80GHz vs 26GHz Radar Level Sensor: Beam Angle, Blind Zone & Small-Tank Fit

When you spec a radar level sensor, the frequency decides two things that matter in real tanks: how narrow the beam is, and how close to the antenna you can measure. This short guide explains the trade-off so you pick the right one instead of the cheapest one.

Beam angle: why 80GHz wins in tight spaces

A radar beam spreads from the antenna. Lower frequency = wider cone. At the same antenna size, an 80GHz sensor throws a much narrower beam than a 26GHz unit.

• In a narrow pipe or small-diameter tank, a wide 26GHz beam hits the wall and returns a false echo.
• An 80GHz narrow beam goes straight down to the liquid and ignores the walls.

If your tank has internal pipes, ladders, or agitators, narrow-beam 80GHz is the safer choice.

Blind zone: how close to the top you can read

The antenna cannot measure right at its own face — that region is the blind zone. On our own 80GHz units the blind zone is 5 cm (same figure on the JJY-YLD128SP transmitter and the JJY-YLD138M-32 module), and the beam is ±2.75°. That 5 cm dead zone is short enough for short tanks where every centimeter of usable span counts — a 1 m tank loses only 5% of its range, and with the module’s 0.05–10 m measuring span you keep 95 cm of readable level.

Quick comparison

Factor	26GHz	80GHz
Beam width (same antenna)	Wider	Narrower
Small / cluttered tank	Risky	Better
Cost	Lower	Higher
Long-range / large silo	Fine	Fine

Which should you choose?

• Small tank, narrow neck, internal obstructions → 80GHz.
• Large silo, open space, budget-sensitive → 26GHz is adequate.

Where to start with JiaJia Eye hardware: for a compact integrated transmitter, JJY-YLD128SP (±2 mm at RS485, 0.05–40 m, ±2.75° beam, 5 cm blind zone, G2 thread, IP67, with local LCD); for building into your own enclosure, the JJY-YLD138M-32 module (same ±2.75° beam and 5 cm blind zone, 0.05–10 m, M32×1.5 thread, RS485 / TTL UART). Both are 80GHz FMCW.

FAQ

Q: Can 26GHz work in a 2-inch pipe? A: Often poorly — the beam is too wide and reflects off the pipe wall. Use 80GHz or a guided-wave alternative for narrow pipes.

Q: Is 80GHz worth the extra cost for a big open silo? A: Usually not — a 26GHz beam has room to spread. Spend the budget on 80GHz where space is tight.

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Draft prepared 2026-10-07. Targets a comparison long-tail where a new site can rank without fighting incumbent brands on head terms. Finalize after F confirms demand.

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