Parametric effect of defected ground structure (DGS) on frequency of a bandpass filter

A stepped impedance resonator bandpass filter (SIR BPF) is proposed and designed by placing defected ground structure (DGS) in the ground plane. DGS is used for its property of miniaturizing the size of microwave filter and also improving the mutual coupling between the resonators. The proposed dumbbell shaped DGS is used to tune the bandpass filter to 2.4 GHz with dimension of 28 mm × 30 mm. A wide tuning range of 0.64 GHz is achieved by tuning the height, length and width dimension of DGS unit cell. This filter gives an insertion loss of -0.23 dB, a return loss of -38.03 dB and -3 dB bandwidth of 0.56 GHz. The tuning of SIR bandpass filter, using DGS structure parameters is discussed here. Moreover, the effect of different parameters of DGS on center frequency is shown and discussed with results.