A New Approach to Design Triple-Band Filtering Power Dividers Based on Coupled Lines

In this letter, a new approach to designing triple-band filtering power divider (FPD) based on coupled lines is proposed. A resistor loaded looped coupled-line structure is utilized to realize the indispensable in-band isolation and power division. Moreover, eight coupled lines that are used in cascaded or loaded ways are imported to introduce multiple transmission zeros (TZs) and transmission poles (TPs) for stopband rejection and multipassband transmission. Four of these coupled lines are also used for controlling bandwidth. Finally, to demonstrate the authors’ design concept, a prototype operating at 2.3, 3.1, and 3.9 GHz with 3-dB fractional bandwidths (FBWs) of 17.4%, 13.0%, and 10.0% is simulated, fabricated, and measured, respectively. The tested results are consistent with the simulation results of electromagnetic simulation software.