Networked RF tag for tracking people by means of loyalty cards

A system and associated tag for detecting and tracking people makes use of a low radio frequency detection tag. Each tag comprises an antenna operate at a at a low radio frequency not exceeding 1 megahertz, a transceiver connected to the tag's antenna operable to transmit and receive data signals at low radio frequency, a data storage for storing the tag identification data, a data processor operable to process data received from the transceiver and the data storage device and causes the transceiver to emit an identification signal based upon the stored identification data, and an energy source to supply power for the operation of the tag's transceiver and data processor. The tag also includes a display operable to display data relating to the tag and to a person carrying said tag. A field antenna is used with a reader, a transmitter and a central data processor to provide communication between the tags and the central data processor.