An object tracking system is provided for tracking the removal of objects from a location and the replacement of the objects at the location. The system includes a radio frequency identification (RFID) tag attached to each of the objects to be tracked and each tag has an antenna. When activated, the...http://www.google.de/patents/US6204764?utm_source=gb-gplus-sharePatent US6204764 - Object tracking system with non-contact object detection and identification
