The invention concerns a terminal generating a high-frequency electromagnetic field by means of an oscillating circuit, adapted to co-operate with at least a transponder when the latter enters said field, comprising means (37) for regulating the phase of the signal in the oscillating circuit with respect to a reference value, and means for detecting, on the basis of a current measurement in the oscillating circuit and a voltage measurement at the terminals of a capacitive element (31) of said oscillating circuit, an electric signature of a transponder.