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

Abstract

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 0.4λg × 0.07λg 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 (|BW20dB/BW3dB|) of 1.28, which indicates high frequency selectivity.