Radiovåg

Radiovåg, or radio wave, is an electromagnetic wave in the radio frequency portion of the spectrum. It encompasses roughly from 3 kilohertz to 300 gigahertz, corresponding to wavelengths from about 1000 kilometers to 1 millimeter. In vacuum they travel at the speed of light, about 299,792 kilometers per second, and in matter with slight variation.

Radio waves can propagate by various modes: ground waves traveling along the surface of the Earth, skywaves refracted by the ionosphere to reach distant locations, and line-of-sight waves that travel in straight paths between transmitter and receiver, limited by the height of antennas. Higher frequencies tend to be line-of-sight; lower frequencies can bend around obstacles but are more affected by atmospheric conditions. They can be polarized and modulated to carry information.

Radio waves are generated by transmitting devices such as antennas fed by radio transmitters and are detected by receivers with antennas converting the waves back to electrical signals. Information is encoded by modulation techniques such as amplitude modulation (AM), frequency modulation (FM), phase modulation (PM), or digital schemes like QAM and OFDM.

Applications include broadcasting (radio and television), mobile and fixed communications, satellite links, radar, navigation systems (for example GPS and aviation), and wireless networks (Wi‑Fi, Bluetooth). In everyday life, non-ionizing nature means radio waves do not ionize atoms, though high-intensity exposure can cause heating; regulatory bodies allocate frequency bands to avoid interference and ensure safety and interoperability.