Browsing by Subject "Metallic structures"

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    Enhanced transmission of microwave radiation in one-dimensional metallic gratings with subwavelength aperture
    (American Institute of Physics, 2004) Akarca-Biyikli, S. S.; Bulu, I.; Özbay, Ekmel
    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 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 grating structure exhibits the best results with ,50% transmission at 20.7 mm, enhancement factor of ,25, and ±4° angular divergence.
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    Highly asymmetric transmission of linearly polarized waves realized with a multilayered structure including chiral metamaterials
    (IOP Publishing, 2014) Li, Z.; Mutlu, M.; Özbay, Ekmel
    We numerically and experimentally demonstrate highly asymmetric transmission of linearly polarized waves with a multilayered metallic structure. The whole structure has a subwavelength thickness and consists of a thin slab of chiral metamaterial sandwiched between two 90° twisted linear polarizers. The chiral metamaterial is made of two sets of twisting cross wires that can rotate the polarization by 90° at resonance, and the two linear polarizers are simple metallic grating polarizers. The operation principle of the whole structure can be well interpreted by using the Jones matrix method. Our experimental results also verify that chiral metamaterials can be safely integrated into complex structures and treated as an effective medium as long as their resonant modes are not affected by the environment.