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The radio spectrum is the part of the electromagnetic spectrum with frequencies from 3 Hz to 3,000 GHz (3 THz).Electromagnetic waves in this frequency range, called radio waves, are widely used in modern technology, particularly in telecommunication.
Radio waves, at the low-frequency end of the spectrum, have the lowest photon energy and the longest wavelengths—thousands of kilometers, or more. They can be emitted and received by antennas , and pass through the atmosphere, foliage, and most building materials.
In 1887, German physicist Heinrich Hertz demonstrated the reality of Maxwell's electromagnetic waves by experimentally generating electromagnetic waves lower in frequency than light, radio waves, in his laboratory, [6] showing that they exhibited the same wave properties as light: standing waves, refraction, diffraction, and polarization.
Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency [1] range from around 20 kHz to around 300 GHz.
Very high frequency (VHF) is the ITU designation [1] [2] [3] for the range of radio frequency electromagnetic waves (radio waves) from 30 to 300 megahertz (MHz), with corresponding wavelengths of ten meters to one meter.
High frequency (HF) is the ITU designation [1] [2] for the band of radio waves with frequency between 3 and 30 megahertz (MHz). It is also known as the decameter band or decameter wave as its wavelengths range from one to ten decameters (ten to one hundred meters).
Shortwave bands are frequency allocations for use within the shortwave radio spectrum (the upper medium frequency [MF] band and all of the high frequency [HF] band). Radio waves in these frequency ranges can be used for very long distance (transcontinental) communication because they can reflect off layers of charged particles in the ionosphere and return to Earth beyond the horizon, a ...
Super high frequency (SHF) is the ITU designation [1] [2] for radio frequencies (RF) in the range between 3 and 30 gigahertz (GHz). This band of frequencies is also known as the centimetre band or centimetre wave as the wavelengths range from one to ten centimetres.