HF (High Frequency)

High Frequency (HF) refers to radio waves in the 3 to 30 megahertz (MHz) range used for long-distance communication. These signals can reflect off the ionosphere—a layer of the Earth's atmosphere—allowing them to travel beyond the horizon and reach distant locations worldwide. HF radio is commonly used by ships, aircraft, military, and amateur radio operators for voice, data, and emergency communication. The strength and clarity of HF signals depend on atmospheric conditions and time of day, making them versatile for global communication, especially where modern infrastructure is limited.