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

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Abstract
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 aluminumgratings (sinusoidal, symmetric rectangular, and asymmetric rectangular shaped) are designed and analyzed. Our samples have a periodicity of 16 mm , and a slit width of 2 mm . Transmission measurements are taken in the 10 – 37.5 GHz frequency spectrum, which corresponds to 8 – 30 mm 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 gratingstructure exhibits the best results with ∼ 50 % transmission at 20.7 mm , enhancement factor of ∼ 25 , and ± 4 ° angular divergence.