Compact coplanar waveguide band‐pass filter at the S‐band

In this paper, it is demonstrated that split‐ring resonators (SRRs) magnetically coupled to a coplanar waveguide (CPW) structure can be applied to the design of miniaturized band‐pass filters. To this end, a two‐stage prototype device consisting of a CPW with two signal‐to‐ground shorts and a series gap, combined with SRRs, is designed and fabricated. By virtue of the subwavelength operation of SRRs at their quasi‐static resonance, the filter dimensions can be made to be very small in comparison to conventional distributed implementations. Other relevant features of the proposed structures are: (i) low insertion losses (<3.5 dB) in the allowed band, (ii) out‐of‐band rejection levels above 30 dB, and (iii) very sharp transition slopes. It is believed that these SRR‐based structures can be of interest for the design of planar filters with potential application in future communication transceivers.