薄涂层介质目标电磁散射的CFDTD分析

针对介质目标表面具有薄涂层材料的电磁散射问题,提出了一种基于等效介质参数的共形FDTD(Conformal FDTD,CFDTD)方法。对于介质目标表面包含薄涂层的共形网格,电场采样点处的介电常数和电导率的等效值通过元胞中介质、涂层和自由空间三者所占的长度加权平均得到,而磁场采样点处的磁导系数和导磁率的等效值利用介质、涂层和自由空间所占的面积加权平均得到。共形网格上电磁场递推式与常规FDTD递推式形式相同,只是递推式系数中的介质参数用相应的等效参数代替。涂层介质球的计算结果说明在保证计算精度的情况下,该方法可比常规FDTD方法节约大量的内存和计算时间。最后用该方法计算分析了复合结构弹翼的电磁散射特性。

Study on CFDTD for electromagnetic scattering by dielectric targets with thin coats

In order to simulate the electromagnetic scattering of dielectric targets with thin-coats,a conformal finite-difference time-domain(CFDTD) method based on effective constitutive parameters is presented.The effective electrical permittivity and electric conductivity for E-field samples on the cells are calculated by weighted-length of the medium,the coating and the free space,the effective magnetic permeability and equivalent magnetic loss for H-field samples are however calculated by weighted-area of the medium,the coating and the free space.The form of FDTD formulas about E-field samples and H-field samples on the conformal cells as the same as the conventional FDTD formulas,and only the parameters in the coefficients of FDTD formulas are replaced by effective parameters.The numerical results of a coating sphere made of medium show that the CFDTD method could save a lot of memory and time in the case of ensuring the calculating precision.The backscattering RCS of a complex missile wing,which made of radar absorbing material(RAM) and metal framework and the surface of the wing is coated by fiberglass-reinforced plastics,is analyzed.