Abstract: During the procedure of calibration for low frequency ultra wide band synthetic aperture radar(UWB SAR),the various calibrators are needed.The electromagnetic scattering models of calibrators are resonance scattering,as result,the scattering model of the calibrators for regular high frequency and narrow band SAR system cannot be used here.The scattering of the calibrators at a given frequency point and incident angle can be calculated using method of moment(MOM),and the scattering of the calibrator at the ultra wideband and various incident angle can be calculated using asymptotic waveform evaluation(AWE) technique.The electromagnetic scattering models of calibrators are given by using the geometric relationship of the UWB SAR system.