Browsing by Subject "Negative permittivity"

Now showing 1 - 4 of 4

Open Access
Experimental and numerical study of omega type bianisotropic metamaterials combined with a negative permittivity medium
(Elsevier BV, 2008) Aydin, K.; Li, Z.; Bilge, S.; Özbay, Ekmel
We report on the transmission properties of the omega (Ω) type metamaterials. Transmission through the periodic Ω-only and Ω-wire metamaterials are studied experimentally and numerically. A resonance band gap is observed for the periodic Ω medium around the resonance frequency of the single Ω unit cell. A transmission band is observed below the resonance band gap, when the periodic Ω structure is embedded in a negative permittivity medium composed of thin metallic wire arrays. We also studied the effect of periodicity on the transmission spectra of Ω type metamaterials.
Open Access
Negative phase advance in polarization independent, multi-layer negative-index metamaterials
(Optical Society of American (OSA), 2008) Aydın, Koray; Zhaofeng, Li; Şahin, Levent; Özbay, Ekmel
We demonstrate a polarization independent negative-index metamaterial (NIM) at microwave frequencies. Transmission measurements and simulations predict a left-handed transmission band with negative permittivity and negative permeability. A negative-index is verified by using the retrieval procedure. Effective parameters of single-layer and twolayer NIMs are shown to be different. Negative phase advance is verified within the negative-index regime by measuring the phase shift between different sized negative-index metamaterials. Backward wave propagation is observed in the numerical simulations at frequencies where the phase advance is negative. ©2008 Optical Society of America.
Open Access
Negative refraction and subwavelength focusing using left-handed composite metamaterials
(SPIE, 2008-01) Özbay, Ekmel; Aydın, Koray
We review experimental studies performed on left-handed metamaterials (LHM) at microwave frequencies. The metamaterial structure is composed of periodic arrays of split-ring resonators and wire meshes and exhibits a left-handed propagation band at frequencies of negative permittivity and negative permeability. Negative refraction is verified using prism shaped LHM and also by beam-shifting method. Subwavelength focusing of a point source is achieved with a resolution of 0.13λ, through a flat LHM superlens.
Open Access
Transmission spectra and the effective parameters for planar metamaterials with omega shaped metallic inclusions
(Elsevier, 2010) Li, Z.; Aydin, K.; Özbay, Ekmel
Planar metamaterials with omega shaped metallic inclusions were studied experimentally and theoretically. Our results show that when the incidence is perpendicular to the plane of the omega structure, the omega medium acts effectively as an electric resonator metamaterial. The stop band of the omega medium is due to the negative part of the electric resonance of the omega structure. The transmission band of the composite metamaterial (CMM) that is based on the omega medium is due to the strong positive part of the electric resonance of the omega structure. Consequently, the transmission band of the CMM does not coincide with the stop band of the omega medium. Furthermore, the transmission band of the CMM is a band with positive refractive indices. Our experimental and numerical results are in good agreement.