A real frequency approach to describe lossless two-ports formed with mixed lumped and distributed elements

Summary The design of microwave filters, matching networks, amplifiers, that is the “Broadband Networks” with mixed lossless lumped and distributed elements, has been a significant concern of the circuit theoreticians of the field. Yet, there has been no complete practical solution introduced in the literature so far. In this paper, an attempt has been made to design broadband networks constructed with a cascade connection of low pass LC ladders connected with commensurate transmission lines. The new design procedure is based on the two-variable description of the Simplified Real Frequency Technique. Up to five mixed-elements explicit equations are given to describe some selected network topologies. In general, synthesis is carried out employing a decomposition technique first introduced by Alfred Fettweis. A “Double Matching Design” exampleis presented to exhibit the merits and the application of the new approach.