Enhanced Transmission through Sub-Wavelength Apertures with Covers of Self-Dual Layers: Theory and Experiment

Coats of self-dual media (SDM), that cover the surfaces adjacent to small apertures in conducting screens, are capable of collecting electromagnetic energy from around the aperture and force it to funnel through it. This effect is due to the non-reflecting nature of the SDM, that allows no outlet for the energy except through the hole. Compared with a reference bare structure, an enhancement of several tens of dBs are seen in simulations, and close to 10 dB in initial experiment. Coating can reside on either side of the screen or on both sides, with further enhancement in the latter case. This structure is non-resonant, allowing for potentially wideband realizations depending on the bandwidth of the synthesized materials involved.