A Wideband and Compact EBG Structure With a Circular Defected Ground Structure

We propose a new analysis method to determine the bandgap characteristics of an electromagnetic bandgap structure with a defected ground structure (DGS). The proposed method is based on a 1-D segmented transmission line model and a piecewise linear approximation of Zo within a unit cell. Although the previous method is only applicable to rectangular DGSs (RDGSs), the proposed method is applicable to any DGS shapes. As an example, the proposed method is applied to a circular DGS and shows a good agreement with full-wave simulations of the unit cell and measurements of 11 × 11 unit cells. The circular DGS achieves a 15% improvement in the stopband bandwidth over the RDGS with the same perforation area. The proposed method allows us to explore a variety of DGS shapes in the search for better stopband characteristics. It also offers the basis for numerical optimization techniques to be used in synthesizing DGS shapes to meet required stopband characteristics.