Reference

Principle

The sensor operates using Doppler radar technology, transmitting microwave signals and detecting frequency shifts caused by moving objects. Since microwaves can penetrate dust, smoke, and certain non-metallic materials, the sensor maintains stable performance even in harsh environments.

Compared with other detection methods, microwave sensing offers the following advantages:

Non-contact detection without physical interaction

Detection performance unaffected by temperature, humidity, light, dust, or airflow

Strong resistance to radio-frequency interference

Low output power, safe for the human body

Wide detection range with high response speed

Capable of detecting both living and non-living objects

Other Supplementary Information

Signal Processing

The following diagram demonstrates the working principle of the sensor module. It works by amplifying a tiny signal which is received by the microwave sensor, and then through the comparison circuit it converts the signal into a square signal with a digital output of 0 or 1 which an Arduino or other micro controller can easily handle.

Antenna Description

Signal Detection Range

Detection Angle: The angle of detection is 72 degrees with the antenna in a parallel direction (azimuth) The vertical (pitch) direction of the antenna is 36 degrees.

Install

Microwaves can penetrate through walls. So sometimes it has inaccuracies when microwaves penetrate through outside walls and detect moving objects in non-target areas. Be sure to choose an installation location to avoid this!

Indicators and Output Status

When the microwave sensor does not detect moving objects, the indicator LED remains off. When the sensor detects moving objects, the LED will turn on and the output level will be change from HIGH to LOW. The LED will automatically turn off about after 0.5s and the output level will change from LOW to HIGH. If the microwave sensor detects continuously moving objects the LED will keep flashing on and off. The output level will fluctuate between HIGH and LOW until the object stops moving.

Distance Adjustment

The microwave sensor has a distance range of 2-16m. The detection distance can be adjusted using the potentiometer. If it is turned in the direction on MIN, the detection distance decreases. If it is turned in the opposite direction, the range increases.

Comparison with IR Sensor