Department of Ocean Technology, Policy and Environment, The University of Tokyo, Tokyo, Japan.
Sensors (Basel). 2013 Apr 2;13(4):4450-67. doi: 10.3390/s130404450.
This paper presents a fundamental simulation method to generate synthetic aperture radar (SAR) images for moving ocean surfaces. We have designed the simulation based on motion induced modulations and Bragg scattering, which are important features of ocean SAR images. The time domain simulation is able to obtain time series of microwave backscattering modulated by the orbital motions of ocean waves. Physical optics approximation is applied to calculate microwave backscattering. The computational grids are smaller than transmit microwave to demonstrate accurate interaction between electromagnetic waves and ocean surface waves. In this paper, as foundations for SAR image simulation of moving ocean surfaces, the simulation is carried out for some targets and ocean waves. The SAR images of stationary and moving targets are simulated to confirm SAR signal processing and motion induced modulation. Furthermore, the azimuth signals from the regular wave traveling to the azimuth direction also show the azimuthal shifts due to the orbital motions. In addition, incident angle dependence is simulated for irregular wind waves to compare with Bragg scattering theory. The simulation results are in good agreement with the theory. These results show that the simulation is applicable for generating numerical SAR images of moving ocean surfaces.
本文提出了一种基本的仿真方法，用于生成运动海洋表面的合成孔径雷达（SAR）图像。我们的仿真设计基于运动感应调制和布拉格散射，这是海洋 SAR 图像的重要特征。时域仿真能够获得由海浪轨道运动调制的微波反向散射的时间序列。采用物理光学近似来计算微波反向散射。计算网格小于发射微波，以演示电磁波与海洋表面波之间的精确相互作用。在本文中，作为运动海洋表面 SAR 图像仿真的基础，针对一些目标和海洋波进行了仿真。模拟了静止和运动目标的 SAR 图像，以确认 SAR 信号处理和运动感应调制。此外，沿方位角方向传播的规则波的方位信号也由于轨道运动而显示出方位移动。此外，还模拟了不规则风浪的入射角依赖性，以与布拉格散射理论进行比较。仿真结果与理论吻合较好。这些结果表明，该仿真适用于生成运动海洋表面的数值 SAR 图像。
