Compact Multi-Mode Filtering Power Divider with High Selectivity, Improved Stopband and In-band Isolation

This letter presents a new compact multi-mode filtering power divider (FPD) design based on co-shared FPD topology with sharp frequency selectivity, improved out-of-band harmonic rejection and port-to-port isolation. Power splitting and quasi-elliptic filtering functions are achieved by masterly integrating only one triple-mode resonator. By loading different open-circuited stubs at the input/output ports, multiple additional transmission zeros (TZs) are generated at both lower and upper stopband, resulting in an improved stopband performance. Meanwhile, a better port-to-port isolation is obtained by adopting frequency-dependent resistor-capacitor parallel isolation network. The proposed multi-mode FPD design stands out from those in the literature by both nice operation performance and compact topology with only one resonator. For demonstration purposes, one triple-mode FPD prototype and its improved one are implemented, respectively. Measured results exhibit the superiority of the FPD design.