3-dB Filtering Power Dividers With Quasi-Reflectionless Behavior at All Their Ports

A class of multi-functional 3-dB filtering power dividers (FPDs) with quasi-absorptive capabilities at all their ports is reported. To this aim, resistively-terminated bandstop-filter (BSF) branches with complementary transfer function with regard to the one of the bandpass-filter (BPF) arms are connected at all the FPD ports. In this manner, the generation of out-of-band RF-signal power reflections that can deteriorate the operation of adjacent actives stages is avoided through their dissipation in the loading resistors of these BSF branches. The design-parameter values for first-to-third-order input/output-quasi-reflectionless FPD realizations are provided. Furthermore, guidelines to control their operational bandwidth are detailed. For experimental-demonstration purposes, microstrip prototypes of a frequency-tunable first-order FPD and a static second-order FPD are manufactured and characterized.