University Team Up-Ends The RFID Metal Problem By Turning The Metal <i>Into</i> The Antenna

One of the historic problems with RFID has been its difficulty in being read on metal or near liquids. A creative research team at North Dakota State University announced last week (February 2) an approach to turn the metal of the product into a functional antenna. It doesn't avoid the metal problem. But it is judo-like in turning the problem around. The big downside for retail, though, is that each of these passive tags will cost 50 cents to one dollar.

The tags are 2 to 2.5 millimeters each, but Research Engineer Cherish Bauer-Reich said her group thinks they can get it down to 1 millimeter. "The tags we've developed actually use the metal container as an antenna, rather than having to make and place another antenna on top of the container," said Bauer-Reich. "Many types of tags have to be spaced away from metal, since it changes the electromagnetic fields around the tags and destroys their ability to communicate. These tags, however, use the metal container as the antenna to transmit information. Because of this unique property, these tags can be used to tag anything from coffee cans at a grocery store to barrels of oil or metal cargo containers, with minimal concern about losing or damaging the tag." She added that their tag's high-permeability materials divert current into the tag's integrated circuit.