RFID

RFID (Radio Frequency IDentification) is a wireless system used to identify tags. These tags may be carried by people or animals or mounted on object or vehicles. They may even be embedded under the skin.

RFID tags are non-contact and non-line-of-sight. This means that you don't have to "swipe" your card for an RFID system to identify you.

Passive RFID vs. Active RFID

Passive RFID tags operate using power from the RFID transceiver. Passive tags are small and inexpensive, but do not have good range.

Active RFID tags are powered, usually by a battery. Active tags are larger and more expensive, but offer a much better identification range.

RFID tags store data, which is typically used for authentication. Passive tags typically store between 32 and 128 bits of data; Active tags can store up to 1MB of data.

Passive tags are Read-Only; Active tags are typically rewritable.

RFID Usage

Passive RFID tags are used in retail Electronic Article Surveillance (EAS) system to reduce shoplifting. These are the little white tags you find attached to clothing items and hidden in the pages of books. Most of the EAS systems are manufactured by Checkpoint Systems or Sensormatic.

Passive tags are also utilized for animal tracking and anywhere else where power is not available and tag cost is more critical than range.

RFID Frequencies

RFID systems operate across a wide range of frequencies. Lower frequency systems are less expensive; higher frequency systems offer increased range. For RFID purposes, 300-500Khz are considered low frequencies, 850-900MHz and 2.4GHz-2.5Ghz are considered frequencies.

RFID systems used to automatically pay highway tolls are high frequency systems.

Additional Reading on RFID

For more information, read Radio Frequency Identification - RFID: A basic primer.

The RFID Case Study Book is an excellent guide to real-world applications of RFID technology.

There is also a free RFID e-Learning Course which you may find interesting.