{"title":"Design of CRLH-TL BPF with controllable attenuation poles","authors":"Atsuya Hirayama, Hinata Ishikawa, Takanobu Ohno","doi":"10.1186/s43067-024-00154-0","DOIUrl":null,"url":null,"abstract":"Compact and pole-controllable resonators and bandpass filter (BPF) using a composite right/left-handed transmission line (CRLH-TL) are designed in this study. The distributed constant line in the CRLH-TL has applied a tap-coupling technique, and one tap-coupled stub is loaded with the left-handed (LH) circuit. Attenuation poles are generated when the input susceptance of the stub diverges. In the tap-coupled CRLH-TL resonator, the attenuation pole is controlled at either the desired lower or higher region frequency than a resonant frequency by adjusting the circuit parameters. Also, the BPF constructed by the CRLH-TL resonators is designed based on a filter design theory, where the attenuation poles are located at lower and higher region frequencies than a negative-first-order frequency. The BPF with microstrip structure is fabricated using MEGTRON6 R-5775 ( $$\\varepsilon _\\text {r}$$ : 3.7, h: 0.63 mm, t: 18 μm), chip capacitors, and wire inductors. The simulated results show that the desired characteristics are approximately satisfied, i.e., we can design the CRLH-TL BPF which is controllable for the attenuation poles at both lower and higher region frequencies than a resonant frequency. The measured results are good agreement with the simulation. The negative-first-order frequency is generated at 2.00 GHz with 133 MHz bandwidth, i.e., the fractional bandwidth is 6.65 %. The resonator lengths in the BPF are shortened by 81.5 % and 75.0 % in comparison with a conventional half-wavelength ( $$\\lambda /2$$ ) openstub, and the size of the fabricated BPF is 0.18 $$\\lambda _\\text {g} \\times$$ 0.17 $$\\lambda _\\text {g}$$ . Therefore, a compact BPF with two controllable attenuation poles is realized by the tap-coupled CRLH-TL.","PeriodicalId":100777,"journal":{"name":"Journal of Electrical Systems and Information Technology","volume":"60 1","pages":""},"PeriodicalIF":0.0000,"publicationDate":"2024-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Electrical Systems and Information Technology","FirstCategoryId":"0","ListUrlMain":"https://doi.org/10.1186/s43067-024-00154-0","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
Abstract
Compact and pole-controllable resonators and bandpass filter (BPF) using a composite right/left-handed transmission line (CRLH-TL) are designed in this study. The distributed constant line in the CRLH-TL has applied a tap-coupling technique, and one tap-coupled stub is loaded with the left-handed (LH) circuit. Attenuation poles are generated when the input susceptance of the stub diverges. In the tap-coupled CRLH-TL resonator, the attenuation pole is controlled at either the desired lower or higher region frequency than a resonant frequency by adjusting the circuit parameters. Also, the BPF constructed by the CRLH-TL resonators is designed based on a filter design theory, where the attenuation poles are located at lower and higher region frequencies than a negative-first-order frequency. The BPF with microstrip structure is fabricated using MEGTRON6 R-5775 ( $$\varepsilon _\text {r}$$ : 3.7, h: 0.63 mm, t: 18 μm), chip capacitors, and wire inductors. The simulated results show that the desired characteristics are approximately satisfied, i.e., we can design the CRLH-TL BPF which is controllable for the attenuation poles at both lower and higher region frequencies than a resonant frequency. The measured results are good agreement with the simulation. The negative-first-order frequency is generated at 2.00 GHz with 133 MHz bandwidth, i.e., the fractional bandwidth is 6.65 %. The resonator lengths in the BPF are shortened by 81.5 % and 75.0 % in comparison with a conventional half-wavelength ( $$\lambda /2$$ ) openstub, and the size of the fabricated BPF is 0.18 $$\lambda _\text {g} \times$$ 0.17 $$\lambda _\text {g}$$ . Therefore, a compact BPF with two controllable attenuation poles is realized by the tap-coupled CRLH-TL.