Device for detecting an approach

A device for detecting an approach of a part of a user's body or of a portable user equipment, intended to be housed on board a motor vehicle, the device comprising:

• a) a control means;
• and
• b) a near-field communication antenna configured to transmit signals at a high frequency selected between 3 and 30 MHZ, said antenna being able to detect the approach of the portable user equipment and to communicate in near-field mode with said portable user equipment, said antenna comprising:
• i) a first section having one continuous winding electrically connected to the control means at a first connection point and a second connection point, the control means for controlling said antenna, and
• ii) a second section electrically connected to the control means at the first connection point and the second connection point, the second section being in the form of a set of comb-shaped rods such that said antenna is able to generate a variation in capacitance in response to the approach of a part of the user's body, and
• wherein, the control means comprises measuring means for measuring a variation in impedance of said antenna, the impedance being modified by the variation in capacitance of the antenna in response to the approach of a part of the user's body, or upon the approach of the portable user equipment.