A compact enhanced-bandwidth hybrid ring using an artificial lumped-element left-handed transmission-line section

A new type of compact enhanced-bandwidth hybrid ring using an artificial lumped-element left-handed (LH) transmission-line (TL) section is proposed. The replacement of the 270/spl deg/ branch of the conventional hybrid ring by a -90/spl deg/ LH-TL branch results in both size reduction and bandwidth enhancement. The working principle of the LH TL used in the hybrid ring is explained and the performances of the component are demonstrated by measurement results. The proposed hybrid exhibits 67% size reduction compared to the conventional one, and shows a 58% and 49% bandwidth enhancements at 2 GHz in the 180/spl deg/-out-of-phase and in-phase operations, respectively.