%0 Journal Article
%T Tunability of Triangular SRR and Wire Strip (TSRR-WS) Metamaterial at THz
%A Parul Dawar
%A Asok De
%J Advances in Optical Technologies
%D 2014
%I Hindawi Publishing Corporation
%R 10.1155/2014/405301
%X This paper adumbrates a novel tunable metamaterial consisting of triangular split ring resonator (TSRR) and wire strip (WS) at THz frequency. Ansoft high frequency structure simulator (HFSS) has been used to design and analyse the metamaterial having Rogers RT/duroid 5870 ( £¿£¿=£¿£¿2.33) and FR4 ( £¿£¿=£¿£¿4.4) as substrate material. Nicolson Ross Weir (NRW) method has been used to retrieve the material parameters from transmission and reflection coefficient. 4% maximization has been obtained in the location of the negative region (or resonance frequency for permeability) by using FR4 with 0.75£¿¦Ìm instead of 1.25£¿¦Ìm as substrate thickness. In addition, 18% minimization has been achieved by using FR4 with 0.25£¿¦Ìm instead of RT/duroid 5870 substrate with the same thickness. Tunability has been proved by showing dependence of resonant frequency over the substrate thickness and substrate material. 1. Introduction ¡°Metamaterials¡± (MTMs) are engineered to modify the bulk permeability and/or permittivity of the medium. It is realized by placing periodically structures that alter the material parameters, with elements of size less than the wavelength of the incoming electromagnetic wave. It results in ¡°meta,¡± that is, ¡°altered¡± behaviour or behaviour unattainable by natural materials. Slight changes to a repeated unit cell can be used to tune the effective bulk material properties of a MTM, replacing the need to discover suitable materials for an application with the ability to design a structure for the desired effect. Examples of MTMs are single negative materials (SNG) like ¦Å negative (ENG) which have effective negative permittivity and ¦Ì negative (MNG) which have effective negative permeability and double negative materials (DNG). The past few years have been very eventful with respect to the evolution of the concept and implementation of ¡°left-handed materials (LHMs).¡± The cross product of E and H is proportional to the k vector and the E or H field. These vectors follow the right hand rule. Power flow is described by Poynting¡¯s vector (S). The material values of particular interest to the electromagnetic community are the values of permittivity, ¦Å, and permeability, ¦Ì. Taken together, ¦Å and ¦Ì determine the speed of electromagnetic propagation through a medium and the square root of their product determines the refractive index (n). A real wave vector indicates a propagating wave, while an imaginary wave vector indicates attenuation (an evanescent wave). Therefore, upon entering a medium with altered material parameters, that is, negative ¦Å and ¦Ì, the group and
%U http://www.hindawi.com/journals/aot/2014/405301/