There are many different types of
radio frequency identification technology. This article explains the
difference between active and passive tags and between low-, high- and
ultra-high frequency systems.
frequency identification is the next wave in the evolution of
computing. Essentially, itís a
technology that connects objects to Internet, so they can be tracked,
and companies can share data about them.
The concept is simple : Place a
transponder Ė a microchip with an antenna Ė on an item and then use a
reader Ė a device with one or more antennas Ė to
read data off of the microchip using radio waves. The reader passes the
information to a computer, so that the data can be used to create
There are many different types of RFID systems, and
installing them and using them to generate data that can be used to cut
costs or boost efficiency is challenging. Itís important to choose the
right type of RFID system for a particular application. Itís also
important to work with an experienced systems integrator
to make sure the system is installed and configured
The purpose of this article is to introduce you to the basics of RFID
technology. We present a lot of technical information. Itís not critical
that you grasp it alt. Understanding the major differences between the
various types of systems will help you choose the right systems
integrator and work with the integrator to choose the right RFID
technology for your needs.
The vast majority of RFID tags or transponders (the tags are often used
interchangeably) use a silicon microchip to store a unique serial number
and usually some additional information (for information on systems that
donít use microchips, see our FAQs).
There are two broad
categories of RFID systems Ė
Passive and Active systems.
Passive RFID tags do not have
a transmitter; they simply reflect back energy (radio waves) coming from
the reader antenna. Active tags have their own transmitter and a power
source, usually Ė but not always Ė a battery (active tags could draw
energy from the sun or other sources). They broadcast a signal to
transmit the information stored on the microchip. (There are also
semi-passive and battery-assisted).
Active RFID systems
Active tags used on large assets, such as cargo containers, rail cars
and large reusable containers, which need to be tracked over long
distances (in a
distribution yard, for example).
operate at 455 MHz, 2.45 GHz, or 5.8 GHz, and
they typically have a read range of 60 feet to
300 feet (20 meters to 100 meters).
Broadly speaking, there are two types
of active tags:
Active transponders are woken up when they receive a signal
from a reader. These are used in toll payment collection, checkpoint
control and other systems. When a car with an active transponder
approaches a tollbooth, a reader at the booth sends out a signal that
wakes up the transponder on the car windshield. The transponder then
broadcasts it unique ID to the reader.
Transponders conserve battery life by having the
tag broadcast its signal only when it is within
range of a
Beacons are used in most real-time locating systems (RTLS), where the
precise location of an asset needs to be tracked. In an RTLS, a beacon
emits a signal with its unique identifier at pre-set intervals (it could
be every three seconds or once a day, depending on how important it is
to know the location of an asset at a particular moment in time).
The beaconís signal is picked up by at
least three reader antennas positioned around
the perimeter of the area where assets are being
tracked. RTLS are usually used outside, say, in a distribution yard (see
Logistics Gets Cheaper by the Yard), but automakers use the systems in
large manufacturing facilities to track parts bins (see RFID Revs Up