Design procedure for coaxial combline filters based on segmentation and space mapping strategies

This paper presents a new procedure for the design of coaxial combline filters, allowing to obtain the real filter dimensions providing the desired frequency response in reduced times. It combines the traditional synthesis procedure based on segmentation with a space mapping strategy to compensate the deviations on the coupling matrix elements. A combline filter providing the desired response can be obtained after very few iterations. Two combline structures, namely, an in-line 6
^th
order filter and a 4
^th
order quadruplet with two symmetrical transmission zeros, has been designed following such technique. The results show the capabilities of the proposed procedure.