DGS-based UWB microstrip bandpass filter and its equivalent circuit

In this paper, the development of defected ground structure (DGS) based ultra-wideband (UWB) microstrip bandpass filter (BPF) and its equivalent circuit are proposed. The use of DGS is aimed to enhance the characteristic of filter and other microwave devices as well. The proposed BPF which is designed on a 0.8mm thick FR4 epoxy dielectric substrate with the dimension of 32mm × 11mm is constructed of microstrip coupled lines and open stubs with DGS underneath. Meanwhile, the used DGS is built from 3 circular dumbbells. The equivalent circuit of BPF comprises of lumped elements of inductor and capacitor and is performed using EM & Circuit simulator. From the characterization, the measured result is agreed qualitatively with the simulated result of equivalent circuit. The characteristic of realized BPF which is comparable with the simulation result has -3dB working bandwidth of 5.36GHz in the frequency range of 1.84GHz to 7.2GHz.