Open AccessCompact lowpass filter with wide stopband using coupled rhombic stubs
Author(s) -
Zhang Bo,
Li Shaosheng,
Huang Jianming
Publication year - 2015
Publication title -
electronics letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.375
H-Index - 146
ISSN - 1350-911X
DOI - 10.1049/el.2014.3490
Subject(s) - stopband , stub (electronics) , low pass filter , filter (signal processing) , topology (electrical circuits) , transmission line , electronic engineering , materials science , physics , optics , band pass filter , computer science , engineering , electrical engineering , telecommunications
A compact and high selective lowpass filter (LPF) with wide stopband is presented using coupled rhombic stubs. The proposed LPF unit is constructed by loading a rhombic stub on a transmission line. Then, a folded three‐element LPF is proposed to achieve compact size and high selectivity by introducing coupling between adjacent rhombic stubs. The operating mechanism of the filter is investigated and explained, by adopting the physically‐based LC‐equivalent circuit model. The implemented final LPF exhibits a wide stopband of up to 11.5 f c with a rejection level of better than 35 dB. Furthermore, the final LPF features a compact size of 0.12 λ g × 0.10 λ g , where λ g is the guide wavelength of f c , and a very high figure‐of‐merit (FOM) of 27 142.