Experimental investigation of subwavelength resonator based on backward-wave meta-material

The recently introduced concept of one-dimensional subwavelength resonator, which comprises a combination of forward-wave material and backward-wave material, is investigated experimentally. The rectangular evanescent waveguide filled with negative permeability uniaxial meta-material based on capacitively loaded loop was used as backward-wave meta-material in 350 MHz band. The waveguide was interfaced with an ordinary (forward-wave) coaxial transmission line terminated with a sliding short. The overall length of this waveguide-coaxial structure was much shorter than the wavelength. The distribution of the phase of the magnetic field along the structures was measured with the help of a small loop antenna and network analyzer, for different settings of the sliding short. The measurement results proved that is possible to meet resonant conditions on the structure whose overall length is much smaller than a wavelength, as it was previously theoretically predicted.