Research On The Effect Of Electromagnetic Defects In Flexible Materials On Surface Wave Transmission Characteristics

With the development of low detectable technologies,including shape shaping,radar absorbing material applications,etc.,strong scattering sources such as specular reflection and dihedral angle of the target are effectively controlled,and non-specular scattering mechanisms such as surface waves have become low detectable targets.Bottlenecks for further performance improvement.Besides,radar absorbing materials face many practical problems in engineering applications,so higher requirements are placed on the materials,including flexible stretch,curved conformal,defect self-healing,etc.Aiming at the above problems,this paper takes the magnetic loss of flexible absorbing material prepared by the casting process as the research object.A study about surface wave absorption properties and electromagnetic parameters of the flexible absorbing material was implemented in detail.The intrinsic electromagnetic parameters of the material to control the surface wave attenuation were analyzed.The physical model of surface wave transmission attenuation was given.Also,based on the scattering effect caused by the occurrence of electromagnetic defects in flexible materials,the physical model of electromagnetic defects was simplified,and the effects of the depth,width,and position of electromagnetic defects and the dispersion characteristics are analyzed.Based on the excellent performance of flexible materials,a practical and feasible repair scheme was provided.The specific conclusions are as follows:(1)A magnetic loss type flexible wave absorbing material is prepared by a casting process.The material has good wave absorbing properties and excellent electromagnetic parameters.Through the dispersion equation,surface wave transmission electromagnetic field diagram,and surface wave attenuation test,the surface wave transmission performance analysis of flexible materials is completed.Magnetic loss type materials suppress surface waves in the frequency range of 1-18 GHz.With the increase of frequency,the attenuation of surface waves by absorber materials increases significantly.Flexible absorbing materials have limited attenuation of surface waves in low-frequency bands,and can effectively suppress attenuated surface waves in high-frequency bands,up to 34.15 dB/m at 18 GHz.Using the controlled variable method,the effects of the intrinsic electromagnetic parameters of the absorbing material on the attenuation of the surface wave were investigated respectively.(2)After a defect occurs in a flexible absorbing material,when the width of the defect in the propagation direction is greater than half the wavelength of the incident wave(?/ 2),the non-specular scattering caused by the surface wave increases sharply.At this time,it is necessary to consider reducing the scattering.As the depth of the defect increases,the scatter generally increases.Defects at different locations have different effects on backscatter.The scattering at the end edge defects is significantly higher than at other locations.The effects of defects are similar in the X-band(8-12GHz).Defects at different locations have different scattering mechanisms,and their repair options need to be considered separately.The flexible absorbing materials studied in this paper can use the tensile properties to self-repair defects and widen their application range and service life.In this paper,the electromagnetic defect analysis of the absorbing material and the non-specular scattering of surface waves are organically combined for analysis,and the model of the defect is simplified and refined.A detailed analysis scheme is given.Finally,the electromagnetic field diagram of surface wave transmission attenuation is given,which makes the mechanism more vivid and intuitive.