Research On Preparation And Mechanism Of Magnetic Absorbing Materials Based On Frequency Selective Surface

With the use and development of high-frequency electronic devices and wireless transmission in commercial and military,the part of electromagnetic absorption and electromagnetic interference field becomes more and more attentive.With the development of modern military,in order to meet the requirements of "thin,light,wide,strong",the absorbing materials used in radar equipment,electromagnetic stealth technology must show a strong ability of electromagnetic wave absorption loss in the widescreen band range.In recent years,in order to combine the properties of wave absorbing and frequency selective,the frequency selective surface has been taken into wave absorbing material.With nickel oxide powder,carbonyl iron powder and vinyl ester resin were prepared by absorbing composite materials with different composition,and the permittivity and permeability of materials were tested by coaxial method in the paper.The design and manufacture of the preparation of a double cylindrical wave absorbing layer,and frequency selective surface(FSS)was composited.The electromagnetic properties of the material and the reflectivity of electromagnetic wave were tested and studied using vector network analyzer by the method of RCS far-field.Based on the dielectric and electromagnetic parameters of absorbing composite materials,dielectric layer material,Ansoft HFSS software was used to simulate the electromagnetic wave reflection of the sample,and the best result was found through orthogonal method,finally FSS wave absorbing composite material structural unit was obtained.The different components of the absorbing agent parameters were substituted into the simulation software,and the result showed that the nickel powder FSS absorbing composite materials appeared two peaks between 1GHz and 18 GHz,the first absorption peak decreased with the increase of the content of nickel powder,from-15.5dB to-5dB;while the second peak increased firstly and then decreased,which enhanced to-19.1dB from-15.9dB(45wt%),finally reduced to-17.2dB.Carbonyl iron powder FSS absorbing composite materials appeared only one electromagnetic wave absorption peak between 1GHz and 18 GHz,with the content of carbonyl iron powder increased from 50wt% to 65wt%,the frequency of Absorption peak shifted to low frequency,from 15.5GHz to 12.4GHz.The peak value of absorption peak and effective bandwidth below-10 dB increased,from-16.5dB and 3.6GHz(14.4GHz-18.0GHz)to-29.4dB and 7.8GHz(8.4GHz-16.2GHz).Compared to the simulation results of the absorbing composite materials with FSS,there were great increases in absorption peak value and effective absorption bandwidth of the absorbing composite materials without FSS.The soft film dielectric layer was prepared by using EVA modified polystyrene,which makes the forming properties of materials better.The filled wave absorbing structure corresponds to the FSS pattern.It can effectively reduce the overall density of the material and enhance the forming property.Preparation of FSS absorbing composite material based on design structure,and the samples' electromagnetic wave reflectivity was tested.The results show that the electromagnetic wave reflectivity of FSS wave absorbing composites is roughly consistent with the simulation results,which verifies the design concept of this paper.At the same time,the phenomenon of differences between testing and simulation to the research provides a new way of thinking.It is revealed that we do further research in the direction of low frequency transmission,high frequency absorption and so on.