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Compact second‐order dual‐ and quad‐band bandpass filters using asymmetrical stub‐loaded resonator and uniform‐impedance resonator
Author(s) -
Xu Jin
Publication year - 2015
Publication title -
microwave and optical technology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.304
H-Index - 76
eISSN - 1098-2760
pISSN - 0895-2477
DOI - 10.1002/mop.28992
Subject(s) - passband , resonator , stopband , band pass filter , stub (electronics) , multi band device , microstrip , microwave , optoelectronics , materials science , electrical impedance , return loss , transition band , physics , electronic engineering , optics , electrical engineering , acoustics , prototype filter , telecommunications , engineering , filter (signal processing) , low pass filter , antenna (radio)
In this article, a second‐order dual‐band bandpass filters (BPF) operating at 1.8 GHz GSM and 5.2 GHz WLAN is first proposed by using asymmetrical stub‐loaded resonators (SLRs). Then, a set of half‐wavelength resonators (HWRs) are embedded into asymmetrical SLRs to produce a passband at 3.5 GHz, and the other set of HWRs are coupled with high‐impedance parallel coupling microstrip lines to generate a passband at 6.8 GHz, so that a second quad‐band BPF is successfully designed. The fabricated dual‐band BPF and quad‐band BPF have compact sizes of 0.052λ g × 0.17λ g and 0.054λ g × 0.195λ g , respectively. In addition, high band‐to‐band isolation, good in‐band return loss, and wide stopband can be also observed. Good agreement is shown between the simulated and measured results. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:997–1003, 2015