Based on the expressions of the super-elliptic method

the center-line and proportion variation patterns

three types of S-shaped nozzle with different outlet shape were designed. A program was developed to combine the equivalent edge currents(EEC) method and iterative physical optic (IPO) method. The EEC method was applied to calculate the contribution of edge diffraction field of nozzle outlet to the radar cross section (RCS) of S-shaped nozzle

and the IPO method was used to calculate RCS created by scattering field of cavities of S-shaped nozzle. The total RCS of S-shaped nozzle was calculated through vector summation of electromagnetic wave generated by two electromagnetic fields. On this basis

RCS characteristics of the S-shaped nozzle with three different outlet shapes were investigated. The results show that the outlet shape has great effects on RCS

and the S-shaped nozzle with circular outlet have the minimum RCS. The dislocation of sawtooth modification can effectively decrease the RCS of nozzle. The S-shaped structure of nozzle makes the RCS of the total scattering filed not symmetrically distribute about 0° detection angle within the range of global detection

which shifts the maximum RCS to the region of the positive detection angle.