In this letter, a compact planer dual-band bandpass filter(BPF) using novel split-ring resonators (SRRs) is proposed. Compared with conventional SRRs, the stepped impedance split ring resonator (SIR-SRR) has better performance on miniaturization. To verify good characteristics of the novel structure, a new resonator-embedded cross-coupled filter, constructed by a pair of new resonators, is designed. This new filter has good characteristics of compact size and high selectivity. The improved SRR unit cell has a size of 0.108λg×0.108λg (where λg is the guided wavelength) at central frequency (2.25 GHz) of upper passband. Simulated results show that two central frequencies of the filter locate at 1.90 and 2.25 GHz with 3-dB fractional bandwidths of 1.0% and 7.7%, respectively. The lower passband band is generated by inner resonator with a via hole to gound plane, while the upper passband is created by outer resonator. Moreover, a good out-band performance is shown in this letter. Its stop-bands are extended 0-1.85 GHz at lower band and 2.4-5.8 GHz at upper band with a rejection level of about 20-dB. The measured and simulated results are well complied with each other.
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