Wave pickup in the form of a printed coil for an electronic portable

Abstract

The portable object comprises a circuit on a double-sided printed circuit with a coil etched on the printed circuit, the coil comprising a plurality of alternating turns etched on each of the faces of the card, with each turn being an open turn connected at each end by means of a respective via passing through the card to the corresponding adjacent end of the next turn disposed on the opposite face of the card, the successive turns thus being connected in series in alternating and concentric manner by means of a set of vias. According to the invention, on a first face of the card, the curvilinear extents of the facing terminal regions of the turns extend beyond the midline between the ends of the turns so as to cause said terminal regions to be interdigitated in alternation, while on the opposite face of the card, the curvilinear extents of the facing terminal regions of the turns are limited so as to leave an empty gap extending approximately radially, the through connection vias being located outside said empty gap along the sides thereof, the card also having at least one etched conductor track interconnecting a point situated inside the coil and a point situated outside the coil, the track passing along the empty gap.