Metamaterial-based compact multilayer filter with skew-symmetric feeds

Split-ring resonator (SRR) metamaterials are introduced in the design of a multilayer filter. Considering the electric coupling to the magnetic resonance, careful examination of the SRR orientations to the external stimulation is presented through full wave analysis. With the skew-symmetric feed scheme, the compact multilayer filter has a center frequency of 6.07 GHz and 7 percent fractional bandwidth with two transmission zeros at 5.79 and 7.1 GHz. Compared with a conventional microstrip filter, the proposed filter shows a significant size reduction and improved selectivity.