Compact Dual-Wideband BPF Based on Quarter-Wavelength Open Stub Loaded Half-Wavelength Coupled-Line

摘要

In this paper, a novel dual-wideband bandpass filter (BPF) is presented by using quarter-wavelength open stub loaded half-wavelength coupled-line. Equivalent voltage-current analysis method is applied to analyze this structure, which shows it has two tunable transmission zeros and dual-wideband frequency response. As an example, a dual-wideband BPF covering 1.228/1.57/6.8 GHz for GPS (Link 1 and Link 2) and RFID applications is designed, fabricated and measured. The fabricated filter has a compact size of 0.043 lambda(g) x 0.213 lambda(g). The measured results show that the fabricated filter has the merits of low insertion loss, good return loss and high band-to-band isolation. The proposed dual-band BPF also has a very simple physical topology and quick design procedure.