Using intentionally mismatching method

ABSTRACT A new ring hybrid is proposed which we call the double ring hybrid. The double ring hybrid is implemented by cascading two branch line hybrids that have intentionally mismatched port impedances between branch line hybrids. The proposed double ring hybrid using two quadrature branch line hybrids not only has the same function as that of the conventional ring hybrid, but also has output ports in the same direction, since the isolation port is located on the opposite side of the output ports. Thus, unlike the conventional ring hybrid, the proposed double ring hybrid may be able to realize cascaded planar structures. The design equations are derived from the concept of the intentionally mismatched port impedances. The proposed double ring hybrid, regardless of whether the two branch line hybrids are connected, has a 12% reduced area compared to the conventional ring hybrid. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:638–642, 2016