A via-less compact bandpass filter with improved selectivity using metamaterial structure

This paper represents a via-less compact metamaterial (MTM) bandpass filter. The proposed filter is configured with a symmetrical series gap capacitance on both side of the feed line and meander line inductance connected with circular arc and rectangular stub to provide virtual ground. Due to coupling between circular arcs impedance matching and selectivity improved. The designed filter is miniaturized and also delivers excellent scattering parameters with measured insertion loss of 0.80 dB and return loss greater than 16 dB. The level of rejection of proposed filter is more than 35 dB in stop band. The MTM properties of designed filter is verified by refractive index diagram. The zeroth order resonance (ZOR) frequency depend on shunt parameters due to open ended structure. The proposed filter is modelled by using ANSYS HFSS 14.0 and simulated results are experimentally verified. Also comparison is shown by this filter with earlier published similar filters. It is suitable for S-band application.