An Improved Image-Based Circular Near-Field-to-Far-Field Transformation

An improved version of the near-field-to-far-field transformation (NFFFT) for determining the radar cross section (RCS) of electrically large targets from the scattered field measured with a monostatic radar over a circle in the near field of the targets is presented. The characteristic feature of the proposed NFFFT is an improved imaging operator which is derived by requiring that the integral transformations involved in the NFFFT scheme be self-consistent for every electrically small scatterer. The presented NFFFT version is expected to lead to more accurate RCS values for strongly asymmetric targets measured at smaller facilities.