Fast ASAR image formation using the shooting and bouncing ray technique

We have recently devised a diagnostic algorithm for imaging antenna-platform interactions from antenna radiation data. The algorithm, termed ASAR (antenna synthetic aperture radar) imaging, utilizes multi-frequency, multi-aspect radiation data and Fourier processing to create a 3D map of the platform showing the locations of dominant secondary radiation on the platform. Such an algorithm can be used to process either measurement data or computed data from electromagnetic solvers. In this paper, we consider the case when the SBR (shooting and bouncing ray) approach is used to simulate the antenna radiation data. It is shown that a fast ASAR imaging algorithm especially tailored for the SBR approach can be derived. By taking advantage of the ray tracing information within the SBR engine, we will show that the ASAR image can be generated directly in the image domain without resorting to any multiple frequency-aspect calculations. Such an idea is similar to the image-domain ISAR formation process we have reported previously (1995). Furthermore, we can apply an FFT-based algorithm to speed up the ASAR image formation time. Using such a fast approach, it is possible to obtain the same quality of ASAR image as frequency-aspect approach at only a fraction of the computation time (minutes versus hours).