A Dual-Band Balanced-to-Balanced Power Divider With High Selectivity and Wide Stopband

A dual-band balanced-to-balanced (BTB) filtering power divider (FPD) is presented, which can achieve an in-phase power division with high selectivity. The proposed FPD is composed of microstrip-to-slotline transition structures (MTSTSs), T-shaped slotline, and multiple stub-loaded resonators (SLRs). A dual-band differential-mode (DM) response with a steep filtering performance is generated by employing SLRs. By adjusting the electrical lengths of SLRs and the gaps between each resonator and microstrip lines, the fractional bandwidth (FBW) is controllable. By introducing slotline resonators loaded with surface-mounted resistors, the isolation between the two output ports is increased. Meanwhile, a wide DM stopband with a high rejection level is obtained. Moreover, good wideband common-mode (CM) suppression is achieved intrinsically, thereby simplifying the design procedure greatly. To verify the theoretical prediction, one FPD prototype is fabricated. A good agreement between the simulated and measured results is observed. To the best of authors' knowledge, the proposed dual-band BTB FPD is first ever reported.