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Showing papers on "Metamaterial antenna published in 2005"


Journal ArticleDOI
TL;DR: The gradient index metamaterial proposed may be suited for terahertz applications, where the magnetic resonant response of SRRs has recently been demonstrated and may prove an advantageous alternative approach to the development of gradient index lenses and similar optics.
Abstract: Metamaterials—artificially structured materials with tailored electromagnetic response—can be designed to have properties difficult or impossible to achieve with traditional materials fabrication methods. Here we present a structured metamaterial, based on conducting split ring resonators sSRRsd, which has an effective index of refraction with a constant spatial gradient. We experimentally confirm the gradient by measuring the deflection of a microwave beam by a planar slab of the composite metamaterial over a range of microwave frequencies. The gradient index metamaterial may prove an advantageous alternative approach to the development of gradient index lenses and similar optics, especially at higher frequencies. In particular, the gradient index metamaterial we propose may be suited for terahertz applications, where the magnetic resonant response of SRRs has recently been demonstrated.

371 citations


Journal ArticleDOI
TL;DR: In this article, a low-profile metamaterial ring antenna using two MCU cells is proposed using negative-refractive-index (NRI) microstrip transmission lines (TL) designed to incur a zero insertion phase at the antenna design frequency.
Abstract: A compact (/spl lambda//sub 0//11 footprint) and low-profile (/spl lambda//sub 0//28 height) metamaterial ring antenna is proposed using two metamaterial unit cells. Each constituent unit cell consists of negative-refractive-index (NRI) microstrip transmission lines (TL) designed to incur a zero insertion phase at the antenna design frequency. This allows the inductive posts to ground, which act as the main radiating elements, to be fed in phase. Hence, the antenna operates as two closely spaced monopoles that are fed in phase through a compact feed network. An embedded matching network ensures good VSWR performance. The theoretical performance of the antenna is verified by full-wave simulations and experimental data obtained from a fabricated prototype at 1.77 GHz. The antenna offers a 120 MHz -10 dB bandwidth and a measured efficiency exceeding 50%.

219 citations


Journal ArticleDOI
TL;DR: In this paper, a double-plate resonance cavity made with metamaterials was used to demonstrate a mechanism for directive emissions, which is significantly thinner than the working wavelength and requires a smaller lateral size.
Abstract: We use experiment and theory to demonstrate a mechanism for directive emissions, which involves a double-plate resonance cavity made with metamaterials. In contrast to other mechanisms employing Fabry-Perot cavities, photonic crystals, or zero index materials, our system is significantly thinner than the working wavelength and requires a smaller lateral size. We show the physics to be governed by subwavelength resonance modes unique to such metamaterial-based cavities.

165 citations


Journal ArticleDOI
TL;DR: In this paper, negative index materials (NIM) or double negative (ONG) media or left handed (LH) materials or backward wave (BW) media have been proposed.
Abstract: Metamaterials are new artificial materials with unusual electromagnetic properties that are not found in naturally occurring materials. All "natural" materials such as glass, diamond and such have positive electrical permittivity, magnetic permeability and an index of refraction. In these new artificially fabricated materials - termed as negative index materials (NIM) or double negative (ONG) media or left handed (LH) materials or backward wave (BW) media - all these material parameters are negative. With these unusual material parameters, new kinds of miniaturized antennas and microwave components/devices can be created for the wireless communications and the defense industries. The electrical permittivity and the magnetic permeability are the main determinants of a material's response to electromagnetic (EM) waves. In metamaterials, both these material parameters are negative. Correspondingly, the refractive index of the metamaterials is also negative. Another strange property of metamaterials is its reverse Doppler effect.

151 citations


Proceedings ArticleDOI
H.R. Stuart1, A. Pidwerbetsky1
03 Jul 2005
TL;DR: In this article, a quasi-static analysis is used to show that a sub-wavelength spherical negative permittivity resonator will have a Q that is a factor of 3/2 above the Chu limit.
Abstract: We consider the use of materials with negative electric permittivity as a building block for constructing effective small antenna elements. In this paper, we show that negative permittivity alone is sufficient for constructing an effective small antenna element. Further, we clarify, here the issue of the radiation Q: a quasi-static analysis is used to show that a sub-wavelength spherical negative permittivity resonator will have a Q that is a factor of 3/2 above the Chu limit. We demonstrate through finite element simulation a practical antenna geometry composed of a coaxial transmission line coupled to a half-sphere of negative permittivity adjacent to a ground plane. The resonator is impedance-matched to the transmission line, resulting in an antenna Q matching that predicted by the quasi-static analysis.

102 citations


Journal ArticleDOI
TL;DR: In this article, the authors used finite-difference time-domain simulations in the frequency domain to study resonance phenomena in left-handed metamaterials consisting of the arrays of split-ring resonators (SRRs) and metal rods.
Abstract: The finite-difference time-domain simulations in the frequency domain are used to study resonance phenomena in left-handed metamaterials consisting of the arrays of split-ring resonators (SRRs) and metal rods. It is demonstrated that, at frequencies corresponding to the band of enhanced transmission of the metamaterial, the half-wavelength resonances occur in both the SRRs and rods. The observed resonances in rods make questionable the applicability of the plasma concept to the analysis of the metamaterial performance. We also show that overlapping of electric or magnetic fields at resonance causes coupling between resonators and assembling them in three-dimensional groups, which rearrange in dependence on frequency inside the transmission band. As the result, the resonance phenomena in the metamaterial proceed essentially nonuniform, although the size of the metamaterial units is less than the wavelength. We suggest that coupling between resonators is capable of providing the electromagnetic response, similar to that observed at the backward-wave propagation in double-negative media. The latter is demonstrated on the example of the all-dielectric metamaterial composed from an array of dielectric resonators.

95 citations


Journal ArticleDOI
TL;DR: In this paper, a one-dimensional left-handed microstrip line (LHML) consisting of the arrays of thin wires and two-layer split-ring resonators is investigated theoretically and experimentally.
Abstract: The novel one-dimensional left-handed microstrip lines (LHMLs) consisting of the arrays of thin wires and two-layer split-ring resonators are investigated theoretically and experimentally in this paper. Unlike the conventional left-handed metamaterials for waveguides or microstrip lines, which are bulky three-dimensional constructions or require the lumped elements for high-pass configuration, this distributed structure can be directly implemented on a substrate by photolithographic techniques without soldering any chip inductors or capacitors. Moreover, it can also be easily realized at a higher frequency region by scaling the dimensions of the structure, making it highly efficient and flexible in millimeter-wave applications. To characterize the inhomogeneous LHML, the effective medium description is developed for extracting the effective electromagnetic parameters, i.e., the complex effective permittivity and permeability, as well as the refractive index. Results show that not only the simultaneously negative real permittivity and permeability, but also the antiparallel phase and group velocities may be achieved in the design passband region. In contrast to the antenna array using the conventional microstrip delay line, the LHML is incorporated in the series-fed microstrip combline array to exhibit the leading phase between the successive elements.

81 citations


Journal ArticleDOI
TL;DR: In this article, a narrow slot coupled to a microstrip line excites a DRA consisting of a small dielectric disc embedded in a larger disc is tested with two different slots providing eight different possibilities.
Abstract: A narrow slot coupled to a microstrip line excites a dielectric resonator antenna (DRA) consisting of a small dielectric disc embedded in a larger disc is built and tested. Two different configurations of DRAs are tested with two different slots providing eight different possibilities. One configuration provides a bandwidth over 50%. These antennas have broadside radiation patterns because of the symmetry presence of the slot with the DRA. Sample of radiation patterns are provided.

74 citations


Book ChapterDOI
02 Aug 2005
TL;DR: In this paper, a super-resolving negative-refractive-index transmission-line lens is used to resolve the super-resolution of Negative-Refractive-Index Transmission Line Lens Compact and Broadband Phase-Shifting Lines.
Abstract: The prelims comprise: Introduction Fundamental Properties Effective Medium Theory A Super-Resolving Negative-Refractive-Index Transmission-Line Lens Compact and Broadband Phase-Shifting Lines Series-Fed Antenna Arrays with Reduced Beam Squinting A Broadband Metamaterial Balun in Microstrip Broadband Power Combiners Using Zero-Degree Phase-Shifting Lines Electrically Small Ring Antenna with Vertical Polarization A Leaky-Wave Backward Antenna Radiating its Fundamental Spatial Harmonic A High-Directivity Backward NRI/Microstrip Coupler Phase-Agile Branch-Line Microstrip Couplers Conclusion Appendix References ]]>

66 citations


Journal ArticleDOI
TL;DR: In this paper, a rod and a ring was designed at infrared frequencies and redesigned at microwave frequencies, and it was shown that this ring exhibits better transmission in a parallel-plate waveguide than the original concentric split-ring resonator.
Abstract: Four properties related to left-handed metamaterials are studied numerically: transmission within a stop-band, backward phase, negative refraction, and partial focusing. The unit cell of the metamaterial under study is composed of a rod and a ring originally proposed at infrared frequencies and redesigned here at microwave frequencies. We show that this ring, because of its symmetry, exhibits a better transmission in a parallel-plate waveguide than the original concentric split-ring resonator. Negative refraction is studied from a prism-shaped metamaterial, while all of the other properties are studied from a slab-shaped metamaterial. In particular, transmission and backward phase are studied on a slab where rings naturally couple with the incident wave, while partial focusing is studied on a slab of rings perpendicular to the direction of propagation. The numerical simulations are based on a two-dimensional periodic method of moments, whose Green's function is computed via Ewald's method, and a three-dimensional finite-difference time-domain technique.

55 citations


Journal ArticleDOI
TL;DR: In this article, a numerical study of resonant negative refractive index (NRI) metamaterials is presented, in which their effective parameters are calculated by means of two different methods.
Abstract: We present a numerical study of resonant negative refractive index (NRI) metamaterials in which their effective parameters are calculated. For a periodic media consisting of split-ring resonators and metallic wires the effective refractive index is compared by means of two different methods. The first one is an inversion procedure in which the effective refractive index is calculated from the reflection and transmission coefficients of a finite structure and the second one consists its calculation from the phase velocity issued from the dispersion diagram. A significant difference between the two cases is highlighted in the frequency interval of interest (NRI regime) and for the finite media, counterintuitive observations are made. These anomalous features are observed in a frequency range in which there is a non-negligible contribution of the higher-order modes to propagation inside the periodic metamaterial. Hence in this particular frequency interval, the media cannot be described by an effective refractive index in a Fresnel sense. In other frequency regions, both methods converge and it will be shown that the metamaterial exhibits a negative refractive index.

Journal ArticleDOI
TL;DR: In this paper, a microstrip inset-fed patch antenna covered by plasma sheath is simulated by using the (FD)2TD algorithm and the coefficients in the electric field update equation for cold plasma are presented in detail.
Abstract: In this paper, a microstrip inset-fed patch antenna covered by plasma sheath is simulated by using the (FD)2TD algorithm. Expressions of calculating the coefficients in the electric field update equation for cold plasma are presented in detail. Computational examples illustrate that the resonant frequency of the patch antenna covered by plasma sheath is changed. The curves presented in this paper may be useful when introducing appropriate corrections in the design of the microstrip patch antennas in the plasma environment.

Proceedings ArticleDOI
04 Dec 2005
TL;DR: In this article, a dual-mode compact microstrip antenna based on the fundamental backward wave supported by a composite right/left-handed (CRLH) metamaterial transmission line is demonstrated.
Abstract: In this paper, a dual-mode compact microstrip antenna based on the fundamental backward wave supported by a composite right/left-handed (CRLH) metamaterial transmission line (TL) is demonstrated The physical size and operational frequencies of the antenna are determined by the CRLH metamaterial's unit-cell This antenna is capable of monopolar radiation at one resonant frequency and patch-like radiation at another resonant frequency Numerical and experimental results of a three unit-cell CRLH-based antenna are used to verify the authors' claims

Journal ArticleDOI
TL;DR: In this paper, the dispersion characteristics of a 2D unit cell with periodic (Bloch) boundary conditions are calculated using a simple, fast 2D loaded TL model with periodic boundary conditions.
Abstract: A uniplanar transmission-line (TL) network has been loaded with lumped elements (chip or printed), enabling one to achieve a two-dimensional (2D) uniplanar negative-refractive-index (NRI) metamaterial. The metamaterial consists of a 2D array of unit cells, composed of TL sections connected in series and loaded in a specified manner. The unit cell dimensions can be designed to be much smaller than the operating wavelength, enabling one to identify the structure as an effective medium, with a negative index of refraction. This NRI metamaterial supports transverse electric (TE) waves, as opposed to related previous work on NRI-TL media that supported transverse magnetic (TM) waves. The dispersion characteristics are calculated using a simple, fast 2D loaded TL model with periodic (Bloch) boundary conditions. Subsequently the dispersion relation is simplified in the homogeneous limit, thus allowing one to identify effective permittivities and permeabilities, which are shown to be simultaneously negative. Simulations demonstrating the negative refraction of a plane wave on an interface between such a NRI uniplanar metamaterial and a commensurate positive-refractive-index (PRI) metamaterial verify the validity of the proposed concept and theory. A fully printed unit cell is presented at microwave frequencies (~10 GHz) along with a prescription for synthesizing an isotropic 3D transmission line NRI metamaterial based on this unit cell.

Journal ArticleDOI
TL;DR: In this article, the authors proposed suspended compact and broadband gap-coupled variations of edge center-shorted and cornershorted square microstrip antennas, which give larger bandwidth with a smaller total patch size.
Abstract: Various suspended compact and broadband gap-coupled variations of edge center-shorted and corner-shorted square microstrip antennas, are proposed. These configurations give larger bandwidth with a smaller total patch size as compared to square microstrip antennas. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1261–1265, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21671

Proceedings ArticleDOI
17 Jun 2005
TL;DR: The cubic-cell transmission line host network is a physical realization of the 3D distributed node TLM lattice which has the same low-frequency properties as the FDTD Yee scheme as mentioned in this paper.
Abstract: We propose a new topology for realizing artificial microwave materials that exhibit a negative refractive index over a wide frequency band. These metamaterials consist of a three-dimensional transmission line mesh that is loaded with reactive series and shunt elements to create negative permittivity and permeability. The cubic-cell transmission line host network is a physical realization of the 3D distributed node TLM lattice which has the same low-frequency properties as the FDTD Yee scheme. This paper describes the topology, the theory, the design, and possible realizations of such a metamaterial. Its wave properties are validated by full-wave simulations using the time domain electromagnetic field simulation tool MEFiSTo-3D Pro.

Proceedings ArticleDOI
03 Jul 2005
TL;DR: In this article, a microstrip antenna with integrated RF microelectromechanical system (MEMS) switches is proposed and demonstrated to operate at dual frequencies with circular polarization at 6.69 GHz and 7.06 GHz.
Abstract: A microstrip antenna with integrated RF microelectromechanical system (MEMS) switches is proposed and demonstrated to operate at dual frequencies with circular polarization. The switches are incorporated into the diagonally fed square patch for controlling the operating frequency and a rectangular stub attached to the edge of the patch acts as the perturbation to produce the circular polarization at 6.69 GHz and 7.06 GHz.

Proceedings ArticleDOI
04 Dec 2005
TL;DR: A directive patch antenna with a metamaterial cover with significantly improved directivity is proposed and a comparison between the conventional patch antenna and the new meetamaterial patch antenna is given.
Abstract: A directive patch antenna with a metamaterial cover is proposed in this paper. Numerical results for the input return loss, radiation pattern, and directivity of such an antenna are presented. A comparison between the conventional patch antenna and the new metamaterial patch antenna is given. The results show that the directivity of the metamaterial patch antenna is significantly improved.

Journal ArticleDOI
TL;DR: In this paper, a transmission-line model for a patch antenna where a half of the patch is loaded with a dispersive material with negative parameters is used to explore the antenna bandwidth characteristics.
Abstract: In this letter, a transmission-line model for a patch antenna where a half of the patch is loaded with a dispersive material with negative parameters is used to explore the antenna bandwidth characteristics. Possibilities to reduce the antenna size using the phase compensation in the loaded patch are considered. Resonant properties of patch antennas loaded with a dispersive material and with a nondispersive medium having /spl epsi/=-/spl epsi//sub 0/,/spl mu/=-/spl mu//sub 0/ are compared with the unloaded case.

Proceedings ArticleDOI
03 Jul 2005
TL;DR: In this paper, a broadband suspended E-shaped microstrip antenna with a single slot was proposed, which reduced the area by half and increased the bandwidth by cutting an S-shaped slot.
Abstract: Variations of a broadband suspended E-shaped microstrip antenna are described. Its even mode compact variation i.e. a rectangular microstrip antenna with a single slot is proposed which reduces the area by half. The bandwidth of the compact S-shaped MSA is increased by cutting an S-shaped slot.

Journal ArticleDOI
TL;DR: In this paper, the authors demonstrate multiple focal lengths at microwave frequencies in a flat lens constructed of a left-handed metamaterial (LHM) with a negative effective index of refraction.
Abstract: We show experimental results demonstrating multiple focal lengths at microwave frequencies in a flat lens constructed of left-handed metamaterial (LHM). In contrast to conventional lenses, which are constructed of materials with positive index and require a curved surface or inhomogeneous structures to focus light or other electromagnetic radiation, no curvature is needed with a LHM because of a negative effective index of refraction. Such a flat lens has the advantage of being capable of changing the focal length by simply changing the distance between the electromagnetic source and the lens.

Journal ArticleDOI
TL;DR: In this paper, a complete set of periodic circuit networks which can realize electromagnetic wave propagation in different two-dimensional (2D) isotropic and anisotropic metamaterials (AMMs) was proposed.
Abstract: We propose a complete set of periodic circuit networks which can realize electromagnetic wave propagation in different two-dimensional (2D) isotropic and anisotropic metamaterials (AMMs). We synthesize the periodic circuits with unit cells of series capacitor or inductor in orthogonal directions, together with either capacitor or inductor shunted to ground. The dispersion relations of the periodic circuits are derived by applying Bloch boundary conditions to the unit cell, which show either elliptic or hyperbolic dispersion surface in phase space. The effective constitutive parameters are obtained by choosing different types and values of the impedance elements in the unit cell. The validity of the circuit models is proved by showing examples that the anisotropic $L\text{\ensuremath{-}}C$ circuits could exhibit the wave propagation characteristics of two 2D AMMs with different cutoff properties, called never-cutoff or anti-cutoff medium. We construct interfaces between isotropic normal medium and AMMs with properly designed $L\text{\ensuremath{-}}C$ circuits and analyze the electromagnetic wave propagation using microwave circuit simulations. We demonstrate extraordinary electromagnetic wave reflection and refraction phenomena including negative refraction, total reflection with reversion of the critical angle and anomalous Brewster effect that have good agreements with the theoretical analysis. Furthermore, we show that the $L\text{\ensuremath{-}}C$ circuit models of AMMs could lead to different approach of actual implementation of 2D AMMs through capacitance loaded transmission line metamaterials. The simulation on actual microstrip line structure demonstrates similar wave propagation phenomena of AMMs, and the losses in the structure only affect the magnitude of the propagating energy.

Journal ArticleDOI
TL;DR: In this article, a configuration with two gap-coupled circular microstrip antennas on the top dielectric layer stacked with one coaxial-fed circular patch on the bottom layer and an air-gap in-between two layers and the ground plane is presented.
Abstract: Different methods to increase the bandwidth of a microstrip antenna, such as use of an air-gap in-between stacked resonators and the ground plane and planar multiresonators, are combined to achieve broad bandwidth with increased gain. A configuration with two gap-coupled circular microstrip antennas on the top dielectric layer stacked with one coaxial-fed circular patch on the bottom layer and an air-gap in-between two layers and the ground plane yield a bandwidth of 1093 MHz (47%) with a gain of 9.54 dB at the S-band frequency of 2.325 GHz. Also, dual-band response with broadside radiation and improved gain at both frequencies is achieved by suitably changing parameters of this configuration. Parametric studies of this configuration on dielectric substrate for both broadband and dual-band operation are presented in this paper. The experiments are performed on broadband and dual-band configurations, which are in agreement with the theoretical results. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 47: 489–494, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21208

Journal ArticleDOI
TL;DR: A band separating device that uses an anisotropic metamaterial exhibiting negative refraction is designed and measured and design issues are discussed, and measurement results are presented.
Abstract: A band separating device that uses an anisotropic metamaterial exhibiting negative refraction is designed and measured. The metamaterial has frequency dispersion in one component of the permeability tensor. A beam is incident onto the metamaterial and undergoes frequency dependent reflection and refraction directing different bandwidths towards three distinct measurement ports. Design issues are discussed, and measurement results are presented.

Proceedings ArticleDOI
03 Jul 2005
TL;DR: In this paper, center-fed circular and square microstrip antennas loaded with shorting vias are studied for miniaturization, and the authors show that the size of microstrip antenna fed symmetrically is large in terms of a wavelength.
Abstract: The size of microstrip antennas fed symmetrically is large in terms of a wavelength. In this paper, center-fed circular and square microstrip antennas loaded with shorting vias are studied for miniaturization.

DOI
01 Mar 2005
TL;DR: In this article, the authors focus on transmission line metamaterials, which are planar structures comprising a network of distributed transmission lines loaded periodically in a dual (high-pass) configuration with lumped inductors, L, and capacitors, C.
Abstract: Metamaterials are artificially engineered structures with unusual electromagnetic properties. In this article, we review the implementation of isotropic metamaterials that exhibit a negative permittivity and a negative permeability, thus leading to a negative index of refraction. Specifically, the article focuses on transmission-line metamaterials, which are planar structures comprising a network of distributed transmission lines loaded periodically in a dual (high-pass) configuration with lumped inductors, L, and capacitors, C. The periodic unit cell is much smaller than the wavelength, thus leading to an effective medium in which the lumped loading elements can be either chip or printed. Based on this transmission-line method, a number of RF/microwave devices are presented, including lenses that can overcome the diffraction limit, compact phase-shifting lines, small antennas, antenna feed networks and baluns, backward leaky-wave antennas and high-directivity coupled-line couplers.

Proceedings ArticleDOI
12 Jun 2005
TL;DR: In this article, the authors proposed and analyzed the use of metamaterial planar layers for synthesizing compact subwavelength leaky-wave radiators in the microwave regime, and showed the salient guidance and radiation properties of the anomalous natural modes supported by these bilayered structures.
Abstract: Here we propose and analyze theoretically the use of metamaterial planar layers for synthesizing compact sub-wavelength leaky-wave radiators in the microwave regime. In particular, the possibility of pairing "conjugate" metamaterials in order to squeeze the dimensions of microwave components is explored here for the leaky-wave operation of an open waveguide consisting of a stack of grounded metamaterial layers. We show the salient guidance and radiation properties of the anomalous natural modes supported by these bilayered structures, giving further physical insights into the phenomenon.

Proceedings ArticleDOI
04 Dec 2005
TL;DR: In this article, a parametric study of a microstrip-line inset-fed rectangular patch antenna and a two-layer electromagnetically coupled (EMC) antenna was performed using software IE3D to investigate the influence of the inset position and air thickness between the two layers on input impedance, resonant frequency, and bandwidth.
Abstract: This paper presents the parametric study of a microstrip-line inset-fed rectangular patch antenna and a two-layer electromagnetically coupled (EMC) rectangular patch antenna. The influence of the inset position and the air thickness between the two layers on input impedance, resonant frequency, and bandwidth is investigated by using software IE3D. The final results show that the inset depth is the primary factor affecting the matching and the air thickness mainly affects the bandwidth. The tested two-layer antenna works at 6.1 GHz with a bandwidth (S/sub 11/ /spl les/ -10dB) of about 11%, 8-dBi gain. The 3-dB beamwidth in the E-plane and H-plane is 57/spl deg/ and 70/spl deg/, respectively.

Proceedings ArticleDOI
07 Mar 2005
TL;DR: In this paper, the authors apply a transmission-line (TL) approach towards CRLH metamaterials to realize novel microwave devices including antennas with characteristics (functionality or performance) surpassing those of conventional (i.e., RH) materials.
Abstract: Recent research on metamaterials with simultaneously negative permittivity (/spl epsiv/) and permeability (/spl mu/), more commonly referred to as left-handed (LH) materials, has stimulated the development of novel concepts and applications. Since right-handed (RH) effects are unavoidable, practical LH materials (LHM) are in reality composite right/left-handed (CRLH) materials. Interestingly, the co-existence of LH and RH contributions in CRLH materials, far from being detrimental, leads to useful phenomena. By applying a transmission-line (TL) approach towards CRLH metamaterials, the unique properties of these metamaterials have been used to realize novel microwave devices including antennas with characteristics (functionalities or performance) surpassing those of conventional (i.e., RH) materials.

Journal ArticleDOI
TL;DR: In this article, a metamaterial substrate consisting of a quasi-periodic metallic planr pattern and a flat metal sheet, interconnected through metallic vias, has been studied and it is shown that this structure possesses multiple in-phase reflection frequency regimes and spectral gaps for transverse-magnetic surface waves, whereas the transverse electric surface waves are suppressed in all frequencies.
Abstract: We report our experimental and theoretical studies on a metamaterial substrate consisting of a quasi-periodic metallic planr pattern and a flat metal sheet, interconnected through metallic vias. We show that this structure possesses multiple in-phase reflection frequency regimes and spectral gaps for transverse-magnetic surface waves, whereas the transverse-electric surface waves are suppressed in all frequencies. In particular, an antenna put on top of this planar structure radiates with very high directivity (D=240) at some frequencies. This phenomenon is mainly governed by the inhomogeneity of the structure, which is a collective effect of perfect magnetic and electric conductors operating simultaneously at the frequency.