A split ring resonator (SRR) based metamaterial structure for bandstop filter applications

In this paper, a bandstop filter has been realized by using split ring resonator (SRR) based metamaterial structure. The geometrical dimensions of the SRRs have been parametrically optimized in such a way that zero transmission (S21 <; - 10 dB) occurs over the frequency range 3.24 to 4.78 GHz with fractional bandwidth of 38.4%. The SRRs are printed on both sides of a 1.6 mm thin FR-4 dielectric, making the structure ultra-thin in nature (~ λ/46 referred to the center frequency of the transmission zero band). The effective permeability of the structure has been retrieved to conclude the mu-resonance at the corresponding transmission zero frequencies. The surface current distributions at different frequencies of transmission minima implicate the different SRRs responsible for bandstop phenomena.