We outline a modified nonlinear chirp scaling algorithm (NLCSA) for one-stationary bistatic synthetic aperture radar (BiSAR) using low-frequency (LF) and an ultrawideband (UWB) signal. The existing NLCSAs for one-stationary BiSAR will be invalidated in an LF and UWB application because the higher-order phase error (HOPE) due to the Taylor series approximation cannot be ignored in this case. We first analyze the effect of the HOPE on bistatic LF UWB SAR imaging theoretically. Then, a modified method based on the higher-order phase compensation (HOPC) and block processing is proposed to deal with the HOPE. Finally, the simulation results demonstrate the correctness of the theory analyses, and the validity of the proposed algorithm is presented.