Shrinking a Rectangular Waveguide Resonator Using Mushroom Metamaterials

This communication proposes a new method to shrink a rectangular waveguide resonator (RWR) using metallic mushroom metamaterials. One such a small RWR is numerically demonstrated to resonate in the
$\boldsymbol{L}-\mathbf{band}$
The electric volume is only
$\mathbf{0}.\mathbf{262}\boldsymbol{\lambda}\times \mathbf{0}.\mathbf{175}\boldsymbol{\lambda}\times \mathbf{0}.\mathbf{044}\boldsymbol{\lambda}$
. The quality-factor for the compact RWR maintains at a high level of nearly 1016, resulted from the low loss property of metallic metamaterials.