This ultrasonic radar project is from [mircemk] who uses a small ultrasonic distance sensor attached to a rotating platform. A motor rotates it around a 180-degree field-of-view and an Arduino ...

Instead, it relies on an ultrasonic distance sensor to detect a hand (or foot) waved in front of the door. An Arduino Leonardo runs the show, sounding a buzzer when the ultrasonic sensor is triggered.

DIY Arduino radar with display 10:27 am March 6, 2019 By Julian Horsey Makers, Arduino enthusiasts and students looking to learn more about ultrasonic sensors, may be interested in this DIY ...