UHF Strip - SAR and ISAR Images of a Tank: Application of Scale - Model Measurements

摘要

UHF images of a tank on the ground were obtained by measuring a scale model of the tank on a ground plane. With a scale factor of 35, the laboratory radar range frequencies of 6 to 18 GHz scale to 171.4 to 514.3 MHz. The dielectric constant of the ground plane material was matched to that of the real ground to insure that the images of the full-scale tank matched those of a full. scale tank. We found that the correlation between images at the same aspect falls off rapidly even for differences in grazing angle of a few degrees. We converted the measured ISAR images to strip-SAR format as would be obtained by an airborne UHF SAR. The correlation between the ISAR and strip-SAR images is high. The correlation, however, falls off as the grazing angle and synthetic aperture length increase. Scale model measurements offer an approach to obtaining multi-aspect images of military targets that are quick and cost effective compared to full scale airborne or turntable measurements. Scale models of a wide array of military vehicles are readily available. Nonmetallic objects such as the ground and vegetation are fabricated from materials that have the same dielectric properties as a function of the scaled X-band laboratory measurement frequency as do the full-scale objects at UHF. This insures that the measurement yield accurate representations of the RCS and images of the full-scale objects.