Wave Number

Antenna - Theory

The wavenumber is a scalar quantity that only depends on the frequency in question, and specifies the phase change per meter for a wave. The quantity (often denoted k or sometimes as beta, the wavenumber) is given in radians/meter:

equation for k, wavenumber

In the above, is the wavelength of operation, f is the frequency and c is the speed of light in the given medium.

The wavenumber k shows up everywhere in antenna theory and physics. For free space calculations, it is basically another way to represent frequency. However, because the wavelength is smaller in dielectric materials with a permittivity or dielectric constant greater than 1, or for a material with a permeability greater than 1, the wavenumber succinctly represents the phase change of a propagating plane wave in terms of radians/meter, with 2*PI radians being one complete cycle, in all mediums. The wave number can also be written as:

another equation for k

See also the wave vector.

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