Design Of Broadband Metamaterial Absorber Research Articles

Design of broadband metamaterial absorber utilized by flower-shaped unit loaded with lumped-resistor

A metamaterial broadband absorber is designed by means of metal pattern and lumped resistance. The optimal structural parameters and resistance are scanned in certain steps to determine. The maximum absorbing bandwidth can achieve up to 8.2 GHz with 3 mm thickness. Subsequently, the angle stability of the absorber can be improved by adding vertical metal through holes. After optimization, the maximum absorbing bandwidth can be further increased to 9.1 GHz (8.3–17.4 GHz), and the effective absorption bandwidth of 3.7 GHz (9.53–13.25 GHz) can still be achieved when the incident angle is 60°. Further analysis reveals that the dissipation of the electromagnetic wave is achieved by ohmic loss caused by the resistive element and magnetic resonance caused by the induced circular current, rather than by temperature or other factors. Finally, to verify the real performance of the designed metamaterial absorber, a 30 cm × 30 cm sample was fabricated, and the reflection coefficient was tested by the NRL arch test method. The results showed that the measured return loss of the absorber was consistent with the simulation results.

A simplified design of broadband metamaterial absorber covering X- and Ku- band

This paper developed a simplified design of broadband metamaterial absorber (MA) covering X- and Ku-band. Based analysis of its equivalent circuit model, this paper moves a step forward in terms of using COMSOL simulation software to optimize and analyze the structure parameters of the MA. The simulation results show that the absorptivity of the designed MA at the entire X- and Ku-band (8 GHz-18 GHz) is more than 90% under normal incidence for both transverse electric (TE) and transverse magnetic (TM) polarization, and with good absorption characteristics under a wide incident angle. Furthermore, compared with the previous reports, the MA designed in this paper with simple structure, and without consideration of loading lumped elements or using new materials, the absolute and relative bandwidth reach up to 10 GHz and 76.92%, respectively. This study can be applied to reduce radar cross-section, stealth and improving the electromagnetic compatibility of devices.

Influence of the imaginary part of the dielectric layer on the bandwidth of metamaterial absorber and the design of broadband absorption

It is well known that dielectric layer imaginary part (or loss tangent of tan(δ)) plays a crucial role in modulating the absorption rate of metamaterial absorber (MA). However, there is not any systematic investigation into whether tan(δ) impacts resonance bandwidth of the MA. Herein, we investigated the dependence of resonance bandwidth of the MA on the change of tan(δ). Three kinds of absorbers with top layers of frequently used metallic patterns of square patch, cross, and strip were demonstrated. To facilitate comparison of the bandwidth, each case of tan(δ) was optimized for perfect absorption. Results proved that the bandwidths of the three absorbers were broadened greatly with tan(δ) increase. Their bandwidth enhancement factors are all at least 10. Based on this, this paper further makes some discussions on the design of broadband MA, which consists of three alternating stack of square patches and dielectric layers with large value of tan(δ) on top of a metallic board. >80% absorption of the resonance bandwidth of the triple-layer absorber can cover a frequency range of 3.689 THz. The relative resonance bandwidth of absorber can reach 138.893%, which is far higher than that of previous broadband absorbers using small value of tan(δ).

Broadband, polarization-insensitive, and wide-angle microwave absorber based on resistive film

A simple design of broadband metamaterial absorber (MA) based on resistive film is numerically presented in this paper. The unit cell of this absorber is composed of crossed rectangular rings-shaped resistive film, dielectric substrate, and continuous metal film. The simulated results indicate that the absorber obtains a 12.82-GHz-wide absorption from about 4.75 GHz to 17.57 GHz with absorptivity over 90% at normal incidence. Distribution of surface power loss density is illustrated to understand the intrinsic absorption mechanism of the structure. The proposed structure can work at wide polarization angles and wide angles of incidence for both transverse electric (TE) and transverse magnetic (TM) waves. Finally, the multi-reflection interference theory is involved to analyze and explain the broadband absorption mechanism at both normal and oblique incidence. Moreover, the polarization-insensitive feature is also investigated by using the interference model. It is seen that the simulated and calculated absorption rates agree fairly well with each other for the absorber.