ITU frequency bands
The International Telecommunications Union has defined a system of terminology for electromagnetic frequencies used for radio and radar. While it is probably the most user-friendly of the three major systems in use, its categories are too coarsely grained for describing radar uses. It is, however, a good set of terms for frequencies used in communications.
See IEEE frequency bands for radar designations used widely in civilian practice, and the EU-NATO-US frequency bands for a nomenclature that works well in fine-grained radar band discussion.
The very lowest bands have no radar applications, but, among other things, have a critical military application in communicating, at a very low data rate, with submerged submarines.
| Frequency range | ITU band |
|---|---|
| 3-30 Hz | ELF (Extremely Low Frequency) |
| 30Hz to 300Hz | SLF (Super Low Frequency) |
| 300Hz to 3000Hz | ULF (Ultra Low Frequency) |
| 3kHz to 30kHz | VLF (Very Low Frequency) |
| 30-300 KHz | LF (Low Frequency; "longwave") |
| 300KHz-3 MHz | MF (Medium Frequency; "medium wave") |
| 3-30 MHz | HF (High Frequency; "shortwave") |
| 30-300 MHz | VHF (Very High Frequency) |
| 300 MHz -3 GHz | UHF (Ultra High Frequency) |
| 3-30 GHz | SHF (Super High Frequency) |
| 30-300 GHz | EHF (Extremely High Frequency) |
Millimeter wave frequencies begin at 18 GHz in SHF and go to the lower third of EHF. Submillimeter wave start roughly above 100 GHz; they blur into the longer infrared light frequencies.
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