Fast RCS Simulation of Target on the Sea Surface Based on the SBR and Advanced Two-scale Method

Plenty of evidence show that the rough sea surface plays a leading role with regard to the composite electromagnetic scattering of the sea surface and the target. Shooting and Bouncing Ray (SBR) tracing mentioned in the related literature may encounter the following two problems. One is that the calculation time to consider the coupling between the two will be greatly increased under fine subdivision. The other is that the calculation accuracy is not high when the sea surface is simulated as a plane. In this paper, the hybrid calculation of Shooting and Bouncing Ray tracing and semi-deterministic complex sea surface with two-scale algorithm is used to predict the electromagnetic scattering. When a ray is irradiated to a surface element on the rough sea surface, a two-scale (KA+AIEM) algorithm is used to calculate the current scattering field. Using the two-scale algorithm, specifically, the scattering contribution of large scale rough surface is calculated by Kirchhoff approximation method and the improved integral equation method is used for the small scale, more accurate electromagnetic scattering calculation can be obtained. This algorithm can effectively shorten the time of sea surface calculation. When the ray is reflected between the target and the rough surface it is necessary to consider the Fresnel reflection coefficient to modify the reflection coefficient. Numerical results show that the scattering intensity of the incident wave is the largest in the mirror direction under different incident angles. Meanwhile, the side of the target and the sea surface form sometimes strong and sometimes weak coupling due to the change of the angle between the target and the sea surface, and the dominant of complex scattering will also change.