Introduction :
A radio wave is an electromagnetic wave whose frequency is lower than 3000 GHz, a wavelength greater than 0.1 mm.
The field of radio is regulated by the International Telecommunication Union (ITU) has established rules of radio communications in which one can read the following definition:
Radio waves or radio waves "electromagnetic waves with frequencies arbitrarily lower than 3000 GHz propagated in space without artificial guide" can be between 9 kHz and 3000 GHz which corresponds to wavelengths 33 km to 0.1 mm.
The wave frequency below 9 kHz radio waves are, however are not regulated.
The radio waves are electromagnetic waves which propagate in two ways:
* In the free space propagation (radiated around the Earth for example)
* In lines (guided propagation in a coaxial cable or waveguide)
The field frequency radio waves ranges from 9 kHz to 3000 GHz.
In a coaxial line, the propagation speed is the same regardless of frequency, we say that the line is dispersive.
A radio wave is an electromagnetic wave whose frequency is lower than 3000 GHz, a wavelength greater than 0.1 mm.
The field of radio is regulated by the International Telecommunication Union (ITU) has established rules of radio communications in which one can read the following definition:
Radio waves or radio waves "electromagnetic waves with frequencies arbitrarily lower than 3000 GHz propagated in space without artificial guide" can be between 9 kHz and 3000 GHz which corresponds to wavelengths 33 km to 0.1 mm.
The wave frequency below 9 kHz radio waves are, however are not regulated.
The radio waves are electromagnetic waves which propagate in two ways:
* In the free space propagation (radiated around the Earth for example)
* In lines (guided propagation in a coaxial cable or waveguide)
The field frequency radio waves ranges from 9 kHz to 3000 GHz.
Radio or electromagnetic wave in space :
The waves caused by a falling rock on the surface of a pond spread like concentric circles. The radio waves emitted by the isotropic antenna (that is to say, radiating uniformly in all directions in space) can be represented by a series of concentric spheres. One can imagine a balloon inflating fast, the speed of light c, very close to 300,000 km / s. After one second, the sphere has 600,000 km in diameter. If the propagation medium is not isotropic and homogeneous, the wave front will not be a sphere. As the radio wave is a vibration, after a period, the wave has traveled a distance denoted lambda and called wavelength. The wavelength is a key feature in the study of the spread, for a given frequency, it depends on the speed of wave propagation.Radio Wave propagation in a line:
A generator connected to a load with a line will cause each of the two conductors of the line to establish an electric current and the formation of a wave moving in the dielectric at high speeds. This speed is less than the speed of light but frequently exceeds 200 000 km / s, which implies that for a given frequency, the wavelength in the line is smaller than in space.In a coaxial line, the propagation speed is the same regardless of frequency, we say that the line is dispersive.
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