A compact multi-band antenna based on metamaterial

In this letter, a compact multi-band antenna is proposed by using composite right/left-handed (CRLH) structure. The metallic patch cut four corners is suggested to be capacitively coupled with one surrounding square ring. The proposed antenna is fabricated on the substrate FR4 (relative permittivity of 4.4). It has a compact size of 12 × 12 × 1.8mm and a good impedance matching in 5.13-5.4 GHz, 5.6-5.9 GHz(covering two bandwidths of WLAN), 8.5-8.65 GHz and 9.8-10.7 GHz four frequency ranges with return loss S₁₁<;10dB, which is capable of monopolar radiation and patch-like radiation. The maximum gains of 4.5 dB, 4.8 dB, 0.2 dB, 1.0 dB and 0.7 dB are achieved at resonant frequencies of f´₊₁ = 5.22 GHz, f₊₁=5.75 GHz, f_-1=8.58 GHz, f´₀=10 GHz and f₀=10.5 GHz respectively.