RCWL-0516 is a doppler radar microwave motion sensor module that can act as an alternative to a PIR motion sensor.
 
The RCWL-0516 Microwave Radar Sensor module has been designed as an alternative to the common PIR motion sensors widely used in burglar alarms and security lights. Like the PIR Sensor, this sensor also detects only movements within its detection range. But instead of sniffing the blackbody radiation from a moving person, this sensor uses a “microwave Doppler radar” technique to detect moving objects.
 
Features:
Working voltage: 4.0-28.0V
Operating Current: 2.8mA (typical); 3mA (max)
Detection Distance: 5-9m
Transmitting Power: 20mW (typical); 30mW (max)
Output Voltage: 3.2-3.4V
Output Voltage Driving Capacity: 100mA
Trigger Way: repeat trigger
Output Control Low Level: 0V
Output Control High Level: 3.3V
Operating Temperature: -20~80 ℃
 
Resources:
1. Interfacing RCWL 0516 Microwave Radar Sensor with Arduino
2. How RCWL-0516 Microwave Radar Motion Sensor Works & Interface It With Arduino