Radio Signals & Environmental Effects: How 433 MHz Is Affected by Metal and Water

CarPro-Tec systems rely on the proven 433 MHz frequency – ideal for wireless communication between sensors, remotes, and the alarm control unit. To ensure optimal performance in your vehicle, it’s important to understand how materials like metal and water impact the signal.

What is 433 MHz?

The 433.92 MHz frequency belongs to the ISM band (Industrial, Scientific, Medical). It is commonly used for short-range communication with low data rates and medium range (typically 10–30 meters indoors, more in open areas).

Source: Texas Instruments: RF Basics

How Metal Affects 433 MHz Signals

• Signal blocking: Metal surfaces reflect or block RF signals. They act like a mirror for radio waves and prevent penetration.
• Multipath interference: Reflections in vehicles can cause interference and signal loss.
• Installation tip: Avoid placing the control unit or sensors directly on or behind metal parts. Use plastic or interior surfaces when possible.

Source: ITU Propagation Handbook

How Water Affects 433 MHz Signals

• Absorption: Water strongly absorbs radio signals. Even wet clothing or the human body can attenuate the signal.
• Reflection: Large water containers or tanks can cause unintended reflections.
• Condensation: Moisture inside the vehicle, especially in cold nights, may weaken signal strength.

Source: IEEE Research on Water & RF

Practical Tips for CarPro-Tec Users

• Sensor placement: Maintain at least 1 cm distance from metal.
• Line-of-sight: Ideally, sensors should face the control unit without physical obstructions.
• Test location: In the event of connection problems, slightly change the sensor position or the position of the CarPro-Tec as a test.

✅ Conclusion

433 MHz is a reliable and power-efficient wireless standard – as long as the installation avoids interference from metal and water. Optimizing the position of your devices can dramatically improve performance.