how to represent refraction index with CST?

i am working about patch antenna with metamaterials (the substrat=dielectriq+SRRs) . my work is based on CST microwave studio. i want to represent the refraction index "n" of substrat and permittivity and permeability of substrat with CST simulator.
how to represent refraction index, permittivity and permeability with CST? i can represent the impedance for example but no refraction index with cst!