Development of an Unbalanced-to-Balanced Filtering Power Divider With Sequential Rotation Phase Characteristic

This letter presents a new development of anunbalanced-to-balanced filtering power divider (FPD) withsequential rotation phase states of 0 degrees, 90 degrees, 180 degrees, and 270 degrees atfour output ports. To satisfy the phase requirement at outputports, a fresh insight of 90 degrees phase-shifting characteristic isbrought from the perspective of electric field distributions on theopen- and short-circuited transmission line (TL) models. Buildingupon this phase-shifting concept, an unbalanced-to-balancedFPD for application in sequential rotation feeding network ispresented, which obviously distinguishes from the conventionalmethod of cascading multiple discrete devices. To verify theproposed concept, a design example is excogitated and measured.The results show that the aforementioned phase states withequal amplitude are successfully achieved at four output ports.Meanwhile, the developed FPD also exhibits phase bandwidth of37% and impedance bandwidth of 8.5%, regarding the criterionof better than 15-dB return loss.