HB100 Microwave Sensor Module 10.525GHz
This is a Microwave moving object detector that is designed by the Doppler Radar principle.
It is mainly used in automatic door control, safety guard systems, automatic video control systems, etc. This module uses a 10.525 GHz band to detect moving.
Doppler Principle: Doppler theory based on time, when radio waves encounter an object in the moving process will be reflected when the waves, the frequency of the reflected wave will hit the object with the movement to change state. If the radio waves encounter an object position is fixed, then the reflected wave frequency and transmitting frequency waves should be equal. If the object moves toward the launch, then the reflected waves will be compressed, which will increase the frequency of the reflected wave; otherwise, the reflected wave's frequency decreases.