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Medium wave (MW) is a part of the medium frequency (MF) radio band used mainly for AM radio broadcasting. The spectrum provides about 120 channels with more limited sound quality than FM stations on the FM broadcast band .
Medium frequency (MF) is the ITU designation [1] [2] for radio frequencies (RF) in the range of 300 kilohertz (kHz) to 3 megahertz (MHz). Part of this band is the medium wave (MW) AM broadcast band. The MF band is also known as the hectometer band as the wavelengths range from ten to one hectometers (1000 to 100 m).
The dispersion relationship depends on the medium through which the waves propagate and on the type of waves (for instance electromagnetic, sound or water waves). The speed at which a resultant wave packet from a narrow range of frequencies will travel is called the group velocity and is determined from the gradient of the dispersion relation ...
At medium wave and shortwave frequencies (MF and HF bands) radio waves can refract from a layer of charged particles high in the atmosphere, called the ionosphere. This means that radio waves transmitted at an angle into the sky can be reflected back to Earth beyond the horizon, at great distances, even transcontinental distances.
Water waves on a mean flow (so a wave in a moving medium) experience a Doppler shift. Suppose the dispersion relation for a non-moving medium is: = (), with k the wavenumber. Then for a medium with mean velocity vector V, the dispersion relationship with Doppler shift becomes: [20]
A transverse wave is the form of a wave in which particles of medium vibrate about their mean position perpendicular to the direction of the motion of the wave. To see an example, move an end of a Slinky (whose other end is fixed) to the left-and-right of the Slinky, as opposed to to-and-fro. [2]
Transmission medium, in physics and telecommunications, any material substance which can propagate waves or energy . Active laser medium (also called gain medium or lasing medium), a quantum system that allows amplification of power (gain) of waves passing through (usually by stimulated emission)
Dispersion may be caused either by geometric boundary conditions (waveguides, shallow water) or by interaction of the waves with the transmitting medium. Elementary particles , considered as matter waves , have a nontrivial dispersion relation, even in the absence of geometric constraints and other media.