3-D characterization of radar targets by means of ISAR/SAR near field imaging techniques

Abstract

Inverse synthetic aperture radar (ISAR) imaging techniques based on indoor near field backscattering measurements turns out to be a powerful tool for diagnostic purposes in radar cross-section (RCS) reduction and for deriving RCS target models, viable for radar systems operating at larger distances, e.g. under far field conditions. This paper presents an advanced 3-D imaging approach, where in addition to the turntable rotation the antenna is moved along a linear path chosen in accordance with the geometry of the target and the aspect angle of interest. For reconstructing the reflectivity distribution a configuration-specific grid of spatial sampling points is employed which reduces the complexity of determining correct values for the scattering amplitudes. The reflectivity distribution reproduces the backscattering seen from an antenna moved along a finite surface (synthetic 2-D-aperture) in the scattering near field of the target, but is to be used to model backscattering for antennas at larger distances, e.g. in the far field. Therefore, the feasibility of this approach is discussed with respect to different applications, i.e. for the diagnostic of RCS reduction and for deterministic or statistical RCS models. Results obtained for a car as X-band radar target are presented in order to verify the features of the imaging system.

Characterization of target camouflage structures by means of different microwave imaging procedures

“…To avoid the elaborate use of a 3-D imaging system [4,5] and to ease the data interpretation a structure without cross-section changes in vertical direction (cylinder) was chosen. If the illumination of the lower and upper end of this cylinder structure is kept weak the scattering configuration can be considered as quasi-two-dimensional.…”

“…Since the measured data (amplitude and phase) of the field backscattered from the test structure (without and with CL) represent the coherent sum of all individual SC information, a decomposition of the total scattering into the individual SC becomes necessary. This decomposition can be accomplished by means of a monostatic inverse synthetic aperture (ISAR) imaging procedure [3][4][5]. This results in a spatial distribution of "real" and virtual scattering centers ("reflectivity distribution").…”