Abstract: A transmitter produces a magnetic alternating field having a predetermined frequency. A receiver is provided with a detector which is able to detect predetermined higher harmonics of the frequency of the alternating field. A transponder includes a signal element made of soft magnetic material. When the transponder is placed in the magnetic alternating field, higher harmonics of the frequency of the alternating field are generated by the signal element. The signal element is in the form of a ring.

Abstract: A detection tag for a resonance detection system. A resonance circuit is supported on an electrically insulative support, and includes and inductive track in a predefined pattern and a capacitive element with capacitor electrodes separated from each other by the support and connected to the respective ends of the inductive track. An electroconductive island is provided on the first side of the support with one of the capacitor electrodes, and is separated from that capacitor electrode by a discharge gap distance, and is also separated from the capacitor electrode on the other side of the support.