Precise Internal Calibration Scheme for Very-High Resolution SAR System and Its Airborne Campaign Results

For future ultra-high resolution spaceborne SAR missions, large beam-steering capability and large antenna aperture are demanded to increase the azimuth resolution and to maintain the sensor sensitivity simultaneously. Thus, large-deployable antenna is a desirable option as compared with planar array antenna for these missions, since it is advantageous in terms of mass, size, and cost. Moreover, its antenna pattern will not have any distortion with mechanical beam-scanning approach. In this paper, a novel reflector SAR system, including its platform configuration, attitude maneuvering strategy as well as SAR payload electronics are presented in detail. Furthermore, the key technique of very-high resolution SAR-internal instrument calibration scheme is also provided so as to remove the imbalance among channels to guarantee coherency and then to extract the range replica consequently. In the end, a carried-out airborne flight campaign is described and its imaging results are presented to validate the effectiveness of our system as well as calibration approach.