Lühilaines

Lühilaines, also known as shortwave radio, refers to radio wave propagation within the radio spectrum with wavelengths ranging from 10 to 100 meters. This corresponds to frequencies between 3 and 30 megahertz (MHz). Shortwave radio signals can travel vast distances, often spanning continents, due to their ability to reflect off the ionosphere, a layer of charged particles in Earth's upper atmosphere. This characteristic makes it particularly useful for long-distance communication.

The phenomenon of shortwave propagation is influenced by various factors, including the time of day, season, and solar activity, which affect the density and behavior of the ionosphere. Different frequencies within the shortwave band are more effective for communication at certain times and distances. For instance, lower frequencies tend to travel further at night when the ionosphere is less dense, while higher frequencies can be better during the day for shorter, but still significant, distances.

Historically, shortwave radio played a crucial role in international broadcasting, allowing news and cultural programming to reach audiences worldwide. It was also vital for military communications, maritime and aeronautical navigation, and amateur radio (ham radio) operations. While modern technologies like satellite communication and the internet have surpassed shortwave in many applications, it remains a valuable tool for certain niche purposes, including emergency communications, hobbyist use, and in regions with limited access to other communication infrastructure. Its resilience and ability to bypass conventional networks ensure its continued relevance.