RCS measurement accuracy in the U/VHF range: Diagnosis for target positioning error and improvement of the procedure

Indoor Radar Cross Section (RCS) measurements suffer from measurement uncertainties. These uncertainties can be exhibited when comparing the computed RCS and the measured data of a canonical target (for example a PEC sphere). The measurement uncertainties mainly come from the defaults of the illumination, and the response of the environment. However, the location of the theoretical center of rotation of the target versus the actual center of rotation of the positioning system also accounts for the measurement accuracy. A diagnosis method has to be implemented on the positioning system, for example after a maintenance operation. Positioning of the target cannot be based on the analysis of the RCS of the target in the U/VHF range (e.g. exploiting symmetries), because the RCS varies slowly with the observation angle. Consequently, a hybrid method, based on both laser tracker and RCS measurements is described in this paper. In order to illustrate the contribution of this method, the RCS of a 2 meter long perfectly conducting cylinder has been measured.