Transponder with overlapping coil antennas on a common core

摘要

A wireless device includes an antenna assembly, including a core (36) and one or more power coils (24,26,28), wound around the core on respective power coil axes, including at least a first power coil having a first power coil axis. One or more signal coils are wound around the core on respective signal coil axes, including at least a first signal coil (30) wound so as to overlap the first power coil, the first signal coil having a first signal coil axis that is substantially parallel to the first power coil axis. Power circuitry (38) is coupled to the power coils so as to receive therefrom first radio signals in a first frequency band, and to rectify the first radio signals so as to generate a direct current. Communication circuitry (40), powered by the direct current, is coupled to perform at least one of transmitting and receiving second radio signals in a second frequency band via the signal coils.