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A quad‐band bandpass filter using stepped impedance resonators with interdigital capacitors
Author(s) -
Chomtong Pongsathorn,
Akkaraekthalin Prayoot
Publication year - 2018
Publication title -
ieej transactions on electrical and electronic engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.254
H-Index - 30
eISSN - 1931-4981
pISSN - 1931-4973
DOI - 10.1002/tee.22668
Subject(s) - resonator , band pass filter , capacitor , return loss , filter (signal processing) , electronic engineering , acoustics , electrical impedance , impedance matching , insertion loss , materials science , optoelectronics , electrical engineering , computer science , engineering , physics , voltage , antenna (radio)
In this paper, we propose a quad‐band bandpass filter (BPF) based on the characteristics of stepped impedance resonators with interdigital capacitor to control the harmonic frequencies. The design includes two pairs of resonators that have resonant frequencies of 1.8 and 3.7 GHz applied for 4G LTE and Wi‐MAX and 2.45 and 5.5 GHz applied for WLAN systems, respectively. These resonators are connected together using the cross‐coupling technique. Also, multisection ports and stubs are employed for matching at all frequency bands, resulting in an insertion loss of <3 dB and a return loss better than 15 dB. Experimental results of the fabricated filter agree very well with those expected from the simulation. The proposed filter has good performance, while the size of resonator is reduced from λ/2 to λ/8. The proposed filter is very compact and useful for four wireless application bands. © 2018 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.