Study on entropy function optimization problem in auto-focusing algorithm applied for radar imaging

Auto-focusing or phase compensation is one important step in inverse synthetic aperture radar (ISAR) imaging. For one of auto-focusing methods, i.e. minimum entropy auto-focusing (MEA) method, the optimal solution is discussed in this paper. Simulation study proves one fact that the cost function of MEA algorithm is not a downward-convex function. Moreover, conclusion is drawn that only original values of compensated phase are chosen properly can MEA algorithm achieves convergence to a global optimal solution.