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.

[1]  T. Itoh,et al.  Application of the transmission line theory of left-handed (LH) materials to the realization of a microstrip "LH line" , 2002, IEEE Antennas and Propagation Society International Symposium (IEEE Cat. No.02CH37313).

[2]  R. Shelby,et al.  Experimental Verification of a Negative Index of Refraction , 2001, Science.

[3]  Tatsuo Itoh,et al.  Dominant mode leaky-wave antenna with backfire-to-endfire scanning capability , 2002 .

[4]  V. Veselago.  The Electrodynamics of Substances with Simultaneously Negative Values of ∊ and μ , 1968 .

[5]  T. Itoh,et al.  Transmission line approach of left-handed (LH) materials and microstrip implementation of an artificial LH transmission line , 2004, IEEE Transactions on Antennas and Propagation.

[6]  G. Eleftheriades,et al.  Negative refractive index metamaterials supporting 2-D waves , 2002, IEEE MTT-S International Microwave Symposium Digest.

[7]  R. W. Vogel,et al.  Analysis and design of lumped- and lumped-distributed-element directional couplers for MIC and MMIC applications , 1992 .

[8]  T. Itoh,et al.  Novel microwave devices and structures based on the transmission line approach of meta-materials , 2003, IEEE MTT-S International Microwave Symposium Digest, 2003.

[9]  T. Itoh,et al.  A branch-line coupler with two arbitrary operating frequencies using left-handed transmission lines , 2003, IEEE MTT-S International Microwave Symposium Digest, 2003.

[10]  Willie J Padilla,et al.  Composite medium with simultaneously negative permeability and permittivity , 2000, Physical review letters.

[11]  T. Itoh,et al.  A broadband left-handed (LH) coupled-line backward coupler with arbitrary coupling level , 2003, IEEE MTT-S International Microwave Symposium Digest, 2003.

[12]  Masahiro Muraguchi,et al.  Reduced-size branch-line and rat-race hybrids for uniplanar MMIC's , 1990 .

[13]  Kai Chang,et al.  Wide-band reduced-size uniplanar magic-T, hybrid-ring, and de Ronde's CPW-slot couplers , 1995 .