A new adaptive prototype for the design of side-coupled coaxial filters with close correspondence to the physical structure

This paper presents a novel kind of circuit prototype suitable for modeling of coaxial cavity filters, where all cavities are coupled sidewise. Initially, the parameters of the prototype are explicitly derived from those of the classical Cohn´s inline filter, which is assumed as the starting point. The main feature of the proposed adaptive model is its one-to-one correspondence to the physical structure, making design feasible without additional optimizations or expensive tuning. Another feature lies in that the prototype is adapted to the structure along the way in the synthesis process. A practical example shows the merits and the accuracy of the proposed prototype. The relationships between the proposed method and existing techniques are also discussed.