热防护层覆盖弹体目标雷达散射截面的修正的等效电流近似法和图形计算电磁学法分析

将修正的等效电流近似法与图形计算电磁学法相结合引入到热防护层覆盖弹体目标的电磁散射问题的研究中.应用修正的等效电流近似法对介质和有耗表面进行散射计算,结合图形计算电磁学法,借助于计算机显示技术,将三维目标图形在计算机屏幕上投影,由图形加速卡完成遮挡和消隐工作,利用图形计算电磁学的积分公式,把三维空间的计算转化为二维空间的计算,大大降低了计算时间和复杂度.计算结果表明:当入射波频率较低时,热防护层的厚度不会影响弹体雷达截面值的大小,当频率升高,随着热防护层厚度的增加,弹体雷达截面值不断减小,说明热防护涂层为有耗介质,介电常数的虚部越大其消耗能量的能力越强,弹体雷达截面变化越明显;当热防护层中存在孔隙,热防护层厚度一定,孔隙率越大,雷达截面值越大,孔隙率为零时,雷达截面值最小.当孔隙率相同,热防护层越薄,其雷达截面值越大;当弹体在高空中出现脱粘现象,对弹体的雷达截面值影响不大.

Modified equivalent current approximation and graphical electromagnetic computing method of analyzing radar cross section of missile target scatterer covered with thermal protection layer

In this paper, we combine the modified equivalent current approximate method and graphical electromagnetic computing method to solve the electromagnetic scattering problems in the missile target covered with the thermal protective layer. The modified equivalent current approximate method is used to calculate the lossy dielectric and combining graphical electromagnetic method, and using a computer display technology, blanking and occlusion, a three-dimensional surface is projected on a computer screen, and the pixels are calculated. The calculation in three-dimensional space is converted into the calculation in two-dimensional space, thereby greatly reducing the computation time and complexity. The results show that when the incident frequency is low, the thickness of the thermal protection layer does not affect the radar cross section value. When the frequency is increased with the thickness of the thermal protection layer, the radar cross section value continuously decreases, which indicates that the thermal barrier coating is a lossy medium: the bigger the imaginary part of the dielectric, the stronger the ability to consume the energy is and the more obvious the change of missile radar cross section is. When the thermal protective layer has pores, the higher the porosity, the greater the value of the radar cross section is; when the porosity is zero, the value of the radar cross section is minimal; when the porosity is the same, the thinner the thermal protection layer, the bigger the radar cross section is. When the projectile phenomenon occurs, it does not affect the radar cross section.
Keywords： thermal protection layer radar cross section the modified equivalent current approximation electromagnetic scattering