22 Facts About Radio waves

Radio waves are generated by charged particles undergoing acceleration, such as time-varying electric currents.

Naturally occurring radio waves are emitted by lightning and astronomical objects, and are part of the blackbody radiation emitted by all warm objects.

Radio waves are generated artificially by an electronic device called a transmitter, which is connected to an antenna which radiates the waves.

Radio waves are very widely used in modern technology for fixed and mobile radio communication, broadcasting, radar and radio navigation systems, communications satellites, wireless computer networks and many other applications.

Different frequencies of radio waves have different propagation characteristics in the Earth's atmosphere; long waves can diffract around obstacles like mountains and follow the contour of the earth, shorter waves can reflect off the ionosphere and return to earth beyond the horizon, while much shorter wavelengths bend or diffract very little and travel on a line of sight, so their propagation distances are limited to the visual horizon.

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Radio waves were first predicted by the theory of electromagnetism proposed in 1867 by Scottish mathematical physicist James Clerk Maxwell.

Radio waves received the 1909 Nobel Prize in physics for his radio work.

Radio waves are radiated by charged particles when they are accelerated.

Natural sources of radio waves include radio noise produced by lightning and other natural processes in the Earth's atmosphere, and astronomical radio sources in space such as the Sun, galaxies and nebulas.

Radio waves are produced artificially by time-varying electric currents, consisting of electrons flowing back and forth in a specially-shaped metal conductor called an antenna.

Radio waves are received by another antenna attached to a radio receiver.

An antenna receiving the radio waves must have the same polarization as the transmitting antenna, or it will suffer a severe loss of reception.

Polarization of radio waves is determined by a quantum mechanical property of the photons called their spin.

Plane polarized radio waves consist of photons in a quantum superposition of right and left hand spin states.

Radio waves are more widely used for communication than other electromagnetic waves mainly because of their desirable propagation properties, stemming from their large wavelength.

Radio waves have the ability to pass through the atmosphere in any weather, foliage, and most building materials, and by diffraction can bend around obstructions, and unlike other electromagnetic waves they tend to be scattered rather than absorbed by objects larger than their wavelength.

Study of radio propagation, how radio waves move in free space and over the surface of the Earth, is vitally important in the design of practical radio systems.

Radio waves passing through different environments experience reflection, refraction, polarization, diffraction, and absorption.

Radio waves are non-ionizing radiation, which means they do not have enough energy to separate electrons from atoms or molecules, ionizing them, or break chemical bonds, causing chemical reactions or DNA damage.

However, unlike infrared waves, which are mainly absorbed at the surface of objects and cause surface heating, radio waves are able to penetrate the surface and deposit their energy inside materials and biological tissues.

Since the heating effect is in principle no different from other sources of heat, most research into possible health hazards of exposure to radio waves has focused on "nonthermal" effects; whether radio waves have any effect on tissues besides that caused by heating.

Radio waves can be shielded against by a conductive metal sheet or screen, an enclosure of sheet or screen is called a Faraday cage.