High-Selectivity Reflectionless Unbalanced-to-Balanced Filtering Power Combiner

Abstract

A high-selectivity reflectionless unbalanced-to-balanced (UTB) filtering power combiner is proposed. The proposed power combiner composes of two absorbing branches, two filtering sections, two transmission lines, a grounded resistor, and a phase inverter. Two transmission zeros respectively located at the lower and upper sides of the passband are achieved by the filtering sections, resulting in high selectivity. The input-port reflectionless response in the bandstop region is obtained by the absorbing branch. A 1.0-GHz UTB filtering power combiner is designed and fabricated. Finally, the measurement performances are given in this paper. The input-reflection absorptive bandwidth and transmission bandwidth are measured as 545 MHz and 132 MHz, respectively. The absorptive bandwidth is 4.12 times the transmission bandwidth.