Super-compact ultra-wideband microstrip band-pass filter with improved performance using defected ground structure-based low-pass filter

Abstract

A super-compact ultra-wideband (UWB) microstrip band-pass filter (BPF) with good selectivity and wide stopband is proposed in this paper. The super-compactness along with wide stopband of the proposed filter is achieved by integrating modified multimode resonator-based UWB BPF and defected ground structure (DGS)-based compact low-pass filter (LPF). The LPF structure is designed using four non-uniform configurations of DGS units along with a 50 Ω microstrip line. Each DGS unit is formed by cascading three isosceles U-shaped DGSs. Further, an equivalent RLC circuit model of the LPF is proposed to validate the numerical simulation and experimental results of LPF. The proposed filter has simulated passband frequency range 3–11 GHz with wide stopband: attenuation better than 40 dB and 25 dB over the frequency ranges 11.7–20.5 GHz and 11.2–30 GHz respectively. The experimental results for the proposed filter are nearly in agreement with corresponding numerical simulation results.

Keywords:

• Super-compact
• wide stopband
• ultra-wideband (UWB) band-pass filter (BPF)
• equivalent circuit model
• defected ground structure (DGS)
• low-pass filter (LPF)