组合目标电磁散射的FDTD/TDPO混合法

为分析组合目标的后向电磁散射,提出了时域有限差分FDTD与时域物理光学TDPO相结合的混合算法。组合目标包括电大尺寸和电小尺寸两个彼此相互分离的部分。采用FDTD方法分析形状或介质较复杂的电小结构部分;采用TDPO方法分析目标的电大尺寸部分。在处理FDTD区对TDPO区耦合时,利用了基尔霍夫积分的近场-近场外推技术,并提出了顺序传递方法,按照FDTD的时域计算顺序将FDTD区对TDPO区的贡献直接传递到远区观察点,计算效率高,所需内存少。对于远区后向散射,TDPO区对FDTD区的耦合则由互易性定理得到。最后给出了验证和应用算例,表明了方法的正确和有效性。

FDTD/TDPO hybrid approach for analyzing EM scattering by combinative objects

A time-domain hybrid approach that combines the finite-difference time-domain(FDTD) method with time domain physical optics(TDPO) is presented for the back scattering problem of combinative objects.The combinative objects are composed by two separate parts: a small-size structure(SS) and a large-size structure(LS) with respect to the wavelength of interest.This approach employs the FDTD to compute the scattering by SS,which has complex shape or medium,TDPO to compute the scattering by LS.When dealing with the coupling of SS to LS,the near-to-near field extrapolation technique based on Kirchhoff's surface integral representation is used and a sequential transfer method is developed.According to the time domain calculation sequence in FDTD,the contribution of SS to LS is transferred directly to far zone observation point.The sequential transfer method has some advantages in high efficiency and small amounts of computer memory.For far zone back scattering,the influence of LS onto SS can be obtained by using the reciprocity theorem.Finally,the validation and application examples are presented,demonstrating the accuracy and effectiveness of this approach.