介质目标的太赫兹波近场散射特性计算

Near-field Electromagnetic Scattering Characteristics of Dielectric Targets in the Terahertz Regime

该文基于广义的Kirchhoff阻抗边界条件和物理光学法,对太赫兹频段介质体近场散射特性进行了研究,给出了介质体近场散射计算公式。针对在太赫兹频段由于波长较短引起的计算量大幅提升的问题,采用以面元为计算单位、以像素为遮挡判断单位的太赫兹频段介质体近场散射的快速计算方法,该方法在保证计算精度的基础上,大大降低了计算复杂度和时间。计算了圆柱体和鸭嘴形介质体在不同距离下的雷达散射截面,并且分析了电磁场与物体相互作用后,相位项在不同距离、不同频率下对介质体雷达散射截面的影响。

The near-field scattering characteristics of dielectric targets are studied in the terahertz band based on the generalized Kirchhoff impedance boundary conditions and the physical optics method. The formula of the near field scattering for dielectric targets is deduced. In the light of the increase in calculation amount caused by the shorter wavelength, a fast computational method using surface element as the calculating unit and pixel as occlusion judgment unit is proposed for the near field scattering computation in terahertz band. The method ensures the calculation accuracy and reduces greatly the computational complexity and the time consumption of occlusion judging. The calculation of the near-field Radar Cross Section（RCS） produced by a dielectric cylinder and a duck mouth scatterer is performed in terahertz band. Meanwhile, the effect of the phase on the near field RCS in different distances and frequency is analyzed.