Study On The Application Of The Physical Optics To The RCS Computation Based On NURBS Modeling Technology

With the emergence of electromagnetic computational method, the design of products that considering with the electromagnetic characteristics and dimension has become more efficient and the cost reduced a lot. The predicting Radar Cross Section (RCS) for large electric objects is the subject that is significant and relates with many fields. Both the geometric modeling technology and high-frequency electromagnetical algorithm are Key issues which play a decisive role in the results of precision and calculation speed. so the work of this dissertation is based on these two aspects.At first, the NURBS modeling technology which is based on parametric surfaces and is the mainstream industrial product modeling method in these days is presented. Compared with traditional modeling methods, the advantage of NURBS modeling is explained. But considering the transformation from NURBS surface to piecewise Bezier representation is necessary to practical application, a fast algorithm of the conversion is proposed. The results show that the decomposition process is simplified and the amount of calculation is reduced.Because of the integral is the core work for calculating scattering field, the process of Stationary Phase Method is discussed. Direct towards the bottleneck problem that searching two-dimensional stationary phase points, a wide range of numerical optimization algorithm and their characteristics are researched. Taking into account both the speed and stability, the conjugate gradient method is selected. After that, based on the incorporation of PO and SPM, the computing formula of the scattering field of perfect conductor is derived. As application of NURBS-PO method, the far field RCS of singly curved and doubly curved patches is computed accurately. A lot of tastes and theoretical analysis shows that the NURBS-PO method has a speed advantage compared with Gauss method while maintaining the same accuracy circumstances. In addition , the advantage gets more obvious as the electrical size of the object becomes larger...