Development And Performance Analysis Of Metamaterial Absorber

Metamaterials are artificial composite materials with extraordinary physical properties that natural materials do not possess.The electromagnetic response mainly depends on the material properties and the microstructure's physical size and structure arrangement.The metamaterial absorber(MMA)can obtain arbitrary permittivity and permeability by reasonably designing the size and structure of the absorber,so as to achieve perfect absorption of electromagnetic waves of a particular frequency.Metamaterial absorber has advantages of thin thickness,small size,simple structure and high absorption rate,which can be widely used in electromagnetic stealth,refractive index sensor,thermal imaging,electromagnetic shielding and other fields.The paper mainly studies the metamaterial absorber in the microwave range,the contents are as follows:(1)A dual-band metamaterial absorber with wide-angle and polarizationinsensitivity is proposed.The MMA is consisted of two copper layers with a FR-4layer between them.And its top layer is consisted of a cross-shaped resonator and a square ring resonator.The calculation result demonstrates that there are two distinct absorption peaks,whose absorptivity are 99.933% at 3.8441 GHz and 99.99% at9.1094 GHz.And its thickness is only 1.34% of the wavelength of the lowest absorption frequency.The dual-band MMA shows polarization-insensitivity for normal incident wave and shows high absorptivity in a wide incident angle for both TE and TM polarization wave.In addition,we discuss the working mechanism.The influences of main parameters on the dual-band MMA's absorption are also analyzed.(2)A polarization-insensitive triple-band metamaterial absorber is proposed.It is composed of three-layer structure: metal-dielectric –metal.The top metal layer is consisted of two close ring resonators.The outer is a square ring resonator and the inner is a circular ring resonator.The simulation result shows that the MMA has three absorption peaks at 3.70 GHz,6.57 GHz and 17.62 GHz,with absorption rate of99.67%,99.05% and 99.98%,respectively.The electric field and surface current distribution of the MMA are given to study its absorption mechanism.The polarization-insensitivity of the absorber is also analyzed.Moreover,the effects of line width and thickness of dielectric layer on absorption are discussed.(3)An ultra-thin and polarization-insensitive metamaterial absorber is designed.The MMA's top layer is only consisted of a square copper film with a cross cut out in the center.The calculation result demonstrates that there are three distinct absorption peaks,which are 5.86 GHz,15.04 GHz and 17.5GHz,and their correspondingabsorption rates are 99.76%,99.11% and 99.90%,respectively.Moreover,the thickness of the MMA is very thin,only 1.05% of the wavelength of the lowest absorption frequency.The MMA also shows polarization-insensitivity for normal incident wave.In addition,we analyze the absorption characteristics of the three absorption peaks and the impact of key structure parameters on the MMA's absorption.(4)A simple six-band metamaterial absorber is designed.There is only a split square metal ring and a square metal sheet in the top layer.The calculation result demonstrates that there are six distinct absorption peaks,which are 8.94 GHz,16.47 GHz,19.35 GHz,23.61 GHz,27.03 GHz and 27.42 GHz,with absorption rate of99.68%,99.52%,99.46%,99.92%,99.89% and 96.22%.And it also show polarization-insensitive for normal incident.Moreover,we explore the MMA's absorption mechanism and analyze the influence of main structural parameters on the MMA's absorption characteristics.(5)We present a polarization-insensitive and ultra-broadband metamaterial absorber,which has higher absorption throughout the whole X-band.The MMA unit cell consists of a metal film and a multilayer-cross-cone structure separated by a dielectric layer.The calculation result shows that the MMA's absorptivity is greater than 96% in the entire X-band(8-12GHz)and the MMA 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 and TM polarization wave.The electric field,magnetic field and surface current distribution of the MMA 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 MMA has a higher absorption rate in the entire X-band,the MMA can be used in electromagnetic stealth,electromagnetic shielding,secret detection and so on.