A five-band metamaterial absorber (MMA) is presented. The proposed absorber consists of a three-layer structure of the top metal resonator, intermediate dielectric layer, and bottom metal plane. The top structure takes the centroid as the center and spreads out in a three-pronged shape with an average of 360°, and the ends bifurcate again. The calculation was carried out by the professional software to iteratively optimize the absorption effect of MMA in the microwave range. The results show that the MA has five peaks at resonant frequencies of 5.984 GHz, 12.232 GHz, 18.128 GHz, 18.414 GHz, and 20.592 GHz, with peaks of 0.9925, 0.9968, 0.9783, 0.9754, and 0.9975. By analyzing the electromagnetic field and surface current distribution of the absorber, the absorption mechanism is further verified, and the corresponding influence on the absorption spectrum is studied according to different polarization angles and incident angles. The effects of different resonator structure size and dielectric layer thickness on absorption rate were also discussed, and the distribution of electromagnetic fields is analyzed to reveal the existence of electric dipole resonance and magnetic resonance. Through comparing experiments and simulations, it is found that the peaks of the 1st, 2nd, and 5th have smaller absorption errors and frequency deviation, while the peaks of the 3rd and 4th have large ones. The five-band absorber has potential application in multiband electromagnetic stealth, bionic sensor, thermal radiation measuring instrument, and so on.
This paper presents a polarization‐insensitive and ultra‐broadband metamaterial absorber (UMMA), which has higher absorption throughout the whole X‐band. The UMMA unit cell consists of a metal film and a multilayer‐cross‐cone structure separated by a dielectric layer. The calculation result shows that the UMMA's absorptivity is greater than 96% in the entire X‐band (8–12 GHz) and the UMMA is polarization‐insensitive for normal incident wave. Moreover, the absorption rate is also more than 80% in X‐band when the incident angle is less than 56° for TE polarization wave. The electric field, magnetic field, and surface current distribution of the UMMA are analyzed to study its absorption mechanism. The influences of different key structural parameters on the absorber are also discussed, including the arm length and arm width of the bottom and top of the cross‐cone structure and the number of layers of the cross metal, consequently, a set of optimized design parameters is obtained. The proposed UMMA has a higher absorption rate in the entire X‐band, the UMMA can be used in electromagnetic stealth, electromagnetic shielding, secret detection and so on.
A facile design of a novel triple-band electromagnetic metamaterial absorber (MMA) with
polarization insensitive property is proposed in this paper. Each unit of the MMA consists of upper copper resonator and bottom copper plate with middle dielectric FR-4 between them. The MMA performs three absorption peaks at 16.919 GHz, 21.084 GHz and 25.266 GHz with absorption rates 99.90%, 97.76% and 99.18%, respectively. The influence of the main structural parameters on the frequencies and absorption rates is analyzed. The absorption mechanism of the absorber is explained by electric field, magnetic field and surface current distributions, which is supported by the electromagnetic parameters, affected with magnetic resonance. The polarization-insensitivity of TE wave is verified by observing the effects of the polarization angle change from 0-90º. The MMA can be applied in radiation, spectrum imaging detector, electromagnetic wave modulator, and so on.
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