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5. Electron-Sheet Metasurfaces for Reconfigurable Beam Patterns.

Author

Fallah, Asma, Camacho, Miguel, and Engheta, Nader

Abstract

Here, a beam-steering structure based on the interaction of antenna radiation with an electron sheet with swiftly moving electrons with a constant velocity is proposed and studied theoretically. Such electron-sheet metasurface, while uniform and homogeneous in its composition, has a dynamic surface conductivity that exhibits nonlocal response that is dependent on the tangential component of the wave vector impinging on it, and may offer a nonsymmetric conductivity distribution with respect of this wave vector component. As a result, asymmetric radiation patterns may be generated from a single magnetic current line source in the presence of such a metastructure. This effect, introduced by the electron sheet with fast-moving electrons on the radiation properties, can be tailored by modifying the number density and the constant velocity of these electron sheets. We explore the effects of the electron-sheet metasurface on the far-zone radiated field in the presence and absence of a perfect electric conducting ground plane. Some of the electromagnetic features, such as the tilt of radiation pattern in the far zone and the field distribution in the near zone, are also discussed. We envision that this reconfigurable beam steering method may find potential applications in THz, microwave, and optical technologies. [ABSTRACT FROM AUTHOR]

Published
2022
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11. A Fully Integrated Sensor-Brain–Machine Interface System for Restoring Somatosensation.

Author

Liu, Xilin, Zhu, Hongjie, Qiu, Tian, Sritharan, Srihari Y., Ge, Dengteng, Yang, Shu, Zhang, Milin, Richardson, Andrew G., Lucas, Timothy H., Engheta, Nader, and Van der Spiegel, Jan

Abstract

Sensory feedback is critical to the performance of neural prostheses that restore movement control after neurological injury. Recent advances in direct neural control of paralyzed arms present new requirements for miniaturized, low-power sensor systems. To address this challenge, we developed a fully-integrated wireless sensor-brain-machine interface (SBMI) system for communicating key somatosensory signals, fingertip forces and limb joint angles, to the brain. The system consists of a tactile force sensor, an electrogoniometer, and a neural interface. The tactile force sensor features a novel optical waveguide on CMOS design for sensing. The electrogoniometer integrates an ultra low-power digital signal processor (DSP) for real-time joint angle measurement. The neural interface enables bidirectional neural stimulation and recording. Innovative designs of sensors and sensing interfaces, analog-to-digital converters (ADC) and ultra wide-band (UWB) wireless transceivers have been developed. The prototypes have been fabricated in 180nm standard CMOS technology and tested on the bench and in vivo. The developed system provides a novel solution for providing somatosensory feedback to next-generation neural prostheses. [ABSTRACT FROM AUTHOR]

Published
2021
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12. Metamaterials: Two Decades Past and Into Their Electromagnetics Future and Beyond.

Author

Ziolkowski, Richard W. and Engheta, Nader

Subjects
*ELECTROMAGNETISM, *COMPUTATIONAL electromagnetics, *PHENOMENOLOGICAL theory (Physics), *METAMATERIALS, *MAGNETIC materials, *NINETEENTH century, *LIGHT scattering
Abstract

The notion of artificially engineered materials, which has a long history dating back to the late part of the 19th century, gained considerable momentum two decades ago. The excitement associated with such metamaterials and the structures they have inspired has not waned since then. Rather, it has substantially grown. Metamaterial-inspired structures continue to challenge our imagination and our physics and engineering foundations. They are impacting wave–matter interactions across many frequencies and even across diverse fields of science and technology. They are now enabling many commercial opportunities. It is anticipated that they will provide access to yet new physical phenomena and will facilitate many novel future applications. [ABSTRACT FROM AUTHOR]

Published
2020
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20. Survey of Electromagnetic Field and Wave Interaction With "Surfaces" [Book/Software Reviews].

Author

Engheta, Nader

Abstract

This book presents a timely set of topics in surface electromagnetics (SEMs). With contributions from prominent and pioneering scientists and engineers in this field, this book covers a wide range of subject matter related to EM field and wave interactions with a variety of structures categorized as "surfaces." The editors, Prof. Yang and Prof. Rahmat-Samii, two of the most outstanding and innovative pioneers in EMs, have compiled and assembled a comprehensive set of topics, ranging from the fundamental aspects of wave– surface interactions, such as the modeling, analysis, and synthesis of SEMs; to guided waves, leaky waves, and the plane wave features of such surfaces in various applied areas, e.g., cloaking and transparency; to orbital angular momentum, microwave, terahertz (THz), and optical applications. [ABSTRACT FROM AUTHOR]

Published
2021
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21. All-metallic ε-near-zero (ENZ) lens based on ultra-narrow hollow rectangular waveguides: experimental results

Author

Orazbayev, Bakhtiyar, Torres Landívar, Víctor, Pacheco-Peña, Víctor, Falcone Lanas, Francisco Javier, Teniente Vallinas, Jorge, Beruete Díaz, Miguel, Sorolla Ayza, Mario, Navarro Cía, Miguel, Engheta, Nader, Universidad Pública de Navarra. Departamento de Ingeniería Eléctrica y Electrónica, Nafarroako Unibertsitate Publikoa. Ingeniaritza Elektriko eta Elektronikoa Saila, and Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa

Subjects
ENZ media, Millimeter waves, Metamaterial lenses
Abstract

Trabajo presentado al 2014 Mediterranean Microwave Symposium. Marruecos, 2014. Here we perform numerical and experimental investigation of plano-concave all-metallic ε-near-zero (ENZ) lens with operational frequency f = 144 GHz. The ENZ lens is achieved by stacking an array of narrow hollow rectangular waveguides working near cut-off frequency. Focusing and radiation properties are numerically analyzed and measured. The enhancement of 5.61 dB and directivity of 17.6 dBi are shown. Good agreement between experimental and numerical results is demonstrated. This work was supported in part by the Spanish Government under contract Consolider Engineering Metamaterials CSD2008-00066 and contract TEC2011-28664-C02-01. B. O. is sponsored by Spanish Ministerio de Economía y Competitividad under grant FPI BES-2012-054909. V.T. is sponsored by the Universidad Pública de Navarra. V.P.-P. is sponsored by Spanish Ministerio de Educación, Cultura y Deporte under grant FPU AP-2012-3796. M.B. is sponsored by the Spanish Government via RYC-2011-08221. M. N.-C. is supported by the Imperial College Junior Research Fellowship.

Published
2014

29. 144 GHz epsilon-near-zero lens antenna

Author

Torres, Victor, primary, Pacheco-Pena, Victor, additional, Orazbayev, Bakhtiyar, additional, Teniente, Jorge, additional, Beruete, Miguel, additional, Navarro-Cia, Miguel, additional, Sorolla, Mario, additional, and Engheta, Nader, additional

Published
2015
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