Introduction

Radio Frequency IDentification (RFID), is a generic term for technologies that use radio waves to automatically identify objects. There are several methods of identification like: bar codes, optical character readers or some biometric technologies, such as retinal scans, but the most common is to store a serial number that identifies the object, and perhaps other information, on a microchip that is attached to an antenna. These technologies are used to reduce the amount of time and labour needed to input data manually and to improve data accuracy.

Advantages of RFID systems over barcodes:
· It is not necessary to have a line of sight between the RFID tag and the reader as there is with a barcode and scanner.
· Information can be rewritten to the tag without having to see the tag. This is true even if the tag is mixed into other items that have been tagged.
· Nearly 100% of RFID tags are readable, unlike items that contain a printed barcode, which can become damaged with improper handling.
· The potential problems associated with substandard print quality of barcodes, which in turn leads to scanning and reading problems, are eliminated.
Other points to consider:
· Barcodes are universally accepted because they are very inexpensive and there are established standards for their use. RFID technology is more expensive and has fewer universal standards in the way they are used.
· Even if RFID technology becomes as widespread as barcoding, it will not totally replace the universally accepted barcode technology
 

Components of an RFID installation

Basically an RFID system is a communication between a reader and a transponder (tag) at a defined frequency as other radio communication.

An RFID system has basically four components: TAGS, READERS, ANTENNAS and CONTROLLER.

A READER (also called interrogator) which can both read and write information from or onto a tag.
The reader is the device that actually sends out the radio waves to create a magnetic field. A passive RFID tag draws its power from this magnetic field, which powers the circuits in the microchip allowing it to transmit data back to the reader.

The CONTROLLER tells the reader, what, when, and for how long to read tags. It collects and processes tag information in order to be use in advanced systems.

The ANTENNA is a coil of copper wire wound design specifically to emit RFID signals. The antenna allows the chip to transmit information to a reader, which also has an antenna.

The TAG (or transponder) is a memory device, usually EEPROM, programmed with a series of bits with built in antenna to receive and transmit data. The basic types of RFID tags can be classified as read/write and read only. The data stored on read/write tags can be edited, added to, or completely rewritten, but only if the tag is within the range of the reader. The data stored on a read only tag can be read, but cannot be edited in any way. Read/write tags are much more expensive than read only tags, so they are not used for tracking most commodity items.
Tags can also be categorised as:
· Active tags, which contain a battery that powers the microchip and allows it to transmit a signal to the reader.
· Semi-active (or semi-passive) tags, which contain a battery to run the circuitry of the chip, but must draw power from the magnetic field created by the reader in order to communicate with the reader.
· Passive tags, which rely solely on the magnetic field created by the radio waves sent out by the reader to create a current that can be received by the antenna within the passive tag.