RFID tags found to work better in building ducts

Researchers say RFID tags could work with temperature and other sensors to reduce a building's wiring costs

A research team at North Carolina State University used a building ventilation duct to help signals from passive RFID tags travel at least three times farther than they normally travel over open space.

The discovery means that a small, inexpensive RFID tag could be used to wirelessly transmit data from any temperature sensor, smoke detector, carbon monoxide monitor or sensors that detect things like chemical, biological or radiological agents in a large building, according to Dan Stancil, one of the main researchers and head of the university's Department of Electrical and Computer Engineering.

Stancil told R&D magazine that using the RFID tags with electronic sensors could be "immediately economically viable" because it would mean wiring would not be needed to connect a building's various sensors, saving money on both the wiring itself and the labor necessary to install it.

The research will be published in the September issue of Proceedings of the IEEE, according to a synopsis in R&D Magazine.

The university team found that metal ducts for heating, ventilation and air conditioning systems act as electromagnetic waveguides to greatly increase the communication range of UHF RFID tags, enabling them to propagate signals about three to six times as far as they can over free space. The tags emitted a radio signal picked up by an RFID reader at the other end of a 30-meter piece of ductwork, the team found. Most UHF RFID tags typically propagate only five to 10 meters over open spaces.

The team studied passive RFID tags, which are activated by a signal from an RFID reader. Active RFID tags, in comparison, regularly emit signals and must have their own sources of power.

In North America, UHF RFID systems operate in the 902-948 MHz band.

Matt Hamblen covers mobile and wireless, smartphones and other handhelds, and wireless networking for Computerworld. Follow Matt on Twitter at @matthamblen, or subscribe to Matt's RSS feed. His e-mail address is mhamblen@computerworld.com.

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