Movement detection device

A device for detecting the movement of part of a user's body and/or the approach of a portable user device, the device being intended to be placed on board a motor vehicle, the device comprising:

• a) a near field communication antenna configured for transmitting and receiving signals at a high frequency with a selected resonance between 3 and 30 MHZ, said antenna comprising at least one winding which is prolonged continuously in the form of at least two sets of strips, a first set and a second set being connected in parallel with said antenna, in such a way that said two sets each have a different variable capacitance and a different sensitivity, said antenna being capable of generating a different variation of impedance on the approach of part of a user's body towards the first or second set;
• and
• b) means for measuring, by electromagnetic coupling with said antenna, a variation of impedance or a variation of resonance frequency of said antenna, the measurement means having a series resonance frequency at the selected high resonance frequency and being capable of detecting the approach of a portable user device or the movement of part of a user's body taking place consecutively opposite the first and then opposite the second set of strips by means of the generated variation of impedance.