A novel bandpass filter (BPF) based on spoof surface plasmon polaritons (SSPPs) using a compact folded slotline structure is proposed and experimentally demonstrated.The proposed novel SSPPs structure compared with a conventional plasmonic waveguide with slot line SSPPs unit structure at the same size,the considerable advantages in much lower asymptotic frequency with tight field confinement,which enable the proposed filter to be more miniaturization.A high-efficient mode conversion structure is designed to transition from TE-mode to SSPPs-mode by gradient slotline lengths.The low-frequency stop-band can be committed with microstrip to slotline evolution on both sides of the dielectric,while the high-frequency cutoff band is realized by the proposed SSPPs structure.The influence of dispersion relation,electric field distribution,surface current,and structural parameters on the transmission characteristics of the proposed BPF are analyzed by finite difference time domain (FDTD).To validate the design concept,the prototype of the miniaturized SSPPs BPF has been manufactured and measured.The experimental results show high performance of the fabricated sample,in which the working in a range of 0.9 GHz-5.2 GHz with the relative bandwidth is 142％,the insertion loss less than 0.5 dB,the reflection coefficient less than-10 dB,and the group delay is less than one ns.This works provides a mirror for realizing the miniaturization of waveguides,and the application and development of high-confinement SSPPs functional devices in the microwave and THz regimes.

Xue-Wei Zhang;Shao-Bin Liu;Ling-Ling Wang;Qi-Ming Yu;Jian-Lou;Shi-Ning Sun

College of Electronic and Information Engineering,Key Laboratory of Radar Imaging and Microwave Photonics,Ministry of Education,Nanjing University of Aeronautics and Astronautics,Nanjing 211106,China;AVIC Research Institute for Special Structures of Aeronautical Composite,Aviation Key Laboratory of Science and Technology on High Performance Electromagnetic Windows,Jinan 250023,China

中国物理B（英文版）

[1]Xue-Wei Zhang;Shao-Bin Liu;Ling-Ling Wang;Qi-Ming Yu;Jian-Lou;Shi-Ning Sun-.High-confinement ultra-wideband bandpass filter using compact folded slotline spoof surface plasmon polaritons)[J].中国物理B（英文版）,2022(01):292-300

slotline

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