Enhanced transmission of microwave radiation in one-dimensional metallic gratings with subwavelength aperture

We report a theoretical and experimental demonstration of enhanced microwave transmission through subwavelength apertures in metallic structures with double-sided gratings. Three different types of aluminum gratings (sinusoidal, symmetric rectangular, and asymmetric rectangular shaped) are designed and analyzed. Our samples have a periodicity of 16mm, and a slit width of 2mm. Transmission measurements are taken in the 10–37.5GHz frequency spectrum, which corresponds to 8–30mm wavelength region. All three structures display significantly enhanced transmission around surface plasmon resonance frequencies. The experimental results agree well with finite-difference-time-domain based theoretical simulations. Asymmetric rectangular grating structure exhibits the best results with ∼50% transmission at 20.7mm, enhancement factor of ∼25, and ±4° angular divergence.