Modern Synthetic Aperture Radar (SAR) systems use Transmit/Receive Modules (TRMs) to create different and flexible patterns required on transmit and receive. However, the phase and amplitude adjustment of each TRM is affected with an error or inaccuracy, which can strongly degrade the required pattern. This paper analyzes the influence of the accuracy of the adjustment of amplitude and phase excitation coefficients for TRMs on the required patterns itself and on the resulting SAR performance for an example multi-channel satellite SAR system. Furthermore some ideas for compensation of the inaccuracy in the processing are given and simulation results shown.