A proximity sensor for a parking area designed to detect the presence of an obstacle constituted by a parked vehicle, comprises a transmitting radar, designed to send electromagnetic pulses towards the obstacle, a receiving radar, designed to receive the pulses reflected by the obstacle, and a processing circuit, designed to compare samples detected in a certain condition of absence of an obstacle in a calibration step with those detected in a condition of detection of an obstacle to determine the presence/absence of the obstacle.