Investigation of Parabolic Antennas As Potential Calibrators For Spaceborne P-band POLSAR Calibration

Traditional artificial passive calibrators like corner reflectors may be extremely hard to be adopted in spaceborne P-band SAR calibration, because of the weight, size, manufacture and installation cost, they are also infrequently to be visited during the mission. Parabolic antennas were used for calibration in some SAR missions, and have the potential to play a bigger role in lower frequency such as the P-band. It's generally considered that they are unlikely to be useful unless they are pointed to the satellite, i.e, the target must be fully cooperative. This results in very few targets meeting the requirement. But in fact, parabolic antennas exist widely, relaxing the limit can make parabolic antennas participate in the calibration more effectively. In this paper, the backscattering pattern of a typical parabolic antenna in P-band is simulated, SAR images of the antenna observed from different azimuth angles are also illustrated, in order to prove that the parabolic antenna still meets the requirement for radiometric calibration even if the antenna doesn't point to the satellite precisely. The possibility of using parabolic antennas for polarimetric calibration is also discussed with simulations.