What is the typical range of the HF (High Frequency) band?

The HF (High Frequency) band is defined by the International Telecommunication Union (ITU) as encompassing frequencies from 3 MHz to 30 MHz. This band is particularly notable for its ability to support long-distance radio communication, especially during conditions that allow for skywave propagation, where radio waves can bounce off the ionosphere and travel beyond the horizon. HF frequencies are widely used for various communication purposes, including amateur radio, maritime communication, and aviation.

The other ranges mentioned in the choices pertain to different parts of the radio spectrum. For example, the range from 30 kHz to 3 MHz is classified as very low frequency (VLF) and low frequency (LF), whereas the range from 30 MHz to 300 MHz falls within the VHF (Very High Frequency) category, and the 300 MHz to 3 GHz range is considered UHF (Ultra High Frequency). Each of these bands serves distinct purposes and has different propagation characteristics owing to their frequency ranges.