Shortwave refers to radio signals in the High Frequency (HF) band that can reflect off the ionosphere to achieve over-the-horizon propagation. Because these waves bounce between the earth and the upper atmosphere, they can transmit voice and data across oceans without satellites or submarine cables. The effectiveness of shortwave links varies heavily with the time of day, season, and solar activity.
The maritime distress net still monitors shortwave because it works out in the deep ocean where VHF can't reach.
Also heard as
- HF
Related terms
HF
High frequency designates the portion of the radio spectrum between 3 and 30 megahertz.
Propagation mode
The specific path or physical mechanism by which an electromagnetic wave travels from a transmitter to a receiver.
VHF
Very high frequency refers to radio waves in the range of 30 to 300 megahertz.