Angularly tunable perfect absorption in graphene-mushroom hybrid structure for all angles

Abstract

In this work, the authors propose a graphene-based tunable perfect metamaterial absorber at microwaves that can achieve perfect absorption at all angles. This is realized by stacking an unpatterned graphene sandwich structure and a dielectric layer on top of a mushroom-type high impedance surface whose resonant frequency is stable for all angles of incidence. A perfect-absorption-angle tunable absorber working at TM polarization is designed and realized, achieving perfect absorption covering a wide range of angles from normal to grazing incidence at the same frequency when the impedance of graphene is modulated by different bias voltages. The design concept of integrating different tunable materials and meta-structures opens up promising possibilities for wave manipulation with applications in smart and multifunctional electromagnetic devices.

Graphene-Based Optically Transparent Metasurface Capable of Dual-Polarized Modulation for Electromagnetic Stealth

“…A 125 μm thick ITO film with surface resistance of 5 Ω/sq is selected as the ground plate that simultaneously enables optically transparency and mirror electromagnetic reflection . The electrolyte layer is ignored theoretically due to its ultrathin thickness (micrometers) compared to the working wavelength (centimeters). , In simulations, periodic boundary conditions with a Floquet port are employed in the x - and y -directions and open boundary condition is utilized in the z -direction along the propagation of the incident plane waves. With a plane wave impinging on the structure, the corresponding reflection coefficients S 11 (ω) can be calculated based on the finite integration method in CST.…”

“…40 The electrolyte layer is ignored theoretically due to its ultrathin thickness (micrometers) compared to the working wavelength (centimeters). 41,42 In simulations, periodic boundary conditions with a Floquet port are employed in the x-and ydirections and open boundary condition is utilized in the zdirection along the propagation of the incident plane waves.…”

Multifunctional Graphene Metasurface for Highly Flexible Control of Microwave Absorption

“…Based on the Kubo formula, the conductivity of graphene is related to the electronic transition in the band (σ intra ), and its surface impedance Z is described as follows 38…”

“…Based on the Kubo formula, the conductivity of graphene is related to the electronic transition in the band ( σ intra ), and its surface impedance Z is described as follows Z = true 1 σ i n t r a = R + j X = prefix− j π ℏ 2 ( ω − j 2 Γ ) e 2 κ B T true[ μ normalc κ B T + 2 ln ( 1 + e − μ c κ normalB T ) true] − 1 where ω is the angular frequency, μ c is the chemical potential, Γ is the phenomenal scattering rate (Γ = 0.1 ps), T is the temperature ( T = 300 K), e is the charge of the electron, ℏ is the reduced Planck constant, k B is the Boltzmann constant, R represents the equivalent resistance of graphene, and X represents the equivalent reactance of graphene. Figure a shows the spectrograms of the real part and imaginary part of the graphene surface impedance.…”

Three‐dimensional printed fractaldielectric‐resonator‐basedbroadband microwave absorber

“…The ultra-thin absorber is generally composed of a three-layer sandwich structure plane periodic array consisting of a metal pattern layer at the top, a dielectric layer and a grounding metal substrate. Since the metamaterial bandwidth is relatively narrow, more PMA with different structures, [20][21][22] and different materials 23,24 are introduced into the design of EM absorbers. In Reference [25], Dingwang Yu et al introduced Minkowski fractal structure into the top metal layer, reducing the size by about 2.5% to solve the problems of large size and complex manufacturing.…”