Electronic entity having an RFID transponder

An electronic entity comprising a transponder, which entity is intended to communicate with an external reader at a first determined frequency and comprises a body (11) provided with a cavity and, in this cavity, a transponder comprising a carrier having a plane and (12A) bearing, connected to one another, an antenna (13) formed from at least one turn following the contour of the carrier and a microcircuit (14), plates made of a conductive material (15A, 15B) being formed on each of these sides facing one another so as to form a capacitor connected in parallel with the antenna, and the body comprising, at least approximately at the level of this cavity, an annular metal zone (16) having an inner contour, the projection of which into the plane of the carrier surrounds said carrier and which is capable of concentrating field lines toward the interior of the turn, the capacitor defining, with the antenna and the microcircuit, a resonant circuit resonating at a second frequency that is substantially equal to the first frequency, the plates of the capacitor (15A, 15B) covering 60% to 90% of the surface delimited by the one or more turns of the antenna.