Systematic Synthesis of Synchronous Four Port Filtering Couplers

This paper presents a synthesis methodology for filtering couplers based on canonical cross-coupled resonators. The synthesis methodology establishes a mapping between the transmission line branch line couplers and the canonical cross-coupled resonator networks. Through this mapping the parameters of a filtering coupler network, which is represented as a coupling matrix, can be obtained. Two synthesis approaches of the parameters of the canonical topology are investigated. A design example employing a rectangular waveguide ten pole filtering coupler is presented as a proof of concept to the usefulness of the design methodology in realizing high power filtering coupler networks.