A two-layer stripline configuration for cascaded trisection bandpass filters

A two-layer stripline configuration for cascaded trisection (CT) bandpass filter is proposed to realize wider fractional bandwidth and higher center frequency. In this configuration, resonators are located alternatively on two different planes to allow strong overlapped coupling between adjacent resonators, and stripline structure enables resonators with higher resonant frequency to be used in the construction of CT bandpass filters. To prove the feasibility of this configuration, a five-pole CT bandpass filter with 10-GHz center frequency and 13% fractional bandwidth is designed with this method and simulated on Ansys HFSS 15.0. The simulation results illustrate that this configuration can realize wider fractional bandwidth as well as higher center frequency compared with traditional planar microstrip configurations.