D.H. Werner

Pennsylvania State University, University Park, Maryland, United States

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Publications (539)624.15 Total impact

  • Anastasios H. Panaretos · Douglas H. Werner

    No preview · Article · Feb 2016 · Optics Express
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    Jeremy A. Bossard · Lan Lin · Douglas H. Werner

    Preview · Article · Jan 2016 · Journal of The Royal Society Interface
  • Clinton P. Scarborough · Douglas H. Werner · Douglas E. Wolfe
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    ABSTRACT: Electromagnetic metamaterials share a perceived disadvantage with miniature radio communication antennas: limited operating bandwidths. In conventional radio systems, tuning has been confined to the radio, requiring broadband antennas and materials. With the advent of software defined and digital radios, adding the antenna into the plethora of tunable radio subsystems can become a reasonable proposition, allowing miniaturized antennas with narrow instantaneous (channel) bandwidths to be tuned across entire communications bands, depending on the channel in use. Moreover, the antenna will provide an effective filtering stage before the signal reaches the radio. The tunable metamaterial presented herein enables an antenna showcasing this functionality and more. Dramatic size reductions are made possible by a tunable, lightweight, miniaturized metamaterial. Tuning the metamaterial and antenna in tandem provides a dynamic operating channel, with a tunable, nearly arbitrary polarization response as an added benefit. Finally, this antenna provides one of the first examples in the literature of a practical device improved by functionalized metamaterials, which has been tested on a real-world platform.
    No preview · Article · Jan 2016
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    ABSTRACT: The theoretical basis for an ultra-thin broadband absorber is established which is comprised of a mushroom-type high impedance surface (HIS) and a pixelized frequency selective surface (FSS). The latter is engineered to exhibit a prescribed series circuit response and it is placed at an electrically small distance above the HIS. Through a transmission line analysis, it is demonstrated that the admittances of the two structures cancel each other, resulting in an almost zero input reactance and a resistance that fluctuates around that of free space within the frequency range of interest. The resulting structure has a total thickness that does not exceed 2 mm while a return loss is achieved for normal incidence from .
    No preview · Article · Nov 2015 · IEEE Antennas and Wireless Propagation Letters
  • Anastasios H. Panaretos · Douglas H. Werner
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    ABSTRACT: A heuristic approach is presented to quantify the broadband isolation performance of nonuniform capacitively loaded electromagnetic bandgap (EBG) surfaces embedded inside a parallel plate waveguide (PPW). The approach is based on the effective mapping of the stop-band properties of the EBG to the attenuation factor (AF) of a homogeneous material slab. Subsequently, it is demonstrated that the electromagnetic wave propagation through the EBG-loaded PPW is equivalent to the propagation through a multilayered medium where each layer is characterized by a different AF. When these AFs are engineered so that their nonzero values spectrally overlap, a cumulative broadband attenuation effect can be obtained. Based on this interpretation, the broad bandgap properties that are characteristic of nonuniform capacitively loaded EBG surfaces are fully quantified.
    No preview · Article · Nov 2015 · IEEE Transactions on Antennas and Propagation
  • Zhi Hao Jiang · Douglas H. Werner
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    ABSTRACT: A compact circularly polarized (CP) co-designed filtering antenna is reported. The device is based on a patch radiator seamlessly integrated with a bandpass filter composed of coupled stripline open-loop resonators, which are designed together as a system. In the proposed design, the patch functions simultaneously as the radiator and the last stage resonator of the filter, resulting in a low-profile integrated radiating and filtering module with a small overall form factor of . It is shown that the filtering circuit not only ensures frequency selectivity but also provides impedance matching functionality, which serves to broaden both the impedance and axial ratio bandwidths. The designed filtering antenna was fabricated and measured, experimentally achieving an , an axial ratio of less than 3 dB and a gain higher than 5.2 dBi over a bandwidth from 3.77 to 4.26 GHz, i.e., around 12.2%, which makes it an excellent candidate for integration into a variety of wireless systems. A linearly polarized version of the integrated filtering antenna was also demonstrated. In addition, further full-wave simulations and experiments were carried out to verify that the designed CP filtering antenna maintains its properties even when mounted on different positions of the human body with various body gestures. The stable impedance and radiation properties also make it a suitable candidate as a wearable antenna for off-body wireless communications.
    No preview · Article · Sep 2015 · IEEE Transactions on Antennas and Propagation
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    ABSTRACT: Transformation optics provides scientists and engineers with a new powerful design paradigm to manipulate the flow of electromagnetic waves in a user-defined manner and with unprecedented flexibility, by controlling the spatial distribution of the electromagnetic properties of a medium. Using this approach, over the past decade, various previously undiscovered physical wave phenomena have been revealed and novel electromagnetic devices have been demonstrated throughout the electromagnetic spectrum. In this paper, we present versatile theoretical and experimental investigations on designing transformation optics-enabled devices for shaping electromagnetic wave radiation and guidance, at both radio frequencies and optical wavelengths. Different from conventional coordinate transformations, more advanced and versatile coordinate transformations are exploited here to benefit diverse applications, thereby providing expanded design flexibility, enhanced device performance, as well as reduced implementation complexity. These design examples demonstrate the comprehensive capability of transformation optics in controlling electromagnetic waves, while the associated novel devices will open up new paths towards future integrated electromagnetic component synthesis and design, from microwave to optical spectral regimes. © 2015 The Author(s) Published by the Royal Society. All rights reserved.
    Preview · Article · Aug 2015 · Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences
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    ABSTRACT: Transformation Optics (TO) provides the mathematical framework for representing the behavior of electromagnetic radiation in a given geometry by “transforming” it to an alternative, usually more desirable, geometry through an appropriate mapping of the constituent material parameters. Using a quasi-conformal mapping, the restrictions on the required material parameters can be relaxed allowing isotropic inhomogeneous all-dielectric materials to be employed. This approach has led to the development of a new and powerful design tool for gradient-index (GRIN) optical systems. Using TO, aspherical lenses can be transformed to simpler spherical and flat geometries or even rotationally-asymmetric shapes which result in true 3D GRIN profiles. TO can also potentially be extended to collapse an entire lens system into a representative GRIN profile thus reducing its physical dimensions while retaining the optical performance of the original system. However, dispersion effects of the constituent materials often limit the bandwidth of metamaterial and TO structures thus restricting their potential applicability. Nonetheless, with the proper pairing of GRIN profile and lens geometry to a given material system, chromatic aberrations can be minimized. To aid in the GRIN construction, we employ advanced multi-objective optimization algorithms which allow the designer to explicitly view the trade-offs between all design objectives such as RMS spot size, field-of-view (FOV), lens thickness, 𝛥𝑛, and focal drift due to chromatic aberrations. We present an overview of our TO-enabled GRIN lens design process and analysis techniques while demonstrating designs which minimize the presence of mono- and poly-chromatic aberrations and discuss their requisite material systems.
    No preview · Conference Paper · Aug 2015
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    ABSTRACT: Recent advances in the field of Transformation Optics (TO) have renewed the interest in gradient-index (GRIN) optical systems. By transforming a classically-inspired aspherical lens to a flat geometry using TO, we can achieve a design with better field-of-view performance than traditional radial GRIN lenses. In order to understand the underlying physics of this performance improvement, we decompose the TO solution into a 2D-polynomial basis and propose to analyze its wavefront error to determine which terms minimize oblique-angle optical aberrations
    No preview · Conference Paper · Aug 2015
  • Jeremiah P. Turpin · Douglas H. Werner · Douglas E. Wolfe
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    ABSTRACT: Spatial tuning of a volumetric metamaterial introduces many new design considerations that strongly affect the performance and practicality of a resulting system implementation. This paper discusses the design rules and procedures for spatially reconfigurable metamaterial systems using a tunable near-zero-index slab with adjustable shape as a representative design example. We propose a split-ring resonator-based metamaterial where each resonator is tuned in and out of resonance using a varactor diode to change the effective material response. The periodic, hexagonal tiles may be combined and connected in a planar spiral to form a cylindrical metamaterial panel whose radius may be arbitrarily large. Multiple panels are then stacked, with appropriate cropping, to form a volumetric metamaterial slab.
    No preview · Article · Aug 2015 · IEEE Transactions on Antennas and Propagation
  • Jogender Nagar · Sawyer D. Campbell · Douglas H. Werner
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    ABSTRACT: One of the benefits of using a multi-objective algorithm is that the tradeoffs between objectives for a given design can be easily visualized. In the study of gradient-index optics, this ability can lead to a better understanding of the tradeoffs between the gradient magnitude, Δn, focus quality, and size of the optic. A gradient-index plano-convex lens is proposed to highlight the limitations of a single- objective optimization while the potential of using multi-objective optimization for chromatic- and oblique incidence-corrections are also discussed.
    No preview · Conference Paper · Jul 2015
  • Sawyer D. Campbell · Donovan E. Brocker · Douglas H. Werner
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    ABSTRACT: The ability to correct for monochromatic aberrations without the need for complex geometry has made gradient-index optics an attractive area of research, but manufacturing challenges have limited their application to a select few areas. In this study, a novel method for fabricating gradient-index lenses using inkjet solid free form three-dimensional printed optical polymers is proposed. A flat gradient-index lens based on the fabrication constraints is optimized using a powerful customized design synthesis tool. Cross-sectional views of its continuous index profile and a representative binary pixel-map are shown.
    No preview · Conference Paper · Jul 2015
  • Donovan E. Brocker · Sawyer D. Campbell · Douglas H. Werner
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    ABSTRACT: Gradient-index (GRIN) lenses are predicted by many to have superior performance compared with lens systems using conventional homogeneous material compositions. Namely, the complexity of classic (i.e. homogeneous) multi-lens sequences required for high performance optical systems can be instead manifested into GRIN profile complexity, allowing for refraction throughout the volume of a lens and not just at the hard surface boundaries. As GRIN material technologies continue to evolve, facilitating more practical GRIN lens implementations, the knowledgebase and design tools to optimize GRIN lens systems must be simultaneously built. In this paper, one of the more unknown, yet crucially important, challenges of GRIN lens design is considered: dispersion. Dispersion and its effects on GRIN lenses are considered and a method to minimize its impact on the performance of GRIN lenses is outlined. Finally, a GRIN focusing lens based on the mixing of Germanium (Ge) and Silicon (Si) is proposed and designed to have minimal focal drift.
    No preview · Conference Paper · Jul 2015
  • Lei Kang · Zhi Hao Jiang · Taiwei Yue · Douglas H Werner
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    ABSTRACT: We provide the first experimental demonstration of the handedness dependent electromagnetically induced transparency (EIT) in chiral metamaterials during the interaction with circularly polarized waves. The observed chiral-sensitive EIT phenomena arise from the coherent excitation of a non-radiative mode in the component split ring resonators (SRRs) produced by the corresponding Born-Kuhn type (radiative) resonators that are responsible for the pronounced chirality. The coherent coupling, which is dominated by the bonding and antibonding resonances of the Born-Kuhn type resonators, leads to an extremely steep dispersion for a circularly polarized wave of predefined handedness. Accordingly, retrieved effective medium parameters from simulated results further reveal a difference of 80 in the group indices for left- and right-handed circularly polarized waves at frequencies within the EIT window, which can potentially result in handedness-sensitive pulse delays. These chiral metamaterials which enable a handedness dependent EIT effect may provide more degrees of freedom for designing circular polarization based communication devices.
    No preview · Article · Jul 2015 · Scientific Reports
  • Zhi Hao Jiang · Micah D Gregory · Douglas H Werner
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    ABSTRACT: A compact circularly polarized (CP) integrated filtering antenna is reported for wearable biotelemetric devices in the 2.4 GHz ISM band. The design is based on a mutual synthesis of a CP patch antenna connected to a bandpass filter composed of coupled stripline open-loop resonators, which provides an integrated low-profile radiating and filtering module with a compact form factor of 0.44λ0×0.44λ0×0.04λ0. The optimized filtering antenna is fabricated and measured, achieving an , an axial ratio of less than 3 dB and gain higher than 3.5 dBi in the targeted ISM band. With the integrated filtering functionality, the antenna exhibits good out-of-band rejection over an ultra-wide frequency range of 1-6 GHz . Further full-wave simulations and experiments were carried out, verifying that the proposed filtering antenna maintains these desirable properties even when mounted in close proximity to the human body at different positions. The stable impedance performance and the simultaneous wide axial ratio and radiated power beam widths make it an ideal candidate as a wearable antenna for off-body communications. The additional integrated filtering functionality further improves utility by greatly reducing interference and crosstalk with other existing wireless systems.
    No preview · Article · Jul 2015 · IEEE Transactions on Biomedical Circuits and Systems
  • Giacomo Oliveri · Douglas H. Werner · Andrea Massa
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    ABSTRACT: The introduction of electromagnetic (EM) media with unique field manipulation properties, collectively labelled as metamaterials, has boosted the interest toward the design, the fabrication, and the testing of artificial materials whose features can be engineered according to the applicative requirements and user objectives. In this framework, the long-term promise of reconfigurable metamaterial theory (i.e., the possibility to change the EM response of a 2-D/3-D material arbitrarily and in real time) has given the designers an extremely wide number of new degrees of freedom for the synthesis of innovative adaptive systems. Moreover, successful experimental validations of reconfigurable metamaterials in the entire EM spectrum from microwaves to optical frequencies have further stimulated academic and industrial interests in developing devices with enhanced performances, efficiency, and robustness. Nevertheless, the exploitation of reconfigurable metamaterials in commercial devices is still an open problem with several challenges from both the theoretical and technological viewpoints. This paper is then aimed at reviewing the latest advances on reconfigurable metamaterial engineering from the methodological perspective also providing a comprehensive and balanced survey on latest concepts, current trends, and envisaged future developments on this active field of research.
    No preview · Article · Jul 2015 · Proceedings of the IEEE
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    ABSTRACT: Chiral-selective nonlinear optics and optoelectronic signal generation are demonstrated in an electrically active photonic metamaterial. The metamaterial reveals significant chiroptical responses in both the harmonic generation and photon drag effect, correlated to the resonance behavior in the linear regime. The multifunctional chiral metamaterial with dual electrical and optical functionality enables transduction of chiroptical responses to electrical signals for integrated photonics. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    No preview · Article · Jun 2015 · Advanced Materials
  • Zhi Hao Jiang · Peter E. Sieber · Lei Kang · Douglas H. Werner
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    ABSTRACT: The concept of invisibility has garnered long-standing interest throughout human history but has only been realized experimentally within the past decade, albeit over a limited bandwidth. While the physical wave phenomenon of a reduced scattering signature has been demonstrated with different cloaking methods such as transformation optics and scattering cancellation, such technology has yet to be incorporated into any practical real-world devices. Through the use of quasi-2D functional metasurfaces, the long-standing issue of simultaneous mutual coupling and radiation blockage is addressed that occurs when two or more electromagnetic radiators are placed in close proximity to one another. The proposed compact and ultralightweight metasurfaces, comprising arrays of subwavelength electric and magnetic resonators with tailored dispersive properties, are capable of fully restoring the intrinsic properties of real-world electromagnetic radiators when placed in a multiradiator environment. This work introduces a general design approach to bridge the gap between the theory and practice for cloaks, which is applicable to microwave, terahertz, and optical radiators, as well as acoustic and thermal sources. Moreover, this technology provides an unprecedented opportunity for enabling high-density deployment of radiating systems with low interference and undistorted signal wave fronts.
    No preview · Article · Jun 2015 · Advanced Functional Materials
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    ABSTRACT: Recent developments in transformation optics have led to burgeoning research on gradient index lenses for novel optical systems. Such lenses hold great potential for the advancement of complex optics for a wide range of applications. Despite the plethora of literature on gradient index lenses, previous works have not yet considered the application of anti-reflective coatings to these systems. Reducing system reflections is crucial to the development of this technology for highly sensitive optical applications. Here, we present effective anti-reflective-coating designs for gradient index lens systems. Conventional anti-reflective-design methodologies are leveraged in conjunction with transformation optics to develop coatings that significantly reduce reflections of a flat gradient index lens. Finally, the resulting gradient-index anti-reflective coatings are compared and contrasted with conventional homogeneous anti-reflective coatings.
    No preview · Article · Jun 2015 · Optics Letters
  • Micah D. Gregory · Spencer V. Martin · Douglas H. Werner
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    ABSTRACT: The covariance matrix adaptation evolutionary strategy (CMA-ES) is explored here as an improved alternative to well-established algorithms used in electromagnetic (EM) optimization. In the past, methods such as the genetic algorithm (GA), particle swarm optimization (PSO), and differential evolution (DE) have commonly been used for EM design. In this article, we examine and compare the performance of CMA-ES, PSO, and DE when applied to test functions and several challenging EM design problems. Of particular interest is demonstrating the ability of the relatively new CMA-ES to more quickly and more reliably find acceptable solutions compared with those of the more classical optimization strategies. In addition, it will be shown that due to its self-adaptive scheme, CMA-ES is a more user-friendly algorithm that requires less knowledge of the problem for preoptimization configuration.
    No preview · Article · Jun 2015 · IEEE Antennas and Propagation Magazine

Publication Stats

6k Citations
624.15 Total Impact Points

Institutions

  • 1987-2016
    • Pennsylvania State University
      • • Department of Electrical Engineering
      • • Applied Research Laboratory
      • • College of Engineering
      University Park, Maryland, United States
  • 2008-2015
    • William Penn University
      Worcester, Massachusetts, United States
  • 2003
    • University of Massachusetts Lowell
      • Department of Electrical & Computer Engineering
      Lowell, MA, United States
    • Università di Pisa
      • Department of Information Engineering
      Pisa, Tuscany, Italy