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Radar level transmitters are non-contact measurement devices that use electromagnetic waves to measure the level of liquids and solids. Compared to ultrasonic and hydrostatic measurement methods, they provide higher accuracy and ensure reliable performance even under harsh process conditions.

WORKING PRINCIPLE

Radar transmitters emit microwave signals toward the material surface and measure the time taken for the reflected signal to return.

Formula: d = (c × t) / 2

Where:
d: distance (m)
c: speed of light (3 × 10⁸ m/s)
t: round-trip time (s)

The difference between the tank height and this measured distance provides the actual material level. Modern 24 GHz and 80 GHz radar technologies offer superior resolution and narrower beam angles.

TYPES OF RADAR

Guided Wave Radar (GWR): Uses a probe or cable to guide the signal, ideal for tanks with foam, vapor, or dust.
Non-Contact Radar: Uses an antenna to transmit signals, suitable for high-pressure, high-temperature, and aggressive chemical environments.

STRUCTURAL FEATURES

Body materials: stainless steel, PTFE coating
Output signals: 4-20 mA, HART, Modbus, Profibus
Protection class: IP67 – IP68
Explosion-proof versions (ATEX & IECEx)
Accuracy up to ±2 mm

ADVANTAGES AND LIMITATIONS

Advantages:

Minimal influence from foam, vapor, and dust
High accuracy and reliability
Long measuring range (up to 70 m)
Withstands harsh process conditions

Limitations:

Proper antenna alignment and mounting are critical
Build-up on antenna surfaces may affect accuracy
Generally more expensive than ultrasonic methods

SELECTION CRITERIA

Tank height and geometry
Physical properties of the measured material
Process conditions (temperature, pressure, vapor, dust)
Communication protocol requirements
Desired measurement accuracy

APPLICATION AREAS

Chemical and petrochemical industries
Oil and gas storage tanks
Power plants
Food and beverage industry (hygienic design models)
Water and wastewater treatment plants

STANDARDS

IEC 61326 (electromagnetic compatibility)
ATEX & IECEx certifications (for explosive atmospheres)
EHEDG (hygienic design – food industry)

CONCLUSION

Radar level transmitters are among the most preferred measurement devices in modern industry due to their non-contact measurement capability, high accuracy, and robustness under challenging process conditions.