90° branch‐line Coupler with Reconfigurable Output Power Ratios

This letter introduces a new 90° branch-line coupler with reconfigurable output power ratios (90° BC-ROPR). Unlike a conventional branch-line coupler structure, each arm of the proposed 90° BC-ROPR is defined by an asymmetrically coupled-line, and its characteristic impedance depends on the configuration of the coupled-line. The main problem that challenged this structure was unwanted loop resonance from the inner transmission lines which form a loop in a disconnected configuration. The proposed structure was designed to obtain 1:1 and 4:1 output power ratios at 3 GHz. Both the simulation and measurement results confirm that the proposed branch-line coupler successfully dealt with the loop resonance and achieved excellent performance. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1878–1881, 2013