Wideband three section branch line coupler using triple open complementary split ring resonator and open stubs

This paper presents the design of a wideband three section branch line coupler using three cascaded open complementary split ring resonator structures and open stubs connected between them. The slow wave effect offered by the open complementary split ring resonator is utilized to achieve size reduction. The low impedance lines of the conventional three section branch line coupler are replaced by the proposed structure which is 50–52% less in length. The fabricated prototype gives a bandwidth of 53% and occupies an area of 17.46% of the conventional one.