Accuracy criteria for radar cross section measurements of targets consisting of multiple independent scatterers

Two theoretical models for radar cross-section (RCS) measurements of electrically large targets consisting of multiple independent point scatterers are developed to determine the accuracy with which sample averages approximate true average RCSs. Two specific sources of measurement error are addressed. The far-field criterion is shown to depend on antenna beamwidth rather than phase planarity of the illuminating field at the target, resulting in a greatly reduced requirement for separation between radar and target. The effect of clutter on the measured signals is found by determination of the joint probability density between the target and the measurement values, and the variance of the error produced by the clutter is shown to be systematically reduced by averaging a number of measured samples