A novel Wideband (WB) Bandpass Filter (BPF) with improved passband performance using a Defected Ground Structure (DGS) is presented in this paper. The proposed BPF is composed of two novel basic WB resonators and six Dumbbell-Shaped (DS) DGSs. By cascading resonators we can achieve better skirt characteristics, and by using DS-DGSs under interdigital coupled I/O lines we can improve the return loss within the passband. The simulated and measured results are found in good agreement with each other showing a wide passband from 4.93 to 11.62 GHz, a wide upper stopband with around 25 dB attenuation up to 20 GHz, and sharp roll-offs around 0.03 in lower and upper edges.
