Design of compact diplexer with novel matching network using cascaded quadruplet filters

Abstract

ABSTRACTThis letter reports a new kind of matching network to design diplexer. The matching network is comprised by two open‐circuited and one short‐circuited transmission lines. By properly adjusting the input admittance of the matching network, each channel of the diplexer can be designed independently. Therefore, the diplexer can be easily realized by the connection of different bandpass filters without further tuning. Moreover, the proposed matching network occupies little place, and thus the size of the diplexer is mostly determined by the filters. Systematic design procedure for the network is fully presented in this letter. To illustrate the concept, a diplexer is designed, fabricated, and measured. Simulated and measured results are found to be in good agreement with each other. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:315–318, 2017