Design of Metamaterial Based Antenna Using Unit Cells

Abstract

Metamaterials are artificial metallic structures having simultaneously negative permittivity (ɛ) and permeability (μ), which leads to negative refractive index. Due to negative index it supports backward waves i.e. inside Metamaterial phase velocities and group velocities are antiparallel. Metamaterial doesn’t obey Snell’s law, Doppler effect, Vavilov-Cerenkov radiation etc. No other material in the world shows the above properties like Metamaterial. Due to these unusual properties Metamaterial can change the electric and magnetic property of electromagnetic wave passing through it and because of these reasons when Metamaterial is used in the fabrication of microwave components and antennas the required properties can be enhanced. Also miniaturization in the size of the component is possible as the structural cell size of Metamaterial is less than one-fourth of the guided wavelength. Using this Metamaterial antenna the demerits of ordinary patch antenna like low gain and efficiency can be overcome and is useful in the field of wireless communication. The rationale behind the work is that small planar antennas are proposed using DNG (Double Negative) Metamaterials. The double negative property is being obtained by introducing unit cell structure. A unit cell consists of microstrip gaps and vias, whose behaviour is equivalent to the combination of series capacitors and shunt inductors respectively. The via leads to negative permittivity and microstrip gap leads to negative permeability. And this negative permittivity and permeability leads to negative refractive index due to this it exhibits unusual properties compared to readily available materials. Due to the unusual properties of the Metamaterials by using a single unit cell the antenna gives of 3.768 dB, overall efficiency of 53.76 and a VSWR of 1.6 at 5 GHz frequency which is very good for point to point wireless communication and wireless LANs. This antenna has better VSWR, gain and radiation efficiency compared to an ordinary patch antenna. And another Metamaterial antenna using three unit cells gives a better gain of 5.197 dB, overall efficiency of 92.5% and a return loss of -13.5 dB at 5 GHz frequency and the gain, efficiency and return loss are 4.183 dB, 60.78%, -14.5 respectively for 2.4 GHz. The results obtained through “CST MICROWAVE STUDIO” design software and are very good for wirelessly access network resources at home and elsewhere with up to 5 GHz performance, like IEEE 802.11a, widely available IEEE 802.11b, downwardly compatible IEEE 802.11g, and advanced IEEE 802.11n.