What is RFID?

RFID, or Radio Frequency Identification Device, is a technology that incorporates the use of electromagnetic or electrostatic coupling in radio frequency. RFID is sometimes called Dedicated Short Range Communication (DSRC). It is an automatic identification technology which uses wireless radio communications to uniquely identify objects, animals, or persons. RFID is coming into increasing use in industry as an alternative to the bar code. The advantage of RFID is that it does not require direct contact or line-of-sight scanning.

How does RFID work?

A RFID system consists of three components: an antenna, a transceiver (often combined into one reader) and a transponder (the tag). The antenna uses radio frequency waves to submit a signal that activates the transponder. When activated, the tag transmits data back to the antenna. The data is used to notify a programmable logic controller that an action should occur. The action could be as simple as raising an access gate or as complicated as interfacing with a database to carry out a monetary transaction. Low-frequency RFID systems (30KHz to 500KHz) have short transmission ranges, generally less than six feet. High-frequency RFID systems (850MHz to 950MHz and 2.4GHz to 2.5GHz) offer longer transmission ranges (more than 90 feet). DOMINANT Semiconductors produces High Frequency tags (13.56MHz), Ultra High Frequency (UHF) passive tags which are from 860 MHz to 950 MHz and microwave tag (2.45GHz).

There are two types of tags, and therefore two types of systems; active and passive. A passive tag is briefly activated by the radio frequency scan of the reader. The electrical current is small, generally just enough for transmission of an ID number. In an active tag, a battery in the tag is used to boost the effective operating range of the tag and to offer additional features over passive tags such as temperature sensing. The radio waves that are sent back and forth between tag and transmitter contain data in the tag, and this data is converted by the reader and transferred into a computer system.