Proceeding of NCRIET-2015 & Indian J.Sci.Res. 12(1):261-266, 2015 ISSN: 0976-2876 (Print) ISSN: 2250-0138 (Online) OVERVIEW ON METAMATERIAL PHYSIC AND ENGINEERING APPLICATIONS DHERE VIDYASHREE V. a1 AND MAHESH S. MAHAPATI b a PG Student, Sveri`s College of Engineering, Pandharpur, Maharashtra, India b Assistant Professor, Sveri`s College of Engineering, Pandharpur, Maharashtra, India ABSTRACT The Electromagnetic metamaterials are defined as macroscopic composites, which are articially structured materials composed of periodic arrays of two or more responses of a specific excitation material. They typically resonant sub-wavelength metallic structures with lattice constants that are much smaller than the wavelength of the incident radiation, provides the freedom to develop magnetic properties or design dielectric that might not exist in conventional materials. It has periodic cellular architecture with three dimension designed to produce an optimized combination, which is not available in nature. By varying the geometrical parameters of the constituent structure of a metamaterial, the realized magnetic properties or dielectric provides negative refractive index characteristics can be engineered. KEYWORDS: Metamaterial, Negative Refractive Index, Macroscopic, Split Ring Resonator The first metamaterials were developed by W.E. Kock in the 1940's with metallic delay lenses and metal-lens antennas.later on the physicist victor Veselgo(1968) presented theoretical investigation[adnan Noor,2010]. A metamaterial gains its properties from its structure rather than directly from its composition. Metamaterials can be distinguished from other composite materials by its unusual properties. Such unusual properties could be a infinite inertia or negative refractive index which are not found in naturally occurring materials. The term was invented in 1999 by Rodger M. Walser from the University of Texas at Austin, and he defined properties of metamaterials as [A.Sihvola,2007]: Electromagnetic metamaterials are man-made structure of composite materials that can be engineered to achieve desired electromagnetic properties. Structure is composite of macroscopically scattering elements. Metamaterial s permeability and permittivity parameters are derive from their structure. They are a new class of ordered nanocomposites that exhibit unusual and exceptional properties which are not observed in nature. The properties arise from qualitatively new response functions which are not observed in the constituent materials and are the result from the inclusion of artificial fabrication, low dimensional in-homogeneities and extrinsic [Aos Al-waidh,2009]. Metamaterials properties : composite of two essential They are not observed in the constituent materials and/or not observed in nature. In 1996, Pendry used an artificial wired medium whose permittivity is negative to realize artificial electric plasma followed by, in 1999 magnetic plasma were realized whose permeability is negative using split-ring resonators (SRR) in Fig.2. Metamaterials are defined as macroscopic composites artificially structured[pendry,1999][ ] B.Monk,2000]. It has periodic cellular architecture with three dimension designed to produce an optimized combination, which is not available in nature produced by two or more responses of a specific excitation. Macroscopic constituents are designed with low dimensionality that allow each component of the excitation to be isolated and separately maximized due to meta-particles contains in each cell. The architecture of metamaterial is selected to combine or isolate specific non-local responses or to strategically recombine local quasistatic responses. The example shows the composites were characterized by different shapes of inclusions and by the volume fraction of inclusions. Composites filled with the inclusions shown in Fig.1 are Split rings, loaded rings, double split rings, helixes, bihelixes and to swiss rolls inclusions were used for creation of effective permeability. Here the required frequency dispersion of a composite permittivity 1 Corresponding author
and to get negative values of ε at above resonance frequencies can enabled using wire. Figure 5: 3-D view of Metamaterial Figure 1: Inclusions fabrication of (a) wire, (b) split ring, (c) loaded ring, (d) double split ring, (e) Ω-inclusion, (f) helix,(g) bifilar helix, (h) ferroelectric cube, (i) and sphere (j) swiss roll Wires (capacitive effect) SRR (Inductive effect) (Negative ε below (Negative µ Plasma frequency ) above resonance) Figure 2: Pendry simple approach to design Wave propagation in media with simultaneously negative ε and µ was discussed and analyzed by Veselago at the end of the 1960s and practical realization of such media is called left hand media. The terms that have been proposed for media with simultaneously negative ε and µ are negativerefractive Index, backward media, double-negative media. LEFT HAND METAMATERIAL The materials with simultaneously negative ε and µ are not found in nature[c. Caloz,2001]. They were artificially constructed man-made structures are called metamaterials. It is an assembly of cell elements. As long the size and spacing between the elements are very smaller than the electromagnetic wavelengths of interest, the incident radiation cannot differentiate the collection of elements from a homogeneous material type. The idealogy behind making a left-handed metamaterial is to make electric and magnetic properties behave separately. Essentially, a LHM is an assembly of two kinds of cell elements SRR produce negative µ and a wire array produce negative ε as shown in Fig.2. Transformation of Maxwell equations have a prominent role in describing metamaterial which is characterized by Maxwell equation in time domain (DaviBibiano 2010): Maxwell equation in time domain is as follows: Figure 3: 1D view of SRR E = jωμh ;.D = ρ H = j+ωεe ;.B = 0 (a) (b) For the plane wave above equations can be reduced to k E = ωμe ; k H = ωεe...(c) Figure 4: 2-D view of Metamaterial, by Smith in 2000 Therefore, for positive ɛ and µ, E, H and k form a right handed orthogonal system as shown in Fig.6. When ɛ and µ are negative the equation (c) changes to equation (d),
k E = ωμe ; k H = ωεe (d) above case shows left handed materials as shown in Fig.6. and their opposite direction and left hand triplet of E, H and k. Figure 8: When light interact with matter it can show reflection, refraction or both Figure 6: RHMs and LHMs NEGATIVE REFRACTIVE INDEX Smith in 2004 had realized gradient refractive index medium to bend electromagnetic waves as shown in Fig.5 and Fig.6 how the light rays bend around the object due to metamaterial making object invisible. The concept of negative refractive index is widely accepted and the focus of the research has moved toward applications. Many metals such as silver and gold have negative ε at visible wavelengths. A material having either ε or µ negative is opaque to electromagnetic radiation.although the optical properties of a transparent material are specified by the parameters ε and µ, in practice the refractive index N is often used. N may be determined from =± εμ. All transparent materials possess positive values for ε and µ and y convention the positive square root is used for N. Some engineered metamaterials have ε < 0 and µ < 0; because the product εµ is positive, N is real; Under such circumstances, it is necessary to take the negative square root for N. Physicist Victor Veselago proved that such substances can transmit light trough it. Metamaterials with negative N have numerous remarkable properties: Snell's law still applies, but as N2 is negative, the rays will be refracted on the same side of the normal on entering the material as shown in Fig.8. Figure 9: Effect on Snell s Law with different materials Figure 7: Bending of light due to Matematerial around the object. In Fig.9. the third quadrant Refractive index in the Snell s law is negative. An incident wave faces negative refraction at the interface. The ray bends in inside direction after refracting into medium which is contrary to positive index
medium. Thus, Left handed material light is refracted in a contrary way as compared to the normal right handed material. The Doppler shift is reversed - a light source moving toward an observer appears to reduce its frequency. Vavilov- Cherenkov radiation points to the other way. The time-averaged group velocity (Poynting vector) is antiparallel (i.e. opposite) to phase velocity. This means that unlike to normal right-handed material, the wave fronts are moving in the opposite direction to the flow of energy resulting into L. Moreover, producing a large metamaterial sample is technically difficult and expensive. According to that metamaterials could be classified to four main groups as shown in Fig 11. The first quadrant: (ε >0, µ>0) represents right handed material.the forward wave propagation takes place in the first quadrant. It is commonly used material as it follows the right hand thumb rule for the direction of wave propagation. The second quadrant : (ε< 0 and µ > 0) describes electric plasmas which support evanescent waves and it is also called ENG (epsilon negative) material. Figure 11: Material Classification The electromagnetic wave in a double negative material (DNM) forms a LH triad, double negative materials are generally referred to LH materials[c. Caloz,2002]. As LH triad means that power flows away from the source (i.e. group velocity is positive) while the phase front travels towards the source (i.e. phase velocity is negative). Thus LH materials support backward wave i.e. wave with antiparallel group velocity and phase velocity. This backward wave which shows the electric field magnitude plot of an air-filled rectangular waveguide with its middle section filled with a fictional LH material of ε = -1 and µ = -1. The fourthquadrant (ε> 0 and µ < 0) also supports evanescent, corresponding to MNG (munegative material) µ. Figure 12: Antiparallel Group Velocity and phase velocity if Waveguide Made of Metamaterial APPLICTION Figure 11: Material refraction in a left-handed metamaterial to that in a normal material Metamaterial as Antenna Metamaterial coatings are been used to enhance the radiation and matching properties of electrically small dipole antennas. It step up the radiated power. Patch antenna with metamaterial cover have increased directivity and Flat horn antenna with flat aperture constructed with zero index metamaterial has improved directivity. Zeroindex metamaterials gives high directivity antennas. A signal Propagating in a zero-index metamaterial
will stimulate a spatially static field structure that varies in time and the phase at any point will have the same constant value once the steady state is reached. Metamaterial can reduce the return loss and enhance the gain of a patch antenna. Some unique applications of metamaterial as an antenna substrate, feed networks, superstrate, phased array antennas, antenna radomes, ground planes and struts invisibility[m.a. Wan Nordin,2012]. to design a superlens which can constitute all evanescent waves to get perfect image. Figure 15: Properties of an optical superlens for imaging beyond the diffraction limit Metamaterial as Sensor Figure 13: Aperture Antennas Metamaterial can be used for designing sensor with specified sensitivity[gorankiti,2012]. They also provide tools to significantly enhance the resolution and sensitivity of sensors. Metamaterial sensors are used in biomedical, agriculture etc. In bio-medical, nested SRR based wireless strain sensors are developed to enhance the sensitivity are widely used. In agriculture the sensors employ SRR to gain better sensitivity are based on resonant material. Figure 14: Marconi monopole (Fractal) antenna Metamaterial as Superlens Metamaterial in superlens use to go beyond the diffraction limit, it has resolution capabilities that go beyond ordinary microscopes.the conventional optical materials suffer a diffraction limit because, only the propagating components are transmitted from a light source. The evanescent waves, the non-propagating components, are not transmitted. The other way to improve the resolution is to enhance the refractive index, but it is limited by the availability of high-index materials. The way to the super lens is its aptitude to significantly enhance and recover the evanescent waves that carry information at very small scales. No lens are yet able to completely reconstitute all the evanescent waves emitted by an object. The future challenge is Figure 16: Metamaterial sensor (a)multiple SRR, (b)sierpinski SRR(c) Spiral Resonator Metamaterial as Cloaks Cloak made of negative index material achieves cancellation of the electric and magnetic field generated by an object, guiding the electromagnet wave around the object.here guiding the wave means transforming the coordinate system in such a way that within the hollow cloak electromagnetic field will be zero thus making the region inside the shell disappear.
Aos Al-waidh (2009), metamaterials, General Engineering Research Institute, John Moores University Pendry, J. B., A. J. Holden, D. J. Robbins, and W. J. Stewart, Magnetism from conductors and enhanced nonlinear phenomena, IEEE Trans. Microwave Theory Tech., Vol. 47, No. 11, 2075 2084, Nov. 1999. Figure 17: Invisibility cloak Metamaterial as Absorber and Phase Compensator The most interesting application is as an absorber[n. I. Landy,2008] and also act as a phase compensator, when wave passes through a DPS (double positive) slab having positive phase shift, while the DNG (double negative material) slab has opposite phase shift so when wave exit from a DNG slab the total phase difference is equal to zero. CONCLUSIONS Metamaterial have an impact across the entire range of technologies where electromagnetic radiation are used and provide a flexible platform for technological advancement. The manipulation of ε and µ through specific inclusion of metal in dielectrics help to achieve a desired substrate properties in order to yield characteristics of optimum radiation. Metamaterial properties, allows reduction in size as compared to other materials for the reconfigurability of microwave devices and the multiband operation and antennas. Combining analytic method for analyzing radiation for homogeneous anisotropic slab, the optimization of structure has becomes possible. Hence Negative refractive index or LHM technology is adapted and are optimized for metamaterial substrate design. The most interesting application is as an absorber and also as sensors for soil moisture and humidity measurement etc. Metamaterials can be approximated as being anisotropic homogeneous materials, not only in scattering phenomenon, but also in embedded radiation. REFERENCES Adnan Noor (2010), Metamaterial Electromagnetic Absorbers and Plasmonic Structures, pp.42-43. A.Sihvola (2007), Metamaterials in electromagnetics, Metamaterials1, 2-11. B.Monk (2000),Metamaterials-Critique and Alternatives, A John willey&sons, INCpublications,Merits. C. Caloz, C.-C. Chang, and T. Itoh, "Full-wave verification of the fundamental properties of left-handed materials in waveguide configurations," J. Appl. Phys. 2001, 90(11). G.V. Eleftheriades, A.K. Iyer and P.C. Kremer, Planar negative refractive index media using periodically L-C loaded transmission lines, IEEE Trans. on Microwave Theory and Techniques, vol. 50, no. 12, pp. 2702-2712, 2002 C. Caloz and T. Itoh, "Application of the transmission line theory of left-handed (LH) materials to the realization of a microstrip 'LH line'," IEEE Antennas and Propagation Society International Symposium, 2002, 2, 412-415 (doi 10.1109/APS.2002.1016111). A. Grbic and G.V. Eleftheriades, Overcoming the diffraction limit with a planar left-handed transmission-line lens, Physical Review Letters, vol. 92, no. 11, pp. 117403, March 19, 2004 M.A. Wan Nordin M.T. Islam N. Misran (2012) A compact wideband coplanar waveguide fed metamaterial-inspired patch antenna for wireless application. GoranKiti, Vasa Radoni, and VesnaCrnojevi Bengin(2012), Soil moisture sensors based on metamaterials, SIST. Enghetaand Ziolkowski, R. W., (eds.) (2006), ElectromagneticMetamaterials: Physics and Engineering Exploration, Willey-IEEE PRESS, NewJersy, U.S.A. Nader Enghta, R. W. Ziolkowski (2006) Metamaterials Physics and Engineering
ExplorationsPublished by John Wiley & Sons, In, Canada. N. I. Landy, D. R. Smith, W. J. Padilla (2008), a Perfect Metamaterial Absorber.