Frequency tunable graphene metamaterial reflectarray In this paper, the radiation characteristics of frequency tunable graphene based metamaterial reflectarray have been investigated. The unitcell consists of graphene two gaps splitringresonator (SRR) printed on a thick SiO 2  substrate. The metamaterial parameters of the unitcell have been calculated at different graphene chemical potentials and different SRR gaps. Using waveguide simulator, the reflection coefficient phase of the graphene metamaterial reflectarray unitcell has been investigated. A 13xc3x9713 graphene metamaterial reflectarray antenna fed by a circular horn antenna is designed and analyzed at different graphene chemical potentials. Fullwave analysis for the graphene metamaterial reflectarray antenna has been applied using the finite integration technique.

Compact UltraWideband Monopole Antenna Loaded with Metamaterial A printed compact monopole antenna based on a single negative (SNG) metamaterial is proposed for ultrawideband (UWB) applications. A lowprofile, keyshaped structure forms the radiating monopole and is loaded with metamaterial unit cells with negative permittivity and more than 1.5 GHz bandwidth of nearzero refractive index (NZRI) property. The antenna offers a wide bandwidth from 3.08 to 14.1 GHz and an average gain of 4.54 dBi, with a peak gain of 6.12 dBi; this is in contrast to the poor performance when metamaterial is not used. Moreover, the maximum obtained radiation efficiency is 97%. A reasonable agreement between simulation and experiments is realized, demonstrating that the proposed antenna can operate over a wide bandwidth with symmetric splitring resonator (SSRR) metamaterial structures and compact size of 14.5 xc3x97 22 mm2 (0.148 xcexbb0 xc3x97 0.226 xcexbb0) with respect to the lowest operating frequency.