Synthesis of miniaturized wideband four-way filtering power divider consisting of unequal-width three-coupledlines

摘要

A miniaturized wideband four-way filtering power divider (FPD) is presentedin this article. It is composed of unequal-width three-coupled-lines (TCLs),stepped-impedance open-circuited stubs, and isolation resistors. By using twogroups of the unequal-width TCLs and the stepped-impedance open-circuitedstubs, size reduced four-way FPD with wideband filtering responses and outof-band rejection is realized. Besides, good output ports matching and isolationare obtained by inserting two types of air-bridge resistors. In the theoreticalanalysis section, the impedance matrix of the unequal-width TCL is introduced,for the first time, and rigorous closed-form design equations for the proposedFPD are also derived. Moreover, the methodology for computer-aideddesign is given based on the design equations. For demonstration, a prototypeoperating at 1.5 GHz is designed, fabricated, and measured. The measuredresults validate the 80% bandwidth with more than 17 dB out-of-band rejection,more than 14 dB isolation and more than 15 dB return loss at all outputports. Compare with the reported four-way FPD with similar bandwidth, a sizereduction of 74% is obtained.