30 research outputs found
Single scattering and effective medium description in multilayer cylindrical metamaterials: Application to graphene and metasurface coated cylinders
Coated and multicoated cylinder systems constitute an appealing metamaterial
category, as they allow a very rich and highly tunable response, resulting from
the interplay of the many different geometrical and material parameters
involved. Here we derive and propose an effective medium approach for the
detailed description and analysis of the electromagnetic wave propagation in
such systems. In particular, we investigate infinitely-long multilayered
cylinders with additional electric and magnetic surface conductivities at each
interface. Our effective medium approach is based on the well known in the
solid state physics community Coherent Potential Approximation (CPA) method,
combined with a transfer matrix-based formulation for cylindrical waves.
Employing this effective medium scheme, we investigate two realistic systems,
one comprising of cylindrical tubes made of uniform tunable graphene sheets and
one of cylinders/tubes formed of metasurfaces exhibiting both electric and
magnetic sheet conductivities. Both systems show a rich palette of engineerable
electromagnetic features, including tunable hyperbolic response, double
negative response and epsilon-near-zero and mu-near-zero response regions
Intelligent Metasurfaces with Continuously Tunable Local Surface Impedance for Multiple Reconfigurable Functions
Electromagnetic metasurfaces can be characterized as intelligent if they are
able to perform multiple tunable functions, with the desired response being
controlled by a computer influencing the individual electromagnetic properties
of each metasurface inclusion. In this paper, we present an example of an
intelligent metasurface which operates in the reflection mode in the microwave
frequency range. We numerically show that without changing the main body of the
metasurface we can achieve tunable perfect absorption and tunable anomalous
reflection. The tunability features can be implemented using mixed-signal
integrated circuits (ICs), which can independently vary both the resistance and
reactance, offering complete local control over the complex surface impedance.
The ICs are embedded in the unit cells by connecting two metal patches over a
thin grounded substrate and the reflection property of the intelligent
metasurface can be readily controlled by a computer. Our intelligent
metasurface can have significant influence on future space-time modulated
metasurfaces and a multitude of applications, such as beam steering, energy
harvesting, and communications.Comment: 10 pages, 8 figure