Abstract
Circular synthetic aperture radar (CSAR) has a 360° observation capability on the central observation scenario. A typical way to process CSAR imaging is to cut data into small sub-apertures because most targets are only coherent at a very small observation angle. There are many sub-aperture imaging methods after development in recent years. The back-projection algorithm is widely used because it is simple and can be applied to an arbitrary trajectory. Because of the limitation of the Nyquist sampling frequency and influence of the antenna sidelobe, azimuth ambiguity is a phenomenon that may occur in the radar imaging process. The existing researches typically choose the back-projection (BP) imaging area according to the SAR platform flight path and the antenna beam width. The limitation of the CSAR imaging area and its azimuth ambiguity region are rarely analyzed theoretically. This paper focus on the sub-aperture imaging of CSAR, based on the BP algorithm, which derives the relationship of azimuth ambiguity with CSAR parameters such as the pause repeat frequency (PRF), slant range angle, velocity of radar platform, etc. This paper proposes an equation for the calculation of the azimuth ambiguity region and analyzes the limitations, which provides theoretical support for CSAR parameter design, imaging area selection, and azimuth ambiguity analysis.
Highlights
Circular synthetic aperture radar (CSAR) is a special imaging mode of SAR whose radar platform moves along a circular track
This study, we focus on the azimuth ambiguity of CSAR and analyze the relationship between
This study, we focus on theparameters, azimuth ambiguity ofthe and analyze the relationship azimuth ambiguity and CSAR
Summary
Circular synthetic aperture radar (CSAR) is a special imaging mode of SAR whose radar platform moves along a circular track. The frequency-domain processor, based on the analysis of the three-dimensional Green’s function, is proposed [8], which is computational and efficient This algorithm is under the assumption that the platform trajectory is well. This study, we focus on theparameters, azimuth ambiguity ofthe and analyze the relationship azimuth ambiguity and CSAR providing expression for the ambiguity areabetween based on azimuth ambiguity and parameters, providing the expression for the ambiguity area based on the back-projection imaging algorithm. We provide a better parameter design method can offer an arbitrarily selected area in the entire reference height plane and avoid azimuth ambiguity.
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