Reconfigurable bandstop filter using Defected Ground Structure (DGS)

The paper presents a new compact reconfigurable bandstop filter using Defected Ground Structure (DGS). The proposed reconfigurable bandstop filter is constructed by employing coupled DGS resonators etched in the ground plane. The bandstop filter consists of symmetrical DGS resonators with a microstrip excitation to obtain a bandstop filter response. The reconfigurability is achieved by short circuiting part of the slots etched in the ground plane. A reconfigurable bandstop filter is designed, analyzed, and implemented on Duroid dielectric substrate with 2.2 dielectric constant and 0.78mm thickness. The filter is designed to switch between the two center frequencies 1.40 and 2.25 GHz with approximately 50MHz rejection bandwidth under the condition of 15dB, rejection. The measured results are in good agreement with the simulations.