A compact dualband bandpass-to-bandstop tunable filter for wireless applications

Abstract

A compact dualband bandpass-to-bandstop tunable filter based on short stub loaded stepped impedance resonators is designed. It uses pin diode for bandpass-to-bandstop filter transformation and varactor diodes for tuning of the center frequency. The filter is designed on Taconic RF-35 substrate to obtain two close dualbands with tuning of center frequencies in the range 1.66–1.88GHz and 1.98–2.29GHz in bandpass mode and dualstops in the range 1.57–1.65GHz and 1.75–1.90GHz in bandstop mode.