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 0.43λ_g × 0.32λ_g, which is the smallest one in the state-of-the-art four-way FPDs.