Data and signals are transmitted via radio waves by a radio. 30 hertz (Hz) to 300 gigahertz (GHz) are the frequencies of radio waves. An electronic device called a transmitter transmits the waves through an antenna, and another antenna connected to a radio receiver receives them. In modern technology, radio is used widely for Radios de comunicacion, radar, radio navigation, remote control, and remote sensing.
Radiation is the transport of information over space by modulating the radio signal (impressing an information signal on the radio wave by changing some aspect of the wave) in the transmitter. With radar, an emitted beam of radio waves reflects off of objects such as aircraft, ships, spacecraft, and missiles to reveal their location. Radar is used to locate and track aircraft, ships, and spacecraft. the radio waves arrive at the receiver, it can determine its position on Earth. The actions of a remote device are controlled by radio signals transmitted from a controller device, such as a drone, garage door opener, or keyless entry system.
Radiation is usually not called radio for applications of radio waves that do not involve transmitting the waves over long distances, such as RF heating in industrial processes and microwave ovens, and medical uses such as diathermy and MRI machines. A radio receiver is also known as a radio.
In 1886, German physicist Heinrich Hertz identified and studied radio waves for the first time. It was Italian Guglielmo Marconi who developed the first practical radio transmitter and receiver around 1895–1896, and radio became commercially used around 1900. An international organization called the International Telecommunication Union (ITU) allocates frequency bands in the radio spectrum for various uses in order to prevent interference between users.
Electrons are used to produce radio waves when they flow back and forth back in a metal conductor called an antenna, accelerating electric charges. When a transmitter transmits, an antenna receives an alternating current of radio frequency. This current is radiated as radio waves by the antenna. An antenna produces an alternating current when waves hit it, which pushes electrons back and forth in the metal. An antenna connected to the radio receiver detects this oscillating current and amplifies it.
Radio waves spread out as they move away from the transmitting antenna, so their signal strength (intensity in watts per square meter) decreases, which means they can only be received within a limited range of the transmitter, where the distance depends on the transmitter power, the antenna radiation pattern, the receiver’s sensitivity, noise level, and the presence of obstructions between the transmitter and receiver. A directional antenna or a high gain antenna transmits or receives radio waves in a specific direction, while an omnidirectional antenna transmits or receives waves in all directions.
Radiation travels at the speed of light through a vacuum, and at very near the speed of light in air, so the wavelength.