Wavelength: 10 km to 1 km
Low Frequency or LF refers to Radio Frequencies (RF) in the range of 30 kHz–300 kHz. In Europe, and parts of Northern Africa and of Asia, part of the LF spectrum is used for AM broadcast service. In the western hemisphere, its main use is for aircraft beacon, navigation (LORAN), information, and weather systems. Time signal stations MSF, DCF77, JJY and WWVB are found in this band. Also known as the kilometer band or kilometer wave as the wavelengths range from ten to one kilometers.

Standard time signals
Radio signals below 50 kHz are capable of penetrating ocean depths to approximately 200 meters, the longer the wavelength, the deeper. The British, German, Indian, Russian, Swedish, United States and probably more navies communicate with submarines on these frequencies.
This section has been tagged since June 2007.
In addition, Royal Navy nuclear submarines carrying ballistic missiles are allegedly under standing orders to monitor the BBC Radio 4 transmission on 198 kHz in waters near the UK. It is rumoured that they are to construe a sudden halt in transmission, particularly of the morning news programme Today, as an indicator that the UK is under attack, whereafter their sealed orders take effect.

For more details on this topic, see Communication with submarines. Antennas