A fast and robust method for target and background estimation in RCS measurements based on ‘hyperaccurate’ algebraic circle fit

The sample data points, which are obtained in radar cross section (RCS) measurement, will distribute theoretically on a circle when the target moving along the direction of the illuminating plane wave. The radius of the circle represents the target signal and the center of the circle represents the background signal. Based on theoretical analysis and numerical simulation, we have implemented the fast `hyperaccurate´ algebra circle fitting algorithms to fit circles to measurement data points. At the same time, a robust least-median-of-squares method has been implemented to eliminate the outliers. According to the fitting accuracy requirement of the target and background, the sampling number and the sampling range are determined. Two different spheres are measured with this algorithm in Compact Antenna Test Range (CATR) and their target signals and background signals are well separated, which improves the measurement accuracy.