Radio Frequency IDentification (RFID)

Radio Frequency Identification (RFID) is the application of radio waves to read and capture information stored on tags affixed to objects. RFID readers are installed at tracking points and can read information from tags when they come into range, which can be of several feet radius. A tag need not be within direct line-of-sight of the reader to be tracked. RFID is used to check identities and track inventory, assets and people. RFID tags can be attached to a variety of objects like cash, clothing, baggage, parcels, and even implanted in animals and people.

Working Principle

There are two parts in a RFID system−

  • a tag or label

  • a reader

RFID tags are affixed on the object and have a transmitter and a receiver embedded on it. It contains the serial number that uniquely identifies a specific object. The tags have two parts−

  • a microchip to store and process information, and

  • an antenna to receive and transmit a signal.

The RFID reader (also called interrogator) captures the information encoded on the tag using an antenna. It is a two-way radio transmitter-receiver that emits a signal for the tag. The tag responds by sending the information embedded in its memory. The reader captures the results and transmits to the RFID computer program, which then performs the necessary processing.

Types of RFID tags

RFID tags are categorized into three types according to power−

  • Passive tags− They use the radio wave energy of the reader to transmit its ID to the reader.

  • Active tags− They are equipped with an on-board battery and transmit their ID periodically.

  • Battery – assisted Passive− They have a small battery on-board and are activated only within the range of an RFID reader.

According to readability, RFID tags are as follows−

  • Read-only tags− They have a factory-assigned ID which serves as a key into a database.

  • Read/write tags− In these tags, object-specific data can be written and retrieved by the system user.

  • Field programmable tags− These are written once by the system, thereby they can be read multiple times.

  • Blank tags− They may be electronically written by the user.

Types of RFID readers

RFID readers are categorized into two types according to power−p>

  • Passive readers− They can only receive signals from active tags.

  • Active readers− They can transmits interrogator signals to both passive, active as well as battery-assisted tags and also receives replies from them.

According to position, RFID readers are of two types−

  • Fixed readers− They are used to create a highly defined and tightly controlled interrogation area. Tags are read when they enter this area. Active readers are deployed here.

  • Mobile readers− They are used for creating handheld tag reading devices. They may be also installed in moving vehicles.