| 摘要 |
An electromagnetic detection system comprising transmission unit for producing in at least one first detection zone an electromagnetic interrogation field. The system includes a plurality of responders having attachment element for attachment to articles to be protected, each including a resonant circuit and when present in a detection zone, in response to the interrogation field, producing a signal. The system further includes a first detection adapted to detect a responder and, on detection of a responder, to produce a warning signal. According to the invention, the responders are designed in such a manner that when the attachment elements are removed or when a responder is damaged, at least one frequency determining parameter of the responder is changed in a predetermined manner. At least one second detection zone is provided wherein responders with the at least one changed frequency determining parameter can be detected.
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