Miniaturization of a printed dipole antenna using metamaterials for RFID UHF technology

In this paper, we propose a new antenna based on metamaterials destined for radio frequency identification (RFID) technology operating in the ultra high frequency band (UHF). This antenna is constituted by a dipole printed on an FR 4 substrate associated to a set of metamaterial cells composed by square split ring resonators (SRR). Thanks to the effect of the negative permeability of these cells around the resonance frequency of the studied antenna, we could improve the antenna performances (gain and directivity) and also reduce its size. In fact the printed dipole antenna initially resonates at 2.8 GHz (Wi MAX). Then by inserting 8 SRR cells in the vicinity of the dipole antenna, the resonance frequency is reduced to 2.45GHz, which corresponds to the UHF RFID applications, with a size reduction of about 13%. This reduction is very important for RFID technology that requires miniature antennas. The MWS CST simulation software is used to determine return loss, resonance frequency, bandwidth, directivity, gain, and radiation pattern.