SN-MW700 C Ceiling Surface Mounted Microwave Motion SensorHow does a Microwave Motion Sensor work? A Microwave Motion Sensor emits waves in the detection area. These waves get reflected back to the receiver when they bounce off a surface. The receiver constantly analyzes the waves that are bounced back. If there is an object individual moving in the room, these waves are going to be altered, and so when the sensor identifies this motion, it automatically sends the signal for initiating the programmed command