电磁不连续和缺陷结构表面波散射特性

Surface wave scattering characteristics of electromagnetic discontinuity and defect structures

对于隐身飞行器设计,当镜面和腔体等主要散射源被抑制后,表面波在电磁不连续和缺陷结构处产生的回波散射和空间散射成为重要的散射源。为研究电磁不连续和缺陷结构的表面波散射行为,通过平板波导激励,建立起表面波传输模型。基于该表面波传输模型,从飞行器表面结构出发,建立了曲面及二面倾角、缝隙和台阶3类电磁不连续或缺陷结构,并开展仿真研究,获得了关键结构参数与回波散射强度和空间散射效率的定量关系。研究表明:凸面不连续结构的表面波在传输过程中不断向空间散射而衰减,当凸面半径超过10倍波导波长时,衰减系数接近0,凹面不连续结构的表面波在传输过程中不衰减;二面倾角结构的倾角在30°范围内时,能够有效抑制表面波的空间散射效率在10%以内,且回波散射较弱;缝隙和台阶的表面波散射与结构尺寸之间存在半波谐振关系,且回波散射和空间散射抑制难以兼顾。研究结果可为隐身飞行器外形结构的表面波散射抑制设计提供指导。

For stealth vehicle design,when the main scattering sources such as mirror and cavity are suppressed,the echo scattering and spatial scattering produced by surface waves at electromagnetic discontinuities and defective structures become important scattering sources.In order to study the surface wave scattering behaviors of electromagnetic discontinuities and defective structures,a surface wave propagation model is established by planar waveguide excitation.Based on the surface wave propagation model,three kinds of electromagnetic discontinuity or defective structures of aircraft,including curved surface,dihedral inclination angle,gap and step,and the quantitative relationship between key structural parameters and echo scattering intensity and space scattering efficiency is obtained by simulation research.The results show that the surface wave of the convex discontinuous structure scatters and attenuates continuously in the propagation process.When the radius of the convex surface exceeds 10 times the wavelength of the waveguide,the attenuation coefficient is close to O,while the surface wave of the concave discontinuous structure does not attenuate in the propagation process.When the diplanar dip angle is within the range of 3o°,the spatial scattering efficiency of surface wave can be effectively suppressed within 10%,and the echo scattering is weak.There is a half-wave resonance relationship between the surface wave scattering of slots and steps and the structure size,and it is difficult to give attention to both echo scattering and spatial scattering suppression.The research results can provide guidance for the design of surface wave scattering suppression of stealth aircraft.