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A n I n t ro d u c t i o n t o R F I D Te c h n o l o g y
What is RFID?
In general terms, Radio Frequency Identification (RFID) is a means of identifying a
person or object based on the use of radio frequencies, i.e. electromagnetic waves that
have a wavelength suited for use in radio communication.
RFID technology uses radio frequencies to read information on devices known as tags
that can be fixed to or embedded into virtually any object, and these tags either reflect or
retransmit the radio-frequency signal. Flat, lower cost versions (or labels) with embedded
ultra-thin RFID tags are usually called smart labels. RFID tags and labels are often called
`smart' because of the flexibility provided by the silicon chips embedded into them. In
most cases, the tag/label can be programmed and/or reprogrammed in the field, so the
same tag/label can be reused to serve multiple functions in a given application. Hence
the tag/label is not static like a barcode label; instead it is dynamic in its performance
capability. (For the sake of clarity and brevity, tags and labels will usually be referred to
just as `tags' in this report.)
How does it work?
A RFID system will consist of two basic parts a reader and the tags.The reader per-
forms several functions, one of which is to produce a radio frequency magnetic field by
means of an antenna.This field provides the power necessary to activate the RFID tag. In
the case of passive tags (without an internal battery) the inbuilt antenna gathers the ener-
gy present in the magnetic field and converts it to the electrical energy which powers
the embedded integrated circuit.Thus, the memory contents of the circuit (the tag infor-
mation) are transmitted by the tag's antenna.The electromagnetic signal from the tag is
picked up by an antenna within the reader and then converted back into an electrical
form.The reader's electronics further process the tag's signal, demodulating the original
data stored in the tag memory. Once this data has been demodulated, a microcomputer
within the reader can perform error checking and data validation, along with further
decoding and restructuring for transmission in the format required by the host computer
system. In the case of active RFID tags, a miniature battery provides the power supply
for the integrated circuit.When interrogated by the reader, this circuit broadcasts a signal
that identifies itself to sensitive reader detection and data transmission circuits.This allows
the active tag to broadcast its data at a considerably greater distance than its passive coun-
Smart Labels
and Smart Tags