Ground parameter for modeling in feko

Hi all
I want to use Infinite ground in feko , multilayer ground ,
but the problem is the specification of the dielectric that i want to use .
if i use 2 layer for the ground , please help me to fill the specification of the dielectrics as :

1-Relative permittivity
2-Dielectric loss tangent or conductivity
3-Relative permeability
4-Magnetic loss factor
5-Mass Density

I google for this parameters, but i can't found anything
thanks.