A Bandstop Filter Based on Modified Defected Ground Structure with Compact Size

This paper reports a compact size bandstop filter using Defected Ground Structure (DGS). The proposed filter consists of squared shaped defect and U-shaped defect sticked on the ground plane. This design is based on a parallel LC circuit model and designed to work at 1 GHz. The filter is implemented on a FR-4 dielectric plate and its size is
$0.049\lambda_{g}\times 0.049\lambda_{g}$
(where
$\lambda_{g}$
is the wavelength in waveguide).