Abstract—In this paper a novel C-shaped Defected Ground Structure (DGS) on a microstrip line is proposed to provide a frequency rejection property with an improved Q factor at 2.4 GHz. Compared to the other DGS introduced structures in literature, the new structure has a simple and compact shape and its rejection characteristic is steeper at the stop band than the other reported structures. Different parameters of the DGS have been optimized for the best frequency response to reject the centre frequency. The proposed DGS is successfully designed and fabricated and the measured results are in a very good agreement with the simulated results.