Application of higher order MOM for RCS

RCS data is the most important source for SAR processing. For electrically large targets, high accuracy and efficiency calculation is a very difficult topic. Higher order moment method is a Galerkin type version of MOM based on integral equation. It uses entire domain basis function in relatively large patches. Compared with sub-domain basis function, such as RWG, this method can reduce unknowns distinctly. It provides possibilities for electrically large models simulation. This paper adopts bilinear quadrilateral elements as the modelling method and higher order hierarchical polynomial expansion as the basis function. This kind of basis function can use different orders on different elements in order to get the highest efficiency. Based on this theory, codes were made to test its accuracy and efficiency. NASA almond and sphere, two classical metallic RCS test targets, are solved with the codes. Simulation results are identical with the measured and the analytical data.