A basic
RFID system consist of three components:
• An antenna or coil
• A transceiver (with decoder)
• A transponder (RF tag) electronically programmed with unique information
The antenna emits radio signals to activate the tag and read and write
data to it. Antennas are the conduits between the tag and the transceiver,
which controls the system's data acquisition and communication. Antennas
are available in a variety of shapes and sizes; they can be built into
a door frame to receive tag data from persons or things passing through
the door, or mounted on an interstate toll booth to monitor traffic passing
by on a freeway. The electromagnetic field produced by an antenna can
be constantly present when multiple tags are expected continually. If
constant interrogation is not required, the field can be activated by
a sensor device.
Often the antenna is packaged with the transceiver and decoder to become
a reader (a.k.a. interrogator), which can be configured either as a handheld
or a fixed-mount device. The reader emits radio waves in ranges of anywhere
from one inch to 100 feet or more, depending upon its power output and
the radio frequency used. When an RFID tag passes through the electromagnetic
zone, it detects the reader's activation signal. The reader decodes the
data encoded in the tag's integrated circuit (silicon chip) and the data
is passed to the host computer for processing. Back
to top.
RFID tags come in a wide variety of shapes and sizes. Animal tracking
tags, inserted beneath the skin, can be as small as a pencil lead in diameter
and one-half inch in length. Tags can be screw-shaped to identify trees
or wooden items, or credit-card shaped for use in access applications.
The anti-theft hard plastic tags attached to merchandise in stores are
RFID tags. In addition, heavy-duty 5- by 4- by 2-inch rectangular transponders
used to track intermodal containers or heavy machinery, trucks, and railroad
cars for maintenance and tracking applications are RFID tags.
RFID tags are categorized as either active or passive. Active RFID tags
are powered by an internal battery and are typically read/write, i.e.,
tag data can be rewritten and/or modified. An active tag's memory size
varies according to application requirements; some systems operate with
up to 1MB of memory. In a typical read/write RFID work-in-process system,
a tag might give a machine a set of instructions, and the machine would
then report its performance to the tag. This encoded data would then become
part of the tagged part's history. The battery-supplied power of an active
tag generally gives it a longer read range. The trade off is greater size,
greater cost, and a limited operational life (which may yield a maximum
of 10 years, depending upon operating temperatures and battery type).
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Passive RFID tags operate without a separate external power source and
obtain operating power generated from the reader. Passive tags are consequently
much lighter than active tags, less expensive, and offer a virtually unlimited
operational lifetime. The trade off is that 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. Read-only tags most often operate
as a license plate into a database, in the same way as linear barcodes
reference a database containing modifiable product-specific information.
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RFID systems are also distinguished by their frequency ranges. Low-frequency
(30 KHz to 500 KHz) systems have short reading ranges and lower system
costs. They are most commonly used in security access, asset tracking,
and animal identification applications. High-frequency (850 MHz to 950
MHz and 2.4 GHz to 2.5 GHz) systems, offering long read ranges (greater
than 90 feet) and high reading speeds, are used for such applications
as railroad car tracking and automated toll collection. However, the higher
performance of high-frequency RFID systems incurs higher system costs.
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The significant advantage of all types of RFID systems is the noncontact,
non-line-of-sight nature of the technology. Tags can be read through a
variety of substances such as snow, fog, ice, paint, crusted grime, and
other visually and environmentally challenging conditions, where barcodes
or other optically read technologies would be useless. RFID tags can also
be read in challenging circumstances at remarkable speeds, in most cases
responding in less than 100 milliseconds. The read/write capability of
an active RFID system is also a significant advantage in interactive applications
such as work-in-process or maintenance tracking. Though it is a costlier
technology (compared with barcode), RFID has become indispensable for
a wide range of automated data collection and identification applications
that would not be possible otherwise. Back
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Developments in RFID technology continue to yield larger memory capacities,
wider reading ranges, and faster processing. It is highly unlikely that
the technology will ultimately replace barcode — even with the inevitable
reduction in raw materials coupled with economies of scale, the integrated
circuit in an RF tag will never be as cost-effective as a barcode label.
However, RFID will continue to grow in its established niches where barcode
or other optical technologies are not effective. If some standards commonality
is achieved - whereby RFID equipment from different manufacturers can
be used interchangeably - the market will very likely grow exponentially.
Radio Frequency Identification
(RFID) — A Basic Primer
A 17-page basic overview from AIM--The Global Association for Automatic
Identification and Mobility.
Download any of white papers
on radio frequency identification (RFID) and topics related to the use of
RFID technology, courtesy of Zebra Technologies:
Gen
2 Implications for Smart Label Printing
This white paper explains the implications of the EPCglobal Gen 2 RFID
standard on smart label printing. It will illustrate the need to support
multiple RFID protocols, cover considerations for upgrading installed
printer/encoders to support Gen 2, and explain how options and variables
within the standard create needs for specific features in printer/encoders. Download (PDF, 82 KB)
Zebra's RFID Readiness Guide: Complying
with RFID Tagging Mandates
This white paper provides the straight information and guidance needed
not only to successfully plan and implement a compliance tagging program,
but to make RFID work for your business too.
Download (PDF, 468 KB)
Bar Coding and RFID: The Key to Traceability
and Safety in the Foodservice Supply Chain
Learn how ADC technologies can deliver needed traceability to the foodservice
industry. Download (PDF,
418 KB)
Increasing Profits and Productivity: Accurate
Asset Tracking and Management with Bar Coding and RFID This paper shows how bar code and RFID can be applied to streamline
many common asset management procedures and includes worksheets to help
calculate the business impact and ROI that improved asset management can
provide. Download (PDF,
408 KB)
Enterprise-Wide Data Collection and Bar
Code Printing for Superior Supply Chain Management
Learn today how your business can reduce errors and costs as it improves
productivity and customer satisfaction with bar code and RFID applications.
Download (PDF,
92 KB)
