Three-dimensional ISAR imaging using a conventional high-range resolution radar

Inverse synthetic aperture radar (ISAR) is a well established technique for determining the distribution of the radar cross section (RCS) in the X-Y plane. The purpose of this effort is to extend the ISAR concept to the Z plane to provide a measurement of the RCS distribution in three dimensions. While various scanning radars have been designed for this application, the intent is to apply an existing wideband instrumentation radar to the task. This paper provides a discussion of the similarities and differences between 3-D ISAR and interferometric ISAR. The required processing for producing 3-D ISAR images is discussed along with the required test set up for using a conventional instrumentation radar for image data collection. The algorithms employed for 3-D ISAR imaging are validated by simulation and field test results. The simulation effort included a sensitivity analysis to study the effects of radar noise, antenna height error and radar phase drift. All of the 3-D ISAR results presented herein are at 35 GHz which is a departure from most systems which use frequencies of 10 GHz or less. The results are promising and indicate that although the level of effort for test planning and conduct as well as data processing is significant, viable results are attainable.