Study of SAR Autofocusing Algorithms and Practical Applications

Abstract

The microwave imaging method based on the synthetic aperture radar (SAR) principle is mathematically a holographic signal processing method that forms a reflection map about the examined ground surface using radar equipment installed on aircraft or a satellite. The axial resolution can be improved by increasing the size of the antenna aperture, however the limited size of the carrier vehicle (especially in the case of UAVs) does not allow applying arbitrarily large antenna. In the interest of increasing the resolution a virtually larger aperture can be synthesized by using signal processing techniques, utilizing the movement of the aircraft, which is able to significantly refine the imaging resolution. Processing principle SAR presupposes the known track progress, however, this is not fully achieved due to the environmental effects (primarily gust). These disorders can significantly worsen the quality of the result of the signal processing. Improving the quality of the completed SAR images can be performed posteriorly by the so called autofocusing algorithms.