Open AccessCompact microstrip lowpass filter with ultra‐wide stopband based on dual‐plane structure
Author(s) -
Jiang Shu,
Xu Jinping
Publication year - 2017
Publication title -
electronics letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.375
H-Index - 146
eISSN - 1350-911X
pISSN - 0013-5194
DOI - 10.1049/el.2017.0637
Subject(s) - stopband , passband , transition band , microstrip , elliptic filter , return loss , low pass filter , materials science , cutoff frequency , resonator , ground plane , insertion loss , optics , band stop filter , bandwidth (computing) , physics , acoustics , optoelectronics , band pass filter , prototype filter , telecommunications , engineering , antenna (radio)
A microstrip lowpass filter (LPF) with ultra‐wide stopband suppression and compact size based on dual‐plane structure is presented. The LPF is composed of high‐impedance resonators loaded by folded patches on the topside plane, combined with hybrid slot and step‐impedance resonators on the ground plane. Multiple transmission zeros are created in the stopband region by different resonators. Thus, an ultra‐wide stopband with 11th‐harmonic suppression is achieved. A demonstration filter with 3 dB cutoff frequency ( f c ) at 2.45 GHz has been designed, fabricated and measured. Results show that the relative stopband bandwidth is 163.8% with attenuation level of 20 dB. The insertion loss is lower than 0.3 dB and the return loss is better than 17 dB in the passband. The size of the LPF is only 8.90 mm × 8.93 mm, which corresponds to 0.115 λ g × 0.116 λ g ( λ g is the guided wavelength at f c ).