Dynamic Volume Equivalent SBR Method for Electromagnetic Scattering of Targets Moving on the Sea

To solve the scattering of targets moving on the sea, based on the volume equivalent shooting and bouncing ray (VESBR) method, a method named dynamic VESBR (DVESBR) is proposed. Because of the motion of the targets and the variation in the sea, the whole geometric model changes at each moment. To avoid wasting time in treating the model by manual operation such as traditional methods, DVESBR utilizes a new ray-tracing strategy to ensure correct boundary conditions. In this new ray-tracing strategy, space partitioning data structure construction and ray-tracing processes for the sea and for each target are independent. In addition, because the draft is greater than zero, the ship is partially embedded in the sea. For this type of 3-D scene, its scattering problem has not been solved. To overcome this difficulty, DVESBR fills the entire space with ray tubes, and then, the scattering of a 3-D scene is converted to the sum of the scattering of all ray tubes. Volume equivalent physical optics (VEPO) is proposed and combined with VESBR to analyze the infinite- and finite-length ray tube conditions. Therefore, DVESBR is able to consider the 3-D scattering problem in which targets move on a rough surface. Numerical simulations demonstrate the effectiveness of DVESBR.