Efficient method of moments for the computation of RCS

The higher order method of moments is based on both higher order current modeling and higher order geometrical modeling. However, the commonly used low order bilinear patch is low in precision and not compatible with the conventional computer aided design (CAD) tools. This paper proposes a truly double higher order method of moments which approximates the structure with NURBS (Nonuniform Rational B-Spline) surfaces. A new set of formulas are introduced to rapidly evaluate the singular impedances and approximate the far-zone impedances. The resultant unknowns are less than 10% of that of FEKO. Besides, we need only adjust the order of the basis functions instead of meshing the structure repeatedly as the frequency increases. The precise model of a missile is conveniently obtained by the CAD tools, and the radar cross section (RCS) obtained by this new technique is validated against that obtained by FEKO.