Novel cross-coupled filter design using improved split-ring resonators based on stepped impedance resonator

• Published in: Microwave and optical technology letters 2011-09, Vol.53 (9), p.1976-1980
• Main Authors: Zhou, Liang, Liu, Shaobin, Kong, Xiangkun, Guo, Yanan
• Format: Article
• Language: English
• Subjects: Impedance; Microwaves; Noise levels; On-line systems; Resonators; Selectivity; split-ring resonator; Stepped; stepped impedance resonator; stepped impedance split-ring resonator; Wavelengths
• ISSN: 0895-2477; 1098-2760; 1098-2760
• DOI: 10.1002/mop.26169

In this letter, a novel miniaturized split‐ring resonator (SRR) structure is introduced in designing high‐frequency selectivity and stopband expanded bandpass filter (BPF) with four transmission zeros.Such fundamental resonators consist of a pair of half‐wavelength hairpin‐shaped ring resonators nested in each other, which improved SRR structure. Compared with conventional SRR, this stepped impedance SRR (SISRR) has better performance on miniaturization. To verify good characteristics of the novel structure, a new resonator‐embedded cross‐coupled filter, which is constructed by a pair of new resonators, is proposed. This novel filter is very compact and has high‐frequency selectivity. The improved SRR unit cell has size of 0.108λg × 0.108λg (λg being the signal wavelength at central frequency (2.2 GHz) of the passband). It also has good in‐band and out‐band performances. Its stopbands are extended 0–2.08 GHz at lower band and 2.4–6.68 GHz at upper band with a rejection level of about 20 dB. The measured and simulated results are well complied with each other. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26169