Browsing by Subject "Electromagnetic propagation"

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    The almost magical world of metamaterials
    (IEEE, 2008-11) Özbay, Ekmel
    In recent years, there has been a burgeoning interest in rapidly growing field of metamaterials due to their unprecedented properties unattainable from ordinary materials. Veselago pointed out that a material exhibiting negative values of dielectric permittivity (epsiv) and magnetic permeability (mu) would have a negative refractive index [1]. Generally speaking, the dielectric permittivity (epsiv) and the magnetic permeability (mu) are both positive for natural materials. In fact, it is possible to obtain negative values for epsiv and mu by utilizing proper designs of metamaterials. Left-handed electromagnetism and negative refraction are achievable with artificially structured metamaterials exhibiting negative values of permittivity and permeability simultaneously at a certain frequency region. The first steps to realize these novel type of materials were taken by Smith et al., where they were able to observe a left-handed propagation band at frequencies where both dielectric permittivity and magnetic permeability of the composite metamaterial are negative [2]. Soon after, left-handed metamaterials with an effective negative index of refraction are successfully demonstrated by various groups.
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    A planar metamaterial with dual-band double-negative response at EHF
    (IEEE, 2009-10-02) Gundogdu, T. F.; Guven, K.; Gokkavas, M.; Soukoulis, C. M.; Özbay, Ekmel
    We report the fabrication and electromagnetic characterization of a planar composite metamaterial (CMM) that is designed to achieve dual-frequency double-negative response at the lower end of the extremely high-frequency (EHF) band. The CMM is based on cut wire pairs and continuous wire elements. Dual-frequency operation is obtained by employing cut wire pairs of two different lengths within the unit cell of the CMM. The magnetic response of the cut wire pairs and the left-handed transmission band of the CMM are demonstrated by experiment and numerical simulations. It is found that the combined electric response of the dual-band CMM is complicated and imposes certain restrictions to the structure design in achieving true left-handed response at both designated frequencies.