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. © 2005 Wiley Periodicals, Inc.