Apparatus for high-frequency near-field communication and for inductively recharging a portable electronic device

A device for high-frequency near-field communication and for the inductive charging of a portable electronic apparatus, the device comprising, firstly for charging, a charging surface for supporting the portable electronic apparatus and at least one charging emitter antenna arranged underneath the charging surface and emitting a magnetic field at a low frequency selected between 30 and 300 kHz, a layer of ferromagnetic material being arranged below said at least one charging antenna, and, secondly for communication, at least one near-field communication antenna emitting a magnetic field at a high frequency between 3 MHz and 30 MHz, the device comprising a printed circuit board for monitoring and controlling charging and/or communication and at least one electric power source for said at least one charging antenna and for said at least one communication antenna, said at least one communication antenna being in the form of at least one communication coil arranged such that part of the field created by said at least one communication coil passes through the layer of ferromagnetic material having a permeability comprising a real part (Par r) and an imaginary part (Par i), the material of the layer of ferromagnetic material being selected so as to have a real part (Par r) greater than 10 with, at the selected high frequency, a ratio between the imaginary part (Par i) and the real part (Par r) between 0.05 and 1 and, at the selected low frequency, a ratio between the imaginary part (Par i) and the real part (Par r) between 0 and 0.5, said device comprising:

• a) at least two communication antennas, with a first communication antenna arranged toward an end portion of the layer of ferromagnetic material and a second communication antenna arranged toward another end portion opposite the end portion bearing the first communication antenna;
• b) means (M1) for measuring values of current, voltage, or phase shift between the voltage and the current at the terminals of at least one of the two communication antennas;
• c) means (M2) for comparing said values thus measured with predetermined, values;
• and
• d) means (M3) for determining the presence of a foreign metal object on the charging surface based on the result of said comparison.