Design of a compact planar UWB filter for wireless communication applications

An ultra-wideband (UWB) bandpass filter (BPF) for wireless communications is proposed in this paper. The BPF contains a stepped impedance resonator (SIR) and an improved split-ring resonator defected ground structure (SRR DGS). Both measurement and simulation are very matched and indicate that the proposed BPF achieves good characteristics with flat insertion loss less than 1 dB, and good return loss less than -15 dB respectively over the whole band of 3.1 to 10.6 GHz, attenuation higher than 20 dB and 15 dB to the lower stopband and the upper stopband, respectively. It only occupies a small area of 10 × 15 mm² and consumes no power.