Very low frequency covers the radio spectrum from 3 kHz to 30 kHz. These extremely long wavelengths can diffract over large mountain ranges and penetrate seawater to a depth of several dozen meters. Militaries use VLF transmitters with massive antenna arrays to send low-bandwidth text messages to submerged submarines.
Heard on the job
The VLF transmission site requires hundreds of acres just to string up the antenna arrays.
Also heard as
- very low frequency