Radiofrequency transponder device with passive optimised resonant circuit

摘要

The device has a passive antenna (34) that is tuned or intended to be tuned in frequency with a transponder. The transponder has an integrated circuit chip linked to an antenna interface defining an electromagnetic coupling surface periphery. The antenna comprises a main loop formed of an external turn and an internal turn (33) comprising surface portions inside the loop. U-, V- or C-shaped recesses (R, R2) of the loop are oriented from the interior to the exterior of the loop. The surface portions are located in the recesses to effect an electromagnetic coupling with a transponder circuit. The recesses are positioned in line with a subscriber identity module (SIM) constituting a radiofrequency or near field communication (NFC)transponder.