Compact Dual-Band Balanced-to-Unbalanced Filtering Power Divider Design With Extended Common-Mode Suppression Bandwidth

Abstract

In this letter, a compact dual-band balanced-to-unbalanced filtering power divider (FPD) is proposed, which is implemented by using a pair of U microstrip lines (MLs) and short-ended stepped-impedance resonators (SESIRs). Under different excitations of differential-mode (DM) and common-mode (CM) signals, different coupling between U ML feeder and SESIRs can be achieved, which accordingly realizes efficient DM transmission and CM suppression in the whole band. Peculiarly, dual differential passbands with high-frequency selectivity performance are realized through the hybrid electric–magnetic coupling between folded SESIRs. In addition, good single-port matching and in-band isolation are achieved by introducing a matching branch and an isolation resistor. For verification, a prototype with center frequencies at 2.46 and 5.19 GHz, respectively, is fabricated and measured, which exhibits good consistency with the simulated results.