MDE-3664B TRIND® Start-up, Service, and Parts Manual · June 2013
Page A-1
Overview
Appendix A - Radio Frequency Identification Defined
Appendix A - Radio Frequency Identification Defined
Overview
The information in this appendix was obtained from Association for Automatic
Identification and Mobility (AIM).
IMPORTANT INFORMATION
A basic RFID system consists of three components:
1. An antenna or coil.
2. A transmitter/receiver.
3. A tag that is 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, a sensor device can activate the
field.
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 1 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.
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 5X4X2-inch rectangular transponder 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 1 MB 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).