Hello there are antennas like stripline fed or coaxial fed antennas in which the input mode is TEM.
but then i thought ,how can TEM be the input of an antenna if TEM in a NON propogating mode?
Thanks.

 

Hello there are antennas like stripline fed or coaxial fed antennas in which the input mode is TEM.
but then i thought ,how can TEM be the input of an antenna if TEM in a NON propagating mode?
Thanks.

It is propagating into space as radiation.
https://interferencetechnology.com/antenna-fundamentals/


Figure 3. (a) Electric field E and (b) magnetic field H and TEM field from dipole charge and current


Figure 4. Power flow resulting in radiation.