High Selectivity Balanced-to-Unbalanced Filtering Power Divider with Stub-Loaded Dual-Mode Resonators

In this paper, a pair of stub-loaded dual-mode resonators (SL-DMRs) are adopted to design a novel balanced to unbalanced filtering power dividers (BTU FPDs), which has high selectivity performance. The 90° horizontal transmission lines of the conventional BTU PD were replaced by the SL-DMRs to realize filtering responses. Moreover, a pair of parallel coupled-lines are used to feed the SL-DMRs, which not only realize variable bandwidth but also improve the stopband performance. To verify the design method prediction, a prototype is designed, fabricated, and measured. The measured responses are agreement well with the simulations, exhibiting a good performances of frequencies selectivity, isolation and common-mode suppression.