Research On Broadband Power-Resistant Absorbing Structure Based On FSS

Absorbing material refers to a type of material that can absorb or greatly attenuate the electromagnetic wave energy projected onto its surface,thereby achieving the purpose of eliminating reflected waves,improving electromagnetic interference resistance,and simulating a vacuum environment.Absorption rate and absorption bandwidth are the two most important indicators of absorbing materials.While in operation,the absorber converts the incident electromagnetic energy into internal energy through different forms of work and dissipates it in the surrounding environment in the form of heat.When the power of elec tromagnetic waves is small,the temperature rise of the material after absorption of electromagnetic energy is not obvious,but when the power is increased,the absorbing material made of combustible materials may make the temperature problem a safety haza rd due to its poor thermal conductivity.With the popularization and promotion of 5G technology,a large number of high-power array antennas are put into use,accompanied by more and more other high-power usage scenarios.Although people have begun to real ize that the lack of power performance will become an increasingly important constraint for the development of absorbers,there is still no solution to the effect of reflectivity performance caused by the method of embedding metal conductors to improve hea t dissipation.Therefore,there is an urgent need for a absorbing body that simultaneously improves the absorption rate,bandwidth performance,and power performance to provide a new design idea.Firstly,this paper briefly introduces the process of genera tion and development of absorbing materials.At present,domestic and foreign scholars have studied the use of frequency selective surface(FSS)to improve the reflectivity of absorbing materials and improve the power resistance of absorbing materials.The current status of the research was analyzed.The Heat Transfer,FSS and Equivalent Medium Theory are expounded,and then the application of metal periodic structure in improving the reflectivity of absorbing materials is introduced.Finally,combined with the Equivalent Media Theory,FSS and knowledge of Heat T ransfer,this paper has done the following research work:1)Based on the the Equivalent Media Theory,the space Transmission Tine Theory and the theory of impedance transformation in multilayer medi a,the MATLAB tool is used to calculate and analyze the cone-shaped absorber,and the results are compared with the results obtained by CST electromagnetic simulation software.The applicable range of Equivalent Media Theory under low dielectric constant is discussed.2)For the problem that the low-frequency reflectivity performance of the flat absorbing material is insufficient and the low-frequency bandwidth is insufficient in the space limited,a variety of flat composite materials for improving the low-frequency reflectivity performance are designed based on the Y-shaped,square-ring and cross-type FSS structures..3)Aiming at the problem of insufficient power performance and low frequency reflectivity of EPP flat absorbing materials,a broadband powe r absorbing structure is designed based on FSS theory and heat transfer theory.The structure realizes that the-10 dB reflectivity bandwidth of the original pure EPP material is increased from 2.57 to 7.83 in the 1-18 GHz band,and the power performance is improved by about 120%.