Design method for matching circuits of general multiplexers

A general design method for matching circuits for multiplexers with arbitrary channel bandwidths and interchannel spacing, based on microstrip non-uniform transmission lines is presented. For verification, an universal mobile telecommunications systems/worldwide interoperability for microwave access triplexer with different channel specifications has been designed and fabricated. The proposed triplexer uses one microstrip matching network and three combined hairpin-line filters. The matching network was designed in three different ways and in the third one, three flat passbands and high channels isolation in the frequency band, 1.92-2.69 GHz have been achieved. Measured results are in good agreement with simulated results that verify the accuracy of the design procedure. The comparison of the results of the proposed triplexer with those of the other triplexers clarifies the benefits of the proposed design method.