Electronically detectable and deactivatable tag and electronic security system with such a tag

A resonant tag circuit with at least one resonant frequency operates in an electronic security system in which the tag circuit is detected and electronically deactivated in order to destroy the resonant characteristics of the tag circuit at the detection frequency. The tag circuit is designed with capacitor plates 10, 12, 22, 24 which are located closer to one another at a selected point 20, 32. In this way, a breakdown mechanism is brought about in the resonant structure of the tag. A deactivation circuit provides electromagnetic energy at a resonant frequency of the tag circuit with sufficient energy to cause electrical breakdown at the selected point 20, 32. In this way, the tag circuit is deactivated by bringing about vaporization of a conductive area or a short circuit between the capacitor plates to destroy the resonant properties of the circuit. <IMAGE>