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Journal ArticleDOI

Free-Space Focusing at C-Band Using a Flat Fully Printed Multilayer Metamaterial Lens

TL;DR: In this paper, a volumetric metamaterial lens exhibiting a negative refractive index (NRI) at C-band is designed and its free-space focusing properties are experimentally verified.
Abstract: A volumetric metamaterial lens exhibiting a negative refractive index (NRI) at C-band is designed and its free-space focusing properties are experimentally verified. The designed lens employs a multilayer geometry and its unit cells are loaded using metal–insulator–metal (MIM) capacitors and dual-arm spiral inductors in a biplanar configuration. These elements, although fully printed and without vias, provide strong reactive loading that enables a unit cell size of $\lambda_0/11$ and allows the metamaterial’s dispersion properties to be accurately modeled in the effective-medium regime using an equivalent-circuit approach. It is also conducive to implementation at high frequencies, where surface-mount components are unusable. The focusing properties of the fabricated lens are confirmed for a band of frequencies around 5.0 GHz in an anechoic chamber using a free-space field probing system consisting of electrically small shielded-loop antennas affixed to a computer-controlled scanner.
Citations
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Journal ArticleDOI
TL;DR: In this article, a low-profile and wideband metamaterial-lens (metalens) antenna based on high-refractive-index metasurface is presented.
Abstract: This paper presents a low-profile and wideband metamaterial-lens (metalens) antenna based on high-refractive-index metasurface. A novel three-layer nonresonant metamaterial unit cell is introduced and analyzed by the full-wave simulation tool. The proposed unit cell is a stacking configuration of four H-shaped lines realized by multiple microwave laminates. It can achieve a large refractive index variation range of 4.76 (from 1.5 to 6.26). In addition, two impedance matching layers based on the proposed unit cell are developed to provide better transmission for incident waves passing through the metalens antenna. The attractiveness of this new metalens antenna is its low-profile thickness of $0.26~\lambda _{0}$ , where $\lambda _{0}$ is the wavelength at 10 GHz. To validate the performance of the metalens antenna, a wideband stub-loaded horn antenna with stable radiation patterns in E- and H-planes is adopted as the feeding antenna source. The measured results demonstrate a wide impedance bandwidth of 66% (7.2–14.3 GHz) and a high aperture efficiency of up to 65%. Moreover, its sidelobe and cross-polarization levels are less than −17 and −25 dB across the entire bandwidth, respectively.

33 citations


Cites background from "Free-Space Focusing at C-Band Using..."

  • ...the refractive index distribution equation of each unit cell on the lens aperture, n (r) = n0 − ( √ r2 + F2 − F)/T , where n0 is the maximum refractive index at the center of the lens aperture, r is the distance of the ray path from the source to the unit cell, F is the focal length, and T is the thickness of the lens [4]–[6]....

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  • ...2866528 index metamaterial (NIM) lenses [4]–[6], low-/zero-index...

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Journal ArticleDOI
TL;DR: In this paper, the authors proposed an ultrawideband and high-gain antipodal tapered slot antenna (ATSA) with a gradient refractive index (GRIN) lens.
Abstract: This letter proposes an ultrawideband and high-gain antipodal tapered slot antenna (ATSA) with a gradient refractive index (GRIN) lens. The GRIN lens consisting six metamaterial lenses is placed in the maximum radiation direction of the ATSA to greatly enhance its radiation capability. We found that the proposed GRIN lens antenna has a wide impedance bandwidth of 175.7% (0.84–13 GHz) and −3 dB gain bandwidth of 65.8% (5.86–11.6 GHz). Its gain is averagely increased by 4.81 dB in the whole operating band, and the maximum gain reaches 20.55 dBi at 9.5 GHz. The simulation and measured results demonstrate that the designed GRIN lens antenna has an excellent performance and is suitable for short-pulse ground penetrating radar systems.

21 citations


Cites background or methods from "Free-Space Focusing at C-Band Using..."

  • ..., negative index metamaterial lenses [10], [11], low-/zero-index metamaterial lenses [12], [13], and gradient refractive index (GRIN) lenses [14]–[17]....

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  • ...Generally speaking, planar lenses [6]–[9] and three-dimensional (3-D) lenses [10]–[17] are typical methods to improve the radiation gain....

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Journal ArticleDOI
TL;DR: In this paper, a metamaterial lens was designed based on a two-dimensional host transmission line network loaded with inductors and capacitors, and the planar negative refractive index (NRI) periodic structure was constructed.
Abstract: A metamaterial lens was designed based on a two-dimensional host transmission line network loaded with inductors and capacitors. The planar negative refractive index (NRI) periodic structure, consi...

9 citations

Proceedings ArticleDOI
04 May 2018
TL;DR: In this article, a novel configuration of left-handed metamaterial (LHM) unit cell based on microstrip line loaded split ring resonator (SRR) has been proposed.
Abstract: A novel configuration of left handed metamaterial (LHM) unit cell based on microstrip line loaded split ring resonator (SRR) has been proposed. Unit cell is optimized to get negative refractive index using a Full wave 3D electromagnetic simulator. The proposed unit cell exhibits negative refractive index over 5.7GHz to 6GHz frequency band. The unit cell structure has low profile and occupies volume of 17x17x1 7mm 3.

7 citations


Cites background from "Free-Space Focusing at C-Band Using..."

  • ...[5] DNG material does not exist in nature; they are generated artificially and are known as metamaterials....

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Journal ArticleDOI
TL;DR: In this article, the design, fabrication and characterization of electro-textile inductor and capacitor patterns on denim fabric as a basis for the development of wearable e-textiles are presented.
Abstract: In this paper we present the design, fabrication and characterization of electro-textile inductor and capacitor patterns on denim fabric as a basis for the development of wearable e-textiles. Plana...

6 citations

References
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Journal ArticleDOI
TL;DR: The authors' simulations show that a version of the lens operating at the frequency of visible light can be realized in the form of a thin slab of silver, which resolves objects only a few nanometers across.
Abstract: Optical lenses have for centuries been one of scientists’ prime tools. Their operation is well understood on the basis of classical optics: curved surfaces focus light by virtue of the refractive index contrast. Equally their limitations are dictated by wave optics: no lens can focus light onto an area smaller than a square wavelength. What is there new to say other than to polish the lens more perfectly and to invent slightly better dielectrics? In this Letter I want to challenge the traditional limitation on lens performance and propose a class of “superlenses,” and to suggest a practical scheme for implementing such a lens. Let us look more closely at the reasons for limitation in performance. Consider an infinitesimal dipole of frequency v in front of a lens. The electric component of the field will be given by some 2D Fourier expansion,

10,974 citations


"Free-Space Focusing at C-Band Using..." refers background in this paper

  • ...largely motivated by the seminal contributions of Veselago [1], who introduced the notion that an NRI slab would serve as a flat lens, and Pendry [2], who discovered that such lenses were...

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  • ...The early works in metamaterials were largely motivated by the seminal contributions of Veselago [1], who introduced the notion that an NRI slab would serve as a flat lens, and Pendry [2], who discovered that such lenses were Manuscript received February 24, 2015; revised July 05, 2015; accepted August 24, 2015....

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Journal ArticleDOI

10,495 citations


"Free-Space Focusing at C-Band Using..." refers background in this paper

  • ...The propagating waves emanated by a free-space source that impinge on a flat NRI metamaterial slab experience negative refraction at both the input and output interfaces, resulting in the creation of both internal and external foci [1]....

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  • ...largely motivated by the seminal contributions of Veselago [1], who introduced the notion that an NRI slab would serve as a flat lens, and Pendry [2], who discovered that such lenses were...

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  • ...The early works in metamaterials were largely motivated by the seminal contributions of Veselago [1], who introduced the notion that an NRI slab would serve as a flat lens, and Pendry [2], who discovered that such lenses were Manuscript received February 24, 2015; revised July 05, 2015; accepted August 24, 2015....

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Journal ArticleDOI
TL;DR: A composite medium, based on a periodic array of interspaced conducting nonmagnetic split ring resonators and continuous wires, that exhibits a frequency region in the microwave regime with simultaneously negative values of effective permeability and permittivity varepsilon(eff)(omega).
Abstract: We demonstrate a composite medium, based on a periodic array of interspaced conducting nonmagnetic split ring resonators and continuous wires, that exhibits a frequency region in the microwave regime with

8,057 citations


"Free-Space Focusing at C-Band Using..." refers methods in this paper

  • ...Whereas the first successful realization of an NRI metamaterial employed split-ring resonators (SRRs) and wires [3], the first metamaterial lens was realized in planar...

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BookDOI
11 Nov 2005
TL;DR: In this paper, the authors define Metamaterials (MTMs) and Left-Handed (LH) MTMs as a class of two-dimensional MTMs.
Abstract: Preface. Acknowledgments. Acronyms. 1 Introduction. 1.1 Definition of Metamaterials (MTMs) and Left-Handed (LH) MTMs. 1.2 Theoretical Speculation by Viktor Veselago. 1.3 Experimental Demonstration of Left-Handedness. 1.4 Further Numerical and Experimental Confirmations. 1.5 "Conventional" Backward Waves and Novelty of LH MTMs. 1.6 Terminology. 1.7 Transmission Line (TL) Approach. 1.8 Composite Right/Left-Handed (CRLH) MTMs. 1.9 MTMs and Photonic Band-Gap (PBG) Structures. 1.10 Historical "Germs" of MTMs. References. 2 Fundamentals of LH MTMs. 2.1 Left-Handedness from Maxwell's Equations. 2.2 Entropy Conditions in Dispersive Media. 2.3 Boundary Conditions. 2.4 Reversal of Doppler Effect. 2.5 Reversal of Vavilov- Cerenkov Radiation. 2.6 Reversal of Snell's Law: Negative Refraction. 2.7 Focusing by a "Flat LH Lens". 2.8 Fresnel Coefficients. 2.9 Reversal of Goos-H anchen Effect. 2.10 Reversal of Convergence and Divergence in Convex and Concave Lenses. 2.11 Subwavelength Diffraction. References. 3 TLTheoryofMTMs. 3.1 Ideal Homogeneous CRLH TLs. 3.1.1 Fundamental TL Characteristics. 3.1.2 Equivalent MTM Constitutive Parameters. 3.1.3 Balanced and Unbalanced Resonances. 3.1.4 Lossy Case. 3.2 LC Network Implementation. 3.2.1 Principle. 3.2.2 Difference with Conventional Filters. 3.2.3 Transmission Matrix Analysis. 3.2.4 Input Impedance. 3.2.5 Cutoff Frequencies. 3.2.6 Analytical Dispersion Relation. 3.2.7 Bloch Impedance. 3.2.8 Effect of Finite Size in the Presence of Imperfect Matching. 3.3 Real Distributed 1D CRLH Structures. 3.3.1 General Design Guidelines. 3.3.2 Microstrip Implementation. 3.3.3 Parameters Extraction. 3.4 Experimental Transmission Characteristics. 3.5 Conversion from Transmission Line to Constitutive Parameters. References. 4 Two-Dimensional MTMs. 4.1 Eigenvalue Problem. 4.1.1 General Matrix System. 4.1.2 CRLH Particularization. 4.1.3 Lattice Choice, Symmetry Points, Brillouin Zone, and 2D Dispersion Representations. 4.2 Driven Problem by the Transmission Matrix Method (TMM). 4.2.1 Principle of the TMM. 4.2.2 Scattering Parameters. 4.2.3 Voltage and Current Distributions. 4.2.4 Interest and Limitations of the TMM. 4.3 Transmission Line Matrix (TLM) Modeling Method. 4.3.1 TLM Modeling of the Unloaded TL Host Network. 4.3.2 TLM Modeling of the Loaded TL Host Network (CRLH). 4.3.3 Relationship between Material Properties and the TLM Model Parameters. 4.3.4 Suitability of the TLM Approach for MTMs. 4.4 Negative Refractive Index (NRI) Effects. 4.4.1 Negative Phase Velocity. 4.4.2 Negative Refraction. 4.4.3 Negative Focusing. 4.4.4 RH-LH Interface Surface Plasmons. 4.4.5 Reflectors with Unusual Properties. 4.5 Distributed 2D Structures. 4.5.1 Description of Possible Structures. 4.5.2 Dispersion and Propagation Characteristics. 4.5.3 Parameter Extraction. 4.5.4 Distributed Implementation of the NRI Slab. References. 5 Guided-Wave Applications. 5.1 Dual-Band Components. 5.1.1 Dual-Band Property of CRLH TLs. 5.1.2 Quarter-Wavelength TL and Stubs. 5.1.3 Passive Component Examples: Quadrature Hybrid and Wilkinson Power Divider. 5.1.3.1 Quadrature Hybrid. 5.1.3.2 Wilkinson Power Divider. 5.1.4 Nonlinear Component Example: Quadrature Subharmonically Pumped Mixer. 5.2 Enhanced-Bandwidth Components. 5.2.1 Principle of Bandwidth Enhancement. 5.2.2 Rat-Race Coupler Example. 5.3 Super-compact Multilayer "Vertical" TL. 5.3.1 "Vertical" TL Architecture. 5.3.2 TL Performances. 5.3.3 Diplexer Example. 5.4 Tight Edge-Coupled Coupled-Line Couplers (CLCs). 5.4.1 Generalities on Coupled-Line Couplers. 5.4.1.1 TEM and Quasi-TEM Symmetric Coupled-Line Structures with Small Interspacing: Impedance Coupling (IC). 5.4.1.2 Non-TEM Symmetric Coupled-Line Structures with Relatively Large Spacing: Phase Coupling (PC). 5.4.1.3 Summary on Symmetric Coupled-Line Structures. 5.4.1.4 Asymmetric Coupled-Line Structures. 5.4.1.5 Advantages of MTM Couplers. 5.4.2 Symmetric Impedance Coupler. 5.4.3 Asymmetric Phase Coupler. 5.5 Negative and Zeroth-Order Resonator. 5.5.1 Principle. 5.5.2 LC Network Implementation. 5.5.3 Zeroth-Order Resonator Characteristics. 5.5.4 Circuit Theory Verification. 5.5.5 Microstrip Realization. References. 6 Radiated-Wave Applications. 6.1 Fundamental Aspects of Leaky-Wave Structures. 6.1.1 Principle of Leakage Radiation. 6.1.2 Uniform and Periodic Leaky-Wave Structures. 6.1.2.1 Uniform LW Structures. 6.1.2.2 Periodic LW Structures. 6.1.3 Metamaterial Leaky-Wave Structures. 6.2 Backfire-to-Endfire (BE) Leaky-Wave (LW) Antenna. 6.3 Electronically Scanned BE LW Antenna. 6.3.1 Electronic Scanning Principle. 6.3.2 Electronic Beamwidth Control Principle. 6.3.3 Analysis of the Structure and Results. 6.4 Reflecto-Directive Systems. 6.4.1 Passive Retro-Directive Reflector. 6.4.2 Arbitrary-Angle Frequency Tuned Reflector. 6.4.3 Arbitrary-Angle Electronically Tuned Reflector. 6.5 Two-Dimensional Structures. 6.5.1 Two-Dimensional LW Radiation. 6.5.2 Conical-Beam Antenna. 6.5.3 Full-Space Scanning Antenna. 6.6 Zeroth Order Resonating Antenna. 6.7 Dual-Band CRLH-TL Resonating Ring Antenna. 6.8 Focusing Radiative "Meta-Interfaces". 6.8.1 Heterodyne Phased Array. 6.8.2 Nonuniform Leaky-Wave Radiator. References. 7 The Future of MTMs. 7.1 "Real-Artificial" Materials: the Challenge of Homogenization. 7.2 Quasi-Optical NRI Lenses and Devices. 7.3 Three-Dimensional Isotropic LH MTMs. 7.4 Optical MTMs. 7.5 "Magnetless" Magnetic MTMs. 7.6 Terahertz Magnetic MTMs. 7.7 Surface Plasmonic MTMs. 7.8 Antenna Radomes and Frequency Selective Surfaces. 7.9 Nonlinear MTMs. 7.10 Active MTMs. 7.11 Other Topics of Interest. References. Index.

2,750 citations


Additional excerpts

  • ...The planar NRI-TL metamaterial has seen applications in the development of novel phase-shifters, couplers, and leaky-wave antennas [5], [6]....

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Journal ArticleDOI
TL;DR: In this article, the authors proposed an alternate perspective on the design and function of such materials that exploits the well-known L-C distributed network representation of homogeneous dielectrics.
Abstract: Recent demonstrations of negative refraction utilize three-dimensional collections of discrete periodic scatterers to synthesize artificial dielectrics with simultaneously negative permittivity and permeability. In this paper, we propose an alternate perspective on the design and function of such materials that exploits the well-known L-C distributed network representation of homogeneous dielectrics. In the conventional low-pass topology, the quantities L and C represent a positive equivalent permeability and permittivity, respectively. However, in the dual configuration, in which the positions of L and C are simply interchanged, these equivalent material parameters assume simultaneously negative values. Two-dimensional periodic versions of these dual networks are used to demonstrate negative refraction and focusing; phenomena that are manifestations of the fact that such media support a propagating fundamental backward harmonic. We hereby present the characteristics of these artificial transmission-line media and propose a suitable means of implementing them in planar form. We then present circuit and full-wave field simulations illustrating negative refraction and focusing, and the first experimental verification of focusing using such an implementation.

1,439 citations


"Free-Space Focusing at C-Band Using..." refers methods in this paper

  • ...form using the NRI transmission-line (NRI-TL) approach [4], in which a host TL such as microstrip is periodically loaded...

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