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Radio Frequency Identification

Radiofrequency identification (RFID) is an identification system that uses radio waves to send data and RFID tags or transponders. The first patented RFID device was a passive radio transponder with an integrated memory by Mario Cardullo. At present, the technology has many applications, particularly in the retail industry because of its small size, low power demands, and high levels of efficiency offered. The application of RFID is seen as the next generation of barcode technology currently in use.

RFID antenna

Types of RFID Tags

RFID tags or transponders come in two variants. The earlier variant of RFID tags is inductively coupled. It comprises a microprocessor made of silicon, a coil of metal that acts as an antenna, and glass or polymer covering. This type of RFID tag did not gain much attention from the retail market because they were too expensive.

The latter version of RFID tags is capacitively coupled; it was developed to make RFID technology more affordable. Each capacitively coupled RFID tag comprises a microprocessor made of silicon, carbon ink (this is conductive) that serves as the antenna, and a paper substrate to which the chip is attached the ink is printed. The small and relatively inexpensive materials used in production significantly lowered the price of each RFID tag. They have also made the tags more durable (tags capacitively coupled could work even when they are crumpled). The lower price comes at the cost of range, however. RFID tags of this type are limited to working within a few inches of the reader.

How RFID Tags Work

Passive RFID tags work in generally the same way, regardless of type. A reader sends out a radio frequency signal that gives just enough energy to activate the tag’s integrated circuit. Once the reader has activated the tag, it begins communicating with the latter. The tag modulates and changes the field (or backscatters the signal being sent out) to transfer data between it and the reader.

Active RFID tags work similarly with one exception: they are equipped with their own power source. Active RFID tags actively send out a signal to be picked up by the reader. Active RFID tags are larger than passive tags and have a larger operation range, higher transmission power, better reliability, and longer product life.

Commercial Interest

Research and development by several different entities are still ongoing to develop a cheaper and more effective passive RFID chip. Meanwhile, RFID tags are widely regarded as the next step after barcode technology to track and inventory items. Wal-Mart, for instance, intends to invest in RFID technology.

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