point source Vs. plane wave excitation

What is the differnce between the excitation of an antenna for example with point source or with plane wave.

What are the consequences and when either of them be preferred.

Thanks

the electromagnetic wave excited by point source is not a plane wave,but a sphere plane wave, which equall phase plane is a sphere not a plane and the mag. is attenuated with distance

I do not understand this question. How do you
excite an antenna with a plane wave?....In HFSS
exist a plane wave which excite the antenna at
different angles and this one act as a receiver antenna
and you can use a point excitation(port) to collect
the energy that iluminate the antenna.
But exciting an antenna with a point source then the
antenna act as a transmitter. And what you collect is
the energy at the boundaries. In other words, there
is no relationship or at least is not apparent. What
would be the base for comparison?....