基于表面阻抗边界条件的等离子体薄涂层电磁散射的时域有限差分分析

摘要

基于表面阻抗边界条件时域有限差分(FDTD)方法研究了一维斜入射情况下非磁化等离子体薄涂层涂敷金属材料的电磁散射特性，该方法忽略对薄层背景材料进行网格剖分，大大减少了计算量。首先推导了理想导体涂敷等离子体薄涂层的表面阻抗频域表达式，然后代入边界条件并变换到时域，再用分段线性递推卷积方法将时域表达式离散得到FDTD迭代式。编程计算了垂直及斜入射情形下的平行极化和垂直极化反射系数，通过验证算例与解析解对比，结果表明该方法的准确性和有效性。最后利用该方法分析了不同入射角对反射系数的影响。%Using the surface impedance boundary condition (SIBC)-finite difference time domain (FDTD) method, the electromagnetic scattering characteristic of non-magnetized plasma coating on metal material is obtained, under the one-dimensional (1D) oblique incident wave condition. The SIBC method can greatly reduce computational memory by ignoring the mesh division of the background material. Firstly, the expression of frequency domain surface impedance is derived, and substituted into boundary condition equation. Then the equation is transformed to time domain via Fourier inverse transformation method, and the formula is quantized to obtain the update equation by piecewise linear recursive convolution (PLRC) method. The algorithm is used to calculate the reflection coefficients of parallel and vertical polarization waves at oblique incident angels. The comparison of the SIBC-FDTD results with analytic solutions shows the validation and effectiveness of proposed method. Finally, the effect of incident angle on reflection coefficient is analyzed by this method.