Scholars@Duke
Steven A. Cummer

Steven A. Cummer

William H. Younger Distinguished Professor of Engineering
Pierre R. Lamond Department of Electrical and Computer Engineering
cummer@duke.edu
Box 90291, Durham, NC 27708-0291
3455 CIEMAS, Durham, NC 27708

Scholarly Works - Conferences

Computationally-Tractable Synthesis of an MXene Metamaterial Absorber with a 3D-Printable Spatially Variable Substrate by a Local Approach

Conference IEEE Antennas and Propagation Society AP S International Symposium Digest · January 1, 2026 We introduce the LOCABINACONN3D methodology to enable the computationally tractable synthesis of MXene metamaterial absorbers (MMA) based on spatially variable 3D-printable substrates. Spatially variable substrates offer enhanced absorption bandwidth compa ... Full text Cite

Broadband multilayer metasurface absorbers with MXene resonators and topology optimized substrates

Conference 19th International Congress on Artificial Materials for Novel Wave Phenomena Metamaterials 2025 · January 1, 2025 We present the synthesis of broadband multilayer metamaterial absorbers (MMA) based on MXenes, which are novel two-dimensional conductive materials with higher ohmic losses than copper. MXene resonator of different conductivity can be implemented at each l ... Full text Cite

Computationally-efficient Synthesis of Inversely-designed 3D-Printable All-dielectric Devices

Conference IEEE Antennas and Propagation Society AP S International Symposium Digest · January 1, 2025 We present a systematic, computationally efficient approach for synthesizing 3D-printable all-dielectric devices. Inverse-design optimization methods lead to devices of a continuous dielectric constant profile with complex and conformal shapes. However, st ... Full text Cite

Design and solution-based testing of a synthetic aerosol particle with asymmetric scattering behavior

Conference Proceedings of SPIE the International Society for Optical Engineering · January 1, 2024 We have modeled, synthesized, and performed preliminary testing of a synthetic aerosol particle with the intent to affect an asymmetric (“one-way”) vision environment when deployed as an airborne plume and aligned in real time via an applied acoustic field ... Full text Cite

Quasi-Bound States in the Continuum for Acoustic and Elastic Waves

Conference International Conference on Metamaterials Photonic Crystals and Plasmonics · January 1, 2023 We study the localization of flexural and acoustic waves in metasurfaces by means of clusters of scatterers. We show that when the scatterers are placed regularly in the perimeter of a circumference the structure forms a resonator which quality factor grow ... Cite

Advanced control of invisible cavity resonators with bianisotropic metasurfaces

Conference 2019 13th International Congress on Artificial Materials for Novel Wave Phenomena Metamaterials 2019 · September 1, 2019 Recently, invisible cavities formed by two parallel metasurfaces have demonstrated the ability to support so-called 'driven' bound states in the continuum. The existence of these modes allows excitation of non-scattering resonant cavities with strongly enh ... Full text Cite

Potential of GPU-based grid traverse algorithm for lightning geolocation

Conference 2019 11th Asia Pacific International Conference on Lightning APL 2019 · June 1, 2019 Differing from the traditional Time Difference of Arrival (TDOA) lightning location technique, Grid Traverse Algorithm (GTA) is to build up a series of grid points based on numerical discretion of lightning locations in a network region concerned and then ... Full text Cite

Bianisotropic Acoustic Metasurface for Highly Efficient Wavefront Transformation

Conference 2018 12th International Congress on Artificial Materials for Novel Wave Phenomena Metamaterials 2018 · November 13, 2018 A fundamental limit for GSL-based metasurfaces is their power efficiency, especially at large deflection angles. Here we designed and fabricated the bi-anisotropic cells for wavefront transformation acoustic metasurface that overcomes this limit, allowing ... Full text Cite

High-effcient Acoustic Anomalous Reflector Based on Power-flow Conformal Metamirror

Conference 2018 12th International Congress on Artificial Materials for Novel Wave Phenomena Metamaterials 2018 · November 13, 2018 In the last years, metasurfaces have attracted much attention due to the capability of tailoring the response in a sub-wavelength scale and their compact implementations. In the particular case of reflective metasurfaces, also called metamirrors, anomalous ... Full text Cite

Reconstructing initial continuous current waveform in rocket-triggered lightning with close magnetic measurement

Conference 2016 Asia Pacific International Symposium on Electromagnetic Compatibility Apemc 2016 · July 26, 2016 We present a new method that remotely measures the initial continuous current in classical rocket-and-wire triggered lightning using a compact dB/dt sensor deployed at 78 m distance from the channel base. The current waveform retrieved from the numerical i ... Full text Cite

Propagation of preliminary breakdown pulses preceding cloud-to-ground lightning discharges

Conference 2015 1st Ursi Atlantic Radio Science Conference Ursi at Rasc 2015 · October 21, 2015 A sequence of electromagnetic pulses lasting from a few milliseconds to several tens of milliseconds is usually observed prior to the first return stroke of a cloud-to-ground lightning flash. The sequence is composed of three parts. It begins with a group ... Full text Cite

Implications of lightning emissions for terrestrial gamma-ray flashes and associated lightning discharges

Conference 2014 International Conference on Lightning Protection Iclp 2014 · December 3, 2014 Featured Work Remote sensing of broadband (<1 Hz to 300 kHz) lightning signals related to terrestrial gamma-ray flashes (TGFs) indicates that gamma-rays in TGFs are typically produced during a slow process that creates a considerable charge moment change within a few mi ... Full text Cite

Unified approach to design linear and nonlinear acoustic metamaterials

Conference 2014 8th International Congress on Advanced Electromagnetic Materials in Microwaves and Optics Metamaterials 2014 · November 5, 2014 We review a new approach to design active acoustic metematerials that results in artificial media covering a large range of linear acoustic responses. We show how this method can be extended to obtain metamaterials having highly non-linear responses. We il ... Full text Cite

Mechanisms of sprite initiation, morphology, and lightning polarity asymmetry

Conference 2014 31th Ursi General Assembly and Scientific Symposium Ursi Gass 2014 · October 17, 2014 Sprites are spectacular optical emissions in the mesosphere induced by transient lightning electric fields above thunderstorms. Recently, significant efforts have been devoted to the understanding of the inception mechanism of sprite streamers, the origin ... Full text Cite

Charge motion and altitude of terrestrial gamma-ray flashes

Conference 2014 31th Ursi General Assembly and Scientific Symposium Ursi Gass 2014 · October 17, 2014 We describe recent coordinated observations of radio emissions and terrestrial gamma ray flashes (TGFs) that provide new insight into the detailed processes that generate this thunderstorm-driven high-energy radiation. These observations include lightning ... Full text Cite

Negative sprites produced by consecutive impulse charge transfers in negative strokes

Conference 2014 31th Ursi General Assembly and Scientific Symposium Ursi Gass 2014 · October 17, 2014 On June 5, 2013, the SpriteCam network recorded a relatively weak sprite over a thunderstorm in Oklahoma. The broadband magnetic fields recorded at multiple stations consistently indicate that this event was produced by a negative cloud-to-ground (CG) even ... Full text Cite

Measurement of sensitive current and charge motion using coherent averaging of remote low frequency magnetic field observations

Conference 2014 United States National Committee of Ursi National Radio Science Meeting Usnc Ursi Nrsm 2014 · October 16, 2014 Measuring lightning charge transfer, especially on time scales longer than several milliseconds, is a challenge. Instrumented towers can measure this quantity precisely but only for a tiny fraction of cloud-to-ground lightning. Electrostatic field measurem ... Full text Cite

Transistor-embedded acousto-optic and nonlinear metamaterials

Conference 2014 United States National Committee of Ursi National Radio Science Meeting Usnc Ursi Nrsm 2014 · October 16, 2014 We present experimental results showing the application of transistor-embedded metamaterials to realize nonlinear and acousto-optic metamaterials. Due to their nonlinear properties, transistors can be used to realize a large variety of useful radio frequen ... Full text Cite

Design and realization of transistor-embedded active RF metamaterials

Conference 2014 United States National Committee of Ursi National Radio Science Meeting Usnc Ursi Nrsm 2014 · October 16, 2014 We present several results that use transistors within the context of metamaterials. Transistors are a fundamental device in the construction of several RF systems and applications. The basic device physics of the transistor allow for the convenient constr ... Full text Cite

Roadmap to electrically self-tuning metamaterials: Design and experimental validation

Conference Proceedings 2014 International Conference on Electromagnetics in Advanced Applications Iceaa 2014 · September 18, 2014 We present the design and experimental validation of a self-tuning metamaterial. We begin with an active two-state split ring resonator and build up to a self-contained system that includes feedback. We show the ability of the active split ring resonator t ... Full text Cite

Overview of the Kansas Windfarm 2013 field program

Conference International Conference on Atmospheric Electricity, ICAE 2014 · January 1, 2014 © International Conference on Atmospheric Electricity, ICAE 2014 Initial observations of lightning attachment to wind turbine generators at a Kansas wind farm in 2012 resulted in a number of insights and left several open questions. This led to the plannin ... Cite

Large charge moment change lightning in an Oklahoma mesoscale convective system

Conference International Conference on Atmospheric Electricity, ICAE 2014 · January 1, 2014 © International Conference on Atmospheric Electricity, ICAE 2014 On 31 May 2013, a line of severe thunderstorms developed during the local afternoon in central Oklahoma, USA. One of the supercells produced the El Reno tornado, which caused significant dama ... Cite

Overview of the Kansas Windfarm 2013 field program

Conference International Conference on Atmospheric Electricity Icae 2014 · January 1, 2014 Initial observations of lightning attachment to wind turbine generators at a Kansas wind farm in 2012 resulted in a number of insights and left several open questions. This led to the planning and re-deployment for the summer or 2013. Ten groups have colla ... Cite

Large charge moment change lightning in an Oklahoma mesoscale convective system

Conference International Conference on Atmospheric Electricity Icae 2014 · January 1, 2014 On 31 May 2013, a line of severe thunderstorms developed during the local afternoon in central Oklahoma, USA. One of the supercells produced the El Reno tornado, which caused significant damage and killed several people. During the 2300 UTC hour (during th ... Cite

Active nonlinear metamaterials loaded with negative differential resistance elements and circuits

Conference Proceedings of SPIE the International Society for Optical Engineering · December 1, 2012 Using active loads in circuits that result in negative differential resistances at various nodes in the circuit are used for producing resistance cancellation, gain, oscillations, and other types of effects not seen in passive circuits. We aim to demonstra ... Full text Cite

Nonlinear and active RF metamaterial applications using embedded devices

Conference Proceedings of SPIE the International Society for Optical Engineering · December 1, 2012 Nonlinear metamaterials have received considerable attention in recent years. The inclusion of nonlinear and active effects in metamaterials expands the possibilities for engineering media with designer properties. We detail our recent efforts to create no ... Full text Cite

Sound manipulation with acoustic metamaterials

Conference American Society of Mechanical Engineers Noise Control and Acoustics Division Publication Ncad · January 1, 2012 Acoustic metamaterials are engineered materials with properties hard or impossible to find in natural materials (e.g. negative effective density and/or negative bulk modulus). Therefore, a myriad of novel applications could be imagined and some of them hav ... Full text Cite

Active and Tunable RF Metamaterials

Conference PROCEEDINGS OF THE 2008 INTERNATIONAL WORKSHOP ON METAMATERIALS · January 1, 2008 Link to item Cite

Design and experimental demonstration of active RE metamaterials

Conference 2007 IEEE ANTENNAS AND PROPAGATION SOCIETY INTERNATIONAL SYMPOSIUM, VOLS 1-12 · January 1, 2007 Link to item Cite

Redesign of the core curriculum at Duke University

Conference ASEE Annual Conference and Exposition, Conference Proceedings · December 1, 2006 Cite

Redesign of the core curriculum at Duke University

Conference ASEE Annual Conference and Exposition Conference Proceedings · January 1, 2006 Cite

Measurements of lightning parameters from remote electromagnetic fields

Conference SPRITES, ELVES AND INTENSE LIGHTNING DISCHARGES · January 1, 2006 Link to item Cite

Theme-based redesign of the duke university ECE curriculum: The first steps

Conference ASEE Annual Conference and Exposition, Conference Proceedings · 2005 Undergraduates in Electrical and Computer Engineering (ECE) at Duke University have benefited from the combination of curricular flexibility and rigorous coursework. The current curriculum is further limited in that the core courses do not offer a vertical ... Cite

The Harang discontinuity in auroral substorms

Conference · January 1, 2000 We have investigated the electrodynamics of the pre-midnight convection reversal during substorm expansion phase through early recovery phase. This is done with measurements of the magnetic field, electric field, ion drift and electron precipitation made b ... Full text Cite

Auroral surge currents and electrodynamics with FAST and VIS

Conference · January 1, 2000 We analyze data from two FAST satellite passes in the vicinity of auroral surges (as seen in the VIS auroraJ imager on the Polar satellite) to study the large scale ionospheric electrodynamics of the surge, focusing in particular on the configuration of fi ... Full text Cite