Miniaturized Wideband Unequal Four‐Way Filtering Power Divider Using Asymmetric Three‐Coupled Lines

ABSTRACT For the first time, a miniaturized wideband four‐way unequal filtering power divider (FPD) based on asymmetric three‐coupled lines (A‐TCLs) is proposed. Two stepped‐impedance resonators (SIR) are loaded on the A‐TCL for enhancing the frequency selectivity and out‐of‐band rejection. Besides, two types of resistors are loaded for good output impedance matchings and isolations. Design equations are derived by combining the methods of even‐odd mode decomposition and voltage‐current analysis. For validation, a prototype with a power division ratio of 1.8:1:1:1.8 is designed. Measurements show that an overlapped bandwidth of more than 60% is obtained with low insertion loss, large out‐of‐band rejection and high frequency selectivity. In addition, the overall size is 0.43 λ g × 0.32 λ g , which is the smallest one in the state‐of‐the‐art four‐way FPDs.