Patent ID: 7511621

Claim:
In a radio frequency tag system for operating within a carrier frequency band above 900 megahertz containing a carrier frequency above 900 megahertz which produces an electromagnetic field, said radio frequency tag system comprising: (a) a transmitter system for transmitting radio frequency electromagnetic energy in the carrier frequency band above 900 megahertz containing said carrier frequency above 900 megahertz so as to produce the electromagnetic field; and (b) a radio frequency tag for receiving power from the electromagnetic field, said radio frequency tag comprising tag circuitry; (c) said radio frequency tag comprising an antenna configuration that is substantially resonant at the carrier frequency band above 900 megahertz and is excited by the electromagnetic field to cause an induced current to be present at antenna terminals of the antenna configuration; and (d) said antenna configuration developing sufficient power to operate said tag circuitry in the absence of transmitted electromagnetic energy for at least fifty microseconds.