Abstract
A novel hybrid algorithm is proposed to reduce the computation cost of the finite-difference time-domain (FDTD) method in calculating the transient near-field scattering from rough surface. The scattering problem is split into the FDTD calculation of equivalent sources on the contour enclosing rough surface and the calculation of the near-field radiation with the two-dimensional (2-D) time-domain Huygens’ principle. The radiation fields are found from a surface integral of the temporal convolution for which the direct numerical integration of the convolution is computationally expensive. In this paper, the 2-D time-domain Green’s function as the convolution kernel is approximated with a sum of exponential terms by using the Prony’s method. Then, the semianalytical recursive convolution (SARC) approach is applied to complete the update of the near-field radiation. Compared with the traditional FDTD, this hybrid algorithm can significantly reduce the memory usage and run time, especially for the large distance between the rough surface and observation point.
Highlights
With the extensive application of the wide-band radar, the transient electromagnetic (EM) scattering from the rough surface has gained increasing attention, which plays important role in the field of radar surveillance, EM imagining, target identification, and stealth, etc. [1,2,3,4]. e previous researches are mainly focused on the simulation of the EM scattering from rough surface in the far-field zone [5,6,7]
In [15], the finite-difference time-domain (FDTD) associated with the Kirchhoff surface integral was proposed to calculate the near-field response of the dipole antenna in the three-dimensional (3D) case, where the dipole antenna was assigned in the FDTD region, and the near-field response outside the FDTD space was calculated by the Kirchhoff surface integral
This difficulty is overcome by applying the Prony’s method to approximate the convolution kernel with a sum of exponential terms, which avoids the complex analysis of the convergence of the series expansion scheme in [21]. e hybrid algorithm combining the FDTD with the 2-D time-domain Huygens’ principle is proposed to calculate the transient near-field scattering from the rough surface, in which the normal part of the convolution integral is calculated by the semianalytical recursive convolution (SARC) approach and the singular part is done using the linear interpolation
Summary
With the extensive application of the wide-band radar, the transient electromagnetic (EM) scattering from the rough surface has gained increasing attention, which plays important role in the field of radar surveillance, EM imagining, target identification, and stealth, etc. [1,2,3,4]. e previous researches are mainly focused on the simulation of the EM scattering from rough surface in the far-field zone [5,6,7]. E hybrid algorithm combining the FDTD with the 2-D time-domain Huygens’ principle is proposed to calculate the transient near-field scattering from the rough surface, in which the normal part of the convolution integral is calculated by the SARC approach and the singular part is done using the linear interpolation. Because a great deal of FDTD meshes between the rough surface and near-zone observation point are removed, the memory usage and run time in the proposed algorithm are dramatically reduced than those in the traditional FDTD method. E rest of this paper is organized as follows: in Section 2, the hybrid algorithm combining the FDTD with the 2-D time-domain Huygens’ principle is elaborated, including the Prony approximation of the convolution kernel and the SARC approach for solving the near-field radiation of the equivalent sources.
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