Miniaturized broadband high out-of-band rejection bandpass filter based on spoof surface plasmon polaritons with defected ground structure

• Published in: Scientific reports 2024-11, Vol.14 (1), p.26722-9, Article 26722
• Main Authors: Yang, Lingling, Liu, Haihong, Cai, Bin, Wu, Ling, Cheng, Yongzhi
• Format: Article
• Language: English
• Subjects: 639/166/987; 639/624/399; 639/766/1130; Bandpass filter (BPF); Defected ground structure (DGS); High rejection; Humanities and Social Sciences; Microwave communications; multidisciplinary; Science; Science (multidisciplinary); Spoof surface plasmon polaritons (SSPPs)
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-024-77705-y

In this paper, a novel compact bandpass filter (BPF) with a wide out-of-band rejection is proposed. It can achieve broadband characteristics by combining hollow bowtie-type spoof surface plasmon polaritons (SSPPs) with complementary H-type defected grounded structures (DGSs) through aperture coupling. Compared with the conventional SSPP unit cells, the hollow bowtie-type structure exhibits much better slow-wave characteristics. The introduced slant antenna type port-coupling can produce a very strong high-performance rejection outside the high frequency stopband. Simulation results show that the SSPPs-DGS-based BPF has an excellent band pass characteristics in a broadband range with − 3dB fractional bandwidth of 43.5% at center frequency f 0 of 2.04 GHz. The return loss in the passband is better than − 12 dB. Furthermore, because of the multiple transmission zeros generated in upper-stop-band, the designed BPF has an extremely strong out-of-band rejection of -40dB from 1.5 f 0 to 4 f 0 ( f 0 is the center frequency). The designed SSPPs-DGS-based BPF is fabricated by conventional printed circuit board (PCB) technology with a compact size of only 0.68λ g *0.34λ g (λ g is the wavelength at the center frequency). The measured results have a good agreement with the simulation ones, which verifies the rationality and feasibility of the design. The miniaturized wideband BPF with broad out-of-band rejection may make it has good application prospect in the new generation microwave communication field.