Focusing of Maneuvering High-Squint-Mode SAR Data Based on Equivalent Range Model and Wavenumber-Domain Imaging Algorithm

Abstract

Due to the complexity of high-squint synthetic aperture radar (SAR) mounted on maneuvering platforms, the traditional geometric model and imaging algorithms cannot be directly applied in the diving or climbing stage for the existence of vertical velocity. Aiming at this issue, an equivalent geometric model of maneuvering high-squint-mode SAR is constructed, and a modified wavenumber-domain imaging algorithm combined with the proposed equivalent range model is proposed in this article. First, the disadvantages of the conventional range model are analyzed in detail and an equivalent range model is proposed to describe the motion characteristic of squint SAR in maneuvering mode, which maintains the azimuth-shift invariance along the flight direction in the new slant range plane. Then, to achieve the requirement of maneuvering SAR real-time processing, a modified wavenumberdomain imaging algorithm with a high usage of the spectrum by axis rotation for high-squint SAR data is proposed. Further, since the equivalent model may introduce the severe distortion in the imaging plane, a novel geometric correction method based on inverse projection is performed to obtain the ground imagery with a little distortion. Finally, simulation and real-data processing results validate the superiority of the proposed algorithm. Index Terms-Equivalent range model, geometric correction, high-squint mode, maneuvering synthetic aperture radar (SAR), wavenumber domain. I. INTRODUCTION S YNTHETIC aperture radar (SAR) [1], as an active microwave sensor, is widely mounted on maneuvering platforms (MPs), such as unmanned aerial vehicles [2], [3] and missiles [4], [5]. Compared with other motion platforms, the SAR sensors mounted on MPs have some special characteristics, such as flexible flight tracks, high-squint observation, and real-time Manuscript

A Novel Two-Step Scheme Based on Joint GO-DPCA and Local STAP in Image Domain for Multichannel SAR-GMTI

“…17 illustrates that the computational complexity of the proposed joint two-step scheme will increase as the t N increase. Considering moving targets usually distribute sparsely in the scene, the number of moving targets in a SAR image with the normal size is in the magnitude order of 1 10 or 2 10 , which is marked by the red circle in Fig. 17.…”