Research On Metamaterial Absorber Based On Square Ring Nested Structure

A metamaterial is a subwavelength artificial electromagnetic material that has a certain special resonance arrangement on the dielectric layer.Different from other materials available in nature,metamaterials have electromagnetic physical properties such as negative magnetic permeability,negative permittivity,and negative refractive index.Its advantage is that it can obtain the desired results by the designer through artificial design of its surface,simulation optimization,etc.,so it has been widely used in electromagnetic applications in recent years.By changing the size of its microstructure,array arrangement,and the number of dielectric layers,different effects of single-frequency absorbing,multi-frequency absorbing and broadband absorbing can be achieved.The main content of this paper includes the following three aspects:(1)Based on the impedance matching theory,a three-frequency metamaterial absorber based on a square ring nested structure was designed,using a metal-dielectric-metal structure.The absorbing rates of these frequencies reached 99.0%,93.5% and 97.7%respectively,and the influence of each part of the annular structure on the absorbing performance was analyzed.And the designed three-frequency metamaterial absorber still has excellent electromagnetic absorption performance when a certain polarization angle and incident angle are changed.The surface electric field and surface current are simulated and analyzed at the operating frequency,and the absorption mechanism is further studied.The simulation and test results show that the metamaterial absorber has the advantages of easy fabrication,simple structure,good stability,lightness and thinness,and has potential application value during the electromagnetic function in a specific frequency band.(2)Since the resistive film can aggravate the ohmic loss,its equivalent impedance can be matched with the air impedance in a wider frequency band,thus achieving the effect of absorbing electromagnetic waves from frequency point to frequency band.In order to broaden the working frequency band and better apply to the conformal application of stealth technology,a broadband flexible transparent metamaterial wave absorber based on the nested structure of square rings is proposed.On the basis of the previous design,the dielectric material and the top and bottom materials were replaced,and the structure of the resonance layer was changed and optimized.ITO(indium tin oxide)is used as the top resonance layer,and flexible transparent material is used as the intermediate dielectric layer.The bandwidth of the working frequency band(absorption rate reaches more than 90%)can reach 10.3GHz.Compared with the previous one,the total thickness is almost unchanged.And the absorber still has excellent absorption rate under the transformation of a certain polarization angle and incident angle,and the surface current,surface electric field,normalized impedance,equivalent permeability,etc.The effective dielectric constant is further studied.The light transmittance of the sample in the visible light band is over 73% after testing.The flexible and transparent metamaterial broadband absorber designed in this paper has the characteristics of easy design,lightness and thinness,and is more suitable for practical applications.It has potential applications in transparent electromagnetic stealth defense systems and wearable electronics.(3)The two designed absorber samples are processed and fabricated by the printed circuit board process and the micro-electromechanical system process respectively.A test system was built based on the free space test method to test the electromagnetic wave absorption results.The data obtained after the test is the same as the simulation data,which verifies the feasibility and reliability of the design.Finally,the main research work of this paper is summarized,and the shortcomings of the research and the content of the next work are summarized and prospected.