A New Structure of Coupled Transmission Line Filters

A new structure of staggered coupled transmission line filters having about half the length of a conventional design is presented. Two topologies are presented, one including short circuits and quarter wavelength resonators, and other having bent half-wavelength resonators coupled to the adjacent ones only in half their total length. Synthesis formulas are given for the case of TEM lines (such as stripline) and a simple optimization procedure is proposed for inhomogeneous structures (microstrip). Measurements are presented to show that the performance of such filters is as expected from the synthesis procedure.