RFID Signals Travel Farther in Air Ducts

Researchers have discovered that ventilation ducts at least triple the distance that radio waves from passive RFID tags can travel inside a building.

The discovery could lead to a new breed of building sensors that use RFID tags to wirelessly transmit data to central monitoring systems without the expense of running wires throughout a building, according to a statement by North Carolina State University.

The wireless sensors could replace today's climate-control systems that use wired thermostats. In addition, the development opens the door to RFID-based smoke detectors, carbon monoxide monitors, or sensors that detect chemical, biological or radiological agents, according to Dan Stancil, head of the university's Department of Electrical and Computer Engineering.

Stancil's research team found that air ducts act as electromagnetic waveguides that boost the communication range of UHF (ultrahigh frequency) radio frequency identification tags. The tags emitted a radio signal that could be picked up by an RFID reader at the opposite end of a 30-meter piece of ductwork; the typical range of an RFID signal over open space is 5 to 10 meters.

This story was originally published in Computerworld's print edition. It was adapted from an earlier version that first appeared on Computerworld.com.

Copyright © 2010 IDG Communications, Inc.

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