How to account for dielectric loss in CST?

How do you account for imaginary part of permittivity in CST while defining a new material? In the dialogue box where you input the value for permittivity of the dielectric used, when defining a normal material, I've tried using imaginary numbers (eg: 3+2i). Can anyone let me know is this the right way to account for the dielectric loss in a substrate/dielectric? And if this is the only way, does CST support the mathematical expression (x+yi) as I didn't get any difference in S21 (insertion loss).

you got the point on S21 insetion loss
the imaginary part is conductivity for dielectrics, try to map it.

Hi kspalla,
I already got a solution of the above query, which is executed by creating a new material defining the the material type as Normal and assigning the real part of permitivity(dielectric) in the Epsilon section and for the imaginary part( accounting for the conductivity of the dielectric due to external field applied) the conductivity(S/m) section in the second tab of the new material dialogue box has to be assinged with a suitable value that relates to the imaginary part of the permitivity. Also when the new material is created, CST shows the dispersive behaviour of the material when conductivity is taken into consideration in the dielectric medium.