Compact and Narrow-Band Bandpass Filter Using Spoof Surface Plasmon Polaritons

• Published in: IEEE photonics technology letters Vol. 33; no. 13; pp. 676 - 679
• Main Authors: Liu, Leilei, Hu, Yangjun, Li, Ruo-Zhou, Zhang, Qingfeng, Zhu, Lei
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.07.2021; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Band-pass filters; bandpass filter; Bandpass filters; Bandwidth; Bandwidths; controllable central frequency and bandwidth; Coupling; Couplings; Dispersion; Dispersion curve analysis; Microwave filters; Optical filters; Passband; Polaritons; Rejection; Spoof surface plasmon polariton (SSPP); Transmission lines
• ISSN: 1041-1135; 1941-0174
• DOI: 10.1109/LPT.2021.3085580

This letter presents a novel narrow-band bandpass spoof surface plasmon polarition (SSPP) filter, which has a controllable passband, good rejection, and a compact structure. It is composed of two end-extending SSPP transmission lines and a pair of L-shaped coupling branches. Both the bandwidth and the central frequency can be adjusted by changing the depth of the SSPP unit and the length of SSPP transmission line behind the coupling branches. The dispersion curves of the SSPP unit are analyzed, and the influences of some structural parameters are investigated. A SSPP band-pass filter is fabricated and measured based on the proposed method, showing a wide 3-dB fractional bandwidth of 11.2% centered at 6.25 GHz and an out-of-band rejection below −15 dB within 1-10 GHz. The measured result shows good agreement with the simulated one.