Effects of defected ground structure slot tuning on frequency and circuit parameters of bandpass filter

In this paper the effect of the slot area to an end-coupled bandpass filter (BPF) is presented. The defected ground structure (DGS) technique is applied in the ground plane to accomplish the resonant frequency tuning of the filter. To achieve the passband the slot is designed with the etched DGS pattern consisting of two identical square-loops having open-loop edge height, h together with open-ends, g and a slot-line, d which forms connection between them. The proposed dumbbell shaped DGS is used to tune the bandpass filter down to 2.4 GHz with dimension of 40 mm × 20 mm. The gap, g, is kept constant at 0.4 mm, and w is varied. A wide tuning range of 1.31 GHz is achieved by tuning the …