine self-align to nanometer accuracy
using low surface tension adhesive.
Design guidelines on the usage of adhesive liquid volume and oversized
binding sites were developed. Tag antenna manufacturing is another major cost

P a g e |2-4
factor. Coil antenna fabricated by printing conductive ink on plastic substrates
are recognized to be lower in assembly cost, but are lower in tag readability
and read range reproducibility. The effects of material, antenna line geometry,
and tag configuration on read range were examined in this study. Tag design
and selection criteria that can compensate for bent tag on cylindrical bottles or
soft packages were developed.
Experimental characterization of the tag behavior revealed the presence of an
antenna geometry-independent read range plateau. Tags designed to function in
the plateau regime enable the use of low precision high volume printing
techniques as fabrication processes to lower tag fabrication cost, without
sacrificing read range consistency. Tag performance can be further increased
using thick lined printed antennas and line compaction to reduce line
resistance. Tags fabricated using these new developed design and fabrication
methods were shown to have read ranges comparable to tags with metal wire
antennas.
Innovations on self-alignment die assembly and printed coil design made the
production scaling to high volume and low cost possible. The die assembly cost
can potentially be brought down to 0.25 cent (US) using hybrid self-alignment
at high volume.
The printed antenna cost, with the compaction process, can be reduced down to
1 cent (US). Using this new compacted printed antenna designed according to
the developed design guidelines and the demonstrated hybrid die assembly
technique developed in this thesis, the total manufacturing cost of a tag is
estimated to be 2.49 cent (US). The tag cost is below the 5 cent (US) threshold
tag cost such that the developed technologies can be adopted as a low cost
foundation for wide adoption of RFID in the marketplace.
2.3 Components of an RFID System
 The transponder, which is located on the object to be identified;
 The interrogator or reader, which, depending upon the design and the
technology used, may be a read or write/read device(in accordance with
normal colloquial usage the data capture device is always referred to as
the reader, regardless of whether it can only read data or is also capable
of writing).
A practical example is shown in Figure 2.2.
A reader typically contains a radio frequency module (transmitter and
receiver), a control unit and a coupling element to the transponder. In addition,
many readers are fitted with an additional interface (RS 232, RS 485, etc.) to
enable them to forward the data received to another system (PC, robot control
system, etc.).

P a g e |2-5
The transponder, which represents the actual data-carrying device of an RFID
system, normally consists of a coupling element and an electronic microchip.
Figure 2.2: An RFID system is always made up of two components.
2.4 Basic Operation
The reader, sometimes called an interrogator or scanner, sends and receives RF
data to and from the tag via antennas. A reader may have multiple antennas that
are responsible for sending and receiving radio waves. The data acquired by the
readers is then passed to a host computer, which may run specialist RFID
software or middleware to filter the data and route it to the correct application,
to be processed into useful information.
2.5 Different Types of RFID
There are several versions of RFID that operate at different radio frequencies.
Three primary
2.5.1 Frequency bands are being used for RFID:
 Low Frequency (125/134 KHz)Most commonly used for access
control, animal tracking and asset tracking.
 High Frequency (13.56 MHz)Used where medium data rate and read
ranges up to about 1.5 meters are acceptable. This frequency also has the

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advantage of not being susceptible to interference from the presence of
water or metals.
 Ultra High-Frequency (850 MHz to 950 MHz)Offer the longest read
ranges of up to approximately 3 meters and high reading speeds.
Applications for RFID within the supply chain can be found at multiple
frequencies and different RFID solutions may be required to meet the varying
needs of the marketplace. Since UHF (Ultra High Frequency) has the range to
cover portals and dock-doors it is gaining industry support as the choice
frequency for inventory tracking applications including pallets and cases.
2.5.2 RFID tags are further broken down into two
categories:
(a) Active RFID Tags are battery powered. They broadcast a signal to the
reader and can transmit over the greatest distances (>100 meters). They can be
used to track high value goods like vehicles and large containers of goods.
Shipboard containers are a good example of an active RFID tag application.
(b) Passive RFID Tags do not contain a battery. Instead, they draw their
power from the radio wave transmitted by the reader. The reader transmits a
low power radio signal through its antenna to the tag, which in turn receives it
through its own antenna to power the integrated circuit (chip).
The tag will briefly converse with the reader for verification and the exchange
of data. As a result, passive tags can transmit information over shorter distances
(typically 3 meters or less) than active tags. They have a smaller memory
capacity and are considerably lower in cost making them and ideal for tracking
lower cost items.
2.5.3 There are two basic types of chips available on
RFID tags, Read-Only &Read-Write:
Read only chips:are programmed with unique information stored on
them during the manufacturing process often referred to as a “number
plate” application.
o The information on read-only chips cannot be changed.
Read-Write chips:the user can add information to the tag or write over
existing information when the tag is within range of the reader.
o Read-Write chips are more expensive than Read Only chips.
Applications for these may include field service maintenance or “item attendant
data” where a maintenance record associated with a mechanical component is
stored and updated on a tag attached to the component.
Another method used is called a "WORM" chip (Write Once Read Many). It
can be written once and then becomes "Read only".

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2.6 Advantages of the Technology
The advantages of RFID can be broadly classified into the following two types:
 Current:These advantages are immediately realizable with the
technology products that exist today.
 Future:These advantages are either available in some form today or will
be available as improved features in the future as the technology
matures.
These are not official terminologies, but are used for the sake of convenience
and to aid in better understanding of a benefit. The following list covers both of
these advantage types, and the rest of this chapter describes how much benefit
is available today versus how much will be available in the future:
1. Contactless. An RFID tag can be read without any physical contact
between the tag and the reader.
2. Writable data. The data of a read-write (RW) RFID tag can be rewritten
a large number of times.
3. Absence of line of sight. A line of sight is generally not required for an
RFID reader to read an RFID tag.
4. Variety of read ranges. An RFID tag can have a read ranges as small as
few inches to as large as more than 100 feet.
5. Wide data-capacity range. An RFID tag can store from a few bytes of
data to virtually any amount of data.
6. Support for multiple tag reads. It is possible to use an RFID reader to
automatically read several RFID tags in its read zone within a short
period of time.
7. Rugged. RFID tags can sustain rough operational environment
conditions to a fair extent.
8. Perform smart tasks. Besides being a carrier and transmitter of data, an
RFID tag can be designed to perform other duties (for example,
measuring its surrounding conditions, such as temperature and pressure).
The following, although often touted as a benefit of RFID, is not considered an
advantage:
 Extreme read accuracy: RFID is 100 percent accurate.
The following sections discuss the previously listed advantages in detail.
2.6.1 Contactless
An RFID tag does not need to establish physical contact with the reader to
transmit its data, which proves advantageous from the following perspectives:

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 No wear and tear.Absence of physical contact means there is no wear
and tear on the readers as well as on the tags for reading and writing
data.
 No slowing down of operations.Existing operations do not have to
slow down to bear the extra overhead of bringing a reader physically
into contact with a tag. Establishing such a physical contact can
sometimes prove impossible. In a scenario in which tagged cases of
items are moving at a rapid speed on a conveyer belt, there is a high
chance that a reader will fail to maintain a physical contact with such a
moving box, resulting in a missed tag read. As a result, had RFID been
contact-based, it could not have been applied satisfactorily in a large
number of business applications (such as supply-chain applications and
so on).
 Automatic reading of several tags in a short period of time.Had
RFID been contact-based, the number of tags read by a reader would
have been limited by the number of tags it could touch at a particular
time. To increase this number, the reader's physical dimensions need to
be increased, resulting in a higher-cost, clumsy reader.
2.6.2 Writable Data
RW RFID tags that are currently available can be rewritten from 10,000 times
to 100,000 times or more! Although the use of these types of tags is currently
limited compared to write once, read many (WORM) tags, you can use these
tags in custom applications where, for example, time-stamped data about the
tagged object might need to be stored on the tag locally. This guarantees that
the data will be available even in absence of a back-end connection. In
addition, if a tag (that is currently attached to an object) can be recycled, the
original tag data can be overwritten with new data, thus allowing the tag to be
reused. Although writable tags might seem like an advantage, they are not
widely used today because of the following reasons:
 Business justification of tag recycling. Virtually all business cases that
involve tag recycling impact business operations. For example, the
following must be factored in: how tags are going to be collected from
the existing objects, when they are going to be collected, how these are
going to be re-introduced to the operations, additional resources and
overhead required, and so on. Unless the tag is active or semi-active and
is expensive, in most situations, generally, tag recycling does not make
business sense.
 Security issue. How can tags safeguard accidental and malicious
overwriting of data by valid and rogue readers when in use? If the
application is used outside an enterprise in an uncontrolled environment,
the security implications multiply many times. Even if such a tag is used

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within the four walls of an enterprise, the issue of security remains. To
satisfactorily address this issue, additional hardware, setup, and
processes might be necessary; this, in turn, can result in high
implementation costs that might prove unjustifiable. Currently, it seems
as if RW tags will continue to be used within the specific secure bounds
of an enterprise.
 Necessity of dynamic writes. If most of the RW tag applications are
going to be used mainly inside the four walls of an enterprise, there is a
high degree of probability of the presence of a network and the ability to
access the back-end system through this network. Therefore, using the
unique tag ID, the back end can store the data without any need to write
this data on the tag itself. Also, process changes can be made to handle
exceptional conditions when the network is down for example, generally
critical manufacturing facilities have two modes of operation, one
automatic and one manual so that if the automatic mode of operation
fails, the operators can switch to the manual mode without stopping
production lines.
 Slower operating speed. A tag write is often slower than a tag read
operation. Therefore, an application that does tag rewrites has a good
possibility of being slower compared to an application that does tag
reads only.
These issues might seem daunting to the reader. However, it is certainly
possible that some RFID applications exist for which using RW tags makes
good business as well as technical sense. An example of such an application is
monitoring the production quality control of a bottling operation for a medical
drug.
First, RW RFID tags are attached to empty bottles, which are then washed in
hot water and sanitizing solutions, dried, and subsequently go through a series
of steps before the drug is placed in these bottles and sealed. It is assumed that
the tags are sturdy enough to withstand the various processing steps. At each
processing step, the parameters of the process such as temperature, humidity,
and so on are written to the tags.
When the sealed bottles roll off the assembly line, their associated tag data is
automatically read by quality control systems. This way, any processing step
that fell short of the minimum requirements can be discovered, and the overall
quality of the bottling process can be quantized.
2.6.3 Absence of Line of Sight
The absence of line of sight is probably the most distinguishing feature of
RFID. An RFID reader can read a tag through obstructing materials that are
RF-lucent for the frequency used. For example, if a tag is placed inside a
cardboard box, a reader operating in UHF can read this tag even if this box is

P a g e |2-10
sealed on all the sides! This capacity proves useful for inspecting the content of
a container without opening it.
This feature of RFID has privacy rights infringement implications, however. If
a person is carrying some tagged items in a bag, an RFID reader can
(potentially) read the tagged item data without this person's consent. If this
person's personal information is associated with the tagged item data (at the
point of sale by the merchant, for example), it might be possible to access this
information (using a suitable application) without the person's consent or
knowledge, which might constitute a privacy rights infringement.
To prevent this, a reader should not read these tags after sale is completed
unless explicitly needed or authorized by the buyer. There are multiple ways to
achieve this objective Note that in some situations, a line of sight is needed to
help configure the tag read distance, reader energy, and reader antenna to
counter the environmental impact. These situations involve UHF tags and the
presence of a large amount of RF-reflecting materials, such as metal, in the
operating environment giving rise to multipath. For example, consider a
machinery tool production line where virtually everything is made of metal.
A large amount of RF energy from the readers installed in this environment
gets reflected from the objects in the environment. In this case, to achieve a
good read accuracy, a tag and a reader must be placed so that there is no
obstacle between them.This is a current advantage of RFID. It is possible that
future improvements in the technology can bypass some of the hurdles faced by
the presence of RF-opaque materials between the reader and the tag. Therefore,
this is a future benefit, too.
2.6.4 Variety of Read Ranges
A low-frequency (LF) passive RFID tag generally has a read distance of a few
inches; for a passive high-frequency (HF) tag, this distance is about 3 feet. The
reading distance of an ultra-high-frequency (UHF) passive tag is about 30 feet.
A UHF (for example, 433 MHz) active tag can be read at a distance of 300 feet
and an active tag in the gigahertz range can have a reading distance of more
than 100 feet.
These reading distances are usually realized under ideal conditions. Therefore,
the actual tag-reading distance of a real-world RFID system can be
substantially less than these numbers. For example, the reading distance of
13.56 MHz tags in general do not exceed a few inches. This wide array of
reading distances makes it possible to apply RFID to a wide variety of
applications. Whereas the LF read distance passive tags are ideally suited for
security, personnel identification, and electronic payments, to name a few, you
can use HF passive tags for smart-shelf applications; passive UHF for supply-

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chain applications, tracking, and many other types of applications; and, finally,
you can use passive tags in the microwave ranges for anti-counterfeiting.
You can use active and semi-active tags in these frequency ranges for tracking,
electronics toll payment, and almost limitless other possibilities. As you can
understand, RFID has virtually an unlimited spectrum of current and possible
applications.
Today, the tags for every frequency type are commercially available. In
addition, the location of an active or a passive tag can be associated with a
reader that reads this tag. Therefore, if a reader installed at a certain dock door
of a warehouse reads a tag in its read zone, the location of this tag can be
assumed to be this dock door at the time of reading.
This location information can then be made available through a private or
public (for example, Internet) network over a wide geographical area. As a
result, the tag can be tracked thousands of miles away from its actual location.
Future improvements of the technology will have limited impact on this aspect
because the entire range of reading distances is currently available using direct
(that is, a reader) and indirect (that is, a network) means. Hence, this feature is
a current advantage of RFID.
2.6.5 Wide Data-Capacity Range
A typical passive tag can contain a few bits to
hundreds of bits for data storage. Some passive tags
can carry even more data. For example, the ME-
Y2000 series (also known as coil-on chip) passive,
RW miniature tag from Maxell operating in the
13.56 MHz range can carry up to 4 K bytes of data
within its 2.5 mm x 2.5 mm space.
An active tag has no theoretical data-storage limit because the physical
dimensions and capabilities of an active tag are not limited, provided this tag is
deployable.
There are two approaches to use an RFID tag for an application. The first one
stores only a unique identification number on the tag, analogous to a "license
plate" of an automobile that uniquely identifies the tagged item; the second one
stores both a unique identification number and data related to the tagged object.
A large number of unique identifiers can be generated with a relatively small
number of bits. For example, using 96 bits, a total of 80,000 trillion trillion
unique identifiers can be generated so, a relatively small number of bits are
sufficient to tag virtually any type of object in the world. However, some
applications might choose to store additional data on a tag locally. The
advantage of storing this data locally is that no access to a networked database
is required to retrieve the object data using its unique identifier as a key, an

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advantage that proves useful if the tagged object is going to be moved around
in areas where the presence of network access to an object database is either
not available or undesirable.
Even when such a network connection is available, the associated application is
such that it must not be impacted by a network outage or delay. Therefore, one
of the benefits of storing data locally on the tags is that the resulting application
can be made largely independent of a back-end system. However, such a
scheme has drawbacks compared to a "license plate" type of approach. First,
data security needs to be addressed so that tag data can neither be accidentally
overwritten by a valid reader nor by a rogue reader intentionally.
The transmission time necessary for a high data capacity tag to transmit all its
data bits correctly to a reader can be several times more compared to just
transmitting the unique identifier. In addition, an increase in data transmission
leads to an increase in error rate of transmission. A high memory capacity tag
will be more expensive than the tags that can store only a unique identifier.
Therefore, just because it is available, using a high memory capacity tag in an
application does not seem like a good idea unless the application specifically
demands it (especially true for applications that have a hard time limit to
perform a specific task). An active tag, however, can use a large data-storage
capacity to support its custom tasks. A small amount of which, most probably
containing the results of these tasks, might end up getting transmitted by this
tag (which is perfectly acceptable because this data is dynamic and can only be
determined by the tag itself by scanning its environment
2.6.6 Support for Multiple Tag Reads
Support for multiple tag reads ranks as one of the most important benefits of
RFID. Using what is called an anti-collision algorithm, an RFID reader can
automatically read several tags in its read zone in a short period of time.
Generally, using this scheme a reader can uniquely identify a few to several
tags per second depending on the tag and the application.
This benefit allows the data from a collection of tagged objects, whether
stationary or in motion (within the reader limits), to be read by a reader, thus
obviating any need to read one tag at a time. Consider, for example, one of the
classic tasks of a financial institution: counting a stack of currency notes to
determine its total count and value.
Assuming these notes have proper RFID tags, the data from these currency tags
can be read using an RFID reader, which can then be used to determine the
total count and the value of the notes in aggregate in a very short period of
time, automatically. This method is much more efficient compared to the
traditional counting techniques.

P a g e |2-13
Now consider another classic example: loading a truck with cases of
merchandise at a shipping dock and receiving it at a receiving dock. Currently,
for these types of applications, either the boxes are not inventoried at all during
shipping time (they are, however, inventoried most of the time at the receiving
dock) or they are inventoried using bar codes (which is manual and time-
consuming).
As a result, business might lose a considerable amount of inventory annually
due to shrinkage or incur a high recurrent overhead in the cost of labor. If RFID
tags can be applied to the boxes before they are shipped, a stationary reader
placed near a loading truck can read all the boxes, automatically, when these
boxes are being loaded into this truck.
Thus, the business can have an accurate list of items being shipped to a
distributor or a retailer. In addition, significant labor costs were saved by
eliminating manual scanning of the labels, which would have been unavoidable
if a technology such as bar code had been used instead. The data collected from
these tags can be checked against the actual order to verify whether a box
should be loaded into this truck (thus reducing the number of invalid
shipments). As you can understand, this particular RFID advantage can speed
up and streamline existing business operations considerably.
Contrary to popular belief, a reader can communicate with only one tag in its
read zone at a time. If more than one tag attempts to communicate to the reader
at the same time, a tag collision occurs. A reader has to resolve this collision to
properly identify all the tags in its read zone. Therefore, a reader imposes rules
on communication so that only one tag can communicate to the reader at a
time, during which period the other tags must remain silent.
This is what constitutes an anti-collision algorithm Note that there is a
difference between reading a tag's data in response to an anti-collision
command versus reading a tag's data completely. In the former case, only
certain data bits of a tag are read; whereas in the latter, the complete set of data
bits of a particular tag are read. In addition, there is a theoretical as well as
practical limitation on how many tags can be identified by a reader within a
certain period of time.
2.6.7 Rugged
A passive RFID tag has few moving parts and can therefore be made to
withstand environmental conditions such as heat, humidity, corrosive
chemicals, mechanical vibration, and shock (to a fair degree). For example,
some passive tags can survive temperatures ranging from 40°F to 400°F (40° C
to 204°C). Generally, these tags are made depending on the operating
environment of a specific application. Today, no single tag can withstand all
these environmental conditions. An active and semi-active tag that has on-

P a g e |2-14
board electronics with a battery is generally more susceptible to damage
compared to a passive tag. A tag's ruggedness almost always increases its price.
This is a current benefit because tags with a variety of resistance to operating
environments are available. However, plenty of room exists for improvement,
and as the tag technology improves, it is expected that more tags will be
available that can better resist harsh environments than their present-day
counterparts. Therefore, this can also be called a future benefit.
2.6.8 Perform Smart Tasks
The on-board electronics and power supply of an active tag can be used to
perform specialized tasks such as monitoring its surrounding environment (for
example, detecting motion). The tag can then use this data to dynamically
determine other parameters and transmit this data to an available reader. For
example, suppose that an active tag is attached to a high-value item for theft
detection. Assume that this active tag has a built-in motion sensor. If someone
attempts to move the asset, the tag senses movement and starts broadcasting
this event into its surroundings.
A reader can receive this information and forward the information to a theft-
detection application, which in turn can sound an alarm to alert the personnel.
It might seem that by just taking off the tag from the asset and then putting the
tag back where it was (while taking the asset away) would fool the tag into
thinking that the asset is stationary again. However, it is possible for such a tag
to sense that it is no longer attached to the asset. The tag can then send another
type of broadcast message to signify this event.
2.6.9 Read Accuracy
In the media, the read accuracy of RFID is mentioned variously as "very
accurate," "100 percent accurate," and so on, but no objective study shows how
accurate RFID reads really are. It would definitely be desirable to back up such
accuracy statements with hard data, because no technology can offer 100
percent read accuracy in every operating environment all the time. Factors on
which RFID read accuracy depends include the following:
 Tag type. Which frequency tags are being used, the tag antenna design,
and so on can have a bearing on the read accuracy of an RFID system.
 Tagged object. The composition of the object, how it is packed, the
packing material, and so on play important roles in determining the
readability and hence the read accuracy. Also note that impact of this
factor depends on the frequency of the RFID system used.
 Operating environment. Interference from existing mobile equipment,
electrostatic discharge (ESD), the presence of metal and liquid bodies,
among other factors, can pose a problem for read accuracy in the UHF
and microwave frequencies.

P a g e |2-15
 Consistency. Tag orientation and placement relative to the reader
antennas can significantly impact read accuracy.
Another issue with RFID is what are called phantom reads or false reads. In
this situation, a random but seemingly valid tag data is recorded by the reader
for a brief period of time. After this time, the tag data can no longer be read by
the reader! The problem arises when a reader receives incorrect data from a tag,
which might happen for various reasons (such as a poorly constructed error-
correcting protocol).
Phantom reads are "bugs" in the supplier system. Incorrect installations might
also give rise to this phenomenon. In general, phantom reads are not an issue.
However, this shows that the objective determination of RFID accuracy is not
easy, that it depends on several factors. It is possible for the accuracy rates of
two identical RFID systems used in different environments to differ. It might
not always be possible to increase the read accuracy and degree of automation
of highly automated systems that are in existence today.
This is a current benefit because several applications generally do
showsufficient accuracy to meet business requirements. However, the read
accuracy of RFID has good potential to improve as improved tags, readers, and
antennas become available in the future. Therefore, this can also be called a
future benefit.
2.7 Disadvantages of the technology
1. Poor performance with RF-opaque and RF-absorbent objects. This is a
frequency-dependent behavior. The current technology does not work
well with these materials and, in some cases, fail completely.
2. Impacted by environmental factors. Surrounding conditions can greatly
impact RFID solutions.
3. Limitation on actual tag reads. A practical limit applies as to how many
tags can be read within a particular time.
4. Impacted by hardware interference. An RFID solution can be negatively
impacted if the hardware setup (for example, antenna placement and
orientation) is not done properly.
5. Limited penetrating power of the RF energy. Although RFID does not
need line of sight, there is a limit as to how deep the RF energy can
reach, even though RF-lucent objects.
6. Immature technology. Although it is good news that the RFID
technology is undergoing rapid changes,
those changes can spell inconvenience for the unwary.
The remainder of this chapter discusses these limitations in detail.

P a g e |2-16
2.7.1 Poor Performance with RF-Opaque and RF-
Absorbent Objects
If high UHF and microwave frequencies are used, and if the tagged object is
made of RF-opaque material such as metal, some type of RF-absorbent
material such as water, or if the object is packaged inside such RF-opaque
material, an RFID reader might partially or completely fail to read the tag data.
Custom tags are available that alleviate some of the read problems for
particular types of RF-opaque and RF-absorbent materials. In addition,
packaging can present problems if made of RF-opaque materials such as metal
foils.
It is expected that improvement in the tag technology will overcome several of
the current problems associated with RF-opaque/RF-absorbent objects.
2.7.2 Impacted by Environmental Factors
If the operations environment has large amounts of metal, liquids, and so on,
those might affect the read accuracy of the tags, depending on the frequency.
The reflection of reader antenna signals on RF-opaque objects causes what is
known as multipath. It is a safe bet in these types of environments to provide a
direct line of sight to the tags from a reader.
Although the tag reading distance, reader energy, and reader antenna
configuration are the major parameters that need to be configured in these cases
to counter the environmental impact, a line of sight helps to achieve this
configuration. In some cases, however, this might not be possible (for example,
in an operating environment where there is high human traffic). A human body
contains a large amount of water, which is RF-absorbent at high UHF and
microwave frequencies.
Therefore, when a person is in between a tag and a reader, there is a good
possibility that this reader cannot read the tag before this person moves away.
So, serious degradation of system performance might result. In addition, the
existence of almost any type of wireless network within the operating
environment can interfere with the reader operation. Electric motors and motor
controllers can also act as a source of noise that can impact a reader's
performance. Some older wireless LANs (WLANs) in the 900 MHz range can
interfere with the readers. This problem mostly exists in older facilities that
have not upgraded their WLAN equipment.
2.7.3 Limitations on Actual Tag Reads
The number of tags that a reader can identify uniquely per unit time (for
example, per second) is limited. For example, today, a reader on average can
uniquely identify a few to several tags per second. To achieve this number, this
reader has to read tags' responses several hundred times a second. Why?
Because the reader has to employ some kind of anti-collision algorithm to

P a g e |2-17
identify these tags; to identify a single tag, a reader has to walk down the range
of possible values.
Therefore, several readings of tag responses are required before a reader can
uniquely determine tag data. A limit applies as to how many such reads a
reader can perform within a unit time, which, in turn, dictates a limit on the
number of unique tags that can be identified within this same time period.
Improvement in the reader technology will undoubtedly increase the number of
tags that can be uniquely identified per unit time, but there will always be an
ultimate limit on this number that no reader will be able to exceed.
2.7.4 Impacted by Hardware Interference
RFID readers can exhibit reader collisionif improperly installed. A reader
collision happens when the coverage areas of two readers overlap and the
signal of one reader interferes with the other in this common coverage area.
This issue must be taken into account when an RFID installation plan is
worked out. Otherwise, degradation of system performance might take place.
This issue can be somewhat solved today by using what is known as time
division multiple access (TDMA). This technique instructs each reader to read
at different times rather than both reading at the same time. As a result, two
readers interfere with one another no longer.
However, a tag in the overlapping area of these two readers might be read
twice. Therefore, the RFID application must have an intelligent filtering
mechanism to eliminate duplicate tag reads. As RFID technology improves,
new solutions to this issue might become available.
2.7.5 Limited Penetrating Power of the RF Energy
The penetrating power of RF energy finally depends on the transmitter power
of the reader and duty cycle, which are regulated in several countries around
the world. For example, a reader might fail to read some cases on a pallet if
they are stacked too deep, even if these cases are all made of RF-lucent
material for the frequency used.
How many such cases can be put on a pallet for proper reading? You can only
determine the answer to this question by experimenting with actual boxes
stacked on an actual pallet in the actual operating environment using actual
RFID hardware. This number will also vary from country to country,
depending on the restriction of reader power and duty cycle. Therefore, the
answer needs to be determined experimentally; it is very difficult, if not
impossible, to determine it theoretically.

Radio frequency identification by rfid project team . faculty of electronic engineering . communication department. menoufia university [combined and uploaded by a member of the team ( mohammed ali )]

Radio frequency identification by rfid project team . faculty of electronic engineering . communication department. menoufia university [combined and uploaded by a member of the team ( mohammed ali )]

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