rádio

Rádio is a technology and service for the wireless transmission and reception of signals through radio waves. It enables the distribution of audio, and in many cases data, over large areas using transmitters, receivers, and antennas. Radio broadcasting and two-way communication systems rely on modulation of a carrier wave to encode information.

History: The development began in the late 19th century with experiments in wireless telegraphy. Guglielmo Marconi is commonly credited with the practical demonstration of radio communication and with establishing the first transatlantic wireless link. Earlier work by Nikola Tesla and Alexander Popov contributed to foundational concepts. Radio evolved from spark-gap experiments to continuous-wave transmission and modulation techniques, with mass broadcasting beginning in the 1920s. Regulatory bodies later allocated frequency bands and established licensing regimes.

Technology: A transmitter sends a carrier signal that is modulated to carry audio or data. Common modulation methods include amplitude modulation (AM) and frequency modulation (FM); digital radio uses various schemes such as DAB, HD Radio, or DRM. The signal is radiated through an antenna and captured by a receiver tuned to the appropriate frequency. Reception may be direct over the air or via satellites and internet streams.

Services and uses: Radio is used for national and local broadcasting, international shortwave services, satellite radio, and digital services. It supports emergency alerts, maritime and aviation communications, and mobile and portable listening. Internet radio and streaming have expanded access beyond traditional airwaves.

Impact and regulation: Radio has played a central role in media, culture, and public life, and its operation is subject to spectrum management and licensing to minimize interference. The technology continues to evolve with digital and hybrid formats.