Tunable asymmetric composite right-/left-handed transmission line directional coupler controlled by applied voltage

A novel electronically-controlled asymmetric directional coupler is presented. This asymmetric structure is composed of a conventional microstrip line and a composite right-/left-handed (CRLH) transmission line incorporating varactors for voltage-controlled operation. Tunable working frequency is achieved as modulating the capacitances of the structure by adjusting the bias voltage applied to the varactors. This directional coupler demonstrates tunable broad bandwidth and tight coupling characteristic by varying the varactors bias voltages from 0V to 12V. Measured and simulated S-parameters versus bias voltage relationship are shown. The loss effect of the varactor is also discussed.

[1]  G. Eleftheriades,et al.  A planar metamaterial co-directional coupler that couples power backwards , 2003, IEEE MTT-S International Microwave Symposium Digest, 2003.

[2]  T. Itoh,et al.  A novel mixed conventional microstrip and composite right/left-handed backward-wave directional coupler with broadband and tight coupling characteristics , 2004, IEEE Microwave and Wireless Components Letters.

[3]  T. Itoh,et al.  A novel composite right-/left-handed coupled-line directional coupler with arbitrary coupling level and broad bandwidth , 2004, IEEE Transactions on Microwave Theory and Techniques.

[4]  Stewart,et al.  Extremely low frequency plasmons in metallic mesostructures. , 1996, Physical review letters.

[5]  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).

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

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

[8]  Ulrich L. Rohde,et al.  RF/Microwave Circuit Design for Wireless Applications , 2000 .

[9]  Yewen Zhang,et al.  Codirectional coupler and power divider mixed microstrip and metamaterials with lumped-elements L-C , 2004, ICMMT 4th International Conference on, Proceedings Microwave and Millimeter Wave Technology, 2004..

[10]  A. Oliner.  A periodic-structure negative-refractive-index medium without resonant elements , 2002 .

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

[12]  T. Itoh,et al.  Metamaterial-based electronically controlled transmission-line structure as a novel leaky-wave antenna with tunable radiation angle and beamwidth , 2004, IEEE Transactions on Microwave Theory and Techniques.

[13]  J. Pendry,et al.  Magnetism from conductors and enhanced nonlinear phenomena , 1999 .

[14]  A tunable one-dimension metamaterial , 2004, ICMMT 4th International Conference on, Proceedings Microwave and Millimeter Wave Technology, 2004..