Browsing by Subject "Phase shifters"

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    Observation of negative refraction and negative phase velocity in true left-handed metamaterials
    (IEEE, 2007) Özbay, Ekmel; Soukoulis, C.M.
    We report a true left-handed (LH) behavior in a composite metamaterial consisting of periodically arranged split ring resonator (SRR) and wire structures. The magnetic resonance of the SRR structure is demonstrated by comparing the transmission spectra of SRRs with that of closed SRRs. We confirmed experimentally that the effective plasma frequency of the LH material composed of SRRs and wires is lower than the plasma frequency of the wires. A well-defined left-handed transmission band with a peak value of -1.2 dB (-0.3 dB/cm) is obtained. We also report the transmission characteristics of a 2D composite metamaterial (CMM) structure in free space. At the frequencies where left-handed transmission takes place, we experimentally confirmed that the CMM structure has effective negative refractive index. Phase shift between consecutive numbers of layers of CMM is measured and phase velocity is shown to be negative at the relevant frequency range. Refractive index values obtained from the refraction experiments and the phase measurements are in good agreement. The experimental results agree extremely well with the theoretical calculations. © 2006 EuMA.
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    Reconfigurable nested ring-split ring transmitarray unit cell employing the element rotation method by microfluidics
    (Institute of Electrical and Electronics Engineers, 2015) Erdil, E.; Topalli, K.; Esmaeilzad, N. S.; Zorlu, O.; Kulah, H.; Aydin, C. O.
    A continuously tunable, circularly polarized X-band microfluidic transmitarray unit cell employing the element rotation method is designed and fabricated. The unit cell comprises a double layer nested ring-split ring structure realized as microfluidic channels embedded in Polydimethylsiloxane (PDMS) using soft lithography techniques. Conductive regions of the rings are formed by injecting a liquid metal (an alloy of Ga, In, and Sn), whereas the split region is air. Movement of the liquid metal together with the split around the ring provides 360° linear phase shift range in the transmitted field through the unit cell. A circularly polarized unit cell is designed to operate at 8.8 GHz, satisfying the necessary phase shifting conditions provided by the element rotation method. Unit cell prototypes are fabricated and the proposed concept is verified by the measurements using waveguide simulator method, within the frequency range of 8-10 GHz. The agreement between the simulation and measurement results is satisfactory, illustrating the viability of the approach to be used in reconfigurable antennas and antenna arrays.