The wide use of radio waves for telecommunication is mainly due to their desirable propagation properties stemming from their large wavelength. The other types of electromagnetic waves besides radio waves, infrared, visible light, ultraviolet, X-rays and gamma rays, can also carry information and be used for communication. So the wavelength of a radio wave, the distance in meters between adjacent crests of the wave, is inversely proportional to its frequency, equal to the speed of light divided by the frequency. Radio waves travel through a vacuum at the speed of light, and in the air at very close to the speed of light. An omnidirectional antenna transmits or receives radio waves in all directions, while a directional antenna or high-gain antenna transmits radio waves in a beam in a particular direction, or receives waves from only one direction. The radio receiver connected to the receiving antenna detects this oscillating current and amplifies it.ДЄs they travel farther from the transmitting antenna, radio waves spread out so their signal strength ( intensity in watts per square meter) decreases, so radio transmissions can only be received within a limited range of the transmitter, the distance depending on the transmitter power, the antenna radiation pattern, receiver sensitivity, noise level, and presence of obstructions between transmitter and receiver. When the waves strike the antenna of a radio receiver, they push the electrons in the metal back and forth, inducing a tiny alternating current. The antenna radiates the power in the current as radio waves. In transmission, a transmitter generates an alternating current of radio frequency which is applied to an antenna. They are generated artificially by time varying electric currents, consisting of electrons flowing back and forth in a metal conductor called an antenna, thus accelerating. Radio waves are radiated by electric charges undergoing acceleration. To prevent interference between users, the emission of radio waves is regulated by law, coordinated by an international body called the International Telecommunication Union (ITU), which allocates frequency bands in the radio spectrum for different uses. The first practical radio transmitters and receivers were developed around 1895вЂ“1896 by Italian Guglielmo Marconi, and radio began to be used commercially around 1900. Radio waves were first identified and studied by German physicist Heinrich Hertz in 1886. The noun radio is also used to mean a broadcast radio receiver. In wireless radio remote control devices like drones, garage door openers, and keyless entry systems, radio signals transmitted from a controller device control the actions of a remote device.ДЄpplications of radio waves that do not involve transmitting the waves significant distances, such as RF heating used in industrial processes and microwave ovens, and medical uses such as diathermy and MRI machines, are not usually called radio. In radio navigation systems such as GPS and VOR, a mobile receiver accepts radio signals from navigational radio beacons whose position is known, and by precisely measuring the arrival time of the radio waves the receiver can calculate its position on Earth. In radar, used to locate and track objects like aircraft, ships, spacecraft and missiles, a beam of radio waves emitted by a radar transmitter reflects off the target object, and the reflected waves reveal the object's location. In radio communication, used in radio and television broadcasting, cell phones, two-way radios, wireless networking, and satellite communication, among numerous other uses, radio waves are used to carry information across space from a transmitter to a receiver, by modulating the radio signal (impressing an information signal on the radio wave by varying some aspect of the wave) in the transmitter. A variety of radio antennas on Sandia Peak near Albuquerque, New Mexico, US

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