Dual-Mode Ring Bandpass Filter Using Defected Ground Structure with a Wider Stopband

Ru Yuan YANG
Min Hung WENG
Hung Wei WU
Tsung Hui HUANG
Han-Ding HSUEH
Mau-Phon HOUNG

IEICE TRANSACTIONS on Electronics   Vol.E87-C    No.12    pp.2150-2157
Publication Date: 2004/12/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Microwaves, Millimeter-Waves
dual-mode,  bandpass filter,  defect ground structure (DGS),  bandgap,  

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This paper proposes a novel dual-mode ring bandpass filter (BPF) using defect ground structure (DGS). The proposed filter provides wide stopband characteristic resulted from the bandgap characteristic of DGS for suppressing spurious response of the dual-mode ring BPF. The H shaped DGS cell is modeled as a parallel LC resonator and the equivalent circuit parameters are extracted. The relationship between bandgap characteristic and design parameters of DGS dimension is discussed and the bandgap characteristic of DGS on the filter performance is also investigated. The novel proposed filter has the frequency characteristics with a central frequency f0 = 7.7 GHz, a 3-dB bandwidth of 4.5% and wider stopband from 9 to 15.5 GHz at the level of -35 GHz. Measured results of experimental filter has good agreement with the theoretical simulation results.