Metamaterial resonators based dual-band antenna

A novel planar dual-band antenna by using composite metamaterial resonator is proposed. The antenna consists of a tapered CPW-fed line and a metamaterial resonator with an outer close ring resonator and an inner split ring resonator (SRR). The CPW-fed line with tapered ground plane and tapered impedance transformer line is employed to improve impedance matching. The metamaterial resonator is utilized to provide dual-band operation at 2.59 to 2.65 GHz and 3.16 to 3.96 GHz with return loss less of better than 10 dB by the two resonant modes of SRR and closed ring resonator, respectively. It is worthwhile to mention that the inner SRR is used for having the lower narrow frequency band because the size of SRR is much smaller than the resonant wavelength, and the close ring resonator is placed outside of the SRR for achieving the upper broad frequency band, which made the dual-band antenna very small. The antenna has 1.2-1.3 dB and 2.1-2.5 dB gains at the lower and upper bands, respectively, and nearly omni-directional pattern in the H-plane in the dual-band.