Lasered-on antenna make RFID tags rugged

Sept. 14, 2006
New radio-frequency identification tags coming out of Switzerland eliminate antenna patterns made with foil.

The Harting RFID tags can take on various forms including a beer keg plug and a bolt-on transponder for carriers and containers. The tags are a liquid-crystal polymer, which has a low dielectric constant and a high heat-deflection temperature.

Instead they use a laser-structured metal coating that produces 3D conductive patterns on an inner cavity of a tag carrier made of thermoplastic. The cavity is sealed via ultrasonic welding to IP54 or IP67 levels.

The RFID tags work in the UHF range and can employ various antenna patterns such as dipoles, inverted F, or patch, depending on available space in the tag. Tag maker Harting Mitronics AG says the typical range for the passive tags is over 16 ft. They also work in close proximity to metals and liquids, says Harting.

The body of the tags is a liquid-crystal polymer (LCP) that can handle temperatures up to 180°C and has a dielectric constant of about 3. The material gets its name from its molecular structure of long, rigid backbones with flexible ends.

When extruded, the rigid rods align in the flow direction, and the polymer takes on some crystalline properties. These properties make LCP a candidate substrate for UHF circuits

The new transponder also won the 2006 Hermes Award given by Deutsche Messe AG for pioneering technology.

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