Is there free software for simulating near field diffraction

[Christofer Br]

I'm looking for a free software I could use to simulate near field diffraction from a 2d periodic array of conductors and dielectrics placed on the surface of a dielectric slab.

 

[slow]

https://sourceforge.net/p/fable/wiki/nearfield simulation/
I don't know if a program like this is useful for you. Almost brings the hope for search and find what you want.