Squint-mode InISAR imaging based on nonlinear least square and coordinates transform

Aiming at the interferometric inverse synthetic aperture radar (InISAR) imaging in the presence of squint, we investigate the influence of squint on the InISAR imaging. First, coupling of the squint additive phase and the target azimuth/altitude coordinates to be solved may make the solution more difficult. Second, the squint angle may lead to estimation error of the vertical coordinates and distortion of the ultimate image. Traditional InISAR imaging algorithms can not solve the above two problems effectively, so we propose a new method which combines the nonlinear least square (NLS) and coordinates transform (CT) to estimate the target coordinates, and a three-dimensional (3-D) image consistent with the real target is obtained accordingly. Simulations show that the proposed method is effective for the squint-mode InISAR imaging.