CQRobot Ocean Microwave Motion Sensor with 10.525GHz Doppler Effect, Compatible with Raspberry Pi and Arduino Board. for Industrial, Measurement, Automatic Doors, Sensor Lights, Reverse Radar etc. : Amazon.de: Business, Industry & Science
The Jeronimus.Net blog: Microwave Radar Sensor RCWL-0516 with Arduino Uno
RCWL-0516 Doppler Radar Sensor Interface with Arduino | Circuits4you.com
RCWL-0516 microwave radar Sensor with Arduino, Circuit and Code