Semidefinite Relaxation Autofocus for Bistatic Backprojection SAR

Semidefinite relaxation (SDR) autofocus has been shown in previous work to provide a tighter relaxation to the constant modulus quadratic program than current radar autofocus techniques. We extend the SDR autofocus derivation to bistatic, near field backprojection imaging and pose a linear, convex approximation. The linear objective function may be maximized or minimized, depending on available a priori knowledge of positions of strong or weak scattering. The proposed technique is demonstrated to work well for both simulated and measured data.