High‐selectivity wideband four‐way filtering power divider with input absorptive feature

Abstract

In the paper, a high‐selectivity wideband four‐way filtering power divider with input absorptive feature is presented. It consists of two parallel‐coupled lines (CLs), two three‐coupled lines (TCLs), two open‐ended stepped branches, one absorptive branch, and two isolation resistors. The wideband filtering response is achieved by cascading the TCLs and CLs. While high selectivity is obtained by loading the open‐ended stepped branch, where two extra transmission zeros are generated. In addition, wide absorptive bandwidth with good isolations between adjacent output ports are realized by combining the absorptive branch with the isolation resistors. Equations are derived by using the two‐parity mode analysis, and main parameters are investigated in detail. For validation, a prototype was designed and fabricated. Test results show that the 3‐dB FBW can reach 87% with a 10‐dB input absorptive FBW of 200%. Besides, for the output ports with 10‐dB return loss and 10‐dB isolation, the FBWs are 94% and 91.5%, respectively. It also features high frequency selectivity and low insertion loss.