Research On Flexible Electromagnetic Metamaterials Absorber

Electromagnetic Metamaterial(EMM) is a kind of artificial composite material which has the special structure design with negative permittivity and negative permeability. In recent years, the scholars at home and abroad have made a lot of researches on the electromagnetic metamaterial, and realized controlling the real part and the imaginary part of the dielectric constant and the magnetic permeability. According to the excellent characteristics of electromagnetic metamaterial, it has been applied in many fields, including military, civilian, and many other fields. One of them is to absorb the incident electromagnetic wave energy effectively, which is called as metamaterial absorber(MMA). It has opened up a new research direction in the field of conventional absorbing materials.With the study of electromagnetic metamaterial absorbers, people is not only satisfied with the superior performance of the planar metamaterial absorbers, but also hope that the metamaterial absorbers can be applied in the more extensive and complex environments. For the consideration of the absorbers conforming to the surface of target, flexible metamaterial absorbers are born. Based on the technology of electromagnetic metamaterial, this paper has designed several planar metamaterial absorbers and flexible metamaterial absorbers. These absorbers have the characteristics of ultra-thin, multi frequencies or broadband absorption, insensitive to polarizations, and insensitive to large angle of incident waves. The methods of equivalent impedance calculation, surface current distribution, and energy loss are described to analyze the absorbing process of designed metamaterial absorbers. At last, through the scientific method, the sample was tested its performance to verify the correctness of the design.In the first part of this paper, two kinds of multi frequencies(double frequencies) metamaterial absorbers are discussed. The first planar metamaterial absorber has been realized the perfect multi frequencies absorption of incident electromagnetic waves. The second metamaterial absorber on flexible substrate has two absorption frequencies in the microwave band with the absorption higher than 96%.In the second part of this paper, a planar broadband metamaterial absorber has been studied. Through loading patch resistance, the absorption of designed broadband absorber is greater than 90%. Transverse Electric wave(TE) and Transverse Magnetic wave(TM) have the similar absorption performances, which means not sensitive to the polarizations of incident waves.In the third part, a flexible ultra-broadband metamaterial absorber has been designed, which can absorb the electromagnetic wave from 6.08 to 13.04 GHz, and the absorption rate is more than 90%. There are many advantages of using flexible substrate, such as bending and conforming to the surface of objects easily. The performance of flexible absorber is better than that of planar absorber when electromagnetic waves incident with a large angle. Besides that, the proposed absorber is ultra-thin and insensitive to the polarization of incident waves.