Array Factor Forming With Regularization for Aperture Synthesis Radiometric Imaging With an Irregularly Distributed Array

When observing from a spaceborne or unmanned airborne platform, aperture synthesis radiometric imaging (ASRI) is sometimes configured with an irregularly distributed array. In the previous study, the array factor forming (AFF) has been proposed to reconstruct the brightness temperature (BT) image of the observed scene. However, it is found that AFF is invalid when system noise is taken into account. In order to solve the problem, AFF with regularization is proposed in this letter. The reason why the conventional AFF becomes invalid is analyzed, and how AFF with regularization provides a stable solution is discussed. Numerical simulation and experimental results show that the BT image reconstructed by AFF with regularization is more accurate than that reconstructed by the conventional AFF, which demonstrates the validation of the method.