The interactions between the antennas is important. If you have highly directive antennas they do not interact and you can replece them by lumped elements of their terminal impedance. If the antennas interact, such as dipoles, then you will have to model the whole array including antenna elements.
Dear my freind, LUPIN
I want to invesitigate about mutual coupling, please assume a dipole array printed in a substrate, if you worked with hfss in this case, please help me