Fast Calculation Of Large Scale Target’s RCS Based On Acceleration SBR Method

Fast calculation of Radar cross section (RCS) has been the focus of research on computational electromagnetics. For electrically large targets, the high frequency method was generally used to calculate the RCS. Since shooting and bouncing ray method (SBR) can count the effect of electromagnetic waves multiple bouncing on the surface, it received extensive attention soon after proposed. After years of development, SBR has become an important means of electrically large target RCS quickly estimated.In this paper, a cylindrical cavity RCS computing case has been studied for the basic principles and implementation steps of SBR. Then the target reconstruction based on triangle flat was discussed, which turns ray intersection with the curved surface problem into ray intersection with the triangular flat problem. To solve the problem, an intersection testing algorithm was proposed in this paper which can enhance the efficiency and versatility of traditional SBR algorithm.An accelerated SBR algorithm was proposed to calculate the object with smooth surface. This method use rough triangle flats model which fit the actual object as the ray intersection seeking objects; thin triangle flats model which shoot ray tubes as an emission window. Compared with the traditional algorithm, the new method can effectively reduce time of finding intersection for radiations and triangle flats. Next, an accelerated SBR algorithm based on multi-resolution grid was introduced.The core idea of this method was to divide the original ray tube into multiple sub-ray tube when the ray tube was not fall within the same triangle flats while tracking the rays. Repeat this operation until the variable-length of ray tube was greater than one-tenth of the wavelength. This method can reduce the time consuming for whole SBR method without degrading the accuracy of the calculation.Finally, the parallel SBR algorithm based OpenMP was researched. The multi-task parallel processing was used to deal with the most time-consuming ray tracing parts. By calculating the RCS of typical target, verify the accuracy and efficiency of this parallel algorithm.