| 摘要 |
A widely accepted type of antipilferage system provides in an interrogation zone a magnetic field which periodically alternates at a predetermined frequency. Such systems further include means for detecting very high order harmonics of the predetermined frequency such as result from the presence within the zone of a marker having nonlinear electrical or magnetic properties. In the present invention, such a marker includes an asymmetrically shaped plece or pieces of low-coercive force ferromagnetic material, including a center section and flux concentrator sections at opposite ends of the center section. Such a marker enables the protection of objects having a maximum dimension which is less than the length of prior art "open-strip" markers. |
