ENVIRONMENTALLY SENSITIVE MULTI-FREQUENCY ANTENNA

摘要

A transponder is secured to a substrate (20) with a temperature sensitive adhesive (30). A pair of tabs (16, 18) acts as a first antenna to allow the transponder to respond to interrogation at a first frequency, and a slot (22) in the substrate acts as a second antenna to allow the transponder to respond to interrogation at a second frequency. When the transponder is secured to the substrate with the temperature sensitive adhesive, the transponder only operates at the second frequency. The temperature sensitive adhesive melts when exposed to a temperature above a predetermined threshold, causing the transponder to decouple from the slot and operate at the first frequency. An alternate embodiment functions similarly for pressure sensing.