A New Defected Ground Structure for Different Microstrip Circuit Applications

In this paper, a microstrip transmission line combined with a new U-headed dumb-bell defected ground structure (DGS) is investigated. The proposed DGS of two U-shape slots connected by a thin transverse slot is placed in the ground plane of a microstrip line. A finite cutoff frequency and attenuatio...

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Bibliographic Details
Published in:Radioengineering 2007-04, Vol.16 (1), p.16-22
Main Authors: S. Das, S. K. Parui
Format: Article
Language:English
Subjects:
bandpass filter
coupler
Defected ground structure (DGS)
lowpass filter
microstrip
Online Access:Get full text
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Summary:In this paper, a microstrip transmission line combined with a new U-headed dumb-bell defected ground structure (DGS) is investigated. The proposed DGS of two U-shape slots connected by a thin transverse slot is placed in the ground plane of a microstrip line. A finite cutoff frequency and attenuation pole is observed and thus, the equivalent circuit of the DGS unit can be represented by a parallel LC resonant circuit in series with the transmission line. A two-cell DGS microstrip line yields a better lowpass filtering characteristics. The simulation is carried out by the MoM based IE3D software and in the experimental measurements a vector network analyzer is used. The effects of the transverse slot width and the distance between arms of the U-slot on the filter response curve are studied. This DGS is utilized for different microstrip circuit applications. The DGS is placed in the ground of a capacitive loaded microstrip line and a very low cutoff frequency is obtained. The DGS is adopted under the coupled lines of a parallel line coupler and an improvement in coupling coefficient is noticed. The proposed DGS is also incorporated in the ground plane under the feed lines and the coupled lines of a bandpass filter to improve separately the stopband and passband performances.
ISSN:1210-2512