# wave number definition for TEM mode

#### yefj Hello, I have a problem visualizeing the following claim.
K is a wave number the phase change as the wave propagates.
i am having trouble imagening the wave.
Why the transversverse components of the wave are zero for tem?
Thanks. #### nomigoraya

##### Full Member level 5 To be hones I am not able to understand what is written in equation as in TEM wave electric and magnetic fields propagate perpendicular to each other and both propagate perpendicular to the direction of wave and it is very easy to visualize as well

#### yefj Hello Nomigoraya, in electromagnetic thery we have beta=sqrt(k^2-k_t^2)
in TEM wave it propagates in Z direction, we have E,H field pointed only in X,Y directions.
Why in this case k_t=0?

#### PlanarMetamaterials Hello yefj,

You are asking why the transverse wavenumber is zero: i.e., why there is no phase variation in the fields in the transverse plane. We know that by definition, there must be zero longitudinal fields. However, if there were transverse phase variations, Maxwell's equations (particularly Faraday's and Ampere's laws) suggest that there will exist longitudinal field components. Therefore, there must be no transverse phase variations.

• yefj

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