# infinite but non-periodic space with PMLs in Comsol [closed]

I have a problem with implementing proper boundary conditions on sides of my simulation (in RF or WaveOptics module of Comsol). I want to obtain an infinite but not periodic space (beacuse then I will put something inside). For example, it can be a glass-vacuum interface with incident plain waves. For such a simulation one can check if Fresnel equations work as they should and if not - the simulation is not properly set. I was trying with PMLs around the simulation area and in/out ports from the bottom/top side. But it doesn't work at all. Should I set another type of boundaries on the sides except PMLs?