how to set the value?

During my simulation I happen to an error message:
when exciting with a plane wave the material at the open boundaries has to be homogeneous.
some people say that it can solve by setting the value of surrounding space(the bachground properties-wurrounding space)
what is the surrounding space mean?
how to set?

which software do you use?

sorry!
I use the cst microwave studio 5.3!
regards!

Hello,

I was reading randomly here and there. Maybe I can help you, maybe not.

The surrounding space in the CST microwave studio is defined within the
'Background material' window. Look in the bottom, you will see 3 pairs of
boxes that can be filled with numbers (by default these numbers are all set
to 0.0 ). Modify the surrounding space from those. Surrounding space is
any extra space the you provide to the structure beyond its maximum
dimensions and this space is filled in with a material depending on your
options (e.g. PEC or dielectric).

In your case, add some extra space behind the place wave (space on the
opposite side of your wave propagation).

Im not sure if this helps, but it should be difficult to figure out the problem.