What is the HF frequency range?

The HF frequency range is defined as 3 to 30 MHz, which is consistent with the International Telecommunication Union (ITU) classification of radio frequency bands. HF, or High Frequency, is primarily used for long-distance communication because it can reflect off the ionosphere, allowing radio waves to travel beyond the horizon. This characteristic makes HF useful for various applications including maritime, aviation, and amateur radio communications.

Other ranges, such as the VHF (Very High Frequency) and UHF (Ultra High Frequency), fall outside of the HF definition, which are categorized as 30 to 300 MHz and above 300 MHz, respectively. Similarly, frequencies below 3 MHz, such as those indicated in the options that suggest 30 to 300 kHz or 300 to 3000 kHz, pertain to LF (Low Frequency) and MF (Medium Frequency) bands. Therefore, the option that identifies the HF range accurately captures the established frequency designation.