Research On The Low-frequency Attenuation Performance Of Surface Wave Of Radar Absorbing Material

With the continuous development of radar scattering cross-section(RCS)reduction methods such as shape technology and radar absorbing materials,and strong scattering sources such as specular reflection and cavity scattering have been effectively controlled,the surface wave and other sub-weak scattering sources have become the main contributions of the target body RCS,which is the focus and hotspot of RCS reduction method research.The surface wave absorbing material is used to control the surface wave,due to the limitation of the bandwidth limit of the absorbing material,it is difficult to achieve effective low-frequency surface wave attenuation under the condition of thickness limitation,so low-frequency surface wave attenuation has become an important direction for the research of wave-absorbing materials.In this thesis,taking magnetic wave-absorbing materials as the research object,the surface wave attenuation characteristics of single-layer and multi-layer wave-absorbing materials are discussed in detail,and the influence of material parameter changes on surface wave attenuation is analyzed.In addition,in view of the problems of low frequencies of absorbing materials,based on the theory of periodic structure,the method of improving the low-frequency surface wave attenuation of the loading cycle structure is explored,and the surface wave attenuation characteristics of the composite absorbing materials loaded by the periodic structure are studied.The following is the specific research content:(1)Based on the theoretical research of the dispersion equation of surface wave transmission,the surface wave attenuation performance of absorbing materials are studied.In order to improve the low-frequency attenuation of surface wave,the influence of material parameters on surface wave attenuation can be improved,and the absorbing material with smaller real part of dielectric constant and larger permeability and virtual part can be selected.(2)Based on the theory of periodic structure,several composite absorbing materials loaded with different periodic structures are designed,and their mirror absorption properties and surface wave attenuation properties are comprehensively analyzed,and their electromagnetic transmission mechanisms are explored.The results show that the composite absorbing material loaded with improved snake pattern has excellent surface wave attenuation performance,absorbing more than 10 d B at low frequency 1.47 GHz,while maintaining good absorption performance in the high frequency broadband range of 4 GHz-15 GHz,and the upper cutoff frequency of surface wave is broadened from 4GHz to 8 GHz.(3)Based on the test method of RCS reduction,the surface wave attenuation characteristics of absorbing materials are studied.The surface wave attenuation characteristics of single-layer absorbing materials with different frequency points,thicknesses and electromagnetic parameters are discussed,and the attenuation changes of multilayer absorbing materials are superimposed.It is found that the attenuation performance of low-frequency surface waves can be improved by increasing the thickness,selecting appropriate material parameters,and superimposing multiple layers of materials,which is consistent with theoretical research.(4)The composite absorbing material loaded with an improved periodic structure is studied.By loading the resistance film,patterned resistance film,and patterned metal step by step optimization,the low-frequency surface wave attenuation performance is improved,and the surface wave attenuation of 1 GHz is finally increased from 3.64 d B/m to 12.87 d B/m,which greatly improves the low-frequency surface wave attenuation performance.In this thesis,starting from the perspectives of classical dispersion equation theory and RCS reduction,the surface wave attenuation characteristics of magnetic absorbing materials are studied,the design methods of composite absorbing materials based on periodic structure loading are discussed in detail,and feasible schemes for improving low-frequency surface wave attenuation are given.