A circuit prototype for the design of side and in-line coupled cavity filters in waveguide

This paper presents a new circuit prototype suitable for modelling filters of the topology, where cavities are coupled to each other either by in-line or side elements. The parameters of the new prototype are explicitly derived from those of a standard in-line filter, which is assumed as reference. The new configuration maintains same response, while the correspondence between circuit parameters and physical structure is one-to-one and of immediate interpretation. A practical example shows the usefulness and accuracy of the proposed prototype.