Patent ID: 8026819

Claim:
A system for detection and tracking of entities, said system comprising: a) a low frequency radio tag, carried by each of the entities, said tag comprising: (i) a tag communication antenna, operable at a first radio frequency not exceeding one megahertz; (ii) a transceiver, operatively connected to said tag communication antenna, said transceiver being operable to transmit and receive data signals at said first radio frequency; (iii) a data storage device, operable to store data comprising identification data for identifying said low frequency radio tag; (iv) a programmed data processor, operable to process data received from said transceiver and said data storage device, and to send data to cause said transceiver to emit an identification signal based upon said identification data stored in said data storage device; and (v) an energy source for activating said transceiver and said data processor, said energy source comprising a tag energization antenna operable to receive radio frequency energy from an ambient radio frequency field of a second radio frequency; b) at least one field communication antenna disposed within a distance from each entity that permits effective communication therewith at said first radio frequency; c) a reader, in operative communication with said field communication antenna, said reader being operable to receive data signals from said low frequency radio tags; d) a transmitter in operative communication with said field antenna, said transmitter being operable to send data signals to said low frequency radio tags; e) a central data processor in operative communication with said reader and transmitter; and f) a field energization antenna operable to produce said ambient radio frequency at the tag energization antenna of said tag.