background material meaning

Hello everybody,

Let assume that I have simple dipole antenna on the top of kind of substrate. All boundries are open unless from the top it is open "add space".

What does mean if I change the permittivity value in background material from "1" to the same value of the permittivity of substrate ???

Regards

it means that your medium around the antenna is not air any more. It is the material you have just defined :)