Design And Optimization Of Metamaterial Broadband Absorber

With the continuous development of information technology,the popularity of communication equipment such as mobile phones and computers has brought convenience to people’s lives,but also accompanied by more and more serious electromagnetic pollution,which may interfere with the stability of communication signals and affect human health.In the military field,reconnaissance and anti-reconnaissance are eternal topics,and radar stealth is an important part of anti-reconnaissance.Absorbing materials can dissipate the electromagnetic wave energy in space through the form of conductance loss,so as to weaken or eliminate electromagnetic pollution and radar reflection signals.Therefore,it is necessary to study absorbing materials in both civil and military fields.Compared with traditional absorbing materials,metamaterial absorbing materials can achieve perfect absorption of electromagnetic waves through structural design,and have the advantages of adjustable structure and thin thickness.After previous studies,broadband electromagnetic wave absorption can now be achieved through multilayer stacking,adding lumped elements and patterned resistive films,which is an important way to achieve thin,light,wide and strong absorbing materials.In this paper,through simulation and optimization design,the metamaterial absorbers in different frequency bands are designed and optimized by loading lumped resistors and resistive films,and the absorbers in low frequency bands that are difficult to realize with traditional materials are designed.(1)A metamaterial broadband absorber is designed by means of metal pattern and lumped resistance.When the thickness is 3mm,the absorbing bandwidth is 8.2 GHz(8.1-16.3 GHz),and its structural parameters are scanned in certain steps to determine the optimal parameters.Subsequently,the angle stability of the absorber is improved by adding vertical metal through holes.After optimization,the effective absorption bandwidth of 3.7 GHz(9.5313.25 GHz)can still be achieved when the incident angle is 60.The absorption mechanism is analyzed by the simulation results of electric field,magnetic field and surface current.(2)Two kinds of broadband metamaterial absorbers are designed based on the resistive film.The first one adopts the structure of double dielectric layers and double resistive films,which achieves effective absorption of 13-43 GHz when the overall thickness is 3.2 mm.The energy dissipation of electromagnetic waves is mainly in the form of ohmic heat of resistive films,and the broadband absorption of this absorber structure is realized by interlayer coupling.The second type of absorber is a honeycomb resistive membrane structure.When the overall height of the structure is 5.5mm,the effective absorption bandwidth is 293 GHz(7-300 GHz),and the relative absorption bandwidth is 190.8%.The absorption rate is greatly affected by the thickness of the dielectric layer,but less affected by the resistance of the resistive membrane,which is beneficial to processing and production.(3)Water,as a common material in nature,has the characteristics of high dielectric constant,high loss and dielectric properties varying with temperature in the microwave band.A low-frequency metamaterial absorber structure is designed with water as the dielectric layer.At the water temperature of 10℃,the bandwidth with absorption rate of 90%or more is 1.251.67 GHz,which is 0.42 GHz,and the frequency band with absorption rate of 80%or more is 1.18-1.77 GHz.And can be realized by temperature adjustment.,the effective absorption of 1.25-1.85 GHz is more than 90%,and the absorption rate of 1.18-1.97 is almost more than 80%of the whole frequency band.