Radar frequencies are designated by letter bands. The (IEEE) classification dates from the Second World War, when the letters were deliberately chosen to be cryptic, and it is still the standard:
| Frequency band | Frequency | Wavelength | Typical use |
|---|---|---|---|
| HF | 3 – 30 MHz | 100 – 10 m | over-the-horizon radar |
| VHF | 30 – 300 MHz | 10 – 1 m | very long-range early warning, counter-stealth |
| UHF | 300 MHz – 1 GHz | 1 m – 30 cm | early warning, ballistic missile warning |
| L | 1 – 2 GHz | 30 – 15 cm | long-range surveillance, air traffic control |
| S | 2 – 4 GHz | 15 – 7.5 cm | medium-range surveillance, weather radar, naval radar |
| C | 4 – 8 GHz | 7.5 – 3.75 cm | compromise band: surveillance + tracking, many GBAD radars |
| X | 8 – 12 GHz | 3.75 – 2.5 cm | fire control, fighter radars, missile seekers, SAR |
| Ku | 12 – 18 GHz | 2.5 – 1.7 cm | high-resolution tracking, satcom |
| K | 18 – 27 GHz | 1.7 – 1.1 cm | of limited use (water vapour absorption around 22 GHz) |
| Ka | 27 – 40 GHz | 1.1 cm – 7.5 mm | missile seekers, short-range tracking, speed guns |
| mm-wave (V/W) | 40 – 110 GHz | < 7.5 mm | automotive radar, active protection systems, 94 GHz sensors |
The pattern you should see in this table:
- Low (HF–UHF): enormous ranges, large antennas, coarse resolution → warning.
- Middle (L–C): the workhorses of surveillance → searching and tracking at range.
- High (X–Ka): compact antennas, narrow beams, high resolution, but weather-sensitive → aiming and guidance.
From the frequency of an intercepted signal you can therefore make an immediate first estimate of its function — and so of the threat. An X-band emission tracking your aircraft is of a different order than an L-band surveillance sweep: the first may mean a weapon is being aimed at you.
In depth: three band systems side by side
The IEEE letters above are not the only classification. In EW and NATO contexts you often meet a second letter system — the NATO/ECM bands A to M — alongside the civilian ITU classification (VLF, LF, MF, HF, VHF, UHF, SHF, EHF). The same frequency thus has three names at once; anyone reading threat data has to switch between them fluently.
| Frequency | ITU | IEEE (radar) | NATO / EU / ECM |
|---|---|---|---|
| 3 – 30 MHz | HF | HF | A |
| 30 – 250 MHz | VHF | VHF | A |
| 250 – 500 MHz | UHF | UHF | B |
| 0.5 – 1 GHz | UHF | UHF | C |
| 1 – 2 GHz | UHF | L | D |
| 2 – 3 GHz | SHF | S | E |
| 3 – 4 GHz | SHF | S | F |
| 4 – 6 GHz | SHF | C | G |
| 6 – 8 GHz | SHF | C | H |
| 8 – 10 GHz | SHF | X | I |
| 10 – 20 GHz | SHF | X / Ku | J |
| 20 – 40 GHz | SHF / EHF | K / Ka | K |
| 40 – 60 GHz | EHF | V | L |
| 60 – 100 GHz | EHF | W | M |
Watch out for the pitfall: radars are usually named in IEEE bands, but jammers and ESM systems often in NATO/ECM bands. "A J-band jammer" thus covers roughly IEEE X/Ku — exactly the region of many fire-control radars and seekers.
