A radio frequency transponder includes at least one battery, which is coupled to provide electrical power for operating the transponder and at least one antenna, which is configured to receive and backscatter RF interrogation radiation from an interrogation device. An integrated circuit is arranged to...http://www.google.ca/patents/US20090045916?utm_source=gb-gplus-sharePatent US20090045916 - Battery-assisted backscatter RFID transponder
