Loss tangent of High resistive silicon substrate in HFSS

wht is difference between dielectric and magnetic loss tangent?

how to set loss tangent for High resistive silicon in HFSS.
either we have to change dielectric or magnetic loss tangent which one should be changed?

silicon's loss mechanism is not same as dielectric loss. For FR4 material, the DC conductance is zero while AC electrical field will incur loss.

Silicon's conductance in DC is not zero. And that means the loss mainly come from the conductivity of the material.