Radio communication in the sea

Because of the electromagnetic properties of seawater, very-low-frequency communication systems are used, Surface-to-submarine, submarine-to-surface, and submarine-to-submarine propagation, as well as antennas and noise, are considered. It is shown that seawater is a good conductor and that atmospheric noise is generally more of a problem in sea communications than thermal noise. Communication ranges are limited by the effects of depth attenuation and atmospheric noise. Ranges in the tens of kilometers are possible for antennas within 5 meters of the surface; bandwidth must be less than 1 Hz and tens of kilowatts of power are required.