| Extremely low frequency ✕ | |
|---|---|
| Abbreviation | ELF |
| ITU band | 1 |
| Min frequency in air (Hz) | 3 |
| Max frequency in air (Hz) | 30 |
| Min period in air (s) | 0.033333 |
| Max period in air (s) | 0.333333 |
| Min wave length in air (m) | 99930819.333333 |
| Max wave length in air (m) | 9993081.933333 |
| Example of use | Communication with submarines |