AN EFFICIENT ANALYSIS ON THE FITTING ERROR CAUSED BY THE DEFORMATION OF METAL PYLON IN THE RCS MEASUREMENT

Target-supporting metal pylon predominantly contributes to background scattering in radar cross section measurement. The separation of scattering from the target and background demands stable background scattering. However, target translation creates variations in metal pylon deformation and changes its scattering, which yields errors in background separation. Analyzing the relationship between the structural parameters of metal pylon and the error caused by its deformation is necessary to reduce errors. A simplified mapping of the relationship is deduced according to the mechanical and electromagnetic theories involved. The approach combines geometrical theory of diffraction for pylon scattering and numerical integration in calculating the deflection of metal pylon to determine the variation of metal pylon scattering, and calculates error in the circle fitting caused by the variation. Simulations with commercial software are employed to verify the efficiency of the numerical model. Although it is slightly contaminated by target-pylon interaction, the approach is 800 times faster than the software simulation. An example of optimization and analysis is provided to demonstrate the trends of optimum structural parameters and fitting error within different pylon weight limits. Such an example proves that the approach can overcome the deficiency of traditional analysis which separately assesses the mechanical and RCS performances of metal pylon.