When selecting a radar distance sensor for water level, flow, or even speed measurement, frequency matters. The three most common bands are 24 GHz, 80 GHz, and 120 GHz. But which one is right for your project?
This guide compares their performance in real-world applications, including radar measure for water, radar flowmeter systems, doppler radar sensor setups, and even emerging uses like traffic speed radar, ground speed radar, and bike radar sensor devices.
How Frequency Affects Performance
Higher frequency millimeter wave radar waves have shorter wavelengths. This creates three key advantages:
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Narrower beam angle – less interference from pipes, ladders, or tank walls
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Better reflection – works better on calm or low-dielectric surfaces
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Smaller antenna size – easier to install in tight spaces
Modern fmcw radar (Frequency Modulated Continuous Wave) technology is used across all bands, providing high accuracy for long distance radar and mmwave sensor applications alike.
Head-to-Head Comparison
24 GHz Radar
Best for: General industrial use, moderate budgets, materials with good reflection.
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Beam angle: typically 10°–12°
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Penetration: good through dust and light rain
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Cost: lowest of the three
Limitations: Wider beam may hit obstructions. Struggles with extremely calm water surfaces.
Use case: Wastewater lift stations, basic distance sensor tasks, some ground speed radar for vehicles.
80 GHz Radar
Best for: Water and wastewater, outdoor tanks, rivers, flumes, and traffic speed radar.
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Beam angle: typically 3°–6°
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Penetration: excellent through vapor, dust, and condensation
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Reflection: works on calm water and low-dielectric media
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Cost: moderate (sweet spot)
Advantages: The most popular choice for radar measure for water. Works with radar flowmeter systems and doppler radar sensor setups for surface velocity. A 77 GHz radar (closely related band) is also common in automotive and traffic applications.
Use case: Clean water reservoirs, river level monitoring, open channel flow, traffic speed radar enforcement, mmwave sensor for industrial automation.
120 GHz Radar
Best for: High-precision applications, very calm surfaces, small tank nozzles, compact bike radar sensor devices.
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Beam angle: typically 2°–3° (extremely narrow)
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Penetration: slightly less than 80 GHz in heavy rain
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Cost: highest
Advantages: Can be installed in very small mounting holes. Best for precision measurement (±1 mm). Emerging bike radar sensor products use this band for compact size and pedestrian detection.
Limitations: More affected by heavy rain or dense dust than 80 GHz.
Use case: Chemical tank gauging, high-precision reservoir monitoring, long distance radar for autonomous systems, bike radar sensor for cycling safety.
Quick Comparison Table
| Feature | 24 GHz | 80 GHz / 77 GHz | 120 GHz |
|---|---|---|---|
| Beam angle | 10°–12° | 3°–6° | 2°–3° |
| Technology | Traditional | FMCW radar | Millimeter wave radar |
| Calm water | Poor | Good | Excellent |
| Dust/rain | Good | Very good | Moderate |
| Cost | Low | Medium | High |
| Best for | Sludge, basic sensors | Radar flowmeter, traffic speed radar, water | Precision, bike radar sensor, compact |
Which Frequency Should You Choose?
Choose 24 GHz if:
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You are on a tight budget for a basic radar distance sensor or ground speed radar.
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The surface is turbulent with good reflection.
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Example: Wastewater wet well.
Choose 80 GHz (or 77 GHz) if:
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You measure water (radar measure for water, radar flowmeter).
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You need reliable doppler radar sensor performance for moving surfaces.
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You want a traffic speed radar or long distance radar for vehicles.
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You prefer the best price-to-performance mmwave sensor.
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Example: River monitoring, traffic enforcement, outdoor tanks.
Choose 120 GHz if:
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You need extreme precision or a very small sensor.
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You are designing a compact bike radar sensor for safety applications.
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The water surface is completely still.
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Example: High-precision reservoir, cycling safety device.
Conclusion
For 90% of water level and flow applications, 80 GHz radar (including 77 GHz radar) is the best choice. It balances cost, beam width, and environmental resistance.
24 GHz remains a budget option for basic distance sensor or ground speed radar tasks. 120 GHz excels in precision and compact bike radar sensor applications.
When in doubt, start with 80 GHz FMCW radar. It works where others fail.
📌 Want to use these radars in your project?
Contact Vivi: susiqi@mwradar.com or WeChat/WhatsApp: +86 181 2377 8519
