Compact Wideband High-Selectivity Filtering Power Divider Using Four-Coupled-Lines

In the paper, a compact wideband filtering power divider (FPD) with high frequency selectivity is presented, which is merely based on the four-coupled-lines (FCLs) and isolated resistors.Since the FCL with diagonal short-circuited of input port has filtering response, an FPD without adding extra resonators can be easily realized.Further, two types of FCLs are cascaded as multi-mode resonators for bandwidth enhancement, and two resistors are added for isolation improvement.For validation, a 3-dB prototype with a size of 0.4 g 0.07 g is implemented.Measurements show that the proposed FPD has a fractional bandwidth of more than 80%.Besides, the stopband rejection is over 35 dB with a rectangle coefficient (|BW 20dB /BW 3dB |) of 1.28, which indicates high frequency selectivity.