NUMERICAL APPROACH ON DOPPLER SPECTRUM ANALYSIS FOR MOVING TARGETS ABOVE A TIME- EVOLVING SEA SURFACE
NUMERICAL APPROACH ON DOPPLER SPECTRUM ANALYSIS FOR MOVING TARGETS ABOVE A TIME- EVOLVING SEA SURFACE
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DOI：
10.2528/pier13020112
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发表时间：
2013
影响因子：
6.7
通讯作者：
C. Qi;Zhiqin Zhao;Z. Nie
中科院分区：
文献类型：
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作者：
C. Qi;Zhiqin Zhao;Z. Nie
为了分析时变海面上三维运动目标的多普勒频谱，提出了一种结合加速技术的混合方法来模拟复合运动模型的电磁散射。该混合迭代方法结合基尔霍夫近似（KA）和多层快速多极子算法（MLFMA）分别求解粗糙海面和目标的电磁后向散射，并通过迭代过程考虑两者之间的电磁耦合效应。为了克服迭代过程中巨大的计算成本，加速方法，可以大大减少计算时间。根据几何光学原理，对海面上的耦合区进行截断。然后采用快速远场近似（FAFFA）加速目标与海面的相互作用。提出了一种连续迭代方法来减少MLFMA过程的收敛步骤。证明了这种加速度混合方法的准确性和有效性。从这样的数值电磁模拟获得的后向散射信号的多普勒谱进行比较不同的入射角，目标速度和表面模型。研究了电磁耦合作用对多普勒谱的展宽效应。
In order to analyze the Doppler spectrum of three- dimensional (3-D) moving targets above a time-evolving sea surface, a hybrid method with acceleration techniques is proposed to simulate the electromagnetic (EM) scattering from the composite moving model. This hybrid iterative method combines Kirchhofi approximation (KA) and the multilevel fast multipole algorithm (MLFMA) to solve the EM backscattering from the rough sea surface and the targets, respectively, then mutual EM coupling efiects between them are taken into account through an iterative process. To overcome the vast computational cost in the iterative process, acceleration approaches which can greatly reduce the calculation time are applied. Coupling area on the sea surface is truncated according to geometrical optic principle. Then a fast far-fleld approximation (FAFFA) is applied to speed up the mutual interactions between the targets and the sea surface. A successive iteration method is proposed to reduce the convergence steps for the MLFMA process. The accuracy and e-ciency of this hybrid method with accelerations are demonstrated. Doppler spectra of backscattering signals obtained from such numerical EM simulations are compared for difierent incident angles, target velocities and surface models. The broadening efiects of the Doppler spectra due to the mutual EM coupling interactions are studied.