Microwave Sensors

Microwave sensors for lighting control use high-frequency electromagnetic waves to detect movement and automatically switch lights on, off, or dim.

Microwave sensors (also called microwave motion sensors, HF sensors or microwave presence detectors) emit continuous microwave signals and measure the reflected waves.

When a person moves within the detection area, the reflected signal changes due to the Doppler effect, triggering the required lighting action.

1. The sensor sends out low-power microwave signals.
2. The signals bounce off surrounding objects.
3. Movement causes a change in the frequency of the reflected signal.
4. The sensor detects this change and activates the light.

• Highly sensitive – detects even small movements (like hand motion)
• Penetrates non-metal materials – can sense motion through: 
  - Glass
  - Thin walls
  - Plastic
  - Doors
• Extended range (up to 34m)

• They work well in large spaces; fewer sensors may be required.
• Reliable in high-temperature or dusty environments.
• Detects motion or presence even when people are sitting or moving slowly.
• Not affected by ambient light or temperature.

Because of their high sensitivity, they may detect movement outside the intended detection area. Higher chance of false triggering (such as moving objects behind walls). Typically, more expensive than PIR sensors. Calls for careful sensitivity and range adjustment.

• Large offices and conference rooms
• Car parks
• Long corridors
• Warehouses and industrial buildings