Independent Metamaterial Absorber Research Articles

Angle Independent Metamaterial Absorber for S and C Band Application

Angle Independent Metamaterial Absorber for S and C Band Application

Polarization Independent Metamaterial Absorber with Anti-Reflection Coating Nanoarchitectonics for Visible and Infrared Window Applications.

The visible and infrared wavelengths are the most frequently used electromagnetic (EM) waves in the frequency spectrum; able to penetrate the atmosphere and reach Earth’s surface. These wavelengths have attracted much attention in solar energy harvesting; thermography; and infrared imaging applications for the detection of electrical failures; faults; or thermal leakage hot spots and inspection of tapped live energized components. This paper presents a numerical analysis of a compact cubic cross-shaped four-layer metamaterial absorber (MA) structure by using a simple metal-dielectric-metal-dielectric configuration for wideband visible and infrared applications. The proposed MA achieved above 80% absorption in both visible and near-infrared regions of the spectrum from 350 to 1250 nm wavelength with an overall unit cell size of 0.57λ × 0.57λ × 0.59λ. The SiO2 based anti-reflection coating of sandwiched tungsten facilitates to achieve the wide high absorption bandwidth. The perceptible novelty of the proposed metamaterial is to achieve an average absorptivity of 95.3% for both visible and infrared wavelengths with a maximum absorptivity of 98% from 400 nm to 900 nm. Furthermore, the proposed structure provides polarization insensitivity with a higher oblique incidence angle tolerance up to 45°.

Design of super compact ultrathin perfect wide‐angle polarization independent metamaterial absorber for C, X, and Ku band applications

AbstractThis article focuses on the design of super compact, polarization insensitive with wide angular stability, ultrathin triple‐band metamaterial absorber. The unit cell comprising patches achieves almost perfect absorption (close to 100%) at C, X, and Ku band thereby justifying the term perfect metamaterial absorber. The structure provides 99.96%, 99.98%, and 99.62% absorptivity at the 4.75 GHz (C‐band), 9.47 GHz (X‐band), and 14.40 GHz (Ku‐band), respectively. The dimension of the structure is super compact of the order of 7.2 × 7.2 × 0.8 mm3 along with the ultrathin profile. The unit cell thickness is 0.012 λlowest (where λlowest is at a lowest cut‐off frequency). The proposed absorber comprises an outermost ring, split ring, innermost ring and square line with triangle patches at the boundary. The combinational effect of rings and internal patch provides perfect absorption at designated frequencies. Further, equivalent circuit is explained for the proposed design. The absorptivity remains insensitive towards transverse electric and transverse magnetic polarized wave and exhibits matched absorption. Moreover, the stability of the proposed design is validated with the different incident (for TE and TM modes) and polarization angles. The results are found close to perfect absorption. Finally, the simulated results are validated with measured results and found in close agreement.

Super compact ultrathin quad‐band with wide angle stability polarization independent metamaterial absorber

AbstractIn this article, a compact ultrathin polarization‐insensitive wide‐angle metamaterial‐based microwave absorber with quad‐band characteristics is presented. The designed microwave absorber provides simulated peak absorption of 99.16%, 98.21%, 98.32%, and 99.76% at 3.7 GHz, 6.4 GHz, 10.7 GHz, and 14.3 GHz, respectively. The absorption frequency lies in microwave frequency bands of S, C, X, and Ku. The unit cell of the proposed microwave absorber consists of two diagonally connected closed ring resonator (CRR) along with one metallic patch enclosed by the inner CRR. Each side of the enclosed patch is connected with inner CRR at the center of length. The unit cell of the proposed 0.0197λlowest (wavelength at lowest frequency) thick multiband absorber fits in a volume of 8 × 8 × 1.6 mm3. The proposed metamaterial‐based microwave absorber exhibits identical absorption characteristics for both transverse‐electric and transverse‐magnetic polarized radiations and also provides well peak absorption for an oblique incidence up to 75°. Finally, the absorber is fabricated and experimental result validates simulated one.

Wide band fractal‐based perfect energy absorber and power harvester

In this article, a novel wide band polarization and incident angle independent metamaterial absorber (MA) and energy harvesting applications which operates at C (4GHz-8 GHz) and X (8GHz-12 GHz) is proposed. The unit-cell of the proposed structure based on fractal circle loop. Four lumped resistors are mounted the structure to obtain a broad band absorption characteristics. Resistors increase the absorption characteristic of proposed MA significantly at mentioned frequency ranges. In addition, under favor of the resistors proposed MA can convert absorbed energy from incident wave to appearing power.

Design and analysis of an ultrathin triple-band polarization independent metamaterial absorber

In this paper, an ultrathin triple-band polarization insensitive metamaterial (MTM) absorber has been presented for C-band applications. The proposed structure is explained as a combination of two absorbers, named as Absorber-I and Absorber-II. It exhibit 91%, 98.9% and 99.5% absorptivity at 4.2 GHz, 7 GHz and 7.4 GHz frequencies respectively. Absorber-I and Absorber-II are individually responsible for the origin of two separate frequency bands at 4.2 GHz and 7 GHz respectively. Further, mutual coupling between Absorber-I and Absorber-II is responsible to generate one more absorption band at the frequency of 7.4 GHz. The fourfold symmetric nature of the proposed unit cell provides polarization insensitivity phenomena. The absorbing mechanism of the designed absorber has been explained by two methods. One is by plotting input impedance of the absorber. Another one is by analyzing the EM wave propagation inside the structure. The proposed absorber has been fabricated and simulation results are experimentally verified.

An Investigation on Compact Ultra-Thin Triple Band Polarization Independent Metamaterial Absorber for Microwave Frequency Applications

This article claims, an investigation on compact ultrathin triple band polarization independent metamaterial absorber for microwave frequency applications. The proposed absorber unit cell consist of two resonators named as Structure-A and Structure-B. Both the resonators are printed on the upper surface of dual side copper coated FR-4 epoxy glass substrate of thickness 0.8 mm. The proposed absorber structure offers three distinct absorption peaks of 99.67%, 99.48%, and 99.42% with FWHM bandwidth of 170 MHz (4.11-4.28 GHz), 350 MHz (9.17–9.52 GHz), and 480 MHz (11.24–11.72 GHz) at 4.19 GHz, 9.34 GHz, and 11.48 GHz, respectively, under normal incidence. In addition to above, the four fold symmetry of proposed absorber structure make it polarization independent. Proposed absorber structure also offers more than 80% absorptivity at different angle of incidence (up to 60°) under transvers electric and transvers magnetic polarization states. The designed absorber unit cell has compactness of $0.11~\lambda _{0} \times 0.11~\lambda _{0}$ with ultra-thin thickness of $0.0111~\lambda _{0}$ , where $\lambda _{0}$ is the free space wavelength with respect to the lowest absorption peak of 4.19 GHz. Absorption mechanism of proposed unit cell has been discussed with the help of normalized input impedance, electric field distribution, and surface current density plots. In order to discuss the metamaterial property of proposed absorber unit cell dispersion diagram has been shown.

Polarization angle independent metamaterial absorber based on circle-shaped resonators with interference theory

We theoretically and numerically designed a perfect metamaterial absorber at microwave frequencies. The proposed design has a very simple geometry, wide band properties and provides perfect absorption for all polarization angles which is one of the most desired properties for an absorber structure to be used in the applications where the source polarization is unknown. In order to explain the absorption mechanism both numerical and theoretical analyses are carried out. Designed structure offers a perfect absorption at around 9.8 GHz. The resonance frequency does not change depending on the source wave polarization. In addition, it can be easily reconfigured for THz and infrared regimes for different applications such as sensors, defense systems and stealth technologies.