Type Of Metamaterial Absorber Research Articles

Theory, design and characterization of metamaterial absorbers: a formal assessment

Metamaterial (MTM) absorbers and their design have been of prime interest in view of their capability to absorb electromagnetic waves of high frequencies. Different types of MTM absorbers have been reported in the last two decades. Keeping this in view an attempt was made to review the progress of MTM absorbers in terms of the theory behind them, designing and construction. This paper reviewed the basic theory and design regulations of a perfect MTM absorber at high, narrow and broad band frequencies. Also we reviewed tunable frequency and coherent absorbers. This exercise was done to focus on recent developments in metamaterial absorbers and present the tested results in a more precise way

Characterizations of reconfigurable infrared metamaterial absorbers.

We propose four types of metamaterial absorbers (MAs) to have tunable absorption resonance and polarization-dependent/independent, single-band, and dual-band switch characterizations. By tailoring four types of MAs with different heights between top and bottom metal layers, absorption resonance can be modified at a 5.92μm wavelength, and the absorption intensity can be attenuated gradually. These characteristics of MA devices can be potentially used in a variable optical attenuator (VOA). By changing the distance between the top unit cells of four devices, the resonances can be tuned in the range of a 1.74μm wavelength with an exponential relationship. All absorption intensities can be maintained over 90%. Furthermore, MA devices also possess single-band and dual-band switch characterizations by controlling the polarization angle of incident light, which helps the MA to have the potential in a multifunctional switch. By comparing the range of switch ratios, it can be spanned 1.76 for dual-band switch function. This Letter provides a strategy to open an avenue for VOA, absorber, detector, sensor, and switch applications in the IR wavelength range.

Broadband and polarization-insensitive metamaterial absorber based on hybrid structures in the infrared region

In this work, a new type of metamaterial absorber is proposed in the infrared region. This structure consists of metal-dielectric-metal. But the difference is that a square groove in the dielectric has been dug, and replaced by a metal. The simulated results show that this structure can achieve a broadband absorption. And the absorption bandwidth can be realized from 60.5 to 115.5 THz when the absorption efficiency is larger than 90%. And this structure is polarization-insensitive for incident electromagnetic waves. In addition, the structure can also achieve better absorption effect for a large incident angle, especially for TM polarized wave. What is more, a remarkably enhanced bandwidth can be realized by using a metal to fill the square groove which is dug in the dielectric. To further explain the mechanism of high absorption, the distribution of the electromagnetic field and power loss density at the resonance frequencies are analysed. And these novel properties make the absorbers have many applications including sensor, cloaking, etc.

THz帯におけるメタマテリアル・アブソーバの製作と吸収特性の評価

Metamaterial absorbers with various sizes were experimentally demonstrated in the terahertz frequency region, and their absorption characteristics were evaluated. They consist of an Au ground plate, a polyimide layer, and Au metamaterial structures. Two types of metamaterial absorbers with crossed shapes and cut-wire shapes were fabricated, respectively. For both types of metamaterials absorbers, 90% of absorption was experimentally obtained around 1.5 THz frequencies.

Designing flexible and versatile metamaterial absorbers

Absorbers play an important role in protecting sensitive electronic devices from electromagnetic interference by absorbing the energy of incoming waves and reducing unnecessary reflection or transmission. In this paper we introduce new types of absorbers based on periodic structures, or the so-called metamaterials, which give us additional degrees of freedom to design the absorbing performance of absorbers with reduced thicknesses. Specifically, we demonstrate two types of metamaterial absorbers: one allowing us to customize absorption and other scattering parameters at selected frequencies; another absorbing only high-power microwaves and transmitting small signals even at the same frequency to maintain wireless communications. These metamaterial absorbers are expected to facilitate solving modern, complex EM interference issues where different-interdependent requirements exist.

Design, fabrication and characterisation of scaled and stacked layers planar metamaterial absorber

In this study, various forms of design, simulation and measurements of a new type of metamaterial absorber (MA) is investigated at X band. In the first step, an ultra-thin absorber is considered with absorptivity of 99% at frequency 9.88 GHz. The thickness of the structure is only 1/120 of the radiation wavelength. In the second step, a multi-layered structure is designed by stacking several layers of the design on top of one another. For the three-layered structure, two absorption peaks appear at 10.17 GHz of 98% and 10.89 GHz of 99%, respectively. In the third step, resonant frequencies are placed near each other by exploiting the scaling property of the MAs. Unit cells with three scaled elements have the absorption peaks at three resonant frequencies of 9.26, 9.6 and 10.10 GHz with the absorptions of 100, 95 and 84%, respectively. Finally, scaled and stacked structures are combined. The absorption spectra of the three-layered scaling structure have four resonant frequencies at 9.32, 9.76, 10.35 and 11.21 GHz with the absorptivities of 99, 100, 97 and 83%, respectively, with a total full width at half maximum-bandwidth of 2260 MHz. Results of the recursive method and the simulations are in good agreement with those of the measurements.

Metamaterial absorbers realized in an X-band rectangular waveguide

In this paper, we demonstrate six types of metamaterial absorbers (MMAs) by measuring their absorptivities in an X-band (8–12 GHz) rectangular waveguide. Some of the MMAs have been demonstrated previously by using the free space measurement method, and the others are proposed firstly in this paper. The measured results show that all of the six MMAs exhibit high absorptivities above 98%, which have similar absorbing characteristics to those measured in the free space. The numerically obtained surface current densities for each MMA show that the absorbing mechanism is the same as that under the free space conditions. Such a demonstration method is superior to the conventional free space measurement method due to the small-scale test samples required, the simple measure device, and its low cost. Most importantly, the proposed method opens a way to enable MMAs to be used in microwave applications such as matched terminations.