A contactless chip card intended to communicate with a chip card reader operating at a first resonant frequency includes a booster antenna provided with an inductive main antenna and with an inductive concentrator antenna, which antennae are connected in series or parallel with a capacitor. The inductances of the inductive main antenna and the inductive concentrator antenna and the capacitance of the capacitor are chosen on the one hand to obtain a second resonant frequency that is far enough from the frequency of the signal emitted by the reader to limit radiofrequency communication with the reader, and on the other hand so that the connection in parallel of a predetermined capacitance brings the resonant frequency of the card into the vicinity of said first resonant frequency of the signal emitted by said reader.