Backward coupling waveguide coupler using left-handed material

An X-band microwave waveguide coupler partially filled with a left-handed material is realized and measured. The electromagnetic wave propagates in the primary branch of the coupler which is filled with the left-handed material and is backward edge coupled into the secondary waveguide, filled with a right-handed material. Near the interface between the left-handed and the right-handed materials, the Poynting vectors have opposite directions, which yields a backward coupling. Such coupler is designed, fabricated, and the backward coupling effect is indeed measured. (c) 2006 American Institute of Physics.