Miniaturization of rectangular waveguide using uniaxial negative permeability meta-material

A rectangular waveguide filled with anisotropic uniaxial meta-material with transversal negative effective permeability is analyzed rigorously. It is shown that such waveguide supports propagation of backward wave below the cut-off frequency, thus, it can be considered as a dual of an ordinary waveguide. The transversal dimension of the waveguide can be arbitrarily smaller than a half of the wavelength, which may be used for fabrication of miniaturized rectangular waveguides. Several experimental miniaturized waveguides filled with different resonant meta-materials in the 7 GHz and 350 MHz frequency bands have been designed, fabricated and tested. The measured results revealed backward-wave pass-band located below the cut off frequency, which is in agreement with theoretical analysis.