Coupling topologies for realizing compact microwave diplexers with dual-mode cavities

In this work, two topologies for realizing compact microwave diplexers in dual-mode cavities are presented. The first topology is a classical one, where the common port is coupled to two resonators in separate paths. The second topology is original because of the excitation of a single resonator by the common port. The interest of the second topology is demonstrated on dual-mode cavity diplexers by eliminating spurious cross-polarized modes which appear when using a classical topology. The proposed topologies have been validated by the design of coupled dual-mode cavity diplexers for satellite applications.