Experimental verification of spoof surface plasmons in wire metamaterials.

In this paper, we experimentally demonstrate the excitation of spoof surface plasmon polaritons (SPPs) on a wire-medium metamaterial slab in the microwave region. The spoof SPPs are excited on the opposite side of the slab from the source, which is desirable for applications such as sensing devices. Using the prism coupling method, we verify the excitation of spoof SPPs by measuring the reflection spectrum and near-field enhancement. The excitation of spoof SPPs is also verified by using the grating coupling method, where we demonstrate transmission enhancement through the metamaterial slab by placing diffraction gratings on both sides of the slab. Numerical investigation shows that the enhanced transmission can be attributed to the dispersion relations of the spoof SPPs and the periodicity of the diffraction grating. These properties can be used to realize extraordinary transmission and directional beaming.