I built an Arduino radar system using an HC-SR04 ultrasonic module and MG90S servo motor. I wrote an entire tutorial on how to wire and use it, and also the software used to create the visualization called a plan position indicator - all written in Python and completely open source. If you're interested, here's the link:
Radar Emulator with Arduino and Python
Here's an image of the radar hardware and software plotted in Python on a Raspberry Pi:
