What is RFID ?

Radio Frequency Identification or RFID is not a new technology, but until the relatively recent past was to expensive to apply except in niche markets. Over the last decade, developments in the manufacture of RFID components and the increasing market demand have led to a large reduction in costs opening RFID up to a much wider range of applications than have been possible before.

A current simple RFID system consists of an interrogating device and a transponder. The interrogator sends out a radio signal at a specific frequency, the transponder transforms the radio signal it receives into electrical energy that it then uses to send back its identification to the interrogator. The interrogating device is known as an RFID reader or scanner and the transponder is known as an RFID tag.

The RFID tag described above is known as a passive tag as it cannot send out its identification without first being activated by the RFID reader. Active RFID tags have a built in battery, they work in the same way as a passive tag, but as more power is available they can transmit a stronger signal back to the reader, thus increasing the range at which they can be read.

The simplest RFID tags have only a unique identification number that can be sent back to the RFID reader. Tags are available that have on board read/write memory that can be modified by a suitable RFID reader. Tags are available in hundreds of shapes and sizes to suit a wide variety of applications. Likewise, there are many RFID readers available from those only able to read a tag identifier at short range to longer range readers which can update the memory on board a tag or read multiple tags at a time.