The extremely-low-frequency (ELF) band is the radio-frequency (RF) band between
30-300 Hz. The ELF band is not of significant use
in communications due to the extremely small bandwidth available and
the enormous antennas required. ELF has one redeeming feature that
makes its use a viable proposition for communications to submarines.
ELF propagation suffers very little attenuation (approximately 1,000 times less
than other radio frequencies) by any medium, particularly the atmosphere
and seawater. Propagation is primarily via surface wave, and the
signal is very stable with little diurnal or seasonal variation.
In addition to submarine communications, some of the audible frequencies
are contained in this band. Although not part of communications
frequencies, electric power is generated in this band.
Other topics in our resources on Communications Systems related to Extremely low frequency include: