Preparation Of All-dielectric Absorbers And Research On Their Microwave Absorption Performance

Although the widespread application of electronic devices and digital instruments has brought great convenience to human life,the accompanying electromagnetic interference and electromagnetic pollution has become an urgent problem to be solved.All-dielectric metamaterial absorber refers to the metamaterial absorber whose material composition is all dielectric,which has the advantages of simple structure,thin thickness,wide absorption band and high absorption rate,and is an ideal material for solving electromagnetic pollution.The rapidly developing 3D printing technology shows great advantages and application potential in preparing complex structures,providing a simple,fast and efficient fabrication method for studying and preparing all-dielectric metamaterial absorber.In this paper,two all-dielectric metamaterial absorbers were designed and prepared using fused deposition molding(FDM)3D printing technology,and their wide-angle properties and broadband absorption mechanisms were investigated.The main research of this paper is as follows:(1)A novel FeSiAl/polylactic acid(PLA)composites pyramid was fabricated by fused deposition molding(FDM)3D printing technology.The study investigated the impact of the geometric parameters of the unit structure on the absorption intensity and bandwidth of electromagnetic(EM)wave(EMW).The findings indicate that the pyramid structure design achieves a minimum reflection loss(RL)of-37.2 dB.This is achieved when the unit structure period length is 22.5 mm,the base thickness is 0.5 mm,and the thickness of the unit structure and the edge length of the upper surface are 7.0 mm and 6.0 mm,respectively.These parameters result in a RL below-10 dB within the frequency band of 6.7–18 GHz.Additionally,the effective absorption bandwidth(EAB)for TE polarization exceeds 11 GHz when the incident angle changes from 0° to 50°,while the bandwidth for TM polarization still reaches 6.9 GHz at70°.The broad absorption properties of the proposed absorber can be attributed to the synergistic enhancement effect of both the structure and material.(2)To solve problems of single loss mechanism of FeSiAl/PLA composites and the high FeSiAl filling(50wt% and 60wt%),the GR/FeSiAl/PLA composite features lightweight and broadband absorption was produced by reducing the FeSiAl content to 30wt% and adding1wt%～5wt% of graphene(GR).Due to the good impedance matching,and the synergistic effect of dielectric and magnetic losses,the GR/FeSiAl/PLA composites containing 4wt% graphene exhibits a minimum RL value of-46.4 dB,and the effective absorption bandwidth(EAB)is4.80 GHz(13.2–18 GHz)with a thickness of 2.2 mm.Meanwhile,the minimum RL value is-31.5 dB and the EAB is 6.40 GHz(11.6–18 GHz)of GR/FeSiAl/PLA composites with graphene content is 5wt% with the same thickness.(3)A new multilayer ladder structure absorber was proposed,the bottom layer of which is a flat plate structure with square holes,and the upper layer includes three cuboids,which feature equal thickness and varying length gradients of edge lengths.The EAB of the designed ladder structure is 12.75 GHz(5.25–18 GHz)when the material of bottom layer is FeSiAl/PLA composite containing 30wt% FeSiAl and the material of the top layer is GR/FeSiAl/PLA composite containing 5wt% graphene.Meanwhile,the period length of the ladder structure is22.5 mm,the thickness of the flat plate is 1.5 mm,and the thickness and the edge length difference of the cuboid are 2.5 mm and 4.0 mm,respectively.At the same time,the EAB of the ladder structure exceeds 10 GHz when the incident angles of TE and TM polarization change from 0° to 50°.In addition,the hollow design can maintain broadband absorption above12 GHz at a volume reduction of no more than 10.8%,and effective electromagnetic wave absorption can be achieved in the full frequency band from 2 to 18 GHz when the designed ladder structure is enlarged by a factor of 2.6 to 3.2.The two proposed all-dielectric metamaterial absorbers in this paper feature excellent broadband and wide-angle absorption properties,and can be rapidly manufactured by a simple3 D printing technology,which provides an important reference for the mass production and commercial application of absorbers.