Dual-band bandstop filter using single tri-section stepped impedance open stub

摘要

In this paper a dual-band bandstop filter using tri-section stepped impedance open stub configuration is presented. Transmission zero positions ( i.e stopbands ) can be controlled by tuning the impedances of the shunt tri-section stepped impedance unit and the series transmission line impedance is used to allocate the transmission poles to sharp the attenuation rate. Design equations were derived using lossless transmission line model. The simulated filter is fabricated using Roger/RT duroid 5870 substrate with thickness of 0.787mm and dielectric constant of 2.33. Good agreement between simulated and measured results is observed.