Fast Electromagnetic Modeling and Imaging Simulation of Spacecraft by Ground Based ISAR

Ground based ISAR has its distinctive advantage for imaging spacecraft in orbit. In order to simulate real radar used for imaging an orbiting spacecraft, this paper applies the Physical Optics (PO) method, which is a high frequency approximation algorithm to calculate the radar echo of complex targets. Based on the simulated scattering data for a range of frequencies and a range of aspect angles, a standard 2D imaging algorithm is applied to generate radar image. In this paper, two cases of imaging geometry are introduced: (1) the ground radar is in the orbital plane of the object; (2) the radar is not in the orbital plane. Equivalent translational and rotational moving model is derived. And the Chinese Shenzhou spacecraft is taken as an example for presenting the simulation result.