A compact tri-band bandpass filter utilizing double mode resonator with 6 transmission zeros

Abstract

A new compact tri-band bandpass filter (BPF) is presented by utilizing 2 double mode resonators incorporating 6 transmission zeros. The proposed BPF is designed to support GSM-900 (0.83-0.99 GHz), GPS (1.575 GHz), and GSM-1800 (1.88 GHz) bands. The proposed BPF has been configured to operate in corresponding even and odd modes. The generated odd mode frequency band is fixed while the even-mode frequency can be set to the desired value by tuning the stub length which makes it easy to design the multiple BPF. Two transmission zeros are introduced on each side of the passband, and overall 6 transmission zeros have been constructed which make the passband highly selective. The designed BPF has been implemented on Rogers-R03006 and verified with measurement.