Abstract-A new efficient technique for the analysis of complex antenna around a scatterer is proposed in this paper, termed the iterative vector fields with uniform geometrical theory of diffraction (UTD) technique. The complex field vector components on the closed surface enclosing the antenna without platform are computed by higher order Method of Moments (MOM), and the scattered fields from the platform are calculated by UTD method. The process of iteration is implemented according to the equivalence theorem. Based on this approach, an approximation method is outlined, in which the computational time is saved largely, while the accuracy is not reduced. The relative patterns obtained from the present method and the approximation method both show good agreements with that obtained from MOM.