DUAL BAND COMBINER ARRANGEMENT

摘要

A dual band combiner for combining two frequency bands having a 2:1 relationship, e.g. 900MHz and 1800MHz. The combiner comprises and upper frequency bandpass filter section and an upper frequency bandstop filter. The bandpass filter section comprises two open-end resonations whose lengths are 1/2 wavelength of the upper frequency band, and the bandstop filter comprises three open-end resonators whose lengths are 1/4 wavelength of the upper frequency band. Because of the 2:1 frequency relationship pronounced selectivity-enhancing transmission zeros are produced at the lower frequency band, thereby providing a combiner that has high isolation between ports while maintaining low insertion loss.