Design and Analysis of Compact UWB Bandpass Filter with Wide Passband Using Defected Ground Structure

A compact ultra-wideband (UWB) bandpass filter (BPF) with wide passband using defected ground structure (DGS) is proposed. The proposed UWB filter is constructed by cascading a high pass filter (HPF) and a lowpass filter (LPF). HPF with short-circuited stubs is used to realize the lower stopband and a LPF is used to attenuate the upper stopband. In order to make the filter size compact, DGS technology is incorporated in the filter design, with this technique the size of filter becomes extremely compact compared with the other UWB bandpass filters in different published papers. In designing the filter integrated with DGS, four rectangular shaped DGS were etched on the ground plane. Furthermore, the bandwidth is enhanced from the original UWB filter, by varying the widths of the rectangular shaped DGS in the ground plane. The BPF is designed with the desired frequency band of 3.1GHz-10.6GHz and a flat group delay across the pass-band. The occupied area of the proposed filter is 22.4mm × 12mm, both simulated and experimental results are provided with good agreement.