The relatively high-frequency oscillation of the nonrigid mechanical baseline structure in the dual-antenna interferometric SAR (InSAR) system will severely degrade the performance of the system. The effects of the baseline roll bending and stretching are especially dominant. In this paper, the two-dimensional (2-D) Fourier domain formulation of the SAR raw signal accounting for the baseline roll bending and stretching is derived and analyzed. A modified 2-D Fourier domain SAR raw signal simulation algorithm is presented, which is valid for baseline roll bending and stretching oscillations of any frequencies as long as a reasonable amplitude limit is satisfied. The validity limits of the modified algorithm are analyzed. Finally, simulation results are presented.