why must we assign the port on a rectangular?

hi,

according to following the pictures, why do we define the port on a rectangular (it in circle)? Must we assign a port on a rectengular? for eamples;

if your answer is in HFSS, i will be happy

thanks

Have never think about this.Hope for answers.

I does not have to be a rectangular...The only thing
a LUMPED port needs is two well stablished connections
and a line that define the orientation. The problem arise
when trying to define those two connection points in
a non line curve as in a curve, it is very difficult and
the software give a warning.