Analysis of Comodulation Effect Induced by Transmitting and Receiving Antennas and Correction Method in Bistatic SAR Radiometric Calibration

In the bistatic synthetic aperture radar (SAR), the comodulation effect induced by transmitting and receiving antennas to the image amplitude is the main factor affecting the radiometric accuracy. Therefore, the corresponding mechanism must be determined, and a correction method must be developed. However, there is no effective calibration target and method for measuring the bistatic SAR range round trip antenna pattern. In this letter, it is pointed out that the comodulation effect is not only related to the transmitting and receiving one-way antenna patterns but also to the range variation of the bistatic angle in the swath caused by the bistatic SAR observation geometry. To increase the radiometric accuracy in bistatic SAR images, a comodulation effect correction method based on accurate antenna models is proposed, and different error factors related to the range round trip antenna pattern are analyzed. Moreover, simulation experiments are conducted to verify the effectiveness of the proposed method.