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Proceedings of the IEEE

Issue 10 • Date Oct. 2011

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Displaying Results 1 - 25 of 26
  • [Front cover]

    Page(s): C1
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  • Proceedings of the IEEE publication information

    Page(s): C2
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  • Table of contents

    Page(s): 1609 - 1610
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  • Is Nuclear Power Globally Scalable? [Point of View]

    Page(s): 1611 - 1617
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  • Metamaterials: Fundamentals and Applications in the Microwave and Optical Regimes [Scanning the Issue]

    Page(s): 1618 - 1621
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  • Electromagnetic Design With Transformation Optics

    Page(s): 1622 - 1633
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (882 KB) |  | HTML iconHTML  

    Transformation optics is an emerging technique for the design of advanced electromagnetic media. Transformation optical devices exploit the form invariance of Maxwell's equations, allowing geometry to play the dominant role in the design process rather than traditional wave or ray optics. The use of coordinate transformations vastly eases the burden of design for a large class of devices, though at the expense of increasing the complexity of the underlying materials used. Although the required constitutive parameters of a transformation optical structure can be challenging-inherently anisotropic and spatially varying, with both magnetic and electric response-nevertheless the parameter requirements can often be met or approximated through the use of artificially structured metamaterials. Here, we review the basic concepts associated with transformation optics and provide several examples to illustrate its application. View full abstract»

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  • Anisotropic Transmission-Line Metamaterials for 2-D Transformation Optics Applications

    Page(s): 1634 - 1645
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1179 KB) |  | HTML iconHTML  

    In this contribution, we present a two-dimensional metamaterial unit cell which synthesizes effective material parameters needed for “transformation optics” applications. The metamaterial consists of a grid of reactively loaded transmission-line segments and is a generalization of a previously presented unit cell in that it also synthesizes off-diagonal elements of the permeability tensor. We apply this unit cell to two “transformation optics” applications, a retro-directive reflector, and a cloak. This cloak is different from the so-far reported split-ring-resonator/wire structures in that it not only synthesizes the required μρ and εz distribution but also the μφ one. For the cloak, detailed radar cross-section (RCS) and bandwidth results are presented. It is shown that the total RCS bandwidth is 33.5%, and that losses influence the cloaking performance not critically, pointing to the possibility of practical “transformation optics” designs using the proposed unit cell. Full-wave simulation results of a transmission-line metamaterial cloak in microstrip technology are presented, verifying that the unit cell presented in this paper synthesizes the effective material parameters needed for “transformation optics” or applications that require effective material parameters with off-diagonal tensor elements. View full abstract»

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  • Broadband Electromagnetic Cloaking Realized With Transmission-Line and Waveguiding Structures

    Page(s): 1646 - 1659
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    Electromagnetic cloaking, or, in other words, techniques making objects “invisible” to the electromagnetic radiation, has attracted much attention in the last few years. Several different concepts have been proposed and studied analytically, numerically, and even experimentally. To make objects, especially strong scatterers, invisible to the impinging electromagnetic radiation is not an easy task. In this paper, we explain how the concept of transmission-line metamaterials, developed in the beginning of the 21st century, can be used in the creation of a special class of electromagnetic cloaking devices. We also make an overview of other approaches to electromagnetic cloaking. View full abstract»

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  • Bulk Metamaterials Made of Resonant Rings

    Page(s): 1660 - 1668
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    In this brief review, we present the fundamentals of bulk resonant ring metamaterial (RRM) theory. Metamaterials made of resonant rings are discussed, and some basic design rules are provided. Homogenization (including spatial dispersion) of 3-D resonant ring latices is reviewed, with emphasis in isotropic designs. Edge effects in finite size metamaterial samples are discussed. Finally, possible applications and future trends are briefly reviewed. View full abstract»

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  • Optical Metamaterials Based on Optical Nanocircuits

    Page(s): 1669 - 1681
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    Here we review the application of the optical nanocircuit paradigm to design and characterize metamaterials with exotic optical properties. The interaction of small nanoparticles with light is equivalently described in terms of optical lumped circuit elements, which relate the equivalent optical voltage across the particles and the optical displacement field current circulating through them. This equivalence goes beyond a simple description of the interaction of an individual nanoparticle with the impinging optical signal, as collections of closely spaced particles may be tailored as complex nanocircuit connections with specific optical response. Inspired by the fascinating concept and potentials of transmission-line metamaterials at microwaves, in which networks of lumped radio-frequency (RF) and microwave circuit elements may provide exotic metamaterial properties, in this paper, we review and discuss how analogous concepts may be translated to optical frequencies at the nanoscale, by applying the nanocircuit paradigm. We present several designs of 0-D, 1-D, 2-D, and 3-D arrays of nanoparticles supporting subwavelength resonances, negative-index propagation, and other exotic optical effects, achieved by suitably combining and connecting nanoparticles operating as optical lumped nanocircuit elements. Fascinating applications of these concepts are proposed in a variety of optical scenarios, considering the influence of natural material dispersion and loss in optical materials. View full abstract»

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  • Development of Bulk Optical Negative Index Fishnet Metamaterials: Achieving a Low-Loss and Broadband Response Through Coupling

    Page(s): 1682 - 1690
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (748 KB) |  | HTML iconHTML  

    In this paper, we discuss the development of a bulk negative refractive index metamaterial made of cascaded “fishnet” structures, with a negative index existing over a broad spectral range. We describe in detail the design of bulk metamaterials, their fabrication and characterization, as well as the mechanism of how coupling of the unit cells can reduce loss in the material through an optical transmission-line approach. Due to the lowered loss, the metamaterial is able to achieve the highest figure of merit to date for an optical negative index metamaterial (NIM) in the absence of gain media. The increased thickness of the metamaterial also allows a direct observation of negative refraction by illuminating a prism made of the material. Such an observation results in an unambiguous demonstration of negative phase evolution of the wave propagating inside the metamaterial. Furthermore, the metamaterial can be readily accessed from free space, making it functional for optical devices. As such, bulk optical metamaterials should open up new prospects for studies of the unique optical effects associated with negative and zero index materials such as the superlens, reversed Doppler effect, backward Cerenkov radiation, optical tunneling devices, compact resonators, and highly directional sources. View full abstract»

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  • Bianisotropic Effective Parameters of Optical Metamagnetics and Negative-Index Materials

    Page(s): 1691 - 1700
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (830 KB) |  | HTML iconHTML  

    Approaches to the adequate homogenization of optical metamaterials are becoming more and more complex, primarily due to an increased understanding of the role of asymmetric electrical and magnetic responses, in addition to the nonlocal effects of the surrounding medium, even in the simplest case of plane-wave illumination. The current trend in developing such advanced homogenization descriptions often relies on utilizing bianisotropic models as a base on top of which novel optical characterization techniques can be built. In this paper, we first briefly review general principles for developing a bianisotropic homogenization approach. Second, we present several examples validating and illustrating our approach using single-period passive and active optical metamaterials. We also show that the substrate may have a significant effect on the bianisotropic characteristics of otherwise symmetric passive and active metamaterials. View full abstract»

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  • Recent Advances in Metamaterial Transmission Lines Based on Split Rings

    Page(s): 1701 - 1710
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (760 KB) |  | HTML iconHTML  

    This paper is focused on metamaterial transmission lines based on split rings. Specifically, the considered lines are those based on the hybrid approach, where complementary split ring resonators (CSRRs) are combined with series gaps and shunt inductive stubs, and those implemented by loading a host line with open split ring resonators (OSRRs) and open complementary split ring resonators (OCSRRs). The dispersion characteristics and the characteristic impedance of such lines, essential for design purposes, are analyzed to the light of the lumped element equivalent circuit models of the lines. Finally, it is shown that hybrid lines are useful for the design of power splitters with filtering capability, and OSRR/OCSRR-loaded lines are of interest for the design of wideband bandpass filters. The achieved performances are satisfactory and device dimensions small. View full abstract»

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  • Metamaterial Dispersion Engineering Concepts and Applications

    Page(s): 1711 - 1719
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    Metamaterial dispersion engineering is presented as a general concept for engineering the phase versus frequency response of microwave materials and devices. Two categories of metamaterials are considered, composite right/left-handed (CRLH) transmission line and multiscale ferromagnetic nanowire (FMNW) metamaterials. The dispersive Drude properties of CRLH metamaterials are derived and corresponding application examples are described in terms of CRLH dominant Taylor dispersive parameters: a tight broadband coupled-line coupler (phase velocity parameter), an ultra-wideband pulse position modulator transmitter (group velocity parameter), and a leaky-wave antenna based real-time spectrum analyzer (group velocity dispersion parameter). FMNW metamaterials are discussed as a double-Lorentz example of a multiscale metamaterial with unique properties, and their applications are illustrated with the example of a dual-band edge-mode isolator based on the recently discovered double ferromagnetic resonance. View full abstract»

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  • Metamaterial-Inspired Engineering of Antennas

    Page(s): 1720 - 1731
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    A variety of antennas have been engineered with metamaterials (MTMs) and metamaterial-inspired constructs to improve their performance characteristics. Examples include electrically small, near-field resonant parasitic (NFRP) antennas that require no matching network and have high radiation efficiencies. Experimental verification of their predicted behaviors has been obtained. Recent developments with this NFRP electrically small paradigm will be reviewed. They include considerations of increased bandwidths, as well as multiband and multifunctional extensions. View full abstract»

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  • Narrowband and Wideband Metamaterial Antennas Based on Degenerate Band Edge and Magnetic Photonic Crystals

    Page(s): 1732 - 1745
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    Historically, antennas and microwave devices relied on isotropic media. This provided for limited degrees of freedom (one for dielectric and another for magnetic) in the design process. In contrast, anisotropic media introduce several more degrees of freedom (at least three more for dielectrics and three additional ones for magnetic) opening a new direction in designing radio-frequency (RF) communication devices and wireless systems. A focus of the paper is the introduction of anisotropic media parameters emulated using simple printed, but highly coupled, transmission lines (TRLs). The paper begins by introducing the equivalence between in-plane anisotropy and coupled TRLs to realize degenerate band edge (DBE) and magnetic photonic crystal (MPC) modes. This is followed by the design of miniature antenna elements via dispersion engineering, demonstrating their performance on small finite substrates. The second part of the paper is focused on concatenating DBE and MPC antenna elements to realize smaller size wideband arrays. Such arrays exploit the current sheet antenna (CSA) concept to achieve the coveted goal of small wideband metamaterial arrays. For example, by constructing an array of antenna elements ~ λ/10×λ/10 in size, highly conformal (very thin) apertures delivering 5 : 1 bandwidth are demonstrated while avoiding grating lobes. In contrast to transitional approaches, the proposed method exploits (rather than suppressing) the metallic ground plane inductance. Instead, the capacitance of the tightly coupled antenna elements is used to cancel the inductance over wide bandwidths. By further employing small size array elements, large bandwidths can be achieved using a smaller footprint. View full abstract»

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  • Evolution of Composite Right/Left-Handed Leaky-Wave Antennas

    Page(s): 1746 - 1754
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    In this paper, the evolution of the composite right/left-handed (CRLH) leaky-wave antennas (LWAs) yielding several novel CRLH LWA is reviewed. Starting with the concept of CRLH LWAs, the concave and convex passive CRLH LWAs are discussed along with the conformation effects in each case and a dispersion engineering method is introduced to compensate for the conformation effect to refocus the main radiation beam. Next, planar and conformal varactor-based electronically controlled CRLH LWAs are reviewed. In the planar case electronic beam steering and beamwidth controlling are discussed while in the case of conformal version electronic radiation aperture selectivity as well as electronic beam focusing is discussed. Finally, a dual polarized CRLH LWA is presented which is a balanced four-port coupled CRLH LW-TL that conserves its CRLH nature under both common-mode and differential-mode excitations but with two orthogonal E-planes resulting in two orthogonal polarizations for the radiated fields. View full abstract»

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  • Steering Phased Array Antenna Beams to the Horizon Using a Buckyball NIM Lens

    Page(s): 1755 - 1767
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    In this paper, we present the design, optimization, fabrication, and measurement of a negative index metamaterial (NIM) buckyball shell lens to steer phased array antenna (PAA) beams to the horizon. The conformal mapping technique of transformation optics is utilized in the design process to facilitate with lens fabrication. A new dual polarization unit cell is designed to avoid the issues associated with short cut wires, were a split ring resonator (SRR) and wire design to be used. The lens is measured using an actual PAA and it demonstrates to-the-horizon scanning as designed, although the material loss is high. An improved unit cell design is proposed to reduce several known loss mechanisms. A new lens design methodology using Bezier curves as seed surfaces is also described. View full abstract»

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  • Strong Light Confinement With Periodicity

    Page(s): 1768 - 1779
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    Photonic crystals were proposed over two decades ago to realize strong light confinement via their perfect photonic bandgaps, but the expected ultrahigh-Q wavelength-sized cavities were achieved just recently in a slightly different system that has only a partial bandgap, more specifically, a modulated mode-gap cavity in a 2-D photonic crystal. It is now possible to store photons for over a nanosecond in a wavelength-sized volume for this type of cavity, which has not been realized in other systems. The same confinement mechanism has provided various interesting cavities including air-core cavities, index-modulation-induced cavities, and dynamic cavities. We discuss the impact and possible applications of the achieved strong light confinement. First, it has a strong impact on photonic integrated circuits and photonic network-on-chip (NoC) applications because these cavities enable us to realize tiny, low-power-consumption, and integratable photonic devices, which are hard to realize conventionally. It is next shown that an ultrahigh- Q cavity system constitutes an extreme slow-light medium. It is also shown that ultrahigh-Q cavities enable the adiabatic tuning of light, which makes it possible to manipulate optical signals very differently from conventional optics. Finally, other possible systems promising for strong light confinement are investigated, such as 1-D photonic crystals and photonic amorphous structures without any periodicity. View full abstract»

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  • The Fundamental Physics of Directive Beaming at Microwave and Optical Frequencies and the Role of Leaky Waves

    Page(s): 1780 - 1805
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    This review paper summarizes various aspects of directive beaming and explains these aspects in terms of leaky waves. Directive beaming occurs in antenna design where a narrow beam is obtainable by using fairly simple planar structures excited by a single source. These structures include Fabry-Pérot cavity structures as well as metamaterial structures made from artificial low-permittivity media. Directive beaming also occurs in the optical area where it has been observed that highly directive beams can be produced from small apertures in a metal film when an appropriate periodic patterning is placed on the film. One aspect that these phenomena all have in common is that they are due to the excitation of one or more weakly attenuated leaky waves, the radiation from which forms the directive beam. This is established in each case by examining the role of the leaky waves in determining the near-field on the aperture of the structure and the far-field radiation pattern of the structure. View full abstract»

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  • Near-Field Plates: Metamaterial Surfaces/Arrays for Subwavelength Focusing and Probing

    Page(s): 1806 - 1815
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    In this paper, we present a brief overview of near-field plates, which are nonperiodic grating-like surfaces/arrays that can focus electromagnetic field to subwavelength resolutions. The general properties of near-field plates are described, and the procedure used to design these devices is outlined. The design of two separate near-field plates is discussed in detail. One of the near-field plates produces a subwavelength line (1-D) focus while the other a spot (2-D) focus. Potential applications of near-field plates are also reviewed. View full abstract»

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  • Speeches by Goldsmith and David Sarnoff [Scanning Our Past]

    Page(s): 1816 - 1820
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  • Future Special Issues/Special Sections of the Proceedings

    Page(s): 1821 - 1822
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  • 2011 IEEE membership form

    Page(s): 1823 - 1824
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  • Coming next month in the November issue of our journal ...

    Page(s): C3
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