An improved 3-D near-field ISAR imaging technique with extended far-field RCS extraction

Abstract

This contribution describes the improvement and extension of a 3-D inverse synthetic aperture radar (ISAR) imaging technique using a cylindrical scanning plane, first presented in [1]. The improvement is based on a modified focusing operator outlining the complete mathematical derivation, which is not given in the literature so far. Furthermore a fast and accurate extraction of the far-field radar cross section (RCS) is presented not only restricted on incident angles normal to the scanning plane but also comprises a larger range of elevation angles

Far-Field Radar Cross-Section Determination From Near-Field 3-D Synthetic Aperture Imaging With Arbitrary Antenna Scanning Surfaces

“…(12). The derivation is similar to those discussed in [8], [11], [12], except that the problem is generalized to the 3-D case of an arbitrary scanning surface. The correction factor should be properly selected such that the integral transformation of Eq.…”

“…Using the angles α and β, we can approximate the quantity s in the vicinity of the scatterer at r 1 as [8], [11], [12] s ≈ (x − x 1 ) sin β cos α + (y − y 1 ) sin β sin α…”

“…As pointed out in [8], [11], [12], one of the challenges in the image-based method is the measurement of a strongly asymmetric target under a shorter antenna separation from the target. Without taking any correction for this situation into account in the imaging process, the accuracy of the RCS prediction is degraded.…”

“…In [8], the correction factor was introduced in the 2-D image reconstruction with a circular scanning trajectory around the target, such that the integral transformation in the radar imaging is self-consistent for every electrically small scatterer. In [11], [12], this correction factor was extended to 3-D cylindrical scanning geometries.…”

Unified Approach For Multiscale Radar Cross-Section Measurement by Synthetic Aperture Imaging

“…Although the image-based technique has been proven to be a powerful and reliable tool for RCS measurement, its accuracy is known to be degraded when measuring the target of strong geometric asymmetry in compact facilities, as discussed in [8]. To compensate for this problem, Osipov et al introduced a correction factor for the 2-D ISAR image reconstruction with a circular scanning geometry [8], and Vaupel extended the concept to a case of 3-D imaging with cylindrical scanning geometry [11], [12]. Based on these works, Watanabe and Yamada derived a generalized correction factor for 3-D synthetic aperture imaging with 2-D antenna scanning along an arbitrary curved surface [13].…”