A Left-Handed Transmission Line Composed of Two Waveguides with Stubs

Hiroshi KUBO  Hidetaka KUWAHARA  Atsushi SANADA  

IEICE TRANSACTIONS on Electronics   Vol.E91-C   No.11   pp.1765-1771
Publication Date: 2008/11/01
Online ISSN: 1745-1353
DOI: 10.1093/ietele/e91-c.11.1765
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Microwave and Millimeter-wave Technologies)
left-handed transmission line,  waveguide,  leaky-wave antenna,  

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A new structure of a waveguide-type left-handed transmission line is proposed. It is composed of two rectangular waveguides with many stubs. One waveguide is put on another waveguide symmetrically. When one mode with odd electric field distribution is excited, the stubs work as open stubs and the mode propagates with very small loss. Guided regions of the left-handed mode and a right-handed mode are discussed using an approximate equivalent circuit. Tuning the structure parameters, the band gap between the two regions can be removed, and the wave propagates continuously from the left-handed frequency regions to the right-handed frequency region. The transmission line is applied to a leaky waveguide. It is confirmed experimentally that the beam angle of the radiation wave changes from the backward to the forward directions.