Comparison and application of near-field ISAR imaging techniques for far-field radar cross section determination

Inverse synthetic aperture radar (ISAR) imaging is a powerful tool for the characterization of scattering properties of radar targets. In particular, near-field techniques allow for short distance imaging with results comparable to those of standard far-field ISAR techniques. The resulting near-field, images can be used to extract the far-field radar cross section (RCS) of the target overcoming the need for long-range measurement setups. This paper compares different near-field imaging techniques and reveals an in-depth insight into the imaging process, especially with regard to the subsequent RCS extraction. The performance of the different techniques together with processing improvements are demonstrated by means of numerical target models as well as by measured data of test objects and a scaled aircraft model.