2-3
Chapter 2
Theory of Operation
This chapter provides the theory of operation for radio frequency
identification (RFID) systems and describes Amtech
®
RFID technology.
Overview of RFID Theory
The term radio frequency, or RF, describes the electromagnetic waves in the 10-kHz
to 10-GHz range. Television, cellular phones, two-way radios, and radar are among
the common technologies using RF energy. Many automatic door-opening systems
are also RF based.
Electronic identification (EID) systems automatically transfer data from an object to
the user’s data management system, usually through an optical (barcode or laser),
magnetic, or RF link. Radio frequency identification (RFID) provides the benefits of
optical and magnetic systems, while overcoming many of their limitations.
Components
The primary components of a RFID system are
• Readers (scanners, interrogators) that process the signal returned by the tag, and
send the tag message to a host computer or control system.
• RF sources (transmitters/receivers) that generate and send out a radio signal to the
tag and preprocess the signal returned from the tag.
• Antennas that transmit the RF signal into the environment and retrieve the
reflected signal from the tag.
• Tags (transponders) that carry unique codes and are attached to objects to be
identified.
An RFID system can include readers, RF modules, antennas, tags, and software,
usually under the control of a host computer (Figure 2-1). Various additional
equipment, such as vehicle detectors, gates, and lights, can be included in the system.
Software can be included in a system, usually to process the data gathered from the
tags.
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