Design Of Broadband Metamaterial Absorber Based On Open-cell Structure

Electromagnetic wave is a double-edged sword,which not only helps people to improve the ability of communication,exploration,weapons and equipment,but also brings a lot of negative effects to people’s life.Therefore,the development of electromagnetic absorption materials has received a lot of attention from researchers.Traditional wave-absorbing materials have large volume,large weight and small working frequency band,so it is difficult to meet the requirements of electromagnetic wave-absorbing performance.Therefore,how to prepare light-weight wave-absorbing materials with strong wave-absorbing ability has become the top priority.The waveabsorbing metamaterials have the characteristics of light weight,adjustable absorption frequency band and simple preparation,which have become the research hotspot of wave-absorbing materials.In this paper,for the study of wave-absorbing metamaterials,the preparation of wide-frequency,high-absorption and ultra-thin wave-absorbing metamaterials is realized through structural design,regulation of dielectric layer and arrangement of dielectric layer,and the internal wave-absorbing mechanism and the influence of structural parameters are studied by combining electromagnetic field and power loss distribution.(1)A special structural design method of "open hole" structure is proposed.The proposed "open hole" structure design can enhance the electromagnetic wave absorbing effect of the absorbing material in X band and Ku band in a certain frequency band(0-18 GHz),broaden the electromagnetic wave absorbing bandwidth,and provide ideas for the subsequent design of metamaterial absorbers.(2)Through the design of the shape structure of the medium layer,the adjustment of the structural parameters,the experimental preparation of Fe Si Al/paraffin material under the thickness of 3.2 mm to achieve 4.42 GHz electromagnetic wave absorption bandwidth,absorption bandwidth increased by nearly 200%.Compared with unstructured absorbing materials,metamaterial absorber enhances the absorbing effect of materials in X band and Ku band,increasing the absorption peak from one to three.The validity and rationality of the "open hole" structure design are verified by the metamaterial absorber prepared by the experiment.By introducing magnetic medium of carbonyl iron powder and adjusting its structure,a kind of metamaterial absorber with thin thickness,ultra-wide absorption band and high absorption efficiency was obtained.When the thickness is 2.2 mm,the effective absorption bandwidth of the circular porous metamaterial absorber based on the carbonyl iron powder/paraffin magnetic material and FR4 material composite structure reaches 11.6 GHz,which is nearly two times higher than that of the Fe Si Al/paraffin material design.(3)Introduce butyl rubber material,mix carbonyl iron powder,prepare carbonyl iron powder/butyl rubber composite material.The flexible wave absorbing metamaterial with a thickness of 2 mm and an electromagnetic wave absorptivity of more than 90% within 11.37～18 GHz was prepared by using a circular porous structure.Through the replacement of the medium layer design and the modification of the material arrangement,the completion of six metamaterial absorbers design scheme,the optimized Fe Si Al/ paraffin material absorption bandwidth increased to10.9 GHz,greatly improving the electromagnetic wave absorption effect of the absorbing material.The results show that the "open-hole" structure can enhance the electromagnetic absorption peak and broaden the effective absorption bandwidth of the wave-absorbing metamaterials within a certain frequency band,which provides a new idea for the development of wide-band wave-absorbing metamaterials.