Electronics Design and Manufacture
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What is RFID.RFID is short for Radio Frequency Identification. Generally a RFID system consists of 2 parts. A Reader,
and one or more Transponders, also known as Tags. RFID systems evolved from barcode labels as a
means to automatically identify and track products and people. You will be generally familiar with RFID
systems as seen in:
How do RFIDs work.Shown below is a typical RFID system. In every RFID system the transponder Tags contain information.
This information can be as little as a single binary bit , or be a large array of bits representing such things
as an identity code, personal medical information, or literally any type of information that can be stored in
digital binary format.
Shown is a RFID transceiver that communicates with a passive Tag. Passive tags have no power source of
their own and instead derive power from the incident electromagnetic field. Commonly the heart of each tag
is a microchip. When the Tag enters the generated RF field it is able to draw enough power from the field to
access its internal memory and transmit its stored information.
When the transponder Tag draws power in this way the resultant interaction of the RF fields causes the voltage
at the transceiver antenna to drop in value. This effect is utilized by the Tag to communicate its information to
the reader. The Tag is able to control the amount of power drawn from the field and by doing so it can modulate
the voltage sensed at the Transceiver according to the bit pattern it wishes to transmit.
Types of RFID Transponders.There are three types of Transponders. Tags are either Active, Passive, or Semi-passive Transponders.
As already mentioned, Passive Transponders have no internal power source. They draw their power from the
electromagnetic field generated by the RFID reader. They have no active transmitter and rely on altering the
RF field from the transceiver in a way that the reader can detect.
Active transponders have their own transmitters and power source, usually in the form of a small battery. As a
result of this they are able to be detected at a greater range than Passive ones. Active Tags remain in a low
power "idle" state until they detect the presence of the RF field being sent by the Reader. When the Tag
leaves the area of the Reader it again powers down to its idle state to conserve its battery.
Semi-Passive Transponders have their own power source that powers the microchip only. They have no
transmitter and as with Passive tags they rely on altering the RF field from the Transceiver to transmit their
Designing a RFID system.Priority 1 Design have a range of RFID products available to those wishing to design and construct their own
RFID systems, We also carry RFID modules for OEM users wanting to quickly incorporate existing products
into their own design. Custom designed systems can also be tailor made to suit your individual requirements.
Contact our design department to find out how.