Electric tunability of microwave permeability dispersion behaviors of metamaterials

By embedding a capacity-variable diode into a split ring resonator (SRR), it is found that the effective capacitance of such an SRR element can be varied by the biased voltage of diode. Therefore the resonance frequency and effective permeability of an SRR element can be tuned. Based on these results, a smart microwave magnetic metamaterial is proposed. Employing the finite-difference time-domain and retrieval method, the variations of resonance frequency and permeability of the SRR element are simulated and calculated by changing the biased voltage. It is found that with the decrease of capacitance due to the increase of biased voltage, the resonance frequencies are shifted towards lower values, and so are the resonance frequencies of permeability dispersion. Finally, the difference in permeability dispersion behavior between SRR structure and natural magnetic material (for instance, ferrite) has been pointed out.