Evaluation of the performance of antenna pattern correction under the influence of unknown antenna pattern changes

An assessment of the influence of antenna pattern changes in microwave radiation estimation taking into account antenna pattern correction (APC) has been conducted. In the usual case, the antenna pattern cannot be known exactly and its changes are unknown in space. Under such conditions, the APC process is not always stable. Therefore it is important to reduce the instability that is called `ill-posedness in the inverse problem´. In the paper, the projection onto convex sets (POCS) method is introduced into the APC process and it is shown that the APC process becomes more stable by using POCS than the usual APC by numerical experiments. It can be concluded that the POCS method is recommended for the APC when the antenna pattern changes are unknown