Literature Review on Metamaterial

Literature Review on MetamaterialLITERATURE REVIEW ON METAMATERIALThe Left-Handed Metamaterial (LHM) has a few unique properties such as negative refraction and backward wave. In this chapter, the basic theories behind their unique properties are presented and some coats of LHM toward the antenna application are discussed.DEFINITION BACKGROUND OF left-hand(prenominal) METAMATERIALElectrocharismatic Metamaterial can be defined as artificial effective homogenous electromagnetic organises with unusual properties not readily found in constitution . A Left-Handed Metamaterial (LHM) 1718or Double controvert Metamaterial (DNG) is an electromagnetic Metamaterial that exhibit negative permittivity and permeability. This phenomenon can be characterized by the negative refraction index and the anti-parallel phase swiftness which is also known as backward wave.HISTORY OF LEFT-HANDED METAMATERIAL (LHM)The initial work on LHM was started by V. G. Veselago from the Lebedjev Physical Institut e in Moscow when he made a theoretical speculation of this artificial material that exhibit negative permittivity and negative permeability. Veselago speculation remain silent for 29 years until 1996, J. B. Pendry from imperial beard College London and his co-author form GEC-Marconi produce a paper about artificial metallic construction which exhibit negative permittivity and negative permeability. Following this fire discovery, in 2001, the first experimental verification was made by Shelby, Smith and Schultz at the University of California. The left handed material structure consists of split ring resonating chamber and thin telegraph inspired by J. B. Pendry as shown in figure of speech 3.1.Figure 3.1 First experimental LHM structureSince the introduction of LHM twelve years ago, some researchers were interested in investigating this artificial material and several of them was using LHM to improve the properties of the microwave devices such as antennas and filters. Many pap ers have been published regarding the LHM integrated with antennas and their properties have been analyzed. The focusing affect of LHM has made a low gain antenna becomes directive and have an increment of gain.FEATURES OF METAMATERIALImprovement in the deed of a small monopole antenna, realized via the use of an ENG envelope that compensates for its high capacitive reactance.Lens effect produced by DNG slabs that are useful for enhancing the directivities of a small antennas, e.g. dipole and Microstrip patches, by collimating the cylindrical waves emanating from these antennas and focusing them at infinity.Creation of super lenses which can have a spatial resolution below that of the wavelength.UNIQUE PROPERTIES OF LEFT-HANDED METAMATERIALSNegative Refractive Index For conventional material with r 0 and r 0, the refractive index is given=, so that the conventional material possesses a overconfident refractive index. Yet, Left-handed Meta-material has both negative permittivity (r r The Snells law is described as ..3.3.1(a)Where 2 the incident is angle and 1 is the refraction angle. Supposing culture medium I and medium II are conventional materials with 10 and 20 respectively, them refracted light will be bent with positive with the normal line OO as indicated by the quaternate light ray in figure3.2. If medium II is a left-handed meta-material with 2Figure 3.2 Passage of a light ray by the enclosure between medium I with positive refractive index 0 and medium II with refractive index .The phase f number expression -= shows that the phase velocity - is related to the index of refraction , here c denotes the speed of light in a vacuum. For LHM has negative refractive index ( Figure 3.3 The energy attend and group velocity propagate forward in LHMs but the phase velocity is backwardVeselago also predicted that the Doppler and Cerenkov effects will be reversed in LHM. An geting source will appear to radiate at a lower oftenness and charged part icles moving faster than the speed of light in the medium will radiate in a backward cone, not a forward cone. These two exotic properties are not employed in this Dissertation, however details about them can be found in.LEFT-HANDED METAMATERIAL STRUCTUREThe first LHM structure consists of split ring resonant circuit (SRR) and thin wire (TW) or capacitance loaded strip (CLS)19. The SRR exhibits the negative value of permeability and the CLS and TW exhibit the negative value of permittivity in a certain range of frequency. fraction Ring Resonator (SRR)(b)Figure 3.4 (a) Circular split ring resonator and (b) Square split ring resonatorA split ring resonator (SRR) as shown in figure3.4 is part of the LHM structure that exhibit negative value of permeability. If the excitation of the magnetic field is perpendicular to plane of the structure, this will generate the magnetic dipole moment. The SRR is a highly conductive structure in which the capacitance between the two rings balances its inductance . The SRR induces high current density structure which creates a large magnetic moment.Capacitance Loaded Strip (CLS) and Thin Wire (TW)(a) (b)Figure 3.5 (a) Capacitance loaded strip (CLS) and (b) Thin wire (TW)figure 3.5(a) shows the capacitance loaded strip (CLS) and figure 3.5(b) shows the thin wire (TW). CLS and TW would produce strong dielectric like response. As electric field propagates parallel through the TW or CLS, it will induce a current along them. This will generate an electric dipole moment to the structure and exhibit a plasmonic-type of permittivity frequency .CST SOFTWARECST was founded in 1992 byThomas Weiland. The main product of CST is CST STUDIO SUITE,which comprises A various modules dedicated to specific application areas. There are modules for microwave RF applications, summarized in CST MICROWAVE STUDIO, low frequency (CST EM STUDIO), PCBs and packages (CST PCB STUDIO), cable harnesses (CST CABLE STUDIO), temperature and mechanical stress (CST MPHYSICS STUDIO) and for the simulation of the interaction of charged particles and electromagnetic fields (CST PARTICLE STUDIO). alone modules are integrated with a system and circuit simulator (CST DESIGN STUDIO). The version is CST Microwave Studio 2010.Figure 3.6 CST Microwave StudioIn next chapter, the figure of the LHM is discussed and the procedure in the simulation of the LHM using CST software is elaborated thoroughly. Besides that, the design of the Metamaterial structures, patch Microstrip antennas are also elaborated.CST Microwave Studio is a richly featured software package for electromagnetic analysis and design in the high frequency range. It simplifies the process of inputting the structure by providing a powerful unfaltering modeling front-end which is based on the ACIS modeling kernel. Strong graphic feedback simplifies the definition of Your device even further. After the component has been modeled, a fully automatic involution procedure (based on an expert s ystem) is applied before the simulation engine is started. The simulators feature the Perfect Boundary Approximation (PBA method) and its Thin Sheet Technique (TST) extension, which increases the true statement of the simulation by an order of magnitude in comparison to conventional simulators. Since no method works equally well in all application domains, the software contains four different simulation techniques (Transient solver, Frequency domain solver, Eigenmode solver, Modal analysis solver) which best fit their particular applications.The most flexible tool is the passing solver, which can obtain the entire broadband frequency behavior of the simulated device from only one calculation run (in contrast to the frequency stepping approach of many other simulators). This solver is very efficient for most kinds of high frequency applications such as connectors, transmission lines, filters, antennas and many more.