Mixed type branch line coupler designs

Abstract

A mixed type branch line coupler combining T-type and pi-type equivalent circuits and keeping main lines characteristic impedance at 50Ω is reported. The new branch line coupler contains only capacitors and open stubs. Two prototypes of two and three branches are designed, simulated and measured. The size reduction reached 40% comparing with the original circuits. The simulated and experimental results show a good agreement within the frequency of interest.