Before the first communications satellites were launched in the 1960s, high-frequency (HF) radio was the principal means to communicate beyond the horizon. Satellite links proved to be more reliable and over time HF was relegated to backup and disaster-recovery roles, with the military as the primary user. However, we are seeing a resurgence in HF radio, in part because new automatic link establishment (ALE) protocols now make HF a reliable, low-cost alternative to satellite.
Today’s users of HF include the military, amateur radio operators, aircraft, utilities, the oil and gas industry, short wave AM broadcast stations and the State Department. Public-safety agencies in North America are likely to encounter HF radio in disaster-recovery operations, often in partnership with volunteer amateur radio operators.
via HF radio becomes low-cost alternative to satellite | High-frequency radio – Urgent Communications article.