RF ID Introduction

RFID technology is a means of identifying a unique object or a person using a radio frequency transmission. This emerging technology is not new in fact; it is currently being used, in numerous applications throughout the world. Originally, implemented during World War II to identify and authenticate allied planes, this was known as Friend or Foe. RFID is still being used today for the same purposes.

The main component of this technology is the transponder/tag1, which in most cases comprises of a chip and antenna mounted onto a substrate or an enclosure. The chip consists of a processor, memory and radio transmitter. These transponders communicate via radio frequency to a reader, which has its own antennas. The readers can interface through wired or wireless medium to a main computer. Transponders are also known as smart or radio tags. The memory will vary, depending on the manufacturer, from just a few characters to kilobytes.

Transponders can either be Read Only (R/O) which are pre-programmed with a unique identification or they can be Read Write (R/W) for applications that require data to be stored in the transponder and can be updated dynamically. Another form of transponder is Write Once Read Many times (WORM). This will allow for an identification number to be written to the transponder once. The information is stored in the memory, it cannot be changed but the transponder can be read many times.

The two most common types of RFID technologies are Active and Passive. Active RFID transponders are self powered and tend to be more expensive than Passive. Having power on board allows the tag to have greater communication
distance and usually larger memory capacity. The most common application for Active RFID is for highway tolls such as the Highway 407 in Toronto
.
As for Passive RFID transponders, which are available with chips and without chips, they have no internal power source therefore require external power to operate. The transponder is powered by an electromagnetic signal that is
transmitted from a reader. The signal received will charge an internal capacitor on the transponder, which in turn will then supply the power required to communicate with the reader.