How does RFID work?

A RFID tag consists of a microchip and a coiled antenna.

RFID tags may be either active or passive.  Active tags tend to be larger and more expensive than passive tags as they contain more electronics due to the fact that they actively transmit data to a reader. 

In comparison, passive tags draw power from the magnetic field generated between itself and a reader to power its microchip’s circuits, allowing it to reflect the RF signal transmitted to them from a reader, adding information by modulating the reflected signal. 

Tags can also be either read-only, volatile read/write, or write one/read many.

In order for communication to occur between a tag and a reader, they must be tuned to the same frequency.  RFID systems can be configured to operate in a variety of frequencies from low to ultra-high frequency (UHF) or even microwave.  Being that RF propagation is different at different frequencies due to power and wave form properties, RFID system configuration must be considered in accordance with the applications that the system is designed to support.  For example, low frequency tags are a good choice for applications in which the distance between tag and reader is small (typically less than a foot) as apposed to UHF, which supports applications at greater distances (up to about 20 feet).

Data gathered for purposes of processing information for and about the tagged RFID item/object may include:

• Description (EPC)
• Time
• Location
• Physical parameters (temperature, pressure, humidity, etc.)