Singularity Analysis in Fast Physical Optics Method for Electrically Large Scatterers

In this work, the singularity in the fast physical optics method based on quadratic quadrilateral patch discretization (Q-FPO) is studied. By introducing first-order integrations, the physical mechanism of the singularities is revealed, and the critical point contributions in different singular cases are extracted. Closed-form expression of physical optics integral in singular case is proposed. The accuracy and efficiency of new method is validated on an electrically large aircraft scatterer with electrical size of 373.3. The computational time of the new method is reduced to 13.0% of the Gordon method and 40.4% of the Q-FPO method.