rövidhullám

Rövidhullám, meaning shortwave in Hungarian, refers to radio waves with wavelengths between 10 and 100 meters, corresponding to frequencies between 3 and 30 megahertz (MHz). These frequencies fall within the high frequency (HF) band of the radio spectrum. Shortwave signals are known for their ability to travel long distances by reflecting off the ionosphere, a layer of charged particles in the Earth's upper atmosphere. This characteristic makes shortwave radio communication particularly useful for international broadcasting, amateur radio, and certain military and maritime applications where global coverage is required.

The propagation of shortwave signals is dependent on various factors, including the time of day, season, and the condition of the ionosphere. During daylight hours, the ionosphere tends to absorb some shortwave frequencies, while at night, it becomes more transparent, allowing signals to travel further. Different frequencies within the shortwave band are optimal for different distances and times. Lower frequencies (longer wavelengths) tend to travel further, especially at night, while higher frequencies (shorter wavelengths) can be better for shorter, long-distance communication during the day.

Historically, shortwave radio played a crucial role in global communication before the advent of satellite and internet technologies. It enabled news dissemination, propaganda, and personal communication across continents. Today, while its prominence has diminished in some areas, shortwave broadcasting continues to serve specific niches, reaching audiences in regions with limited access to other media or for specialized purposes. Amateur radio operators also extensively use the shortwave bands for international contacts and experimentation.