Sharp-rejection bandstop filter based on signal interference technique integrating with conventional open stubs

摘要

A novel sharp-rejection bandstop filter (BSF) based on signal interference technique integrating with conventional open stubs is proposed in this letter. The two paths are constructed by embedding a U-shaped short-circuited stepped-impedance resonator (SIR) structure in the traditional BSF with open stubs. The impedance ratio of the SIR can be tuned to control the bandwidth of the BSF. The ripple level and selectivity can be adjusted through regulating transmission lines impedance and the coupling coefficient. Four transmission zeros with sharp-rejection can be realized. The BSF is verified by circuit implementation and good agreement between the simulated and measured results can be observed.