Abstract: A novel method is developed to calibrate the non-ideal transfer function and I/Q imbalances in quadrature modulate/demodulate systems which occur frequently in wideband radar systems, without changing the hardware of the radar calibration system. Based on analyzing channel errors in radar systems and taking account of time-frequency relationship of chirp signal, split-pulse method called is adopted to separate image frequency component due to I/Q channel error. Then, the complete description of channel error is got and the calibration function is constructed which is used to correct the raw radar echo in frequency domain. The effectiveness of this method is verified by the experiment of channel error correction in wideband radar system with 500 MHz effective band width. Results show that the method proposed is characterized by high feasibility and performance.