Page "Radiation" Paragraph 35

Very low frequency or VLF refers to radio frequencies ( RF ) in the range of 3 to 30 kHz.

Since there is not much bandwidth in this band of the radio spectrum, only the very simplest signals are used, such as for radio navigation.

Also known as the myriameter band or myriameter wave as the wavelengths range from ten to one myriameter ( an obsolete metric unit equal to 10 kilometers )