Ultra-wideband surface plasmonic bandpass filter with extremely wide upper-band rejection  

作　　者：Xue-Wei Zhang Shao-Bin Liu Qi-Ming Yu Ling-Ling Wang Kun Liao Jian Lou 张雪伟;刘少斌;余奇明;王玲玲;廖昆;娄健(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)

机构地区：[1]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

出　　处：《Chinese Physics B》2022年第11期303-308,共6页中国物理B（英文版）

基　　金：Project supported by the National Natural Science Foundation of China(Grant Nos.U2141232,62071221,and 62071442);the Aeronautical Science Foundation of China(Grant No.2019ZA037001)。

摘　　要：An ultra-wideband bandpass filter(BPF)with a wide out-of-band rejection based on a surface plasmonic waveguide(SPW)slotline with ring grooves is designed and analyzed.A paired microstrip-to-slotline transition is designed for quasiTEM to TM mode conversion by using a microstrip line with a circular pad and the slotline with the same circular slot.The mode conversion between the TM and the surface plasmon polariton(SPP)mode is realized by using a gradient slotline with ring grooves and an impedance matching technique.The upper cut-off frequencies of the passband can be adjusted by using these proposed SPP units,while the lower frequencies of the passband are created by using the microstrip-toslotline transitions to give an ultra-wideband BPF.The dispersion curves of SPP units,electric field distribution,and the transmission spectra of the proposed ultra-wideband bandpass filter are all calculated and analyzed by the finite-difference time-domain(FDTD)method.The simulated results show that the presented filter has good performance including a wide3-dB bandwidth of 149%from 0.57 GHz to 3.93 GHz,an extremely wide 40-dB upper-band rejection from 4.2 GHz to18.5 GHz,and low loss and high selectivity in the passband.To prove the design validity,a prototype of the BPF has been manufactured and measured,showing a reasonable agreement with simulation results.The unique features of the proposed BPF may make it applicable for integrated circuit and plasmonic devices in microwave or THz frequency ranges.

关 键 词：surface plasmonic waveguide(SPW) bandpass filter out-of-band rejection ULTRA-WIDEBAND 

分 类 号：TN713.5[电子电信—电路与系统]