LAUSR

A modified quarter-wavelength ( λ /4) stepped-impedance resonator (SIR) is proposed to design a miniature dual-band bandpass filter (BPF). The proposed λ /4 SIR has two individually controllable resonances for constructing dual passbands. Moreover, two independent geometrical parameters are adopted to realise individual adjustment of the coupling strengths between two adjacent λ /4 SIRs at the dual passbands. As a result, both the centre frequencies and bandwidths of the two passbands of the filter can be individually designed. Furthermore, multiple transmission zeros are created by the introduced source-load coupling, which improves highly the selectivity of both passbands. The dual-band BPF is designed at 2.35 and 5.8 GHz, and its simulated and measured responses are presented and show good agreement.