A Vertically Stacked Quasi-Elliptic Waveguide Filter with Crossly Coupling Vias

This paper proposes a four-pole quasi-elliptic waveguide filter using multilayer low-temperature cofired ceramic (LTCC) technology. The cavities of the filter can be stacked vertically, while a pair of through hole vias are used to realize the cross coupling path for the quasi-elliptic response. Thus, the circuit size can be reduced by the overlap of the cavity resonators. The proposed filter has 20% size reduction in comparison with a conventional four-pole quasi-elliptic waveguide filter.