kõrgsagedusraadio

Kõrgsagedusraadio, often abbreviated as HF raadio or shortwave radio in English, refers to radio waves in the high-frequency band of the radio spectrum, ranging from 3 to 30 megahertz (MHz). These frequencies have the unique property of being able to bounce off the Earth's ionosphere, allowing them to travel vast distances, even around the globe. This characteristic makes HF radio communication particularly useful for long-distance applications.

Historically, HF radio played a crucial role in international communication, broadcasting, and maritime and aviation navigation before the advent of satellite technology. It was the primary means of long-distance voice and data transmission for many decades. Today, while other technologies have emerged, HF radio remains relevant for certain applications. These include amateur radio (ham radio) operators who use it for hobbyist communication worldwide, military and government communications due to its resilience and ability to bypass some modern jamming techniques, and in remote areas where other forms of communication infrastructure are unavailable.

The propagation of HF radio waves is highly dependent on atmospheric conditions, particularly the state of the ionosphere, which varies with the time of day, season, and solar activity. This variability can lead to unpredictable signal strength and range. Despite these challenges, the relatively low cost of HF equipment and its global reach continue to ensure its ongoing use in various sectors.