Which frequency range corresponds to HF (High Frequency)?

High Frequency (HF) refers to the frequency range of 2 to 29.999 megahertz (MHz). This range is significant for various forms of communication, particularly in military and aviation applications, because it supports long-distance communication by utilizing the ionosphere for radio wave propagation.

In the context of radio communications, HF is capable of bouncing signals off the ionosphere, allowing for greater distances than would typically be possible with lower frequency bands. This makes HF essential for operations where line-of-sight communication is not feasible, as signals can travel beyond the horizon by reflecting off layers of the Earth's atmosphere.

The other frequency ranges listed do not correspond to HF. For instance, the ranges provided in the choices covering higher megahertz values belong to different bands used for various applications, such as VHF (Very High Frequency) or UHF (Ultra High Frequency) communications, which are suited for different types of transmissions entirely. Understanding these distinctions is vital for effective communication in diverse operational environments.