title: A compact bandpass filter with enhanced stopband characteristics by an asymmetric cross-shape defected ground structure.
abstract: In this paper, we present an effective technique to enhance stopband bandwidth for a bandpass filter by using an asymmetric, cross-shape defected ground structure (CSDGS). A single CSDGS can provide a higher attenuation rate near passband and broader stopband bandwidth. Moreover, with the asymmetric CSDGS, two different resonant frequencies can be excited and controlled independently, resulting in synthesizing a passband. The synthesized bandpass filter can be modeled by parallel LC resonant circuits in connection with T-networks. The bandwidth and insertion loss of this bandpass filter at 4.2 GHz is 28.6% and -1.44 dB, respectively, and 20 dB rejection in the stopband is up to four times the central frequency. All the synthesized bandpass filters have been measured and are in good agreement with simulated results.
authors.forename: Han-Jan
authors.initials: HJ
authors.lastname: Chen
authors.forename: Tsung-Hui
authors.initials: TH
authors.lastname: Huang
authors.forename: Chin-Sheng
authors.initials: CS
authors.lastname: Chang
authors.forename: Lih-Shan
authors.initials: LS
authors.lastname: Chen
authors.forename: Jui-Hong
authors.initials: JH
authors.lastname: Horng
authors.forename: Yeong-Her
authors.initials: YH
authors.lastname: Wang
authors.forename: Mau-Phon
authors.initials: MP
authors.lastname: Houng