1,742 research outputs found
Tomorrow's Metamaterials: Manipulation of Electromagnetic Waves in Space, Time and Spacetime
Metamaterials represent one of the most vibrant fields of modern science and
technology. They are generally dispersive structures in the direct and
reciprocal space and time domains. Upon this consideration, I overview here a
number of metamaterial innovations developed by colleagues and myself in the
holistic framework of space and time dispersion engineering. Moreover, I
provide some thoughts regarding the future perspectives of the area
General Mapping between Complex Spatial and Temporal Frequencies by Analytical Continuation
This paper introduces a general technique for inter-mapping the complex
spatial frequency (or propagation constant) and the
temporal frequency of an arbitrary
electromagnetic structure. This technique, based on the analytic property of
complex functions describing physical phenomena, invokes the analytic
continuity theorem to assert the unicity of the mapping function, and find this
function from known data within a restricted domain of its analycity by
curve-fitting to a generic polynomial expansion. It is not only applicable to
canonical problems admitting an analytical solution, but to \emph{any}
problems, from eigen-mode or driven-mode full-wave simulation results. The
proposed technique is demonstrated for several systems, namely an unbounded
lossy medium, a dielectric-filled rectangular waveguide, a periodically-loaded
transmission line, a one-dimensional photonic crystal and a series-fed patch
(SFP) leaky-wave antenna (LWA), and it is validated either by analytical
results or by full-wave simulated results.Comment: 11 pages, 11 figur
Nonreciprocal Phase Gradient Metasurface: Principle and Transistor Implementation
We introduce the concept of nonreciprocal nongyrotropic phase gradient
metasurfaces. Such metasurfaces are based on bianisotropic phase shifting unit
cells, with the required nonreciprocal and nongyrotropic characteristics.
Moreover, we present a transistor-based implementation of a nonreciprocal phase
shifting subwavelength unit cell. Finally, we demonstrate the concept with a
simulation of a 6-port spatial circulator application
Angle-Independent Nongyrotropic Metasurfaces
We derive a general condition for angle-independent bianisotropic
nongyrotropic metasurfaces and present two applications corresponding to
particular cases: an angle-independent absorber/amplifier and an
angle-independent spatial gyrator
Time-Reversal Routing for Dispersion Code Multiple Access (DCMA) Communications
We present the modeling and characterization of a time-reversal routing
dispersion code multiple access (TR-DCMA) system. We show that this system
maintains the low complexity advantage of DCMA transceivers while offering
dynamic adaptivity for practial communication scenarios. We first derive the
mathematical model and explain operation principles of the system, and then
characterize its interference, signal to interference ratio, and bit error
probability characteristics
Design, Concepts and Applications of Electromagnetic Metasurfaces
The paper overviews our recent work on the synthesis of metasurfaces and
related concepts and applications. The synthesis is based on generalized sheet
transition conditions (GSTCs) with a bianisotropic surface susceptibility
tensor model of the metasurface structure. We first place metasurfaces in a
proper historical context and describe the GSTC technique with some fundamental
susceptibility tensor considerations. Upon this basis, we next provide an
in-depth development of our susceptibility-GSTC synthesis technique. Finally,
we present five recent metasurface concepts and applications, which cover the
topics of birefringent transformations, bianisotropic refraction, light
emission enhancement, remote spatial processing and nonlinear second-harmonic
generation
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