What is RFID?
Radio Frequency Identification (RFID) is an advanced identification
technology. It uses radio-frequency waves to identify, detect, track
and sort variety of objects including people, garments, pallets,
containers and vehicles. It can be used in applications such as
Proximity access control,
time-and-attendance management, vehicle identification,
laundry/textile identification, asset tracking, inventory control
and factory automation.
RFID relies on radio frequency or
"waves" between a card or tag and a reader in order to
make an identification. Because RFID
is a "contactless" technology, it requires neither
contact with a reader or a direct line
of sight to a reader (as does bar code technology).
RFID, therefore, reduces the problems
associated with those "contact" or "line-of-sight"
technologies. For instance, a "good"
read can occur through sunlight, wet, cold (-30°C ), frost, dirt,
grease, and many corrosive chemicals.
How Does RFID
An RFID system consists of
components--the Reader, the antenna and the card/tag. They work
together to provide the end user with a non-contact solution to
uniquely identify people, animals or objects.
The reader performs several functions, one of which is to produce a low-level
radio frequency magnetic field. The RF magnetic field emanates from
the reader by means of a transmitting antenna, typically in the form
of a coil. The magnetic field serves as a "carrier" of power from
the reader to the RFID card or tag.
The RFID card or tag contains an antenna, also in the form of a coil and an integrated
circuit (IC). The IC requires a small amount of electrical power in
order to function. The antenna in the tag provides a means for
gathering the energy present in the magnetic field produced by the
reader and converts it to an electrical form of energy for use by
the IC. When a card or tag is brought into the magnetic field
produced by the reader, the converted energy powers the IC. This
enables the transmission of the IC's memory contents in the form of
an electromagnetic signal to the reader via the tag's antenna.
The tag information is received by an antenna within the reader and converted back into an
electrical form. The reader contains a sensitive receiving system
that is designed to detect and process the tag signal. Once the tag
data has been processed, a microcomputer within the reader checks to
verify that the signal received is valid.
Once the reader has checked and
validated the received data, the data is then decoded and
restructured for transmission to the end-user's host computer. This
restructuring provides the data in both an electrical form and a
protocol (or format) that is required by the host computer system.
Once the restructuring process is complete, the data is transmitted
to the host system.
RFID Tag consists of a microchip attached to an antenna that is
packaged in a way that can be applied to an object.
The tag picks up signals from and
sends signals to a reader. The tag contains a unique serial number,
but may have memory to store applicable information also. RFID Tag
can be Active or Passive depending on the application requirement.
The microchip antenna is the conductive element that enables the
microchip to send and receive data. Readers also have antennas which
are used to emit and receive radio waves.
This is the device used to communicate with RFID microchips. The
reader has one or more antennas, which emit radio waves and receive
signals back from the tags. The reader is also called as
interrogator because it “interrogates” the signals from the
microchip. The reader is equipped with appropriate software to
transform raw data into actionable information.
Benefits of RFID
RFID benefits the user similarly to other automatic identification
technologies in that it
reduces the need to collect data by
cumbersome means like paper and pencil. Often the amount of data to
be collected is so overwhelming and the time needed to process the
information is so long that the only practical method of collecting
the data is automatically with computer technology.
Automatic data acquisition improves
the value of the information in a system by making the information
available sooner. In a manufacturing facility the value of finding
out that work in process has been misrouted is valuable if
discovered quickly. Unlike the barcode, RFID enable the auto
identification of items, without the need to place the barcode label
in front of the reader. RFID solves this problem by wirelessly
transmitting the identification information of the items to the
reader. No line of sight is required.
Automatic data acquisition
Speeding distribution throughout
entire supply chain
No line-of-sight nature
Tag can be read through snow, fog,
More reliable tracking
Operating frequency is the determining
factor for the type of application an RFID system is best suited
for. These frequencies include high frequency (850-950 MHz and 2.4-5
GHz), intermediate frequency (10-15 MHz) and low frequency (100-500
RFID systems are suitable for
applications requiring a longer read range such as supply chain,
inventory, assembly lines, toll-collection systems and railroad car
and intermodal container tracking.
RFID systems are just now beginning to
emerge in the financial transaction processing areas of smart card
RFID systems are used for applications
requiring shorter read ranges. These include access control, work in
process tracking and asset management. As you move up in frequency,
you not only receive an increase in passive read range but also an
increase in the speed at which the device can operate. Longer range
tags in the hundreds of MHz and GHz are measured in yards and miles.
Lower frequency tags in the
125 kHz and 13.56 MHz range have read
ranges measured in inches and feet. Application requirements for
minimum read range, cost ceilings, speed of operation and
communications complexity drive the decision as to which frequencies
RFID VS. BARCODE
Unlike barcode, RFID can be read
simultaneously. RFID can read up to hundreds of items in a
single read compared to a single item per read in barcode.
RFID does not require a “line of
sight”. There is no need to place the barcode label in front of
the reader. RFID can be embedded inside the product itself.
Unlike barcode, RFID is very
difficult to copy and is ideal for confidential identification
of products, people or assets.
RFID tags and readers have no
moving parts so the system rarely needs maintenance and can
operate for extended periods of time.
RFID is ideal for dirty, oily, wet
or harsh environments.
RFID is fast: The tag and reader
communicate in virtually milliseconds. Actual throughput depends
on communication with the host computer, but the total speed of
a good read is 30 to 100 milliseconds on a read only tag.
There are six key characteristics of RFID that affect the
communication between a tag and reader: Range, Range Adjustment,
Propagation, Directionality, Multi-Tag Collection and Memory.
Range is defined as the maximum distance for successful Tag-Reader
communication. Read range difference will vary and can be
very-short, short, or long.
Very Short Range:
approx. up to 60cm (2 ft)
Short Range: approx.
up to 5 m (16 ft)
Long Range: approx.
100+ m (320+ ft)
Range Adjustment will also play a role in RFID tag read
functionality. Range adjustment is the ability to adjust range and
is categorized as very good or poor. Very good range adjustment can
be fine-tuned to a specific distance. Tag-Reader communication is
guaranteed within the specified range and tag-reader communication
outside the range is impossible. Whereas poor range adjustment
cannot be adjusted well at all. When there is a signal fall-off
pattern or a reflection, tag-reader communication in the physical
area is not guaranteed.
Propagation is the ability to perform tag-reader communication
through or around objects and material. With very good propagation,
the radio frequency can penetrate through objects allowing
successful communication between tag and reader. Plus, very good
propagation allows for penetration through water, liquids and human
tissue and may even go through metal. Whereas poor propagation works
on in line-of-sight and any obstacle such as a wall, people or
vehicles between the tag and reader will prevent any successful
Directionality is the ability to achieve directional RF coverage
using directional antennas. There are two types of directionality:
Omni-directional and Directional. Omni-directional coverage has
similar RF coverage in all directions. With directional coverage,
the RF coverage is much stronger in one specific direction.
Multi-tag collection is the ability to quickly and reliably
collect large number of tags within a designated area.
Memory is key in RFID communication — it determines the read
only, read/write, or write once read many capabilities in the
tag-reader communication. Some tags have small memory size at 16
bits and others have larger memory with 512 KBytes or more.
Active vs. Passive
RFID tags are categorized as either active or passive. Active RFID
tags typically have both read and write capabilities so tag data can
be rewritten and/or modified. Active RFID tags can transmit specific
data or instructions to a reader (where the tag has been or
important information about the items in the container). A passive
tag can not actively send information — it is read only. Plus,
active tags are powered by an internal battery which gives them a
longer read range.
Passive RFID tags operate without a separate external power source
and obtain operating power generated from the reader. They have
shorter read ranges than active tags and require a higher-powered
reader. Read-only tags are typically passive and are programmed with
a unique set of data (usually 32 to 128 bits) that cannot be
modified. Passive tags are lighter, have smaller form factors and
are less expensive then the more powerful active tags.
Active and Passive RFID are two fundamentally different
technologies, each with unique advantages. While often considered
competing technologies, they actually complement each other,
balancing cost and capability. Active and Passive RFID offer
tremendous potential for combined use within many applications,
including air cargo and intermodal cargo management. Along with
technical performance and regulatory issues, this opportunity for
combined use must also be considered when selecting a frequency for