Analysis of Dumbbell Shaped Defected Ground Structure with Low-Pass Filter at X-Band for Radar Application

Abstract

In this paper, an improved periodic defected ground  structure (DGS) with low-pass filter at X-band is analyzed. The dumbbell shaped DGS which are etched at the ground plane is chosen for this analysis. Initially, a filter is designed and simulated using identical DGS, and equally sized. By varying empirically the sizes of the DGS, an improved frequency response was obtained. So as to validate the performances of the proposed changes in the filter, simulation process was implemented between the uniform periodic DGS and the improved non uniform periodic DGS circuit. The result indicates the latter has better performance in the stopband with good transition band and suppressing ripples. The dumbbell shaped DGS with low-pass filter designed at cutoff frequency of 10 GHz, which is suitable for X-band in general and radar applications in particular. The equivalent circuits for the proposed dumbbell shaped DGS with low-pass filter and its matching LC parameters are given. The improved and proposed DGS with low-pass filter provides a size of 18 × 7 mm² was fabricated. The measurement results show agreeable consistency with the simulated results.