Radio frequency identification (RFID) is a method of identifying, locating and tracking objects, animals and even human beings using radio frequency transmissions. An RFID system consists of a transceiver or tag -- a small microchip with an antenna, capable of transmitting and receiving radio frequency signals -- a scanning device or reader and a database.
Uses
RFID transceivers can be attached to individual products, cartons or pallets for the purposes of asset management, inventory control -- raw materials, work in progress and finished goods -- and supply chain management, thereby improving performance and reducing waste. They can similarly be embedded in identification badges to provide hands-free access to secure areas or implanted beneath the skin of pets, such as cats and dogs, so they can be returned to their owners if they are lost.
Passive
Passive RFID transceivers remain mute until they receive a signal from a reader. The simplest form of RFID transceiver has a microchip that contains just a single binary digit, or "bit", which can be switched on or off; this type of transceiver, known as an electronic surveillance tag, is used to prevent shoplifting in retail outlets. Another type of passive RFID transceiver contains a unique numerical code, or serial number, which is used to reference further information about the tagged item from a database. Passive RFID transceivers are typically smaller and less expensive than active RFID transceivers.
Active
Active RFID transceivers, on the other hand, have their own power source -- in the form of small batteries -- and are capable of transmitting stronger radio frequency signals over longer distances than their passive counterparts. The principal difference between active and passive RFID transceivers, however, is active transceivers broadcast signals of their own accord, without needing to be energized by an RFID reader first. In some cases, the exact, three-dimensional position of an active RFID transceiver can be determined by a process known as triangulation.
Semi-active
Semi-active, or semi-passive, RFID transceivers need to be energized by a reader before transmitting, but, like active RFID transceivers, contain a battery. The purpose of the battery can be either to strengthen the radio frequency signal in difficult environments -- the presence of large metal objects and other sources of interference -- or to power a sensor. The sensor collects data even when the RFID transceiver itself is inactive and transmits it to the reader when the transceiver is read.
Tags: RFID transceivers, RFID transceiver, active RFID, radio frequency, active RFID transceivers, capable transmitting, frequency signals
