kortvågsbånd

Kortvågsbandet, also known as the shortwave band, refers to a range of radio frequencies between 3 and 30 megahertz (MHz). These frequencies fall within the high frequency (HF) portion of the radio spectrum. The term "shortwave" originates from the fact that wavelengths in this band are shorter than those used for earlier, lower-frequency broadcasting, such as medium wave.

One of the defining characteristics of the kortvågsband is its ability to propagate signals over long distances, often across continents and oceans. This is due to a phenomenon called ionospheric reflection, where radio waves bounce off the Earth's ionosphere. The effectiveness of this reflection varies with the time of day, season, and solar activity, making shortwave communication less predictable than line-of-sight methods but enabling global reach.

Historically, the kortvågsband has been crucial for international broadcasting, allowing news and cultural programs to be transmitted worldwide. It has also played a significant role in amateur radio (ham radio) operations, enabling hobbyists to communicate with others across the globe. Military and maritime communications have also relied heavily on shortwave frequencies for long-range contact. While newer technologies like satellite communication and the internet have reduced its dominance in some areas, the kortvågsband remains a valuable tool for specific applications requiring wide-area coverage without extensive infrastructure.